Plants as Affected l>y Insufficient Water. 143 



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

 drought is sufficiently severe or sufficiently prolonged, 

 diminution 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 quality 

 of tobacco. Leaves thus affected have a peculiar spot- 

 ted 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). 



