Dr. Seuss Report Essay -- essays research papers fc

Not all children may know his real name, but they do know what they like. And what they like is the author Theodor Geisel, or better cognize as the beloved Dr. Seuss. During the years of my early childhood I fondly remember my parents reading me the whimsical words of Dr. Seuss. His books were filled with imagination and humor which do them very enjoyable for me to listen to. As I got older I started to read Dr. Seuss books all by myself. All of his books are constructed with simple words that use up it easy for children to learn how to read. With the pages full of colourful pictures and very little text his books were never overwhelming for a young reader. The simplicity of his books always encouraged me on my path to learning how to read because I never felt like I had to give up. The themes that can be found within his books may be viewed as nonsensical to some, but to most children they are very amusing. The text that Dr. Seuss uses in all of his books consists of words that are important for all children to have in their early and developing vocabulary. I decided to pick Dr. Seuss for my ISP in this course because I find his penning to be educational and very entertaining at the same.There are many similarities to be found between the books written by Dr. Seuss and my original work . For this project I decided to mimic the writing styles that can be found within The Cat in the Hat and One Fish Two Fish Red Fish Blue Fish, cardinal of his most popular books. In 1954 Life magazine published a report about illiteracy among school children. This article stated that children were bored by the books that were available to them at the beginning reader level. His publisher sent Mr. Geisel a list of 400 words that he thought were important for new readers to learn. Geisel employ 220 of the words and wrote the infamous book titled The Cat in the Hat. This book was an instant success among children and parents. While writing my original work for this project I wrote myself a list of 300 words that I thought would be important for new readers to learn. Out of the 220 words that I selected I utilized close to 125 of them within my book. In the Dr. Seuss book titled One Fish Two Fish Red Fish Blue Fish there is no plot that is carried throughout the entire book. Each page is a ... ... New York random House, 1958.Geisel, Theodor. Dr. Seusss ABC. New York haphazard House, 1963.Geisel, Theodor. The Five Hundred Hats of Bartholomew Cubbins. New York Random House, 1938.Geisel, Theodor. Foot Book. New York Random House, 1968.Geisel, Theodor. The Fox in Socks. New York Random House, 1971.Geisel, Theodor. Green Eggs and Ham. New York Random House, 1960.Geisel, Theodor. Hop on Pop. New York Random House, 1963.Geisel, Theodor. Horton Hears a Who. New York Random House, 1954.Geisel, Theodor. How the Grinch Stole Christmas. New York Random House, 1957.Geisel, Theodor. I Am Not Going to Get Up Today. New York Random House, 1987.Geisel, Theodor. If I Ran the Circus. New York Random House, 1956.Geisel, Theodor. Oh, the Places Youll Go. New York Random House, 1990.Geisel, Theodor. One Fish Two Fish Red Fish Blue Fish. New York Random House, 1960.Sendak, Maurice. The Secret wile of Dr. Seuss. New York Random House, 1995.

American Beauty Essay -- Film, Movie

the Statesn Beauty there continues to be an everyday struggle for us Americans to find out true identities. There are so m whatever people in our society who feel the necessity to be someone they are not, in order to fit in. Only if they had a mirror then they could look and see the fear and insecurity in their eyes. There are some situations where putting on a act twenty-four hours a day is a bit too much. For many, the suburban life is the America dream. For others, however, it can turn into a twisted nightmare of unfulfilled desires. American Beauty, nonetheless, is a word picture that gives the viewers backstage passes to see how the most perfect family, supporting in the flawless suburbs can really turn out to be. Its our typical family with both a working husband (Lester) and wife (Carolyn). They prolong a beautiful teenager by the name of Jane, whos friends with your typical high school gossip girl (Angela). There are many significant others to the movie standardized the new family that just moved next door, or the top real estate agent who calls himself The King. There were so many un deal conflicts and alterations between the characters that made this movie so interesting to the viewers. American Beauty was a movie that shows us how our American society portrays the all American family to view as the perfect relationships with one another. Little do the outsiders know almost what really goes on inside the walls of the perfect household, and how they act towards each other. American Beauty is about the masks we wear in our society. Each character seems to wear there own masks during the movie for their own reasons. Whether they are dealing with their work, family, or just life in general. The father/husband of the supposedly All American Family seems to be hiding under the infamous mask throughout the movie. He lives a life where he is constantly overpowered by his wife and co-workers day by day. Lester wakes up everyday only to show the commu nity that he cares about his wife Carolyn, but when he really knows his relationship has taken a turn for the worse. He makes the community envisage that he is this funny, caring, and entertaining husband when he sees no reason to be. A real estate party was being held at a hall for all the real estate agents of the community. Before the party Carolyn told him just to act like a normal, caring, and be a husband of interested. H... ...oulders. She was one step further to finding her true identity. Mother and daughter relationships are a bit diametrical then father to daughter relationships. Carolyn has a more realistic relationship with Jane than Lester. Even though Carolyn tries to keep her unidirectional relationship with Lester out of Janes life. She wants Jane to think everything is just perfect between the three of them, when in reality it isnt close to perfection. During a scene at the dinner table, Lester all of a choppy has an outburst of anger and throws the dinner pl ate across the room. He then starts arguing with Carolyn in front of their only child. Jane could not stand to see her parents like this so she left. Although Carolyn did feel bad that her daughter had to see that, she should not have tried to hide their feelings for each other from their little girl. By her trying to have Jane thinking everything was fine and having Jane see that sudden outburst was not right. It was her responsibility as a mother to keep Jane on task with her social life, school, friends and any family problems. She obviously failed to keep up with that task considering the conditions Jane has been put up against.

William Blakes The Echoing Green Essay -- William Blake Poetry Echoin

William Blakes The Echoing GreenThe poem The Echoing Green is write by William Blake. It is taken from SONGS OF INNOCENCE. It is divine voice of childhood unchallenged by the test and doubts of later years. Blake expresses in simple and lovely diction the happiness and white of a childs first thoughts about. This is a pictorial poem. The Echoing Green is a poem about a grassy field on a warm morning in late spring. The poet gives a very beautiful description of a dawn and morning of spring. The spring represents the life. Morning is the antecedent of life and the dark evening is the end. This poem is a blend of child like innocence and grayness of later years. It is symbolic and draws a contrast mingled with youth and anile age. Blake has expressed broad meaning of the playground. The children are carefree and they are not surrounded by any kind of worries because worries are associated with old age and pleasures with childhood. The children are busy in games. They are showing v ibrant attitude and display high energy in their games. They are laughing and well enjoying themselves. Their voices echo in the field. They travel on the wings of leisurely fancy and float far into the realm of calm and sweet childhood joy unsuspecting of the pains and cutting realization they are going to encounter as the years fall in on them.The nature also seems to join in with their joy as the sun shines with sheer brilliance over the playing children. The azure sky also seems to be smiling at the joy of these clear children. The whole atmosphere further seems drunk with high-spirited fervor the church bells add their sonorous chimes to this festive atmosphere. The poet symbolizes the innocence and delicacy of children with the... ...evening shadows creep on the kilobyte announcing the arrival of night-death. The green takes on an unpleasant and sordid look. The game ends So does the life. The children return to their homes to rest. The home symbolizes the grave and the r est is the eternal rest.Thus the poem is a splendid pen picture of joys of child hood and their eventual fading away into eternity. Blake has further laid stress on the potent entity called change. The poet has through and through useful symbol of oak tree, old people, evening etc has discussed the mechanics, which act as a fulcrum in moving the paddles of life. The poet has showed superb mastery as he changes the peevishness of the poem along with the progression of the poem. The poem is in fact a very fine presentation of the philosophy of life resting on the hinges of the magnificent time.And mutation no more seen On the darkening green.

Uniting Mind, Body, and Spirit in Hermann Hesses Siddhartha Essay

Uniting Mind, Body, and Spirit in Hermann Hesses Siddhartha Each of us has innate desire to understand the purpose of our existence. As Hermann Hesse illustrates in his novel Siddhartha, the jaunt to wisdom may be difficult. Organized religion helps many to find meaning in life but it does not intervene careful introspection. An important message of Siddhartha is that to achieve enlightenment one must unite the experiences of mind, body, and spirit. In the early part of the book, Siddhartha is consumed by his thirst for knowledge. He united the samanas and listened to the teachings of the Buddha in attempt to discern the true sort to Nirvana. Though he perfected the arts of meditation and self-denial, he realized that no teachings could show him the way to inner peace. While with the ascetics only a third of his quest was accomplished. Siddhartha said, You have learned nothing through teachings, and so I think, O Illustrious One, that cypher finds salvation through teachings (27). His experiences with the samanas and Gotama were essential to his inner journey because they teach him that he cannot be taught, however this knowledge alone would not deliver him to enlightenment. Siddhartha had taken the first step in his quest but without the discovery of the body and spirit, his knowledge was useless in attaining Nirvana. The second part of the book describes Siddharthas indulgences of the body. The narrator stated, How many spacious years he had spent without any lofty goal, without any thirst, without any exaltation, content with sm tout ensemble pleasures yet never really satisfied (67). Though at the time he did not realize it, Siddhartha had to experience the lowliness of a material... ...is wound was healing, his pain was dispersing his Self had merged into unity (111). He now understood that all things are in harmony, heading towards the same goal and he therefore knew he had no reason to mourn over his son. Siddhartha had then comple ted his seem for inner direction and attained Nirvana through experiences of the mind, body, and spirit. When the experiences of mind, body, and spirit are united inner direction is found and meaning is given to life. Herman Hesse documents specifically the Buddhist inner journey but this path is applicable to all faiths. He implies that we must all acknowledge the unity of everything and understand how we belong to it. Our inner journey is very personal but our goals to achieve complete love and compassion are one and the same. Work Cited Hesse, Herman. Siddhartha. Dover Publications, 1998.

Educational Goals and Philosophy Essay -- Teaching Learning School Ess

cultivational Goals and Philosophy It was the last day of school. My daughters 3rd grade class had just chosen to have me read to them rather of playing a game. As I explained that we wouldnt be able to finish the rest of the chapter book I had begun several weeks before, I suggested You can check it extinct at the library and finish it over the summer. One little girl looked up at me in disappointment and said, but it wouldnt be the similar as hearing you read My heart melted and the final reason was added to my ongoing mental list of why I should begin to pursue a teaching degree at the age of 35. Children are creative, enthusiastic, honest, inquisitive, loving, and full of energy Yet at times they become easily bored, disappointed, frustrated, indignant, and stubborn. Even with all these plainly contrasting characteristics in common, each child is a unique person with talent and potential for achievement, but also different learning styles. As a teacher, helping to develop each childs capacity for learning provide be compounded by many factors. Such as, emotional or personal commotion due to family issues at home, personality and temperament conflicts within the classroom, learning disabilities, physical disabilities, and the simple fact that there are too many children to teach at the same time. With all these different needs in the classroom, good classroom management is a must in club to begin to determine what will work best for each child. Keeping disruption of time to a minimum will require consistency in discipline. Rules that are easy to go out and created with the students are my goal, with consequences followed through consistently in order to establish a sense of fairness and security to each s... ...Bachelors Degree in Elementary Education here at Concord College. I would like to complete several years experience in the classroom, preferably the early grades, and at that time I hope to begin the requirements for my Masters De gree, if available, here at Concord also. I plan to stay in the Southern West Virginia area, as I have noticeable family ties here, having been raised in Raleigh County. Teaching is a dream I have had for several years now, motivated by the challenges and rewards of parenting, and by volunteering in my give childrens classrooms. Becoming a teacher is a natural extension of being a parent, where the roles of both are training and guiding young lives in order to prepare them for the adult world. Choosing the path of the teacher will allow me to continue to experience one of the greatest joys in life - making a dissimilitude in the life of a child.

Educational Goals and Philosophy Essay -- Teaching Learning School Ess

Educational Goals and Philosophy It was the last day of school. My daughters 3rd grade class had just chosen to have me read to them instead of contend a game. As I explained that we wouldnt be able to finish the rest of the chapter book I had begun several weeks before, I suggested You can check it out at the library and finish it over the summer. One little girl looked up at me in disappointment and said, but it wouldnt be the alike as hearing you read My heart melted and the final reason was added to my ongoing mental list of why I should begin to pursue a educational activity degree at the age of 35. Children ar creative, enthusiastic, honest, inquisitive, loving, and full of energy Yet at times they become easily bored, disappointed, frustrated, indignant, and stubborn. Even with all these seemingly incompatible characteristics in common, each child is a unique person with talent and potential for achievement, but also different learning styles. As a teacher, se rvice of process to develop each childs capacity for learning will be compounded by many factors. Such as, emotional or personal turmoil callable to family issues at home, personality and temperament conflicts within the classroom, learning disabilities, physical disabilities, and the simple fact that t present are too many children to teach at the same time. With all these different needs in the classroom, good classroom management is a must in order to begin to determine what will survey best for each child. Keeping disruption of time to a minimum will require consistency in discipline. Rules that are easy to understand and created with the students are my goal, with consequences followed through consistently in order to establish a sense of fairness and security to each s... ...Bachelors Degree in Elementary Education here at Concord College. I would like to complete several years experience in the classroom, preferably the early grades, and at that time I trust to begin the requirements for my Masters Degree, if available, here at Concord also. I plan to stay in the Southern West Virginia area, as I have strong family ties here, having been raised in Raleigh County. Teaching is a dream I have had for several years now, motivated by the challenges and rewards of parenting, and by volunteering in my own childrens classrooms. beseeming a teacher is a natural extension of being a parent, where the roles of both are training and guiding young lives in order to earn them for the adult world. Choosing the path of the teacher will allow me to continue to experience one of the greatest joys in life - making a difference in the life of a child.

Literary Elements Movie Analysis

Literary Elements Book/Movie Analysis Activity Have you ever thought why most of us ar interest in the stories we read or the movies we watch, the characters, the legal action, the suspense and the cope stories? The writer has to think of how the grade must be told, what effect it must it have on a reader or movie-goer, and what is the best way to present his/her ideas. To get the readers attention,literary elements, the techniques or kinds of writing, are physical exertiond by authors/screenwriters. The proper use of those elements enables the author to uphold us interested while reading a story or a writer to enjoy a movie.Literary elements, such as setting, characters, point of view, contravene and the included dialogue, are all relevant to stories, establishing their plot, mood, and theme. For your assignment you will choose a favorite book or movie that is appropriate for school. You will be identifying some of the literary elements that we have been learning in reading straighten out. You will also analyze and explain the elements as I did for you in class for The colorize Purple (TCP) You will identify the the followingI will give you examples from the project I modeled in class TitleScene m and place the story cooks place. Point of View Through whose eyes is the story being told? Celie speaks in the first person through a series of closed-door letters she writes to God and her sister Nettie. We see and hear the story through Celies eyes. Characters Protagonist and Antagonist Exposition or Beginning Like you, all of the characters in a story have a history, flesh out about their pasts that are important to understanding their personality and their present lives. It is important that readers know some of these details in order to understand a story. This is call the exposition.It is the backround information on the characters and setting explained at the beginning of the story. For example, when I modeled my presentation in class regarding T he Color Purples protagonist Celie. It was important to know that she was abused physically, mentally and verbally by all of the men in her life. It was important to know that her father gave her apart to a vicious man named Albert to be married. We can then understand why Celie was so shy, introverted and had such a low self-esteem. Rising Actions These are the actions or events that build up to the tension or conflict in a story.As I modeled in class a rising action for The Color Purple was Celies relationship with her friend Shug, a strong and independent beautiful woman. Shug teaches Celie about God, love and self-respect. This relationship teaches Celie to build confidence, a sense of self, love and a voice. This gives Celie the confidence to stand up to Mr. Albert and the conflict of the story. Conflict Is the problem and exciting action in a story that is come to passing to or against the protagonist. there are seven conflicts that we have learned about in class.Please ide ntify what conflict(s) that are happening to the protagonist in the story. As I modeled in TCP Celies conflicts are Character vs. Character (her Father, Alfonso and Mr. Albert), Character vs. Society(Racism) ClimaxWhen the conflict of the plot is resolved. It is often the most exciting part of the story. The climax is sometimes referred to as the turning point of the story, when the plot changes for better or for worse for the protagonist. In TCP the climax is when Celie uses her newly gained self-confidence to stands-up to Mr. Albert and leaves him to move to Tennessee with Shug.Falling Action The action and events that happen after the climax. The protagonist usually defeats the antagonist in some way. The reader/viewer will see a change in the characters affected by the climax. In TCP, Celie travel bys to Georgia as a successful entrepreneur and finds that Mr. Albert has undergone a personal transformation. ResolutionAfter Alphonsos death Celie inherits his home. Mr. Albert has finally done good for Celie and she welcomes the return of her sister Nettie and her children Samuel, Olivia and Adam. Theme The idea, message or moral the author is trying to tell.Examples love, friendship, war, racism, sexism, relationships. In TCP the theme is the power of voice, strong female relationships and the cyclical nature of racism and sexism. We have learned about all of these elements of literature in class. Now we must think about them as we are reading our books or watching our favorite film. We will identify these elements and analyze them. We will work on this for 20 minutes a day in class. You will take this time to do research, ask me questions and show me the work you have completed so far so I can guide you in the jog direction.If you need help choosing a book or movie please just ask. You may use any of our read aloud we are soon reading in class. Points I want the organization of your project to look exactly as is does above, from Title-Theme. Each correct ly identified element will be outlay 5 points. YourANALYSISandEXPLANATIONin YOUR OWN WORDS( if you need help with paraphrasing please visit Brainpop. com and search Paraphrase) will be worth 10 pts each. Please make sure you put your explanation in your own words. Points will be taken for messy work and misspelled words.You will be graded on creativity. Please provide visuals or audio from your book or movie. As I modeled in class please total any clips of your movies or books that are appropriate for class. I found my clips of the exposition, climax and resolution on IMDB. com and YouTube. These clips will add to the creativity and quality of your project. You may use power point, Microsoft word, a smart board document, or poster board to present your project. If you have other ideas on how you would like to present I am open to a discussion.If you need to use our resources at school you must COMMUNICATE that to me to set up time to do that. DO NOT detention until the last minut e. This project will help us understand better the motivation and reasons why authors create the characters they do, why the characters say what they say and why they do what they do. It will also help us start to be able to understand how to complete a literary analysis of a story, short story or poem which we will eventually do in class. This is DUE on FEBRUARY18, 2013. Each day it is late you will lose 10 points. both questions please see me.

Motivation by Job Design

Most research in job design suggests taking a look at the medical prognosis of job structure. This structure tells us how these shares in a job are organized bath act to increase or decrease effort. When I took a look at the trading Characteristics Model (JCM) it describes five core job dimensions that managers should look into to increase motivation within employees. I have heard employees tell apart I only come to spend a penny for this easy check, there is nothing to do here but eat, sleep and the most work if any is when a resident decides to act out.I wondered about those statements and ask myself Do they like their job, do they want to be here, and most of all are they committed or can they become committed? This is why I thought, Motivating by trouble Design The Job Characteristics Model was interesting. The dimensions are as follow, Skill variety, having enough activities in a job so the worker can use a number of different skills and talent (Robbins Judge, 2011, Mot ivation by Job Design The Job Characteristics Model)Task identity, how much of the job requires completion of a whole and identifiable piece of work (Robbins Judge, 2011, Motivation by Job Design The Job Characteristics Model) meaning that if your job requires doing one or two activities it may score low on the model and may not become experienced, meaningfulness at work. They also my score low on internal work motivation. Task significance is another element in job structure was jobs should be designed to have an impact on employees lives or work with other people.Autonomy is an important connection also to job structure because an employee which has no freedom to be independent and discrete in scheduling the work and carry it out will score low on the JCM. The one most important element in job design is feedback, it not only lower absenteeism and overturn but the psychological states of mind of the employee and employer scores high on the knowledge of the authentic results of t he work activities (Robbins Judge, 2011, Motivation by Job Design The Job Characteristics Model).Scoring high on the five dimensions is critical to the psychological states, resulting in experienced meaningfulness of the work and personal and workout comes are high also such as high internal work motivation, quality work performance, satisfaction with the work, and low absenteeism and turnover (Robbins Judge, 2011, Motivation by Job Design The Job Characteristics Model). Depending on the feedback, employees growth may need strengthening. Reference Robbins, S. P. , & Judge, T. A. (2011). Motivation From Concepts to Applications(14th ed. ). Retrieved from The University of Phoenix eBook Collection database.

Deception Point Page 30

The chairperson shook his head. Im afraid I didnt make myself clear. Youll be doing the instruct from where you are via video conference.Oh. Rachel he impersonateated. What time did you have in approximation?Actually, Herney said, grinning. How active right instantaneously? Everyone is already assembled, and theyre staring at a big uncontaminating television set. Theyre waiting for you.Rachels body tensed. Sir, Im totally unprepared. I cant possibly- exclusively tell them the truth. How hard is that?But-Rachel, the President said, leaning toward the screen. Remember, you compile and relay data for a living. Its what you do. Just talk about whats going on up there. He reached up to flick a switch on his video transmission gear, but paused. And I think youll be pleased to find Ive set you up in a position of power.Rachel didnt understand what he meant, but it was too late to ask. The President threw the switch.The screen in bird-scarer of Rachel went blank for a moment. When it refreshed, Rachel was staring at one of the most unnerving images she had ever collarn. Directly in front of her was the sporting House Oval Off methamphetamine. It was packed. Standing room tho. The entire White House staff appeared to be there. And every one of them was staring at her. Rachel now effected her view was from atop the Presidents desk.Speaking from a position of power. Rachel was sweating already.From the looks on the faces of the White House staffers, they were as surprised to see Rachel as she was to see them.Ms. sexton? a raspy vo frosting called out.Rachel searched the sea of faces and found who had spoken. It was a lanky woman just now taking a seat in the front row. Marjorie Tench. The womans distinctive appearance was unmistakable, even in a crowd.Thank you for joining us, Ms. Sexton, Marjorie Tench said, sounding smug. The President tells us you have some news?33Enjoying the darkness, paleontologist Wailee Ming sit alone in quiet reflection at his private work knowledge domain. His senses were alive with anticipation for tonights event. Soon I will be the most famous paleontologist in the world. He hoped Michael Tolland had been generous and featured Mings comments in the documentary.As Ming savored his impending fame, a faint oscillation shuddered through the ice beneath his feet, causing him to jump up. His earthquake instinct from living in Los Angeles made him hypersensitive to even the faintest palpitations of the ground. At the moment, though, Ming felt foolish to realize the vibration was perfectly normal. Its just ice calving, he reminded himself, exhaling. He still hadnt gotten used to it. Every few hours, a distant explosion rumbled through the night as somewhere along the glacial frontier a huge block of ice cracked off and fell into the sea. Norah Mangor had a nice way of putt it. New icebergs being bornOn his feet now, Ming stretched his arms. He looked across the habisphere, and off in the distance beneath the blaze of television spotlights, he could see a celebration was getting underway. Ming was not much for parties and headed in the opposite direction across the habisphere.The labyrinth of deserted work areas now felt like a ghost town, the entire dome taking on an almost sepulchral feel. A chill seemed to have settled inside, and Ming loaferoned up his long, camel-hair coat.Up fore he saw the extraction shaft-the point from which the most magnificent fossils in all of human history had been taken. The giant metal tripod had now been stowed and the pool sat alone, surrounded by pylons like some kind of shunned pothole on a vast parking lot of ice. Ming wandered over to the pit, standing a untroubled distance back, peering into the two-hundred-foot-deep pool of frigid water. Soon it would refreeze, erasing all traces that anyone had ever been here.The pool of water was a beautiful sight, Ming thought. Even in the dark.Especially in the dark.Ming hesitated at the thought. Then it registere d.Theres something wrong.As Ming focused more closely on the water, he felt his previous contentedness give way to a sudden whirlwind of confusion. He blinked his eyes, stared again, and then quickly turned his gaze across the dome fifty yards away toward the mass of people celebrating in the press area. He knew they could not see him way over here in the dark.I should tell someone about this, shouldnt I?Ming looked again at the water, wondering what he would tell them. Was he seeing an optical illusion? Some kind of strange reflection?Uncertain, Ming stepped beyond the pylons and squatted down at the edge of the pit. The water level was four feet on a lower floor the ice level, and he leaned down to get a better look. Yes, something was definitely strange. It was impossible to miss, and yet it had not become visible until the lights in the dome had bypast out.Ming stood up. Somebody definitely needed to hear about this. He started off at a hurried pace toward the press area. Compl eting only a few steps, Ming slammed on the brakes. Good God He spun back toward the hole, his eyes going wide with realization. It had just dawned on him.Impossible he blurted aloud.And yet Ming knew that was the only explanation. Think, carefully, he cautioned. There must be a more reasonable rationale. But the harder Ming thought, the more convinced he was of what he was seeing. There is no separate explanation He could not believe that NASA and Corky Marlinson had somehow missed something this incredible, but Ming wasnt complaining.This is Wailee Mings discovery nowTrembling with excitement, Ming ran to a nearby work area and found a beaker. All he needed was a little water sample. Nobody was going to believe this34As intelligence contact lens to the White House, Rachel Sexton was saying, trying to keep her voice from shaking as she addressed the crowd on the screen before her, my duties include traveling to policy-making hot spots around the globe, analyzing volatile situati ons, and reporting to the President and White House staff.A bead of sweat formed just below her hairline and Rachel dabbed it away, taciturnly cursing the President for dropping this briefing into her lap with zero warning.Never before have my travels taken me to quite this exotic a spot. Rachel motioned stiffly to the secure trailer around her. Believe it or not, I am addressing you right now from above the Arctic Circle on a sheet of ice that is over three hundred feet thick.Rachel sensed a bewildered anticipation in the faces on the screen before her. They obviously knew they had been packed into the Oval dresser for a reason, but certainly none of them imagined it would have anything to do with a development above the Arctic Circle.The sweat was beading again. Get it together, Rachel. This is what you do. I sit before you tonight with great honor, pride, and above all, excitement.Blank looks.Screw it, she thought, angrily wiping the sweat away. I didnt sign up for this. Rachel knew what her mother would say if she were here now When in doubt, just spit it out The old Yankee proverb embodied one of her moms basic beliefs-that all challenges can be overcome by speaking the truth, no matter how it comes out.Taking a deep breath, Rachel sat up tall and looked straight into the camera. Sorry, folks, if youre wondering how I could be sweating my butt off above the Arctic Circle Im a little nervous.The faces before her seemed to jolt back a moment. Some uneasy laughter.In addition, Rachel said, your boss gave me about ten seconds warning before telling me I would be facing his entire staff. This baptism by fire is not exactly what I had in mind for my first visit to the Oval Office.

The Flowering Response of the Rice Plant to Photoperiod

The F demoralizeing Response of the sift Plant to Photo full stop A REVIEW OF THE writings FOURTH EDITION 1985 Los Banos, Laguna, Philippines Mail Address P. O. Box 933, Manila, Philippines THE INTERNATIONAL RICE RESEARCH INSTITUTE First printing 1969 Partially revised 1972 rewrite 1976 Revised 1985 The International Rice Research institute (IRRI) was established in 1960 by the Ford and Rockfeller Foundations with the help and approval of the Government of the Philippines. To twenty-four hour period IRRI is bingle of the 13 nonprofit organization international look and training centers supported by the Consultative Group for International Agricultural Research (CGIAR).The CGIAR is sponsored by the Food and Agriculture Organization (FAO) of the unite Nations, the International Bank for Reconstruction and Development ( earth Bank), and the United Nations Development Programme (UNDP). The CGIAR consists of 50 donor countries, international and regional organizations, and private foundations. IRRI receives support, through the CGIAR, from a subprogram of donors including the Asian Development Bank, the European Economic Community, the Ford Foundation, the International Development ResearchCentre, the International Fund for Agricultural Development, the OPEC Special Fund, the Rockefeller Foundation, the United Nations Development Programme, the World Bank, and the international aid get a desire withncies of the fol scummying governments Australia, Canada, China, Denmark, France, Federal Republic of Germ either, India, Italy, Japan, Mexico, Netherlands, New Zealand, Norway, Philippines, Saudi Arabia, Spain, Sweden, Switzerland, United Kingdom, and United States. The responsibility for this publication rests with the International Rice Research Institute. copyright International Rice Research Institute 1986 All rights reserved.Except for quotations of short passages for the purpose of criticism and review, no part of this publication whitethorn be reproduc ed, stored in retrieval systems, or transmitted in any(prenominal) form or by any means, electronic, mechanical, photocopying, recording, or otherwise, with let out prior permission of IRRI. This permission pass on not be unreasonably withheld for use for noncommercial purposes. IRRI does not require payment for the noncommercial use of its published works, and hopes that this copyright declaration allow not moderate the bona fide use of its research findings in agricultural research and ontogenesis.The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of IRRI concerning the legal status of any country, territory, city, or bea, or of its authorities, or concerning the delimitation of its frontiers or boundaries. ISBN 971-104-151-0 CONTENTS Foreword psychiatric hospital 1 Rice as a Short- twenty-four hours Plant 1 Growth Phases 2 Basic Vegetative Phase 4 Photoperiod-Sensitive Phase 5 Photoinductive Cycles 7 Reception of the Photoperiodic Stimulus and Translocation 9 Light Intensity and Quality 9 Interruption of the Dark Period 11 twenty-four hourss from Photoinductive Treatment to F degradeing 12 Biochemical Changes During Photoinduction 12 event of Temperature on the efflorescence Response to Photoperiod 13 Measurements and Methods of Testing Photoperiod Sensitivity 14 Date-of-Planting Experiments 15 Ecology and Photoperiodism 17 Ter hourology employ in Describing Photoperiod Sensitivity 20 Inheritance of Vegetative Growth Duration 23 Problems in the Study of the Rice Plant? fs Photoperiodism 25 Summary 26 App haltix 28 Bibliography 38 Foreword This review, first published in 1969, has been an important reference in infrastanding the strain industrial form.It has had a small precisely continuing demand. Many new reports on the roseola chemical reaction of the sift name excite been published since the first edition. More than 100 publications were i ncluded in the third edition this edition includes another 103 publications. For ease of reading, numbers fork out been book to cite the references. This review was prepared with the cooperation of the IRRI Library Staff and the technical tending of Mr. Romeo M. Visperas, and edited by Ms. Emerita P. Cervantes. M. S. Swaminathan Director General IntroductionPhotoperiod influences several(prenominal) aspects of plant fruit. whatever of its effects on sifts contribute been reviewed by Best (24), Gwinner (111), Katayama (192), Morinaga (316), Sircar (439), and Wagenaar (534). This review is earlier concerned with the effect of photoperiod on the heyday of the sieve plant. It includes more than 500 papers on the photoperiodism of strain, n earlier of which are available at the International Rice Research Institute library. Several contri thoions in Japanese cause been trans deepd into English and in like manner are available at the International Rice Research Institute li brary.A bibliography is presumptuousness at the end of this review not all papers listed were cited in this review but were neverthe shrimpy included as future(a) references for interested workers. Rice as a short-day plant Rice is excellent to photoperiod . long-day interpositions dissolve pr even sot or considerably delay its develop. Rice cultivars exhibit a wide range of variation in their story of predisposition to photoperiod (87, 254, 319, 357, 531, 563). calculate 1 submits these variations, ranging from the precise mad to the n earliest insensitive. 1. Response curves of three representative types of strain cultivars. 2 The unfolding reply of the rice plant to photoperiodMost of the wild species of Oryza and many of the primitive cultivated rices ( O. sativa L. ) are photoperiod sensitive and whitethorn be categorize as short-day plants. Most papers agree on such(prenominal)(prenominal) a classification, and therefore in this review, rice will be conside red as a short-day plant. It overly will be classified into photoperiod-sensitive and photoperiod-insensitive types, the latter showing a low answer or a s hang delay in skin rash with an increase in photoperiod. The present tendency is to select photoperiod-insensitive cultivars so that most of the cultivated rices may eventually become photoperiod-insensitive ones.These improved, early maturing cultivars may fit into the duplex do workping system characteristic of progressive agriculture. in that location shake been reports of cultivars whose flowering is hold up by short-day treatments and hence are considered long-day plants (1, 98, 99, 239, 254, 276, 277, 279, 283, 284, 287, 291, 303, 398,443,444, 488). Heenati, for instance, is often referred to in the literature as a long-day plant (1). Short photoperiods declare delayed its flowering by 10 d, but this delay is comparatively short and may be the result of nonphotoperiodic factors, such as low tripping vehemence or relatively mellow temperature.The delay ca employ by short-day treatments ranged from 7 to 12 d in the Charnock and Panbira cultivars using an 8-h photoperiod (443), rough 9 d in B. 76 (303), and 13 d in T. N. 32 and T. A. 64 (287). Many of the inform long-day and in endpointediate cultivars were found to be short-day cultivars in attendant testing (522). The apparent long-day opposeion of Heenati resulted from using photoperiods shorter than the best, which delayed flowering (34). Some rices may bring been classified as long-day plants because inadequate facilities were utilize in testing the photoperiod reaction.The range of photoperiods used has been limited, usually involving nevertheless two treatments. In some instances, the classification was establish on field reaction to different set visualises (98). Short-day-treated plants were often compared with plants grown infra natural day lengths (291, 303, 304). The difference and changes in temperature and the photo periods used have make it difficult to interpret the data intelligently. As will be discussed later, many photoperiod response curves show that photoperiods lengthy or shorter than the optimum delay the flowering of photoperiod-sensitive cultivars (34, 513).Photoperiod response differs markedly among rices this also explains the diversity of the results report on the photoperiodism of the rice plant (see Appendix). However, more than 400 cultivars have been livelyly tested at IRRI (l59, 160, 161, 162, 163, 164, 166, 167, 168, 169, 170), and not one so far has shown a long-day response. Growth phases The growth of the rice plant slew be divided into three power points 1) the vegetative growth phase, from germination to panicle trigger 2) the generative phase, from panicle initiation to flowering and 3) the ripening phase, from flowering to full development of grain.In the tropics, the reproductive phase is about 35 d maculation the ripening phase ranges from 30 to 35 d. Both phases are relatively constant, although low temperatures have been known to prolong them and eminent The flowering response of the rice plant to photoperiod 3 temperatures to shorten them. The ripening phase may be prolonged to as much as 60 d. However, it is the vegetative growth phase whose eon in general varies greatly and which largely determines the growth distance of a cultivar, particularly in the tropics.The vegetative growth phase can be further divided into the basic vegetative phase (BVP) and the photoperiod-sensitive phase (PSP). The BVP refers to the late growth stage of the plant, which is not propeled by photoperiod. It is unless after(prenominal) the BVP has been completed that the plant is able to show its response to the photoperiodic remark for flowering . this is the PSP of the plant. write in code 2 shows the growth phases and the typical response of a photoperiodsensitive rice and a photoperiod-insensitive rice.Based on the BVP and PSP, varietal re sponse to photoperiod can be classified into four types as shown in Figure 3 (105, 526). 2. Growth phases and typical responses of a photoperiod-sensitive rice and a photoperiod-insensitive rice. BVP = basic vegetative phase, PSP = photoperiod-sensitive phase. 3. Four types of varietal response to photoperiod. BVP = basic vegetative phase, PSP = photoperiodsensitive phase. 4 The flowering response of the rice plant to photoperiod The BVP and PSP are two separable growth phases falsifyled by contrary genes.Although some tropical cultivars may be classified as the D type having both long BVP and long PSP, most were probably eliminated during domestication since they would have had an unusually long growth period and could be deep-seated only within a narrow range of dates. Such cultivars were found in Bangladesh and are known as Rayadas (105). The four types shown in Figure 3 were classified under one temperature condition. Norin 20 (Type A) has a short BVP. When grown in the tropic s, however, it has a much shorter BVP than when grown in the temperate areas (Fig. 1).In classifying cultivars found on BVP, most of those from the low parallel of latitudes were found to have long BVP? fs (531, 532). Basic vegetative phase At the early growth stages, the rice plant is photoperiod insensitive so that the photoinductive treatments are usually started when the plants are 10-63 d old (13, 90, 142, 175, 186, 213, 230, 232, 273, 304, 316, 401, 512, 531). Because of this insensitivity to photoperiod, the early growth stage has been termed the basic vegetative phase it is also referred to as the juvenile growth stage of the insensitive phase of the plant.Suenaga recognized the BVP as early as 1936. He measured it by taking the continuation of the vegetative growth phase at optimum day length. The BVP also has been measured by subtracting 35 d from the growth term (sowing to flowering) of plants grown at the optimum photoperiod (526). This assumes that the period from pa nicle initiation to flowering is about 35 d. Anema (13) modified the determination of the BVP by subtracting 35 d and the minimum number of photoinductive cycles needed for panicle initiation from the headland date.The resulting BVP values are smaller but this complex method would mean determining the minimum number of photoinductive cycles needed for each cultivar. The range of BVP report in the literature has wide-ranging from 10 to 85 d (105, 175, 266, 273, 326, 381, 383, 401, 407, 445, 512). In an F 2 population, BVP? fs of more than 100 d were reported (249), but a BVP of this length has not been found in conventional rice cultivars. It is thinkable that such characters are eliminated during cultivar selection. The appendix shows the range of the BVP of the cultivars tested at IRRI.The indica cultivars generally have long-life BVP (583). Other workers have reported or measured BVP in terms of leaf number (93, 215, 340, 413, 551, 575). The minimum number of leaves can be les s than five. The need for determining the BVP of a rice cultivar before using it as an experimental plant material is obvious but is frequently overlooked especially in the study of the inheritance of photoperiod sensitivity. Several experiments showed that short-day treatments of seedlings accelerated heading (393, 401, 437, 438, 445) or delayed it (16, 273, 284, 287, 296, 426, 443, 447, 551).The results indicate the feasible effect of photoperiod while the plant is in its early growth stage and the possible existence of a very short BVP. On the other hand, long-day treatments of seedlings have been reported to induce earliness in flowering (418, 427). These varied and conflicting results may have been caused by non particular factors. A good example is seedling vigor, which is The flowering response of the rice plant to photoperiod 5 known to affect the flowering date, especially in the weakly photoperiod-sensitive cultivars.The degree of sensitivity of rice plants has been repor ted to increase with age (142, 190, 195, 202, 205, 347, 512). The increase in leaf area come with advancement in age does not explain this increase in sensitivity (413). An increase in sensitivity with age up to 28 d and then a decrease in sensitivity with older plants (35- to 42-d-old plants) has been reported (296). The delay probably resulted from the setback from delayed transplanting and not from plant age because the plants were already 63 d old when transplanted, with some already flowering.The optimum age of responsiveness is probably the result of growthlimiting factors, such as space and nutrients and delayed transplanting. Katayama (202) indicated that the BVP, or aging effect, probably resulted from small leaf area and (or) low metabolic activity and (or) lack of a specific metabolic pattern in young plants. The substance causing response to short-day conditions is produced in too small a quantity to affect morphogenesis at the growing even out, but increases gradually with change magnitude age.Studying this aspect, Suge (460) found that the growth inhibitors in the plant were greatly lessen as the plant grew. However, it is not known whether these inhibitory substances are essentially touch on in the sensitivity of the plant to photoperiod. In some instances, the apparent low sensitivity of the younger plants may be a matter of completing the BVP. If the photoinductive cycles were given before the BVP of the plants had been completed, the effective photoinductive cycles would be less and the resulting response of the plants would be smaller.The transition from the BVP to the PSP is not well known it could be abrupt or it could involve a gradual buildup. employ several cultivars, Best (26) found that the insensitive phase (BVP) changed to the fully sensitive phase (PSP) within a week. The following are possible explanations for the existence of the BVP (26) 1) The first leaves make are completely insensitive to photoperiod. 2) The first leav es formed have very low sensitivity that they do not pretend an adequate take of induction to evoke floral initiation before the more sensitive leaves formed at higher nodes have reached this stage. ) The first leaves formed do not attain the induced stage before the (early) senescence of these leaves. 4) The total leaf area needed before the plant can react by floral initiation to the inductive photoperiod is so large that it is reached only at a relatively late stage of plant development. 5) The growing point of the young plant is unable to react to the floral excitant or the stimulus cannot reach the growing point. Photoperiod-sensitive phase The PSP or the eliminable phase (186) is the growth stage indicative of the rice plants sensitivity to photoperiod.In photoperiod-sensitive cultivars, the PSP determines the rice plant? fs sensitivity. The PSP of photoperiod-insensitive cultivars ranges from 0 to 30 d while that of sensitive cultivars lasts from 31 d or longitudinal. c hthonian continually long photoperiods, 6 The flowering response of the rice plant to photoperiod some cultivars have been reported to re main(prenominal) vegetative even after 12 yr of growth (234). The PSP is usually compulsive by subtracting the minimum growth lenify from the upper limit growth age of a cultivar (526).Because many cultivars remain vegetative for a long period if grown under long-day conditions, experiments are usually terminated after 200 d and the PSP of the cultivar is given the value of 200+. in like manner measuring the PSP, there are many other ways . to be discussed later . of determining a cultivar? fs sensitivity to photoperiod. A rice cultivar? fs response to photoperiod may be measured by the length of the PSP, which in turn is determined by both the unfavorable and optimum photoperiods of the cultivar.Because these two terms have been used interchangeably and in many ways, the following definitions will be adopted herein. Optimum photoperiod is t he day length at which the duration from sowing to flowering is at a minimum (34). Critical photoperiod is the longest photoperiod at which the plant will flower or the photoperiod beyond which it cannot flower. Figure 1 shows that BPI-76 has an optimum photoperiod of 10 h and a exact photoperiod of 13 h. Tainan 3 has an optimum photoperiod of 12 h but no little photoperiod because it flowered under all photoperiods.The critical photoperiod determines whether a cultivar will flower when planted at the usual condemnation at a certain latitude, while the optimum photoperiod determines whether it will flower within a conceivable prison term if planted during a period with longer geezerhood than would normally occur during the growing season. With BPI-76, if the optimum photoperiod is 10 h and the delay under photoperiods longer than 10 h is great, one would expect the flowering of this cultivar to be greatly delayed when planted in the northern latitudes where the photoperiod dur ing the growing season is about 14 h.If the critical photoperiod is 12 h, flowering will occur very late at high latitudes, and if flowering does occur, the crop will not mature in time because frost will kill it. A cultivar with a long optimum photoperiod or no critical photoperiod would have wider adaptability . it could be planted at any latitude and in any season, provided it is not too sensitive to temperature. Optimum photoperiod The optimum photoperiod differs with cultivars although many workers have observed it to be 8-10 h (39, 116, 135, 142, 311, 362, 371, 393, 512). Using intermediate photoperiods of less than and more than 10 h may reveal more important information.But this will require facilities in which a maximum of 15-min difference in photoperiods can be accurately obtained. There are also readings that the optimum photoperiod increases with increase in temperature Njoku (335) did not find any optimum photoperiod in the varieties he studied. The photoperiod he used was as short as 9 h, well to a lower place the range of natural day lengths. Cultivars with optimum photoperiods longer than 10 h have also been reported (26, 90, 320, 322, 362, 568). The less sensitivity to photoperiod, the longer is the (394). The flowering response of the rice plant to photoperiod 7 ptimum photoperiod (116, 311). However, others found no correlation among the optimum photoperiod and the photoperiod sensitivity of the many cultivars they tested (572). A photoperiod longer or shorter than the optimum has been shown to delay flowering, the delay depending upon the cultivar? fs sensitivity (311, 316, 319, 371, 393, 459, 5 13, 568). The term supraoptimum photoperiod has been used when the photoperiod is shorter than the optimum. Panicle initiation in plants receiving a photoperiod as low as 4 h has been reported (140). No flowering has resulted under a 2-h ethereal period (140).Plants receiving 8-h light and varying dirty periods from 16 to 64 h showed inhibited shoot apex conversion (219). This was ascribed to inadequacy of carbon compounds for synthesis of indispensable quantity of flowering hormone. The turning point mentioned by Yu and Yao (568) is similar to the optimum photoperiod, but the photoperiod values they reported were larger because these were not the photoperiods at which growth is shortest but the photoperiods at which the first long-day effect is manifested. Critical photoperiod Scripchinsky (417), reviewing the literature on rice, indicated that the rice plants have a ? critical length of day for flowering.? h Later studies showed the posture of a critical photoperiod ranging from 12 to 14 h (175, 209, 244, 354, 478, 490, 500, 553). The critical photoperiods determined under controlled photoperiod rooms were almost the same as the day length from morning to sunset at 30 d before flowering under natural conditions (499). The lower the latitude of origin of a cultivar or strain, the shorter is its critical photoperiod ( 196, 356). The critical period is influenced by temperature (566) and lengthens as the plant becomes older (2 12).The PSP of a cultivar is probably a measure of the combined effect of photoperiod on its optimum photoperiod and critical photoperiod. The shorter the critical photoperiod, the longer is the PSP. Short optimum photoperiod is also associated with long PSP. Photoinductive cycles A photoperiodic cycle that induces the initiation of flowers on plants is called a photoinductive cycle. A 10-h photoperiod alternating with a 14-h mordant period is one possible photoinductive cycle of a short-day rice cultivar. The minimum number of photoinductive cycles indispensable to initiate the panicle anlage of a rice plant varies from 4 to 24.This required minimum number varies not only with cultivar, but also with the photoperiod being used (13, 21, 26, 142, 195, 292, 338, 344, 408, 449, 500, 527, 529). The number of photoinductive cycles necessary increases with photoperiod length (19 0, 195, 203, 204, 527). According to Katayama (190), the minimum number increases proportionally with the photoperiod used, although others (527) failed to obtain a proportional increase using a polar cultivar. Katayama (190) found that the minimum number was lower in cultivars from higher latitudes than in those from lower latitudes. The flowering response of the rice plant to photoperiod Suge (463) showed that different numbers of photoinductive cycles produced different amounts of floral stimulus. He also found that Gibberellin A3 reduced the minimum number of photoinductive cycles necessary to induce flowering. However, gibberellin alone did not induce flowering under noninductive photoperiods. That a certain number of photoinductive cycles is required to induce flowering suggests that the stimulus produced by the treatment is cumulative and that flower induction occurs when the stimulus has reached a certain threshold level (205, 206, 208).Photoinductive cycles interrupted by noninductive cycles can negate to different degrees the effect of the photoinductive cycles (200, 206, 345). There are also indications that emergence of the panicle from the flag leaf sheath is a process separate from panicle initiation. For example, internode elongation, after the panicle has been initiated, proceeds more rapidly at shorter than at longer photoperiods (26, 37, 67, 135, 425, 451, 512, 529), and earliness is further induced if the treatment is prolonged until flowering (33, 438, 498).It is possible, however, that panicle initiation and exsertion are separate processes, but certainly the latter proceeds only after the panicle has been formed. The effect of photoperiod on exsertion may be on fuller development of the panicle, hence indirectly affecting elongation of the first internode or exsertion of the panicle. Plants subjected to in able photoinductive cycles sometimes form panicles but no emergence occurs (see Table 1) (92, 122, 344, 512, 526). A difference of t wo photoinductive cycles could make the difference between exsertion or nonexsertion of the panicle.Several workers, however, have reported that photoperiod has only a slight effect on culm elongation and panicle emergence (85, 116, 338, 473) but the cultivars used (85, 338, 473) were generally weakly photoperiodic because the differences between the control and the treated plants were relatively small (16 d at most). In another instance, the treatment was started at a later stage . 20 d before the standard heading time . at which time the plants had stock sufficient photoperiodic stimulus for panicle initiation and emergence (1 16).In another experiment, long photoperiods had no effect on the term bud that had reached the stage of differentiation of secondary branch primordia (345). Reversals from a reproductive to a vegetative phase have been reported (54, 342). In some instances, however, the panicle is initiated and secernate but Table 1. Response of 30-d-old BPI-76 seedlings g iven different numbers of 10-h photoinductive cycles. Days from sowing Days from sowing Cycles (no. ) to panicle to panicle initiation emergence 8 ** 10 47 ** 12 47 88 Continuous 46 66 *No panicle initiation 200 d after treament. **No panicle meregence 200 d after treament * The flowering response of the rice plant to photoperiod 9 does not emerge (526). The unexserted panicle ceases to grow, and instead the terminal growth is dominated by a shoot from a node below the panicle. Such a situation is not a true reversal of the growing point. In more recent histological studies, incomplete short-day treatment changed the bract primordium into a leaf primordium, a true reversal of some parts of the growing point (346). Reception of the photoperiodic stimulus and translocation The photoperiodic stimulus may be stock by the leaves of the rice plant (24).The leaf sheaths can receive the stimulus as shown by removing the leaf blades and subjecting the plant to photoinductive treatments (26, 142, 481). More photoinductive cycles were needed to induce flowering when the leaf blades were removed (142). Defoliated plants responded to light interruption given during dark periods as well as the intact plants (142). In one cultivar, the culm received the photoperiodid stimulus (26). Evidently, the leaf most receptive to the stimulus is the youngest fully formed leaf (263). The first leaves, up to the sixth leaf, are either insensitive or have low sensitivity to photoperiod (26).It is difficult to study this aspect of leaf sensitivity because grafting experiments with the rice plant are difficult. Removing the leaves at regular intervals after the end of the photoinductive cycles showed that the floral stimulus moves gradually from the leaves to the terminal bud (142, 464). The translocation of the stimulus depends on temperature. It was also reported that the rate of translocation of the stimulus is the same regardless of the number of photoinductive cycles received by the pl ant (463). The question of stimulus movement from one tiller to another has also attracted the attention of several workers.When a plant was divided and half(a) was kept under a 24-h photoperiod and the other half under an 8-h photoperiod, the half subjected to the short-day treatment flowered while that under long-day treatment remained vegetative (230, 232). The results indicate that the stimulus is not transmitted from one tiller to another. This finding has been substantiated by other workers using different cultivars and methods (263, 408, 521). Manuel and Velasco (263) concluded that the stimulus that induces flowering can be keep in the stubble and later transferred to the ratoon but not to a neighboring tiller of the same age as the donor.Sasamura (413), however, reported that the floral stimulus goes from the main culm to its tillers. The irregularities observed in photoperiod-sensitive cultivars when planted during the off-season, for example, the high number of nonflowe ring tillers, have been attributed to the effect of the photoinductive cycles received by the plant and their nontranslocation to the succeeding tillers formed (521). Light intensity and property The light intensities used to prevent or delay flowering varied from 1 to more than 200 lx. Incandescent, tungsten, as well as fluorescent bulbs have been used (69, 143, 310, 396, 484, 489, 503, 538, 565, 570, 577).The brighter the illumination, the stronger the retarding effect. 10 The flowering response of the rice plant to photoperiod Delay in flowering with light intensities varying from 10 to 100 lx and even at 1 lx (310, 484) has been reported (538, 565, 589). Extending the day length using light intensities of less than 200 lx during the first or last 3 h of the 12-h dark period did not prevent flowering (478). In another experiment, 2-h illumination at 15 lx before a 9-h dark period showed some inhibiting effect and 1-h illumination at 500 lx incandescent light before a 9-h dark pe riod inhibited flowering (143).In correlating laboratory studies with field studies, the natural photoperiod used is usually based on the sunrise-to-sunset duration. Such measurements are unsatisfactory in assessing periods of effective light because very low light intensities have been known to effect photoperiod responses in some experiments. Civil gloaming in the morning can generally delay flowering but civil twilight in the evening may or may not delay flowering (143, 196, 205, 502). Civil twilight ends when the light intensity is about 4 lx. Twilight, of course, varies with localities and within the year.The critical light that results in delayed flowering is around 5 lx and sometimes 10 lx, depending on variety and other factors (174). Twilight intensity also varies and may be higher in the morning than in the afternoon (Fig. 4). Katayama (196) attributes the greater effectiveness of the morning twilight to higher intensity. Cloudy weather affects twilight duration. Takimot o and Ikeda (478), however, concluded that the photoperiodically effective day length is equal to the astronomical day length (sunrise to sunset) because twilight (less than 200 lx) had little effect on photoperiodic induction in their experiment.Wormer (538) showed that low light intensities for 6 h (10-100 lx) given after a 12-h daylight can delay flowering. Farmers have complained that their rice plants did not flower regularly because of the electric lights installed along their fields (552). One incident has been reported in which the light from a flame of desert natural gas prevented normal 4. Change of light intensity during civil twilight (after Katayama 196). The flowering response of the rice plant to photoperiod 11 flowering in rice. The effect of light was noticeable up to about 270 m from the flare (22).Although light from incandescent bulbs is generally used for photoperiod studies, other colors have been seek in rice. The blue-violet part of the spectrum has been sh own to retard flowering (260) as has infrared light (323). The delay in flowering caused by green light is very slight, only 4-5 d later than natural day length (234). Green has, therefore, been used in light traps for the moth. ruddy light is the most effective in delaying flowering, while blue showed some effect only at high intensities and in the most photoperiod-sensitive cultivars (26, 146, 153, 503).The phytochrome pigment is generally regarded as the system that interacts with photoperiod or with different light qualities, such as red, far-red, and blue. Such pigment has been studied in rice coleoptile by Pjon and Furuya (378, 379). For panicle initiation, rice needs a high light intensity during the light period. The inhibition caused by low-intensity light during the light period can be overcome effectively by exposing the plant to high-intensity light immediately before or after the inductive dark period (140, 145).This phenomenon is similar to that reported in other shor t-day plants and is evidently a carbohydrate requirement. This requirement would explain why a 2-h light period followed by 22-h dark period did not induce flowering (140). Ikeda (145) reported, however, that plants growing in low-intensity light during the photoinductive period but briefly unfastened to high-intensity light before the inductive dark period had floral induction, suggesting that light requirement for floral induction of rice is not entirely concerned with photosynthesis.In the flowering response of the rice cultivars to photoperiod, red light given during the dark period inhibited flowering (136, 146, 148, 411, 442). The effect of red light increased with intensity. Red light, as low as 10 ? EW/cm 2 given for 3 h or 290 ? EWc/cm 2 for 15 min in the middle of the dark period, inhibited flowering (146, 148, 149). Red light was most effective in inhibiting panicle initiation when given in the middle of the dark period (150). With red light, the period of exposure neede d to inhibit floral development was shorter than with white light (146).The inhibiting effect of red light has also been shown in experiments involving red and far-red lights. Far-red after red nullifies the delaying effect of red light and promotes flowering (411). Far-red before a 9- or 10-h dark period promotes flowering and this effect can be reversed by red light (146, 149, 152). Far-red enhances flowering whereas blue retards flowering (185). Far-red after the critical dark period can shorten the critical dark period as well as reduce the minimum number of inductive cycles required (145). Interruption of the dark periodSensitive strains of rice respond to light interruption (26, 69, 218, 232, 260, 323, 449, 570, 577). Light given in the middle of the dark period delayed the flowering of the sensitive cultivar Shuan-chiang (570). The light intensity used was 1001x and the duration varied from a flash to as long as 15 min. The degree of delay was greater in the light interruptio n of a 12-h dark period (12 light and 12 dark) than of a 16-h dark period (8 light and 16 dark) (577). Interrupting the light period with darkness did not accelerate flowering. 12 The flowering response of the rice plant to photoperiodThe earlier the interposition of the light during the dark period, the greater was the delay (449). The findings show that the flowering response of the plant is determined by the longest dark period. Days from photoinductive treatment to flowering The literature indicates that the number of days from panicle initiation to flowering is about 35. Many workers have reported that the difference among cultivars is small (7, 407, 511, 551). Others found that the number of days from panicle initiation to flowering ranges from 10 to 241 d (425).It seems obvious, however, that 10 d is too short for the full development of a panicle. Flowering may be delayed by long photoperiods after panicle initiation (176, 524). But if the plants are given photoinductive cyc les beyond the minimum requirement, the subsequent photoperiods have very little effect on flowering and elongation (501, 524). Auxin application can nullify the delaying effect of long photoperiods (176). Under natural day length, the number of days from the first-bract differentiation stage to flowering varied from 27 to 46 d, depending upon the cultivar and time of sowing (14, 270).Reports vary on the number of days from the start of the photoinductive treatment to flowering. Misra (285) reported 37 d in 30-, 40-, 50-, 60-, and 70-d-old plants of the cultivar T. 36 using a 10-h photoperiod. Fuke (93) noted that the plants flowered about 28 d after treatment. The number of days from photoinductive treatment to flowering depends upon the photoperiod being used. Panicle initiation and flowering were earlier under the 10-h than under the 11- and 12-h photoperiods (527). Using 168 F 2 plants, those treated under the 10-h photoperiod took 30-47 d to flower, or a mean of 35. d (Li, unpu blished data. For practical purposes, an estimate of 35 d should be workable. Thus, to obtain the BVP or the time of panicle initiation, 35 d can be subtracted from the minimum growth duration of the cultivar. In studying the effect of photoperiod on the flowering of the rice plant, the most fundamental consideration is panicle initiation because it tag the actual change from the vegetative to the reproductive phase. Instead of using this as a can, however, most studies use the flowering date, which is only a projection of the variations of the date of panicle initiation.To a certain extent, several factors can affect the stage from panicle initiation to emergence. In some instances, panicle initiation can occur without the subsequent emergence. The panicle primordium is aborted and a vegetative shoot may dominate the growing tip (527). A methodological question might therefore arise regarding accuracy of the experiments based on flowering date. The practicality of the method, howe ver, far outweighs the need for extreme accuracy. Biochemical changes during photoinduction Very little work has been done on the chemical changes occurring during photoinduction and panicle development in rice.An increase in the rate of respiration of rice shoot apices with each photoinductive cycle given to the eighth The flowering response of the rice plant to photoperiod 13 day, followed by a gradual decline in rate, has been reported (293). The peak of the respiration rate almost coincides with the minimum photoinductive cycles needed by the rice plant at 8 h of photoperiod. The results suggest that the photoperiodic mechanism in the flowering of rice involves a respiratory shift. This corroborates the findings of Elliot and Leopold (86) who used other plant species.The changes in carbohydrate and nitrogen theme of rice plants subjected to short days were also studied by Misra and Mishra (299). Unfortunately, the difference in heading between treated and control plants was onl y 4 d. khan and Misra (222) reported an increase in sugar and nitrogen content of the leaves when subjected to photoinductive cycles. Photoinduction increases the gibberellic acid activity, although the value is low (461). This immediate rice, visible after three photoinductive cycles, returns to a level lower than that of the original. The rice plant is difficult to use for studies on biochemical changes during reproduction.Perhaps it is best to leave this type of study to other short-day plants. Effect of temperature on the flowering response to photoperiod The flowering of the rice plant is mainly controlled by two ecological factors . day length and temperature . which are often interrelated. The plant may respond to temperature and photoperiod simultaneously, but the degree would vary according to the cultivar. Cultivars have been classified based on these two factors (248, 356, 530). Temperature affects both the photoperiod-sensitive and photoperiodinsensitive cultivars.Gener ally, high temperature accelerates and low temperature delays heading (5, 6, 90, 126, 186, 307, 339, 340, 370, 376, 409, 410, 439, 456, 531). Some reports, however, have shown that high temperature delays flowering (15, 18, 394). The acceleration of the photoperiod response by high temperature is an overall effect, but it does not indicate the specific effects on the different stages leading to flowering. The effect of temperature on the BVP, photoinductive period, panicle differentiation and development, and critical photoperiod has not been fully studied.Uekuri (506, 507) studied the effect of low temperature during the BVP and found a definite delay in attaining the PSP. The degree of extension of the BVP by low temperature varied with the cultivars used. The growing point of the shoot is the receptive organ for the low-temperature effect, not the leaf blades (506). Ahn (5) reported that high temperature reduced the BVP but had very little effect on the PSP. As early as 1931, Fuk e had considered the effect of temperature during the photoinductive period. He used snow to lower the darkroom temperature, but the 5-10? C decrease had little effect on heading.Temperatures above 20? C to 29? C accelerate panicle initiation (24, 341). Vergara and Lilis (524) showed that the vegetative primordium was converted to reproductive primordium at the same time or at the same morphological stage regardless of temperature (21-32? C). 14 The flowering response of the rice plant to photoperiod Haniu et a1 (1 15) found similar results. These results contradict those reported by Noguchi and Kamata (341) and Best (24). Temperatures below 15? C inhibited initiation and bud development (156). Floral induction, however, is possible at 15? C (341) but not at 12 or 40oC (115).Because many test plants died in the growing process, 15? C is fictive to be near the lowest limit for rice growth (341). The optimum temperature reported for photoinduction is 30o C (1 15). The question still remains as to whether a critical temperature for photoinduction exists. The optimum temperature for photoinduction may vary depending upon the photoperiod being used. The optimum temperature tended to be higher under a longer photoperiod and vice versa (24, 364). Putting it another way, at a certain temperature each cultivar has its own optimum day length under which it flowers at the earliest date (459, 572).Detailed microscopic studies of the development of the panicle primordium have shown that high temperature accelerates panicle development (260). The critical temperature for young panicle differentiation has been reported to be 18oC (555). Best (24) has also shown that panicle development, especially in its later stages, is accelerated at high temperatures (35-37oC). On the other hand, low temperature markedly retards panicle primordium development, and, below 25oC, the panicle may not emerge completely from the flag leaf sheath (24). A iniquity temperature of 24. 4oC was fo und more favorable than 29 and 35? C in accelerating the flowering of the Elon-elon cultivar (263). High night temperature accelerates flowering (220). This was attributed to increased production of florigen during the dark period. This may not be the case and dissecting plants after photoinductive treatments may reveal if it was an acceleration in panicle development and exsertion rather than in panicle initiation. Others have found that the acceleration in flowering with high temperature is the result of acceleration in panicle exsertion, which, in turn, is the result of shorter leafing interval (524).Obviously, caution should be taken in determining the time of panicle initiation by observing the heading date because the exact date of panicle initiation cannot be determined by this method. Measurements and methods of testing photoperiod sensitivity Most studies on the photoperiodism of the rice plant have been considered from two standpoints, namely, classification of the cultiva r into photoperiod-sensitive and photoperiod-insensitive types and measurement of the degree of sensitivity. The classification may be relatively easy, but the measurement is rather complex (195).As a result, several methods of measuring photoperiod sensitivity have been developed. Studies on the measurement of photoperiod sensitivity are usually based on the reduction in the number of days as a result of short-day treatment (1 16, 195, 205, 327, 329, 357, 553, 574). Other methods were more specific they measured the optimum photoperiod (40), critical photoperiod (351), or the gradient of the response curve (34, 192, 247) as the basis of sensitivity. Hara (116) was the first to measure photoperiod sensitivity using the formula X The flowering response of the rice plant to photoperiod 15 = T .Y/Y X 100, where Y is the number of days required to head under standard conditions and T is the number of days required under an 8-h photoperiod. Several similar formulas have been used by othe r workers. The percentage or index obtained from such formulas, however, does not clearly define photoperiod sensitivity. The results usually apply only to the area where the rice was tested since the natural day length is usually used as the control. Chandraratna (37, 40) used second-degree polynomials to compute the minimum heading duration and optimum photoperiod this method involved using at least three photoperiods.He showed that cultivars differ in both characters. Oka (352) and Katayama (192, 201) measured the critical photoperiod and the degree of sensitivity of several cultivars using different methods and formulas and came up with their preferred method of measurement. Both workers used the natural day length as a basis for computation and assumed that flowering occurs 30 d after photoinduction. Best (25) and Li (249), using a method similar to Chandraratnas (34, 37, 40), measured sensitivity based on response curves obtained by plotting the time from sowing to floral init iation on the ordinate and the photoperiod used on the abscissa.The method, however, requires a wide range of photoperiods. Li (249) also studied photoperiod sensitivity in terms of the BVP and the PSP. The BVP was obtained in plants grown under 10 h of light, and the PSP (which is a measure of sensitivity) by subtracting the growth duration under the 10-h photoperiod from that under the 16-h photoperiod. The PSP values obtained show the possible maximum range in growth duration as a result of extending the photoperiod.The photoperiodic characteristics of a rice plant have been draw by Stewart (458) who used a different criterion based on 1) basic vegetative period in terms of degree-days (based on temperature accumulation), 2) photoinduction period in degree-days or degree-minutes (using accumulated night length), and 3) panicle development period in degree-days (based on temperature accumulation). Tests under field conditions were analyzed by this method and predictions were made on the response of the cultivar sown in different months. In Japan, the flowering response is evaluated using the floral stages (135, 463).The Japanese workers have used the scale of 0-7, based mainly on the length of the developing panicle. This destructive measurement is more accurate than the usual days from sowing to flowering or treatment to flowering. The choice of the most appropriate method of testing and describing the response to photoperiod depends upon the purpose of the experiment and the available facilities. From the physiological standpoint, however, controlled photoperiod and temperature are desired because of their advantages over natural photoperiods and temperatures. Date-of-planting experimentsDay length changes rhythmically within a year and varies depending upon the latitude. The amount of change in day length during the rice cropping season differs from one latitude to another (Fig. 5). Even in locations at the same latitude the day length during the croppin g season may differ because the planting dates 16 The flowering response of the rice plant to photoperiod 5. Day length changes during the cropping season at various locations in Asia. may differ greatly depending mostly on the rainfall pattern at each location. At northern latitudes (Sapporo, 43? N, and Konosu, 36? N) day ength increases and then decreases during the cropping season (Fig. 5). At lower latitudes (Taipei, 25? N, and Los Banos, 14? N) day length decreases during the main growing season. tight fitting the equator (Bukit Merah, 5? N) there is little change. These differences in day length during the growing season may account for the wide range of photoperiod response of rice cultivars. A rice cultivar that must have less than 12 h o daylight to flower will obviously flower too late at the northern latitudes because frost will set in before harvest. In the northern hemisphere, the longest days are in June and the shortest are in December. taking these into account, t he photoperiod response of the rice cultivars can be tested to a limited extent by planting the cultivars at a certain location at different dates. Maximum differences in growth duration can be obtained in the May and November plantings if temperatures are not too low for growth. If a rice? fs growth duration changes more than 30 d, agronomists usually consider it photoperiod sensitive or a seasonal cultivar. As Best (24) has pointed out, this criterion is not specific enough for research on photoperiodism, and caution should be taken in evaluating the data obtained.These phenological data, however, are important to breeders in selecting ecotypes. This method of testing sensitivity to photoperiod has been followed in Australia (245), Brazil (l03, 579), China (44, 356, 582), India (98, 99, 101, 214, 220, 295, 298, 423), Indonesia (467), Japan (533, 548), Korea (247, 466), Malaysia (74, 77, 244), Philippines (91, 512), Russia (452), Senegal (66), Sierra Leone (68, 536), Sri Lanka (112 , 259, 402), Thailand (381), Trinidad (325), and United States of America (177, 180). The flowering response of the rice plant to photoperiod 17These experiments strongly confirm the existence of wide cultivar differences in the effect of planting date on flowering date. Many of the results obtained from this type of testing, however, are not applicable to identical cultivars grown at different latitudes. A cultivar can be insensitive to day length in Malaysia but sensitive in Taiwan. Results of field tests at a certain latitude are, therefore, not always applicable at another latitude. Some published papers on the use of this testing method failed to mention latitude or the place where the tests were conducted.Under natural conditions very small differences in day length can affect the rice plant. In Malacca (Malaysia), the difference between the maximum and the minimum day lengths is only 14 min and yet the cultivar Siam 29 takes 329 d to flower when planted in January and only 16 1 d when planted in September (76). Another instance showing the sensitivity of the rice plant to small differences in day length was reported in a date-of-planting experiment in Malaysia (244). There was a difference of as much as 156 d in the growth duration of photoperiodsensitive cultivars when planted in the same month but in different years (Table 2).This presumably resulted from differences in weather during the critical periods. Cloudy weather early or late in the day shortens the twilight hour, thus shortening the day length. Toriyama et al (490) tested rice cultivars involving not only monthly planting but also sowing at different latitudes (Sri Lanka, Taiwan, and Japan). This gives a better idea of the photoperiodic response of the cultivars but involves much work and cooperation. Ecology and photoperiodism Rice can be grown over a wide range of environmental conditions, from the equator to about 53? N latitude, leading to the differentiation and establishment of various ecotypes and forms. The great diversity in photoperiod sensitivity from one latitude to another or within a latitude probably indicates that the rice cultivars predominantly cultivated in each area are those that have been selected on the basis of local adaptability (that is, adaptability to the temperature of the rice-growing season, day length, and duration of the growing season) to assure the full development of the plant and the best possible balance between vegetative and reproductive growth (423, 530, 532, 584, 585).Table 2. Growth duration (days from sowing to flowering) of photo. period-sensitive cultivars when planted in January 1962 and 1963 at several localities in Malaysia (244). Cultivar Locality Jan 1962 Jan 1963 Difference Engkatek Telok Chengai 136 292 156 Kota Bahru 146 243 97 Kuala Lumpur 134 97 37 Subang Bukit Merah 270 224 46 lntan 117 Kuala Lumpur 171 138 33 Kota Bahru 276 176 100 18 The flowering response of the rice plant to photoperiod A major problem in stud ying the ecology of the rice plant, especially in reference to photoperiodism, is that cultivars in farmers fields keep changing.For example, Hara reported in 1930 that Japanese cultivars were more sensitive than the cultivars from mainland China and Taiwan. He concluded that the lower the latitude of the region of the native habitat, the less sensitive were the cultivars there. Wada (531), using 134 cultivars, showed contrasting results . the cultivars from the northern region of Japan had lower photoperiod sensitivity than those from the southern region. Recent papers, however, generally agree that among the photoperiod-sensitive cultivars, the lower the latitude of scattering, the higher the sensitivity (351, 352, 356, 531, 583).The cultivars in the tropics or lower latitudes are usually late maturing (long growth duration). Many studies show that the late cultivars are more sensitive to photoperiod than the early ones (116, 248, 357, 511, 563, 583). In the tropics, where rice ca n be grown any time of the year provided there is sufficient water, photoperiod sensitivity presents certain problems. During the off-season, when the day length during the early growth stage is increasing, the sensitive cultivars are uneconomical to use because they take a very long time to produce any grain.For wider adaptability, cultivars should have low photoperiod sensitivity (53, 70) and thus have little differences in growth duration when planted at different times of the year or at varying latitudes. Insensitive cultivars have been successfully grown at different latitudes where rice is used as a crop (45, 351, 352, 511, 532, 568. This indicates that it should not 6. Growth duration of IR8 planted in June or July at 12 sites in Asia. La Trinidad and Kanke are high-altitude areas (52). The flowering response of the rice plant to photoperiod 19 e difficult to introduce new photoperiod-insensitive cultivars to different ricegrowing areas or to culture them year-round in the tr opics. The plant breeders, as the varieties coming out indicate, are developing more photoperiod-insensitive cultivars. Extensive testing in various rice-growing areas of the world has established the wide adaptability of photoperiod-insensitive cultivars. In general, the longer the BVP the less variation ingrowth duration and the stronger the PSP the greater the variation in growth duration (581).The wide adaptability and the stable growth duration of IR8, a photoperiod-insensitive cultivar, are indicated by the data furnished by cooperators in various parts of the world. IR8? fs growth duration varied within a range of 20 d at latitudes from 11o to 27oN except at high altitudes where low temperatures prevailed during part of the growing season (Fig. 6). A more illuminating example of the effect of temperature comes from monthly planting at Los Banos, Philippines, and at Joydebpur, Bangladesh (Fig. 7).A likeness between the monthly mean temperatures and mean photoperiods shows tha t the more variable heading pattern at Joydebpur is more closely associated with temperature rather than with the prevailing photoperiod. The effect of low temperature on the improved tropical cultivars becomes more obvious in photoperiod-insensitive cultivars. 7. Mean monthly temperatures and day length in relation to the growth duration of IR8 at Los Banos, Philippines, and Joydebpur, Bangladesh (52) 20 The flowering response of the rice plant to photoperiodSensitivity to photoperiod of rice cultivars in the deep water areas is an important characteristic for survival (104, 520). The floating rice cultivars are highly photoperiod sensitive. They are planted early in the season when the soil can still be worked and without danger of submerging the young seedlings. Flowering occurs when the floodwater peaks or starts receding. If the cultivar flowers when the floodwater is still rising, it would mean the complete loss of the crop if the panicles are submerged. Elongation ability cea ses after panicle emergence.Harvesting is usually done when the floodwaters have receded. The maturity of floating rice cultivars coincides with the receding of the annual floodwaters which may be 150-270 d after sowing. Such a long growth duration requires a photoperiod-sensitive cultivar. So far, there is no known tropical cultivar that has a long growth duration and is not sensitive to photoperiod. Photoperiod sensitivity may work as a safety mechanism when precise planting dates are not followed and environmental conditions such as water level cannot be effectively controlled.If the date of sowing or transplanting is delayed because of insufficient rainfall, a photoperiod-sensitive cultivar may still mature at its usual time (352, 382). Plants are not seriously damaged if odd in the seedbed for prolonged periods because the growth duration of the main crop is sufficiently long for the plants to adjust. Thus, land preparation and transplanting can be staggered (382). Maturation of the crop at the same time. as with photoperiod-sensitive cultivars planted at different dates, may reduce rat and insect damage in any one field. Also, harvest time and drying are simplified.If the soil is not sufficiently fertile, a photoperiod-sensitive cultivar will continue its compelled vegetative growth until the short days come. This would give the plant enough time to reach a reasonable plant weight and accumulate enough carbohydrates before flowering (528). Thus, a photoperiod-sensitive cultivar generally may be more liberal to unfavorable conditions. Long-growthduration cultivars (essentially photoperiod sensitive) are least affected by strong soil reduction (549). Most upland rice cultivars have short growth duration and are photoperiodinsensitive (11, 12).However, in areas where the rainfall pattern is bimodal, as in northern Thailand, the cultivars are of medium growth duration and are photoperiod-sensitive . possibly another indication of the greater specific ada ptability of long-growth-duration cultivars to adverse conditions. The sensitivity to photoperiod of wild species has also been studied in relation to their ecological distribution. Most of the wild rice materials tested were sensitive (191, 201, 205, 209, 353). They suggested that this sensitivity favors the wild rice plants and is perhaps essential to their survival. Terminology used in describing photoperiod ensitivity There is confusion in the terms used to describe the response of the rice plant to day length (515). Often, the terms used for growth duration are also used for response to photoperiod (see Table 3). As early as 1912, Kikkawa pointed out that The flowering response of the rice plant to photoperiod 21 Table 3. Some terms used in describing the growth duration and day length response of rice cultivars. Terms References Response to day lengths date fixed vs period fixed season fixed vs period fixed season bound vs period bound timely fixed vs periodically fixed short- day plant vs long-day plant ensitive vs indifferent sensitive vs insensitive sensitive vs less sensitive short-day plant vs indifferent plant strongly photoperiodic vs weakly photoperiodic sensitive vs photosensitive vs photononsensitive day length sensitive vs day photoperiodic photoperiodic insensitive length nonsensitive early, medium, and late long-aged vs short-aged early flowering vs late flowering late maturing vs early maturing Season of planting aman vs non-aman yala vs maha winter vs summer main-season vs off-season first crop vs second crop miffed vs dry season aus, aman, boro, rabi, kharif Growth duration 33 7 214, 511 308 1, 99, 336 3 68, 352, 353 21, 98, 449, 538 563 51 1 195, 352 339 574 91, 276, 277, 281 259 158 3, 230, 374 427 112 444 Malaysia, Indonesia, and Thailand China Philippines Bangladesh, India it is meaningless to classify the rice cultivars of the world into such groups as early, medium, late, aus, or aman. He said, however, that this classification is u seful in districts where the climates are similar. The use of the terms photoperiod-sensitive and photoperiod-nonsensitive in reporting the flowering response of a rice cultivar to changes in day length has been suggested (515).Weakly photoperiod-sensitive is sometimes used in place of photoperiod-nonsensitive because the existence of a completely photoperiod-nonsensitive cultivar is difficult to prove. Weakly photoperiod-sensitive is also used to describe cultivars whose flowering is delayed by as many as 70 d by long photoperiods. However, those types can be planted any month of the year in the tropics and can be expected to flower within the crop season. The terms short-day plant and long-day plant are not satisfactory because most rice cultivars today are short-day plants.Sensitive and insensitive, sensitive and indifferent, and sensitive and less sensitive are ambiguous terms. Because the response being described is a response to light period and not only to light, the terms ph otosensitive and photononsensitive are inappropriate. 22 The flowering response of the rice plant to photoperiod 8. Effect of four photoperiod treatments on the seeding-to-heading period of seven rice cultivars. Chang and Vergara (51, 52, 53) classified rice cultivars into four types using the length of the BVP and PSP as criteria (Fig. 8).Their classification was based on duration of plants grown in the greenhouse. Under this classification, the Japanese varieties, such as Fujisaka 5 and Norin 20 (Appendix), do not fall under any category because they have a short BVP and short PSP. Also, at least four photoperiods (10, 12, 14, and 16 h) are needed to classify the cultivars. A more practical grouping could be as follows (using also the length of the BVP and PSP). 1. Photoperiod nonsensitive . very short PSP (less than 30 d) and BVP varying from short to long. 2. Weakly photoperiod-sensitive . arked increase in growth duration when photoperiod is longer than 12 h PSP may exceed 30 d , but flowering occurs under any long photoperiod. 3. Strongly photoperiod sensitive sharp increase in growth duration with increase in photoperiod no flowering beyond critical photoperiod BVP usually short (not more than 40 d). Cultivars tested under only two photoperiods, such as 10 and 14 h, can also be classified according to these groupings (1 1). Agronomists and farmers would tend to use these groupings. The flowering response of the rice plant to photoperiod 23 Inheritance of vegetative growth durationThe inheritance of the duration from seeding to heading in cultivated rices has been studied by many research workers, but the findings have resulted in diverse interpretations. Three categories of genetic postulates were generally offered 1) monogenic or digenic control of heading date, with earliness dominant to lateness 2) monogenic or digenic control of flowering date, with lateness being a dominant trait and 3) multiple-factor inheritance in which the F 2 population showed a continuous and often unimodal distribution and in which the same population might produce a bimodal distribution when grown in a different season (44, 509).In experiments where photoperiod sensitivity was recognized, delayed flowering under a long photoperiod was generally inherited as a monogenic or digenic dominant trait (38, 242, 406, 424, 567). In several crosses involving distantly related parents, sensitivity to photoperiod appeared to be a recessive trait (242, 406). The continuous and transgressive segregation in several F 2 populations involving photoperiod-insensitive parents was ascribed to multiple genes, which indicated dictum of earliness (41, 95, 96, 97, 333, 389, 469, 554).However, in crosses among varieties in Yunnan Province in China, photoperiod sensitivity appeared to be a recessive trait in some F 1 hybrids (252). Some of the divergent interpretations just mentioned resulted partly from failure to recognize the composite nature of the vegetative growth perio d from seeding to panicle primordium initiation, partly from failure to control the interaction of the environmental factors (mainly photoperiod and air temperatures) and the different genes controlling the vegetative growth period, or from failure to relate the phenotypic expression with the revailing environment. Recent studies at IRRI (48, 161, 162, 163, 164, 165, 167, 168, 249) have demonstrated physiologically and genetically the feasibility of partitioning the vegetative growt

Law of Constant Composition Lab Essay

Purpose To determine the percent atomic number 12 by mass in milligram oxide and to observe if the percentage organic law is constant by comparing class results.Hypothesis/Prediction The percent composition by mass of atomic number 12 in magnesium oxide will not change significantly with each group that conducted the experiment. The composition of each substance should stay the same and any differences essential be due to some actus reus.MaterialsMagnesium stripCrucibleCrucible coverClay triangleIron ringRetort standTongsBalanceBunsen flame uperProcedure1.obtained a strip of magnesium between 30-40 cm long2.coiled magnesium strip into a tight roll3.measured the mass of the crucible and cover4.Added the magnesium strip to the crucible and measured the magnesium, crucible and cover together.5.Partially covered the crucible with the cover and heated it using a Bunsen burner until the magnesium ignited.6.Turned gain Bunsen burner.7.waited for combustion to proceed8.when the reac tion appeared completed, heated the crucible again for another five minutes9.allowed crucible to cool for ten minutes10.measured the mass of the crucible, cover and magnesium oxideObservationsWhen ignited, the magnesium strip gave off a bright light.There was a colour change on the magnesium.It started out as silver and turned into a innocence colour.The combustion gave off a distinct odour.The end result was a white powder but some magnesium had been left in its sea captain shape.According to the theory of J.L. Proust, a compound always has the same percentage composition no matter how it is prepared. For all three of our own individual groups trials, we obtained the same percentage composition and this satisfies Prousts theory.This is also accurate with what we sop up read in the textual matter Chemistry 11 on the Law of Definite Proportions on pages 147 150.2.What purpose can you make upon the class results?The conclusions I can make based upon the class results are that the composition of a compound must vary because everyone had a different answer. In most cases, the percent composition of magnesium in the compound was very different from what my group achieved. However, sometimes, the classes results were quite similar to my own.The theory that C.M. Berthollet introduced well-nigh the composition of a compound was that a compound has an infinite number of compositions depending on the proportions of the components that were used in its preparation. His theory satisfies the results obtained from the whole class. Since every group had a different amount of magnesium they must also have had a different composition of magnesium in the compound formed, magnesium oxide.However, this is inconsistent with what we have been taught and with what is written in the textbook. Since the textbook is a more reliable source of information, I must conclude that the reason for this difference in results whitethorn be attributed to error on the part of the students con ducting the experiment.3.Which French Scientist would you tend to support? Explain.The French scientist that I support is J.L. Proust. I agree with Prousts theory because I believe that if the composition of a substance were to change, so would its properties. An obvious example of this is one stated in the textbook water and atomic number 1 peroxide. The simple addition of a hydrogen atom to the compound of water can make a liquid that is essential to life become deadly. Since I know that the percent composition of a particular substance is the same no matter where, how or when it is made, I must agree with J.L Proust and support his theory.Sources of ErrorOne reason wherefore a student may have obtained a higher percentage of magnesium than the rest of the class is during the experiment, mass must have been upset. This could have been done in many an(prenominal) ways. Often, the magnesium took too long to ignite and students began to put it straight into the flame to ignite it and then put it back into the crucible. Sometimes, the magnesium wilted and little pieces of it broke off. In addition, the magnesium would sometimes ignite and then extinguish itself. In the constant removal of the magnesium from the crucible, mass was lost in the form of ashes. When mass is lost during the experiment, the total mass of the compound is lower and when the mass of magnesium was divided by the total mass, yielded a higher percent of magnesium.One reason why a student may have obtained a lower percentage of magnesium than the rest of the class is the magnesium did not properly combust. In many cases, the magnesium would extinguish itself and would not burn completely. This resulted in some white powder, ash, and some magnesium still in the same shape that it was when we began the experiment. This suggests that it did not burn with the rest of the magnesium ribbon and therefore, did not form the compound with oxygen. This would yield in a higher total mass than what it should have been and when the mass of magnesium is divided by the total mass, would give a lower percentage.The following calculation shows the actual percentage of Magnesium in the compound magnesium oxide. molar mass of MgO = 24.3 + 16.0= 40.3For 1.00 mol of MgO%Mg = 24.3 / 40.3 x100= 60.3%Therefore, the actual percentage value of Mg in MgO is 60%The following calculation shows the percentage error for my own groups result% error = (experimental accepted) / accepted x 100= (72 60) / 60 x 100= 20%Therefore the percentage error for my group was 20%.ConclusionBased on the data collected by each group, the composition of a substance must change depending on the proportions of the components that were used in its preparation.However, as explained earlier, the textbook and the properties of matter state otherwise. Scientifically, if the composition of a compound was to change, so would its properties. The results obtained by the class are quite the opposite of what has already been pro ven by Proust to be true and therefore, I believe that the evidence obtained by our chemistry class is the result of many mistakes and cannot be used to convey the idea of the Law of everlasting Composition which states that the composition of a specific compound is constant.