CROP DEVELOPMENT UNDER IRRIGATION 165 



pale green and soft. In the case of corn, it has been shown, 

 also, that with little water the leaves are narrow and 

 pointed, whereas with much water they are wide and 

 more rounded, and their screw-like turning increases. 

 Wilms showed that, in the case of potatoes, a small amount 

 of water produced a thick leaf containing long cells and 

 few stomata or breathing pores per square inch, while 

 much water produced thinner leaves containing short 

 cells and many more stomata per unit of surface. That 

 is, in color, form, consistency, cell-structure, and other 

 properties, both the leaves and the stems respond definitely 

 to varying quantities of water. This emphasizes the power 

 of the irrigation farmer, by merely varying the quantity 

 of water applied to plants, ta change the color of the plant, 

 the stiffness of the stalks, the shape of the leaves, and 

 many other similar properties. Every part of the plant is 

 changed to correspond with the water at the disposal of 

 the plant. 



Of more direct interest, however, to the farmer, than 

 the size and shape, is the relative proportion of leaves, 

 stalks or other parts of a crop. The leaves of plants, 

 whether large or small, are usually of higher nutritive 

 value than the stalks. It is desirable therefore, when a 

 crop is grown for forage to secure the largest proportion 

 of leaves. The few available investigations make it clear 

 that the proportional parts of leaves and stalks are dis- 

 tinctly affected by the quantity of water used in irriga- 

 tion. In the Utah experiments, with wheat, oats and peas, 

 the proportion of leaves in the whole plant became higher 

 and higher as the water was increased, whereas with 

 potatoes the reverse occurred. When the leaves and 

 stalks alone were compared, it was found that, as with 

 potatoes, the less water used the leafier were the plants. 



