Yoshida - 1981 - Fundamentals of Rice Crop Science

More documents

Recommendations

Info

22 FUNDAMENTALS OF RICE CROP SCIENCE 1.21. The growth of individual leaves on the main culm of the rice plant (adapted from Tanaha 1954). At early stages of leaf growth, weight increases are associated with elongation. After the completion of elongation, the weight continues to increase because of an accumulation of proteins and starch and an increase in cell wall materials such as hemicellulose. The leaf weight decreases at later stages of growth because proteins, sugars, and starch are translocated to upper leaves. 1.4.3. Leaf growth of a crop The leaf growth of a rice crop, as a whole, can be measured in terms of the weight of whole leaves per unit of ground area, and of leaf area of whole leaves per unit of ground area. Because leaves intercept incident solar radiation, leaf area index is widely used in the research of crop photosynthesis and growth analysis. Leaf area index (LAI) is defined as: sum of the leaf area of all leaves LAI = . (1.1) ground area of field where the leaves have been collected The same unit must be used for both leaf area and ground area. Even though a leaf has two surfaces, it is customary to measure only one. In crops such as wheat, all the exposed green tissues, including leaf blades, leaf sheaths, and culms, are measured for LAI. In rice, however, it is common to measure only the area of leaf blades because photosynthesis by sheaths and culms is negligible. LAI values imply the magnitude of leaf area relative to ground area. Thus, LAI = 2 means that a crop has a leaf area twice as large as the ground area. If all the leaves are arranged flat in one plane parallel to the ground with no dead space, the leaves of a crop with LAI = 1 covers the ground surface completely. But all the leaves are neither flat nor in the same plane. Hence, LAI values greater than 1 are needed to rover the ground surface. LAI increases as growth advances and reaches a maximum at around heading when the rice plant has its 5 largest leaves. After heading, however, LAI declines as the lower leaves die (Fig. 1.22).
GROWTH AND DEVELOPMENT OF THE RICE PLANT 23 1.22. Leaf area index (LAI) and light transmission ratio (LTR) of 4 varieties under 0 and I50 kg N/ha at successive growth stages, 1967 dry season (Yoshida and Ahn 1968). A rice crop can attain maximum LAI values of 10 or greater at heading time. The critical LAI value at maximum crop photosynthesis is about 5-6. Because LAI is the sum of the area of whole leaves, it can be analyzed as follows: LAI = average leaf size × number of leaves per shoot × number of shoots per hill (or plant) × number of hills (or plants) per unit of ground area. (1.2) In agronomic practice, spacing and nitrogen application are the two major factors influencing leaf area growth under most conditions. Spacing determines the number of hills per unit of ground area, and both nitrogen application and spacing affect average leaf size, number of leaves per shoot, and number of shoots per hill. In addition, tillering capacity of a variety modifies the influence of spacing and nitrogen application. Several techniques are available for estimating leaf area (Yoshida et al 1976): 1) use of electronically operated area meter, 2) blueprint-gravimetric method, and 3) leaf length-width measurement. Recent advances in electronics have produced an instrument to accurately measure the area of any irregular shape. The leaf lengthwidth measurement is the easiest among the three and it uses a correction factor ( K ). The leaf area is given as: Leaf area (cm 2 ) = K × length (cm) × width (cm) (1.3) The correction factor used for rice leaves ranges from 0.67 to 0.80, depending on variety and growth stage. The value of 0.75, however, can be used for all growth stages except the seedling stage and maturity.
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 31: GROWTH AND DEVELOPMENT OF THE RICE
Page 75 and 76: 66 FUNDAMENTALS OF RICE CROP SCIENC
Page 83 and 84:
74 FUNDAMENTALS OF RICE CROP SCIENC
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:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
A traditional tall variety vs an im
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
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?