Yoshida - 1981 - Fundamentals of Rice Crop Science

More documents

Recommendations

Info

PHYSIOLOGICAL ANALYSIS OF RICE YIELD 249 Table 7.7. Effects of carbon dioxide enrichment before and after heading on growth and grain yield of IR8. a Sugar Crop growth and rate starch b (g/m 2 per wk) in Treatment Yield leaf Before After Grain Grains Filled (t/ha) sheath heading heading wt c (10 3 /m 2 ) spikelets and culm (mg) (%) (%) Dry season Control 9.0a d 22 173a 99a 23.1a 45.7a 74a CO 2 before 11.6 b 30 224 b 157 b 25.9 b 50.9 b 77a heading e CO 2 after 10.9 b 22 173a 147 b 25.1 c 44.6a 86 b heading f Wet season Control 5.7a 18 122a –14a 24.3a 28.8a 78a CO 2 before 7.7 b 25 179 b 8ab 26.2 b 34.1 b 81ab heading e CO 2 after 6.9 b 18 122a 38 b 26.1 b 29.5a 85 b heading g a Yoshida (1976). b As glucose. c Dried at 75°C for 3 days. d Any 2 means followed by the same letter are not significantly different at the 5% level. e For 30 days. f For 28 days. g For 29 days. there appears to be an optimum number of spikelets for maximum grain yield under certain conditions and attempts to increase spikelet number per square meter will not result in increased grain yield. An estimation of potential yield suggests that solar radiation per se is not limiting to the current yield level unless adverse conditions exist. It is highly desirable that the above question be clarified experimentally. Among climatic factors, the CO 2 concentration in the atmosphere limits rice yield. Yields can be increased by CO 2 enrichment in plastic enclosures (Yoshida 1976). However, it is not practical to increase the CO 2 level around plants growing in a field because the additional CO 2 would diffuse rapidly into the open air and virtually none would be available to the plants. The CO 2 enrichment, however, can be used as a tool for analyzing the factors limiting yield. Table 7.7 shows that grain yield was increased from 9 to 11.6 t/ha by preflowering enrichment and to 10.9 t/ha by postflowering enrichment in the dry season; it was increased from 5.7 to 7.7 t/ha by preflowering enrichment and to 6.9 t/ha by postflowering enrichment in the wet season. The preflowering enrichment increased grain yield by increasing the spikelet number per unit of land area and weight per grain. The field-grain percentage remained the same as that for control plants. Because plants subjected to CO 2 enrichment before flowering were exposed to the same environment as control
250 FUNDAMENTALS OF RICE CROP SCIENCE Table 7.8. Effects of carbon dioxide enrichment before and after flowering on grain yield and yield components of IR8, IRRI, 1972 dry season. a Time of CO 2 enrichment In relation Develop- Filled Grain to flowering mental Yield c Grains c spikelets c wt c,d (days) stage b (t/ha) (10 3 /m 2 ) (%) (mg) Control e – 10.2 c 40.4 c 85.4 b 23.7 d –33 to –24 I 11.3 b 45.0ab 84.2 b 23.8 d –24 to –14 II 11.4 b 43.4 bc 86.2 b 24.7 c –14 to 0 III 10.2 c 38.9 c 85.8 b 25.0 bc –33 to 0 I–III 13.3a 48.2a 87.6 b 25.7ab 0 to 30 IV 11.5 b 38.9 c 92.4a 26.0a a Yoshida (1976). b l = neck-node differentiation to differentiation of secondary rachisbranch, II = differentiation of spikelets, III = differentiation of pollen mother cell, reduction division stage to flowering, IV = flowering to harvest. c Any means followed by the same letter are not significantly different at the 5% level. d Panicles have been dried at 75°C for 48 h, threshed, then grains were placed at 50°C for 12 h and weighed. e None. plants after flowering, the results may imply that solar radiation during ripening did not limit grain filling and, hence, the additional spikelets produced by the CO 2 enrichment were well filled in both the dry and wet seasons. Further CO 2 -enrichment experiments in the dry season demonstrated that preflowering enrichment increased grain yield from 10.2 to 13.3 t/ha, i.e., 30% increase over the control, whereas the postflowering enrichment increased grain yield by 10% (Table 7.8). The same experiment also revealed that the effective stages for CO 2 enrichment before flowering is the time from the neck-node differentiation to the spikelet differentiation stages. In the preflowering enrichment, the yield increase is attributed to increased spikelet number, and, to a lesser extent, also to increased grain weight. In the postflowering enrichment, the yield increase resulted from increased filled-spikelet percentage and increased grain weight. These two experiments suggest that the sink size, largely determined by spikelet number per unit of land area, is not completely limiting. Postflowering enrichment increased the grain yield by increasing filled-spikelet percentage and weight per grain. However, the magnitude of such grain yield increases seem distinctly limited because both filled-spikelet percentage and grain size cannot be increased greatly. The total spikelet number per unit of land area is greatly increased by the CO 2 enrichment or possibly by increased photosynthesis before flowering. If the total spikelet number can be increased, neither photosynthetic capacity nor light nor CO 2 concentration after flowering is likely to limit grain-filling at Los Baños, Philippines. Thus, to increase yield further, some way of increasing the spikelet number or yield capacity (spikelet number × potential weight per grain) must be found.
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:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
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 209 and 210: PHOTOSYNTHESIS AND RESPIRATION 201
Page 221 and 222: 214 FUNDAMENTALS OF RICE CROP SCIEN
Page 223 and 224: A traditional tall variety vs an im
Page 257: Table 7.6. An example of high yield
Page 261 and 262: REFERENCES AGRICULTURAL POLICY STUD
show all

Yoshida - 1981 - Fundamentals of Rice Crop Science

Create successful ePaper yourself

Delete template?

Save as template?