Yoshida - 1981 - Fundamentals of Rice Crop Science

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MINERAL NUTRITION OF RICE 153 3.18. Changes with time in pH and concentration of zinc in the soil solution of flooded soils (Forno et al 1975). 3.19. Relationship between amounts of zinc added to the nutrient solution and the dry weights of shoots and roots of IR8 and IR184-67 when harvested 37 days after germination (Forno et al 1975).
154 FUNDAMENTALS OF RICE CROP SCIENCE concentrations in the soil solution alone cannot explain why rice suffers from zinc deficiency on Kala Shah Kaku soil. 3.10.3. Effects of bicarbonate and organic acid on zinc absorption Bicarbonate and organic acid may accumulate to toxic levels in submerged soils depending on soil pH, organic matter content, and soil temperature. A concentration of 15 or 30 mM HCO 3 - causes a reduction of about 70% in the 65 Zn content of the shoots, but only a reduction of about 5% in the roots (Fig. 3.20). These results suggest that the effect of HCO 3 - on zinc transport to the shoots is greater than its effect on absorption by the roots. HCO 3 - has a similar effect on zinc transport from root to shoot in wheat (Forno et al 1975a). In calcareous and other alkaline soils, bicarbonate concentrations exceeding 10 mM are common during 3-6 weeks after submergence. Thus, the inhibitory effect of bicarbonate on zinc absorption is likely to be one of the major causes of zinc deficiency in alkaline soils. The effect of acetic acid on zinc absorption varies with pH. At pH 4.5, acetic acid at a concentration of only 0.3 mM reduces the 65 Zn in the shoots by 70% and in the roots by about 77%. At concentrations of 10 and 30 mM, plants wilt, and the 65 Zn activity in the shoot and root tissues is reduced by 94% and 97%, respectively (Fig. 3.21). At pH 7.5, however, additions to the culture solution of acetic acid up to 3 mM have no detectable effect on 65 Zn uptake; the effects are small even at a concentration of 10 mM. However, at 30 mM, the 65 Zn activity in the roots is reduced by 51%, while that in the shoots is reduced by 75%. 3.20. Effect of NaHCO 3 on the 65 Zn absorbed by the rice variety IR8 at pH 7.3 (Forno et al 1975a).
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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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66 FUNDAMENTALS OF RICE CROP SCIENC
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100 FUNDAMENTALS OF RICE CROP SCIEN
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Page 203 and 204: 5.1. PHOTOSYNTHESIS 5.1.1. Photosyn
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PHOTOSYNTHESIS AND RESPIRATION 205
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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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