Yoshida - 1981 - Fundamentals of Rice Crop Science

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CLlMATlC ENVIRONMENT AND ITS INFLUENCE 107 2.21. Monthly balance of precipitation minus evapotranspiration at Los Baños, 1967–1971 (Yoshida 1978). Table 2.15. Average water requirement of a paddy field in the Philippines. a Wet season Dry season Daily solar radiation b (cal/cm 2 ) 367 463 Daily evapotranspiration (mm) 4 5 Seepage and percolation (mm/day) 2 4 Daily total (mm) 6 9 Monthly total (mm) 180 270 a Yoshida(1979). b Average values for wet season (July–November) and dry season (January–May).
108 FUNDAMENTALS OF RICE CROP SCIENCE October 1969, and August 1971. Thus, the rainfed rice, even in monsoon Asia, is exposed to frequent water shortages — the major reason for unstable rice production in the rainfed rice regions. 2.5.13. Effect of water deficit on growth and yield Water stress at any growth stage may reduce yield. The most common symptoms of water deficit are leaf-rolling, leaf-scorching, impaired tillering, stunting, delayed flowering, spikelet sterility, and incomplete grain filling. The rice plant is most sensitive to water deficit from the reduction division stage to heading. Three days of drought at 11 days and at 3 days before heading reduces yield significantly by causing a high percentage of sterility (Table 2.16). Once sterility occurs, there is no way for the plant to compensate. On the other hand, water deficits during the vegetative stage may reduce plant height, tiller number, and leaf area, but yield will not be affected by the retarded growth if water is supplied in sufficient time to permit the plant’s recovery before flowering. 2.5.14. Effect of water excess on growth and yield Depending on topography and rainfall patterns, low-lying areas may be subjected to different water depths and to different durations of high water. These areas may be tentatively divided into the following categories (Vergara et al 1976): a. Deep-water areas. The water is between 150 cm and 400 cm deep and usually remains in the field for 3-4 months. Special varieties known as floating rice are planted in these areas. Large areas of floating rice are found in Bangladesh, northeast India, and Thailand. b. Flood areas. Flood areas include the margins of deep-water areas, low-lying areas, and tidal swamps. The water is less than 150 cm deep and usually remains in the field for several months. Tall indica varieties, known as flood rice, are commonly used. Table 2.16. Effects of drought on yield and yield components of rice a Drought treatment Yield Panicles Sterility Filled 1000- (days from (g/hill) (no./hill) (%) spikelets grain wt heading) (%) (g) –55 18.0 11 –51 16.8 11 –43 19.5 11 –35 20.0 12 –27 17.0 11 –19 15.7 11 –11 6.5 10 – 3 8.3 10 + 5 16.5 11 +13 20.5 10 No stress 22.7 10 a Matshushima (1962). 11 9 14 11 12 34 62 59 10 7 15 70 21.8 66 22.0 65 21.5 60 20.5 54 20.2 52 20.8 29 21.6 38 20.9 59 21.9 66 22.5 65 21.9
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FOREWORD Rice is vital to more than
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CONTENTS Foreword Preface GROWTH AN
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3.2. Adaptation to Submerged Soils
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4.5. Corrective Measures for Nutrit
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1 .1. OUTLINE OF THE LIFE HISTORY T
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GROWTH AND DEVELOPMENT OF THE RICE
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Page 65 and 66: GROWTH AND DEVELOPMENT OF THE RICE
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5.1. PHOTOSYNTHESIS 5.1.1. Photosyn
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PHOTOSYNTHESIS AND RESPIRATION 197
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Photosynthetic characteristics Meas
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A traditional tall variety vs an im
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Table 7.6. An example of high yield
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REFERENCES AGRICULTURAL POLICY STUD
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Yoshida - 1981 - Fundamentals of Rice Crop Science

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