Plants as Affected by Insufficient Water. 143 



insufficiently supplied with water. Potatoes usually ripen 

 earlier in dry seasons than in wet ones. If the drought 

 is sufficiently severe or sufficiently prolonged, diminu- 

 tion or failure of seedage results. 



230. Toughness of Plant Tissues Results from 

 Drought. The crispness and tenderness that give qual- 

 ity to salad vegetables, as celery, lettuce, radish, etc., 

 due to a distended condition of their cell-walls, is largely 

 wanting when the water supply during growth has been 

 insufficient. 



Insufficient water during growth injures the qual- 

 ity of tobacco. Leaves thus affected have a peculiar 

 spotted appearance when cured, and do not "sweat" 

 properly. 



231. Crumbling of the Surface Soil (cultivation) 

 tends to Prevent Drought, since it greatly lessens the 

 points of contact in the soil particles, and thus inter- 

 feres with the rise of the soil water by capillary attrac- 

 tion to the surface where evaporation chiefly occurs. 

 An air-dry surface layer of crumbled soil also tends to 

 prevent evaporation by keeping the soil cooler beneath. 

 A puddled crust on the surface of the soil, as is formed 

 by rain on soils containing clay, tends, on the other 

 hand, to restore capillary action and thus to promote 

 evaporation. Some gardeners cultivate their hoed crops 

 as soon as possible after rains for the main purpose of 

 breaking this crust and thus stopping the capillary 

 action. 



Cultivation is also beneficial by aerating the soil (93). 

 The roots of plants should never be forgotten nor 

 ignored in cultivating crops (109). 



