TABLE OF CONTENTS XV 



C. THE RELATION OF WATER TO PLANTS 



CHAPTER VI 



PAGES 



CONDITIONS DETERMINING THE USE OF SOIL MOISTURE BY 



PLANTS '. 108-126 



Absorption of water by roots, 109 Transpiration, 110 

 The initial percentage of soil moisture, 111 Distribution 

 of water in the soil, 114 The effect of time, 115 The 

 depth of soil, 116 Physical composition of soils, 117 

 Chemical compositions of soils, 118 Plowing, 120 

 Cultivation, 121 Manuring, 121 Vigor of plant, 121 

 Root-system, 122 Age of plants, 122 The kind of crop, 

 123 The seasons, 124. 



CHAPTER VII 



THE WATER-COST OF DRY MATTER . 127-157 



Carbon-assimilation, 128 Plant age and carbon-assimi- 

 lation, 129 Conditions of growth, 130 The transpira- 

 tion ratio, 131 The seasons, 136 The soil, 137 

 Mineral food or soil fertility, 139 Cultural operations, 

 141 The vigor of the plant, 143 Varying quantities 

 of water, 144 Maximum yield with given quantity of 

 water, 151 The nature of the crop, 154 Summary, 155. 



CHAPTER VIII 



CROP DEVELOPMENT UNDER IRRIGATION 158-172 



Response to irrigation, 159 Proportion of roots, 160 

 Proportion of leaves and stems, 163 Proportion of heads 

 and grain, 166 Other plant parts, 169. 



