Yoshida - 1981 - Fundamentals of Rice Crop Science

More documents

Recommendations

Info

NUTRITIONAL DISORDERS 189 ance for nutritional disorders in various crops (Wright and Ferrari 1976). A similar attempt in rice is under way (Ponnamperuma 1976a, 1977). To overcome a nutrient deficiency by varietal improvement depends on the assumption that a soil contains a certain amount of the nutrient to be used. One variety may be better able to use a soil nutrient than another. In fact, the contribution of varietal tolerance to rice grain yield was estimated at 0.5–0.8 t/ha for phosphorus deficiency, 0.5–1.5 t/ha for zinc deficiency, and 0.2–0.7 t/ha for iron deficiency at yield levels of 2.5–4.0 t/ha (Mahadevappa et a1 1980). When the plant’s requirement is large relative to the soil nutrient reserve, however, its differential ability may not contribute much. In theory, once a soil nutrient is depleted, varietal tolerance is no longer effective. This consideration may apply to deficiencies of most nutrients except iron. Iron is a micronutrient for higher plants but it is a macroconstituent of soil. Under such conditions, varietal improvement of the plant’s ability to use soil iron is a logical approach to the cure of iron deficiency in plants. One more point worth considering is to compare gains and losses for the varietal improvement as a means to overcome a nutrient deficiency in the soil. A long-term phosphate experiment indicates that grain yield decreases with time unless the crop receives phosphate fertilizer (Fig. 4.1). When no phosphate is applied, the total soil phosphorus content in both the surface soil and in a furrow slice decreases as a result of the crop’s removal of phosphorus. The total soil carbon and nitrogen contents also decrease. Studies on nitrogen fixation by azolla (Watanabe et al 1977) and blue-green algae (Mitsui 1960) show that phosphate application is necessary to increase nitrogen fixation. If an efficient phosphate user (rice variety) is grown without phosphate fertilizer, the nitrogen fixation by azolla and 4.1. Effect of phosphate application on rice yield in the long-term fertilizer experiment, Shiga, Japan. 1930–1957 (Shiga Pref. Agric. Exp. Stn. 1961).
190 FUNDAMENTALS OF RICE CROP SCIENCE 4.2. Nutritional disorders of rice in Asia (Tanaka and Yoshida 1970). blue-green algae will be minimal and there will be decreases in soil fertility. If phosphate fertilizer is applied, there is no need to improve the rice variety for phosphorus absorption. Varietal difference in phosphorus absorption from soil becomes negligible even at low levels of applied phosphorus (see Fig. 3.17). Varietal improvement as a means of correcting a toxicity problem is worth trying because correction by other means is often difficult and costly. 4.6. NUTRITIONAL DISORDERS OF RICE IN ASIAN COUNTRIES Many nutritional disorders of rice have been reported from various rice-growing countries (Table 4.9, Fig. 4.2). These nutritional disorders can be related to soil conditions (Table 4.10). The following summarizes the soil conditions under which the nutritional disorders may occur. The reader is advised to refer to Chapter 3 for more details. Flooded soil undergoes reduction, and the concentration of iron may increase to a level high enough to induce iron toxicity. Iron levels in the soil solution are largely determined by the soil pH and the content of readily decomposable organic matter. Low pH and high organic matter content are associated with high iron concentrations.
Page 3 and 4:
FOREWORD Rice is vital to more than
Page 5 and 6:
CONTENTS Foreword Preface GROWTH AN
Page 7 and 8:
3.2. Adaptation to Submerged Soils
Page 9 and 10:
4.5. Corrective Measures for Nutrit
Page 11 and 12:
1 .1. OUTLINE OF THE LIFE HISTORY T
Page 13 and 14:
GROWTH AND DEVELOPMENT OF THE RICE
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
66 FUNDAMENTALS OF RICE CROP SCIENC
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
100 FUNDAMENTALS OF RICE CROP SCIEN
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148: 138 FUNDAMENTALS OF RICE CROP SCIEN
Page 197: 188 FUNDAMENTALS OF RICE CROP SCIEN
Page 203 and 204: 5.1. PHOTOSYNTHESIS 5.1.1. Photosyn
Page 205 and 206: PHOTOSYNTHESIS AND RESPIRATION 197
Page 207 and 208: Photosynthetic characteristics Meas
Page 223 and 224: A traditional tall variety vs an im
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Table 7.6. An example of high yield
Page 259 and 260:
Page 261 and 262:
REFERENCES AGRICULTURAL POLICY STUD
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
show all

Yoshida - 1981 - Fundamentals of Rice Crop Science

Create successful ePaper yourself

Delete template?

Save as template?