The educated imagination Essay Example For Students

The educated imagination Essay What is the relevance of literature in the world of today? (Frye 27) Frye asks many rhetorical questions, such as this, throughout his essays to formulate a mutual connection with the reader. This connection that is between the author and the reader is a connection of the imagination. The part of the imagination that is being used my both parties are quiet different however. The authors imagination input is, as Frye puts it, the power to create. The readers imagination, then, is the power to understand, together forming the essentials of literature. This common link is achieved primarily by archetypes, being the fulfillment of the readers desire to associate and make connections with. As humans, we seek this connection to literature and being able to connect and belong to something soon becomes the ultimate goal of literature all together. In William Goldings Lord of the Flies, a group of English schoolboys living in an uninhabited island seek a connection to the outside, objective world. They find a need to build shelters to remind them of the world they lived in that they had already familiarized themselves with. We will write a custom essay on The educated imagination specifically for you for only $16.38 $13.9/page Order now In addition, they feel the need to continue their everyday routines such as raising their hand when answering a question. Ralph, when addressing to the other boys with solution as to what they were going to do on the island mentions, we cant have everybody talking at once. Well have to have Hands up like at school. (Golding 44) This need to connect to the objective world is evident wherein there is a desire to connect, that soon becomes the need to belong. Literature fulfills this need through the extent of the imagination. Frye begins by saying, the world of literature is a world where there is no reality except that of the human imagination. (Frye 57) This is similar to our objective world, where we make reality what we believe to be reality. In William Goldings Lord of the Flies, the group of English schoolboys fear an imaginary beast that roams the island terrorizing the island. In reality, however, the beast is just an extent of the boys imaginations that has been brought into existence as a result of their behaviour. Simon, at a group gathering says, maybe there is a beast. maybe its only us. (Golding 80) The beast ultimately becomes suggested to be just a figure of the imagination, formed by the boys imaginations from being apart from their familiarized objective world. This imagined world then, has no reality within literature except for what the imagination perceives it to be. Elena has already mentioned conventionalism as being an evident factor distinguishing reality and literature wherein literature has no consistent connection with ordinary life. Instead, this vivid connection is made with the imagination. When reading a piece of literature, connections are fallaciously believed to be made within reality, when actually it is made with our imagination. Frye earlier defined the imagination to be the world we want to have. Therefore, this signifies that literature reflects a world that we desire, which doesnt necessarily mirror reality. Frye later defines imagination as the power of constructing possible models of human experiences. Therefore, it is through experiences that we enhance our imagination to create literature. Experience is a broad word including the experiences of the literary world. Frye agrees that it is the literary experiences that have a greater value than experience gained within life when he says no matter how much experience we may gather in life, we can never get the dimension of experience that the imagination gives us. (Frye 61) Frye provides the example of Shakespeare, the writer of numerous plays depicting different shades of human emotion- from comedies to tragedies to exemplify this concept. .uc6138dc5673b05843f40a7897bca9f10 , .uc6138dc5673b05843f40a7897bca9f10 .postImageUrl , .uc6138dc5673b05843f40a7897bca9f10 .centered-text-area { min-height: 80px; position: relative; } .uc6138dc5673b05843f40a7897bca9f10 , .uc6138dc5673b05843f40a7897bca9f10:hover , .uc6138dc5673b05843f40a7897bca9f10:visited , .uc6138dc5673b05843f40a7897bca9f10:active { border:0!important; } .uc6138dc5673b05843f40a7897bca9f10 .clearfix:after { content: ""; display: table; clear: both; } .uc6138dc5673b05843f40a7897bca9f10 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .uc6138dc5673b05843f40a7897bca9f10:active , .uc6138dc5673b05843f40a7897bca9f10:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .uc6138dc5673b05843f40a7897bca9f10 .centered-text-area { width: 100%; position: relative ; } .uc6138dc5673b05843f40a7897bca9f10 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .uc6138dc5673b05843f40a7897bca9f10 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .uc6138dc5673b05843f40a7897bca9f10 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .uc6138dc5673b05843f40a7897bca9f10:hover .ctaButton { background-color: #34495E!important; } .uc6138dc5673b05843f40a7897bca9f10 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .uc6138dc5673b05843f40a7897bca9f10 .uc6138dc5673b05843f40a7897bca9f10-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .uc6138dc5673b05843f40a7897bca9f10:after { content: ""; display: block; clear: both; } READ: The Road Not Taken EssayShakespeare couldnt possibly have experienced, in reality, the guilt of killing a king as in Macbeth nor could he have experienced the passionate love resulting in an untimely death, as in Romeo and Juliet. Despite this lack of realistic experience, Shakespeare manages to create literature; the reason for this being that his literature wasnt based on realistic experience, but rather literary experience. Literature, then, is a concrete world of immediate experience, where experience is made into reality. The limit of literature is imagination, which exceeds the capabilities of our objective world. Frye says, The real realities, so to speak, are things that dont remind us directly of our own experience but are such things which are bigger and more intense than anything we can reach, except in our imagination which is what were reaching with. Ideally, Frye is supporting his earlier point of literary experience having a greater influence on successive literature, and imagination being the idealistic tool to attain this literary experience. Relating back to Fryes overall essay statement, literature is an extent of the imagination going beyond our objective world, creating a work for our imagination to extend into. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our International Baccalaureate Languages section.

Educational Philosophy Outline and Rationale Essays

Educational Philosophy Outline and Rationale Essays Educational Philosophy Outline and Rationale Essay Educational Philosophy Outline and Rationale Essay Educational Philosophy Outline and Rationale Philosophies pertaining to education have changed with the influence of cultural and environmental changes throughout the years. In this paper an outline and rationale will describe my personal educational philosophy. My philosophy will also expand to support the components of the metaphysics, epistemology, axiology, and logic that aided in its development. My personal mission statement as a future educator will also be included in the paper. There were several components of the philosophies that I wholeheartedly embraced; while other components were rejected due to my inability to relate to their ideals. My Personal Philosophy as it Pertains to Education Outline I. The Educators Responsibility A. Always maintain that every child has the ability to learn. 1. Maintain that all children learn at different paces 2. Provide a stimulating methodology that is muli â€Å" layered for to approach broad spectrum of students. 3. Provide a fun and engaging atmosphere towards learning B. Ascertain that the child is able to mastery a skill at the given level C. Procure additional tutorial support for students in need. D. Maintain a positive regards towards all aspects of teaching II. Student and Parents Responsibility A. Students 1. Be physically and mentally present 2. Active participation with the teacher and their peers. B. Parents 1. Team up with the teacher to maintain and active venue of communication that will enable the resolution of any problems or concerns. 2. Participate in the PTA. 3. Provide a stable environment for learning in the home. III. The School Administration and Community Responsibility A. To actively select and promote a solid curriculum 1. Built on results that support a broad spectrum of students needs. 2. That is engaging and filled with manipulative along with standardized test. 3. To promote creativity along with logic in the classroom. B. Work together in tandem to established extracurricular educational programs. 1. Tutorial Support beyond the afterschool programs. 2. Science walks in the residential areas of the students. 3. Work alongside volunteer of parents to create relevant programs that pertain to core fundamental skills C. Enlist local businesses to create a learning internship for students to learn in real time. Metaphysic is based on nature of the reality. I embrace the pragmatist approach that provides a hand on learning experience. This creates the foundation of reality that is relevant to a student. Though I do agree that a studentâ„ ¢s perception can affect his learning I do not accept that their reality changes as decreed by the existentialist philosophy. Neither am I on broad with the realist philosophy because I believe that it is based on rote memorization. Epistemology deals with knowledge and knowing of a subject. The philosophies that emphasize this idea the most Pragmatism and Progressivism; where knowledge is enhance in an applied and interactive manner. Axiology deals with the values that aided in the composition. In this component the philosophy of Idealism resonates with me. A core belief and value is that all students have a right to an education and exposed to additional resources when needed. If a student is failing it is our responsibility to identify th e what and the why to determine a resolution. Unlike a the realist philosophy true learning can be noted when the child has the ability to determine what methodology works best for him. Logic deals with the ability to reason. In order to reason effectively a student must be have a basis created from the fundamental skills math, science, and the ability to read which reflected in the philosophy of essentialism. Unlike the rote memorization that is emphasized in the philosophy of realism; essentialism ensure that all students equip the basics skills to best of their ability. My personal philosophy of education is utilized on a daily basis whether I am acting as role of a caregiver with developing toddlers, facilitator in the tutorial centers established in the community, or a life skills specialist. My goal and ultimate desire is to communicate to each child that they have the ability to learn in some shape, form, or fashion. The words I can are embraced wholeheartedly and they are encouraged to try and try again. My methodology is infused with praises and affirmations to help them exceed beyond their imaginations. When the theoretical application fails we use real life examples and apply a hands on interactive concept. Overall my ultimate desire that I can create a movement to get all parties involved in the success of the student, i.e. the community, the parents, and beyond. My mission statement is: That I will always be fully present, ready, and able to help direct the student his highest potential. To always seek assistance beyond myself when I am unable to assist my student effectively. To always be open and willing to learn from continued education, from my peers, and my students. To explore different methodology that will assist each child in developing their logical and creative thinking. To always remember that the impact I make today which a child; will create the social infrastructure of the future. Too close I have outlined my personal philosophy as it pertains to education and relations to the concepts underline by metaphysics, epistemology, axiology, and logic. I have provided the philosophies that I most embrace and the ones that I do not believe in. Sighted examples of the philosophies and how I utilize them currently. Finally I have provided the mission statement that I utilize in my field of work. . References Gutek, G., (2009) New perspectives on philosophy and education. New Jersey: Pearson. Ornstein, A. C. Levine, D.U. (2008). Understanding the Teaching Profession Historical and Philosophical Foundations-Foundations of Education. Boston New York : Houghton Mifflin Company.

By Fredrik Erixon of the European Centre for International Political Economy

By Fredrik Erixon of the European Centre for International Political Economy Russia s command to fall in the World Trade Organisation ( WTO ) , filed in 1993, has been the longest accession saga in the history of the universe trade organic structure. Yet now, after bilateral trades with the US and the European Union that secured their support for the rank command, Russia looks set to fall in the pantheon of rules-based planetary capitalist economy at some point following twelvemonth. This is welcome intelligence. Russia would profit from being portion of the WTO nine. Its exports will non acquire much of a encouragement because they are dominated by the hydrocarbons and minerals ( stand foring more than two tierces of entire exports ) and they are already traded at zero or really low duties. But Russia will profit from lower monetary values of imported consumer and industrial goods, and, hopefully, from an addition in foreign direct investing ( FDI ) . If the Kremlin besides decides to follow the WTO regulation book, rank will assist to restrain Russia s fickle trade policy, particularly its regular descents into protectionism. Naturally, that would be of value for exporters to Russia ( and for importers of Russian goods, excessively, as Russia on a regular basis uses export revenue enhancements ) , but the biggest donee would be Russia itself. The biggest casualty of protectionism is ever the state that imposes such steps. Other states would profit from Russian WTO rank through a decrease in duties mean duties will travel down from 12-14 per centum to around 8 per centum and from an betterment in their predictability. The sectors that will profit specifically from a decrease in duties are civil aircraft, building, agricultural and scientific equipment, and medical devices. Russia will necessitate to present greater transparence ( and less favoritism ) in its system for merchandise criterions, licences and other alleged non-tariff barriers ( NTBs ) . Furthermore, sectors dependent on rational belongings, such as chemicals and biotechnology, will profit from holding resort to the WTO s agreement on rational belongings rights ( TRIPS ) to train Russia s shambolic IPR policy. Finally, foreign Bankss and insurance houses will be granted bigger chances to make concern in Russia. But there are besides hazards and downsides to holding Russia as member of the WTO. The biggest hazard is that the Kremlin will merely ignore opinions against Russia in the dispute-settlement system, the anchor of the WTO. As the WTO itself can non implement opinions that require policy alteration in a state, the system requires that states respect the authorization of the dispute-settlem ent organic structure and that bigger and more powerful states avoid playing power games with smaller states over opinions. The instance for esteeming opinions is simple: it is in everyone s involvement that states adhere to hold regulations. The failing is the same as for all systems that depend on enlightened involvement for a common good: some may liberate drive on the system in the belief that it benefits them, at least in the short term. And if some are free-riding, others will follow. And the system will unknot. This hazard is underlined by Russia s recent history of flashing international understandings ( and, as in the instance of the Energy Charter Treaty, retreating from understandings ) in the belief that no 1 would hold the bravery to contend the Kremlin to the acrimonious terminal. Russian rank will besides add a new bed of troubles for WTO dialogues, like the current Doha Round. Russia will be portion of the protectionist wing of the rank and will defy in countries that are cardinal to universe trade today and in future, like liberating up services trade, cutting ruddy tape that prevents trade, and restricting the freedom to subsidise domestic houses at the disbursal of foreign rivals. It will besides implement the resistance to turn toing old issues, like cut downing or extinguishing duties on consumer and industrial goods. Russia s fabrication sector is weak it merely represents 6-7 per centum of Russia s export and suffers from the Dutch disease: the heavy trust on hydrocarbon exports have pushed the existent exchange rate to such a grade that the fabrication sector has suffered. Many industries are saddled with old Soviet engineerings, and they survive on subsidies and boundary line protectionism. There are positive marks that Russia is acute to alter its economic theoretical account. The new Kremlin rhetoric on modernisation and the denationalization plans suggest that energy and state-based economic dictatorship is on a downward tendency. The new morning in its rank command for the WTO is besides a good mark. But the marks are far excessively few to be cheerful about Russian economic policy. Like earlier, optimism over the WTO accession can shortly switch to pessimism. The old theoretical account is entrenched in the Kremlin economic mind and there are many powerful figures that dislike the thought of being constrained by international understandings or increased foreign competition. President Medvedev has now secured the support from the US and the European Union for its WTO command. Now he needs to take the battle with Kremlin co-workers and oligarchs. That may go a far bigger job. Fredrik Erixon is manager of the European Centre for International Political Economy ( ECIPE ) , an economic think armored combat vehicle based in Brussels

Integrative Strategic Plan for Davis Service Group Plc Essay

Integrative Strategic Plan for Davis Service Group Plc - Essay Example The selected location also possesses most of the required features which are favorable to the company’s business operations. The report is intended to analyze the decision of entering the Australian market on the basis of several factors such as the analysis of the market and industry, the economic analysis, and other associated factors. A strategic approach has to be taken towards entering the new market of Australia. Â  The language barrier is one of the critical issues observed in the expansion of the business operations of Davis Service Group. As the company has its base in the UK where the language used for communication is different from that of Australia. Though English is considered as the global language for business communications. Â  The difference in currency and their corresponding values in the international market have also proved to be another major barrier. The currency of UK is pounds while in Australia the common currency used for business transactions is Australian dollars. The difference in their values poses a major impact on the business which could lead to a potential loss of export and import of goods and raw materials. Â  For the company, it is also very crucial to consider the cultural difference between the two nations. There could be a wide difference between the behavioral aspects of UK and Australia. So the company is required to consider the Australian culture prior to entering the Australian market. Priorities have to be given to local differences which could be found within the nation of Australia. The company has to give equal importance to all of those cultures and traditions. Â  Certain legal and administrative differences between the two nations also create a barrier which includes government policies, rules and regulations of the nation which is different from that of UK. Several international norms and standards are maintained to reduce such difference to promote international business operations. Â  

Role Models and how their leadership traits impact your personal Term Paper

Role Models and how their leadership traits impact your personal character and behaviors - Term Paper Example In this paper, I intend to discuss how my grandmother became my role model and how her ethical and transformational leadership qualities inspired me to positively change my behavior, attitude and thinking skills. I had always been inspired by how my grandmother’s strategic behavior motivated others to step into her shoes. She was German by birth. She had a strong military background and as every one of us knows, militia always has strong discipline, morals and standards. My grandmother had such strict ethical standards that no one could ever think of doing wrong to another person in front of her. She had a high morale and always told us not to get afraid of hardships and calamities. Her greatest possession was the German heritage whose best qualities she tried to inculcate in her offspring. She was strong both physically and mentally and thus was a great source of strength for the entire family. She had great leadership qualities. She had a brawny vision which enabled her to s olve problems with ethical values. It was the honesty of her inner self that made her do wise and just decisions. She was able to give voice to her vision in front of opposition. She was brave enough to make people appreciate her ethical directions and values.

Pharmacy Essay Example for Free

Pharmacy Essay This is funny to admit at this stage of my pre-registration year, but I do not fully understand the role of a pharmacist. Those of you who read my blogs may be thinking – â€Å"why? † Surely after four years at university and four months of pre-registration training I should understand the role of the pharmacist. But the truth is I don’t, and here’s why. Throughout my pharmacy degree I gathered experience in four sectors that pharmacists can work in which included; academia, hospital, community and the industrial sector. My first experience was in academia and I could understand the role of a pharmacist here. Being a registered pharmacist in this sector is not necessary. This is because an academic career does not necessarily involve the practise of pharmacy. However specific areas e. g. pharmacy law and ethics and pharmaceutics, may require registration and a more clinical focus. In general, teaching is a part of the pharmacy code of ethics under section 7 ‘Take Responsibility For Your Working Practices’ with 7. 3 stating ‘Contribute to the development, education and training of colleagues and students, and share your knowledge, skills and expertise’. The academic sector for a pharmacist’s career therefore makes sense and the day-to-day role can be described as that similar to any other academic. The next area in which I worked was community. Primarily the pharmacist’s role here is to ensure the essential services stated by the PSNC are being delivered. From my understanding, this is what defines the pharmacist’s role in community. The location of community pharmacies will dictate what additionally services are available and the pharmacists may or may not have to adapt to these roles e. g. flu vaccination, smoking cessation. The role of a community pharmacist can be very clear cut. In my opinion, the role could be expanded to increase collaboration with General Practitioners and Commissioning Groups and I feel there are areas where community pharmacists can have more of an impact. As a pre-registration student, I look at the future of community pharmacy with great interest regarding the potential roles of pharmacists. During my third year I obtained some hospital experience. The main motivation in my application for the hospital pre-registration was to discover the role of a clinical pharmacist. I remember how surprised I was when I compared the clinical check of community pharmacist to that of a hospital pharmacist a subject a fellow blogger has been discussing. In hospital the role of the pharmacist varies greatly and it is here where I get lost. There are clinical pharmacists who spend their time at a ward based level working within multi-disciplinary team. There are medicines information pharmacists who spend time researching and finding answers to medicine related queries. There are pharmacists who work in the production unit managing and ensuring products are of satisfactory quality. There are pharmacists who work in clinical trials, mental health, risk management, teaching, information technology, service managers†¦ The list seems endless. It is here where I struggle to define the role of a hospital pharmacist because with the variety of the jobs comes different skill sets and therefore a hospital pharmacist becomes indefinable. Clinically (which is the area I’m interested in), hospital pharmacy has expanded greatly developing roles for prescribers and consultant pharmacists. But these roles are few and far between depending on funding, need, and all sort of other complications/variables. With the observations and knowledge I have so far, I feel the role of hospital pharmacist has no set definition and there can be future innovative roles for pharmacists in this sector. A conference and placement in industry was my final experience before my pre-registration year. Shadowing pharmacists within industry was interesting however there is no set definition of an industrial pharmacist. This is because apart from being a Qualified Person, being a pharmacist in industry has, in my opinion, no benefits to that of any other scientists. Pharmacy does however cover the whole of a medicines journey (from medicinal chemistry right up to issues surrounding patient compliance) and pharmacists in industry will have that awareness that could be used to their advantage. To conclude, I have discussed my opinions and thoughts regarding the role of a pharmacist in various sectors. I have not mentioned the role of a pharmacist in the primary care setting or within media or politics. However, hopefully I have demonstrated that, in my opinion, the role of the pharmacist cannot be defined because it varies massively.

The Scramble for Africa Essay -- World History

The Scramble for Africa is one of the best examples of colonization in world history. Europe alone managed to colonize the entire African continent in a period of roughly twenty five years, spanning from 1875 to 1900. The quest for power by European nations was only one of the driving forces for this race for colonization. The geographical location and the natural resources to be exploited in certain regions of the continent were important factors in the race for land. Another factor that contributed to the colonization of Africa was the end of the slave trade. The need for new capitalism to exist between Europe and Africa after the call for the abolition of slavery became great. European traders were searching for new avenues for making money, as well as new ways to exploit of the natives of Africa, due to their perceived weakness as a people, made the quest for occupation relentless by European nations. Political, economical and social ambitions all led Europe to partition Africa i nto separate colonies and the race to see what country could establish a monopoly in Africa became a European obsession. There is a consensus among historians that the political Scramble for Africa was begun by King Leopold of Belgium. King Leopold had been a supporter of Henry Stanley, a Welsh journalist and explorer of Africa. In the late 1870s, Stanley had been on another expedition to the Africa, mapping the Congo River from its origins to the ocean. Leopold had developed an interest in the Congo region in Africa. He sent Stanley as his private envoy of his International African Association in an effort to establish a foothold in the Congo region. Leopold had not been forthcoming in his intentions to Stanley. He led Stanley to believe it was his ... ... the continent of Africa resulted in millions of deaths, from mistreatment to disease to outright warfare waged against them. In many regions, the European countries raped the land of its nature resource with little concern for the land or the people who lived on the land. Although their were some positive improvements such as better transportation and healthcare, African cultures were destroyed and lives were lost in the process of European colonization. Works Cited Achebe, Chinua. Things Fall Apart. New York: Anchor Books, 1994. Print. â€Å"Democratic Republic of Congo profile.† BBC News. BBC. Web. 10 January 2012. â€Å"Imperialism.† Merriam-Webster’s Collegiate Dictionary. 11th ed. 2008. Print. Ogbaa, Kalu. Understanding Things Fall Apart: A Student Casebook to Issues, Sources, and Historical Documents. Westport, Connecticut: Greenwood Press, 1999. Print.

The Flowering Response of the Rice Plant to Photoperiod

The Flowering Response of the Rice Plant to Photoperiod A REVIEW OF THE LITERATURE 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 Revised 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. Today IRRI is one of the 13 nonprofit international research 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 United Nations, the International Bank for Reconstruction and Development (World 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 number of donors including: the Asian Development Bank, the European Economic Community, the Ford Foundation, the International Development Research Centre, 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 agencies of the following governments: Australia, Canada, China, Denmark, France, Federal Republic of Germany, 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 may be reproduced, stored in retrieval systems, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of IRRI. This permission will 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 will not diminish the bona fide use of its research findings in agricultural research and development. 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 area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. ISBN 971-104-151-0 CONTENTS Foreword Introduction 1 Rice as a Short-day 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 Days from Photoinductive Treatment to Flowering 12 Biochemical Changes During Photoinduction 12 Effect of Temperature on the Flowering Response to Photoperiod 13 Measurements and Methods of Testing Photoperiod Sensitivity 14 Date-of-Planting Experiments 15 Ecology and Photoperiodism 17 Terminology Used in Describing Photoperiod Sensitivity 20 Inheritance of Vegetative Growth Duration 23 Problems in the Study of the Rice Plant? fs Photoperiodism 25 Summary 26 Appendix 28 Bibliography 38 Foreword This review, first published in 1969, has been an important reference in understanding the rice plant. It has had a small but continuing demand. Many new reports on the flowering response of the rice plant have been published since the first edition. More than 100 publications were included in the third edition; this edition includes another 103 publications. For ease of reading, numbers have been used to cite the references. This review was prepared with the cooperation of the IRRI Library Staff and the technical assistance of Mr. Romeo M. Visperas, and edited by Ms. Emerita P. Cervantes. M. S. Swaminathan Director General Introduction Photoperiod influences several aspects of plant growth. Some of its effects on rices have been reviewed by Best (24), Gwinner (111), Katayama (192), Morinaga (316), Sircar (439), and Wagenaar (534). This review is primarily concerned with the effect of photoperiod on the flowering of the rice plant. It includes more than 500 papers on the photoperiodism of rice, most of which are available at the International Rice Research Institute library. Several contributions in Japanese have been translated into English and also are available at the International Rice Research Institute library. A bibliography is given at the end of this review; not all papers listed were cited in this review but were nevertheless included as future references for interested workers. Rice as a short-day plant Rice is sensitive to photoperiod . long-day treatments can prevent or considerably delay its flowering. Rice cultivars exhibit a wide range of variation in their degree of sensitivity to photoperiod (87, 254, 319, 357, 531, 563). Figure 1 shows these variations, ranging from the very sensitive to the nearly insensitive. 1. Response curves of three representative types of rice cultivars. 2 The flowering response of the rice plant to photoperiod Most of the wild species of Oryza and many of the primitive cultivated rices ( O. sativa L. ) are photoperiod sensitive and may be classified as short-day plants. Most papers agree on such a classification, and therefore in this review, rice will be considered as a short-day plant. It also will be classified into photoperiod-sensitive and photoperiod-insensitive types, the latter showing a low response or a slight delay in flowering 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 multiple cropping system characteristic of progressive agriculture. There have been reports of cultivars whose flowering is delayed 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 have delayed its flowering by 10 d, but this delay is relatively short and may be the result of nonphotoperiodic factors, such as low light intensity or relatively high temperature. The delay caused by short-day treatments ranged from 7 to 12 d in the Charnock and Panbira cultivars using an 8-h photoperiod (443), about 9 d in B. 76 (303), and 13 d in T. N. 32 and T. A. 64 (287). Many of the reported long-day and intermediate cultivars were found to be short-day cultivars in subsequent testing (522). The apparent long-day reaction of Heenati resulted from using photoperiods shorter than the optimum, which delayed flowering (34). Some rices may have been classified as long-day plants because inadequate facilities were used in testing the photoperiod reaction. The range of photoperiods used has been limited, usually involving only two treatments. In some instances, the classification was based on field reaction to different planting dates (98). Short-day-treated plants were often compared with plants grown under natural day lengths (291, 303, 304). The difference and changes in temperature and the photoperiods used have made it difficult to interpret the data intelligently. As will be discussed later, many photoperiod response curves show that photoperiods longer 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 reported on the photoperiodism of the rice plant (see Appendix). However, more than 400 cultivars have been critically 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 can be divided into three stages: 1) the vegetative growth phase, from germination to panicle initiation; 2) the reproductive 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 while the ripening phase ranges from 30 to 35 d. Both phases are relatively constant, although low temperatures have been known to prolong them and high 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 duration generally varies greatly and which largely determines the growth duration of a cultivar, especially 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 juvenile growth stage of the plant, which is not affected by photoperiod. It is only after the BVP has been completed that the plant is able to show its response to the photoperiodic stimulus for flowering . this is the PSP of the plant. Figure 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 response 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 controlled by different 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 planted 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 tropics, however, it has a much shorter BVP than when grown in the temperate areas (Fig. 1). In classifying cultivars based on BVP, most of those from the low 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 duration of the vegetative growth phase at optimum day length. The BVP also has been measured by subtracting 35 d from the growth duration (sowing to flowering) of plants grown at the optimum photoperiod (526). This assumes that the period from panicle 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 heading 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 reported in the literature has varied 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 possible 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 longer 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 less 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 possible 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 nonspecific 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 reported to increase with age (142, 190, 195, 202, 205, 347, 512). The increase in leaf area accompanying 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 point, but increases gradually with increasing age. Studying this aspect, Suge (460) found that the growth inhibitors in the plant were greatly reduced as the plant grew. However, it is not known whether these inhibitory substances are essentially involved 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. Using 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 formed are completely insensitive to photoperiod. 2) The first leaves formed have very low sensitivity that they do not reach an adequate level 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 required 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 stimulus or the st imulus cannot reach the growing point. Photoperiod-sensitive phase The PSP or the eliminable phase (186) is the growth stage indicative of the rice plant's 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 longer. Under continually long photoperiods, 6 The flowering response of the rice plant to photoperiod some cultivars have been reported to remain vegetative even after 12 yr of growth (234). The PSP is usually determined by subtracting the minimum growth duration from the maximum growth duration 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+. Besides 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 critical 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 the 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 critical photoperiod of 13 h. Tainan 3 has an optimum photoperiod of 12 h but no critical photoperiod because it flowered under all photoperiods. The critical photoperiod determines whether a cultivar will flower when planted at the usual time at a certain latitude, while the optimum photoperiod determines whether it will flower within a reasonable time if planted during a period with longer days 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 during 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 indications 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 below 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 between 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 light period (140). Plants receiving 8-h light and varying dark periods from 16 to 64 h showed inhibited shoot apex conversion (219). This was ascribed to inadequacy of carbon compounds for synthesis of requisite 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 presence 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 sunrise 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 dark period is one possible photoinductive cycle of a short-day rice cultivar. The minimum number of photoinductive cycles necessary to initiate the panicle primordium 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 (190, 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 different 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 photoinductiv e 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 insufficient photoinductive cycles sometimes form panicles but no emergence occurs (see Table 1) (92, 122, 344, 512, 526). A difference of two 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 received sufficient photoperiodic stimulus for panicle initiation and emergence (1 16). In another experiment, long photoperiods had no effect on the terminal 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 differentiated but Table 1. Response of 30-d-old BPI-76 seedlings given 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 pri mordium 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 received 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 plant (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 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 conserved 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 nonflowering 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 quality 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 period 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 twilight 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. Takimoto 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 waste 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 tried in rice. The blue-violet part of the spectrum has been shown 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. Red 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 short-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 exposed 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 needed 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 period Sensitive 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 interruption 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 photoperiod The 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 cycles 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, unpublished 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 marks the actual change from the vege tative to the reproductive phase. Instead of using this as a basis, 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, however, 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 content 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 only 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. Generally, 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, Fuke had considered the effect of temperature during the photoinductive period. He used snow to lower the darkroom temperature, but the 5-10? †¹C decrease had little effect on heading. Temperatures above 20? †¹C to 29? †¹C 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? †¹C). 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? †¹C inhibited initiation and bud development (156). Floral induction, however, is possible at 15? †¹C (341) but not at 12 or 40oC (115). Because many test plants died in the growing process, 15? †¹ C is assumed 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 night temperature of 24. 4oC was found 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 cultivar 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 other 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 Chandraratna's (34, 37, 40), measured sensitivity based on response curves obtained by plotting the time from sowing to floral initiation 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 described 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 experiments Day 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 cropping 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? †¹ N, and Konosu, 36? †¹ N) day ength increases and then decreases during the cropping season (Fig. 5). At lower latitudes (Taipei, 25? †¹N, and Los Banos, 14? †¹N) day length decreases during the main growing season. Near the equator (Bukit Merah, 5? †¹N) 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, the 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 17 These 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 161 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 duratio n 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 studying 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 ofdistribution, 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 can 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 tropics. 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 ingro wth 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 comparison between the monthly mean temperatures and mean photoperiods shows that 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 photoperiod Sensitivity 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 ceases 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 left 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, harvesting 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 resistant 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 adaptability 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 duratio n 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 wet 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, an d 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 useful 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 photosensitive 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 duration The 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 dominance 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 period 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

Our freedom to make ethical choices is only an apparent freedom Essay

Agent Smyth: Why, Mr. Anderson? Why do you do it? Why get up? Why keep fighting? Do you believe you’re fighting for something? For more than your survival? Can you tell me what it is? Do you even know? Is it freedom? Or truth? Perhaps peace? Yes? No? Could it be for love? Illusions, Mr. Anderson. Vagaries of perception. The temporary constrects of a feeble human intellect trying to desperately to justify an existence that is without meaning or purpose. And all of them as artificial as the Matrix itself, although only a human mind could invent something as insipid as love. You must be able to see it, Mr. Anderson. You must know it by now. You can’t win. It’s pointless to keep fighting. Why, Mr. Anderson? Why? Why do you persist?! Neo: Because I choose to. In every person the most basic desire of all is to be free, being able to act at will, not under compulsion or restraint. As I democratic society, we like to think of ourselves of being 100% free, but we are not. In every choice we make there are compulsions and restraints inflicting on the choices we have ever made from the beginning. The older and more independent we appear to be the more of these constraints we are compelled with. These choices we make can be applied to morality. There are many ways in which our freedom, in reality, is limited. By law we are restricted to acts that systems of government deem acceptable. Social acceptance means the majority to act within a bracket of normality and within bounds of what is socially acceptable. If I wanted to go to school naked on every Friday I would socially and lawfully be unable to this. Therefore I am not free to express myself due to external laws forced upon me against my free will. However even though these laws are in place I still have the power to break them therefore making me free. Merovingian: Please Mon Cherie, I have told you, we are all victims of causality. I drank too much wine, I must take a piss. Cause, and effect. Au revoir. Causality also means that I a person can never truly become free. If I already know the consequences of an action then my choice has already confined. For example I would like to throw microwaves off motorway bridges but I know that this may cause innocent motorists to die therefore I don’t. The mind with which we make our decisions has been influenced by a whole range of external factors. These must reduce our moral responsibility and hence be restricting of true freedom. Personal and psychological differences within people will provide them with different abilities and hence different freedoms and limitations. People can only act in the way that their personalities allow them, by causing them to react to situations in a specific way. But what if free will is non-existent and we are only convinced we have self-control because devices in fact control us beyond our own perception. In this case everything is pre determined and the choices we face are pre decided for us leaving us with the illusion that we have chosen ourselves and decided our own fate; exercised free will. Morpheus: Everything begins with choice. Merovingian: No, wrong. Choice is an illusion created between those with power, and those without Hard determinism, considers everything in the present to be directly caused by events that preceded them. Everything including the actions we take and the choices we make are caused directly by another event. Each human mind is the product of its experiences and in every situation will react according to what it has learnt, in a similar way to a computer that has been programmed. However this links back with responsibility, if a human was already pre destined to perform a certain task they should receive no praise for correctness in taking the action, as what they have done was done not out of free will, but because they were programmed, or already decided. The action says nothing about the moral worth of the person as it had an external cause, and was not done through free will and intention. The hard determinist view that everything is decided by a constant line of causes, and that humans are not free simply because every thing we supposedly decide is already caused and so determined, ultimately means that human free will is an illusion. Free will is something we feel we experience when making decisions and choosing but is really non-existent, the actions we partake in are already set and what we feel we decide is irrelevant to anything that actually happens. For example if I sat down in a room I would be free to step out of until I realised the door was locked. I am free to make this choice but when but my choice is irrelevant as I unable to do anything about it. Determinism removes this moral responsibility and so removes ethical decisions. However with freedom comes responsibility. Libertarianism presents the opposite idea that we are completely free therefore giving people total moral responsibility. The existence of human free will are largely based on the defined different between ones personality and ones moral self. While we have a sense of freedom, a sense deliberating over our options. Because of this, they would argue that universal causation is not necessarily relevant to human actions. They do not deny any influence to the human mind that could have an effect on the way in which one might act, but they claim that there is still a large aspect of freedom of choice involved. Oracle: Bingo! It is a pickle, no doubt about it. Bad news is there’s no way if you can know whether I’m really here to help you or not. So it’s really up to you. You just have to make up your own dam mind to either accept what I’m going to tell you or reject it. Candy? Neo: Do you already know if I’m going to take it? Oracle: Wouldn’t be much of an Oracle if I didn’t. Neo: But if you already know, how can I make a choice? Oracle: Because you didn’t come here to make the choice, you’ve already made it. You’re here to understand why you made it. I thought you’d’ve figured that out by now. Neo: Why are you here? Oracle: Same reason. I love candy. Libertarians views are idealistic they provides to us with the ultimate goal of being totally free. But if take this freedom then we should also be prepared to accept the responsibility that comes hand to hand with. For example if I allow my son to watch pornography involving a 15 year old and he turns out to be a paedophile than I would be totally to blame for these consequences. As with all workable theories finding the right balance is essential. Soft determinism is the third deterministic view and one where determinism and free will are completely compatible. It describes that we are morally responsible for our action although some are determined. Therefore the decisions we are free and able to make in our own minds count as the causes by which everything is made to occur. The midway position suggests that some of our actions are conditioned while others have a complex number of causes. For example there could be a number of reason why someone does not eat food, whether it be a diet, religious beliefs, famine or lack of money. â€Å"Real freedom,† in the question seems to suggest the freedom to take these fully conscious, and reasoned ethical decisions without relying a higher power. To conclude I believe that as human beings we are not free. Our behaviour and morals will always be determined social acceptance, laws, causality, and upbringing. However we have the power in ourselves to break down these constraints and become free, if a door is locked then break it down, if I want to throw microwaves of motorways then I will do so. When we become totally free this leads to anarchy and chaos. When it comes down to it is not a case of whether we are free or not it is whether we choose to be. Architect: Precisely. As you are undoubtedly gathering, the anomaly is systemic, creating fluctuations in even the most simplistic equations. TV Screens: You can’t control me! I’m gonna smash you to f***ing bits, I’m gonna show you, you can’t make me do anything. Neo: Choice, the problem is choice