COTTON SOILS AND CLIMATIC ADAPTATIONS 79 



roots. This abnormal development causes the plants 

 to wilt rapidly and shed their foliage and fruit during 

 the droughty conditions which so often prevail in late 

 summer. 



Experience has shown that if April, May, and June 

 have been favorable, cotton can withstand considerable 

 rain during the period from the middle of July to the 

 middle of August. Excessive rain during the latter period 

 of growth and maturity induces a rank growth of weed 

 to the detriment of the fruit. 



88. Temperature and sunshine. — In considering the 

 influence of temperatiu-e and sunshine upon the develop- 

 ment of cotton one must divide the hfe-history of the 

 plant into twp periods. The first is that in which the 

 plant is in full vegetative growth, extending from 

 planting time until about the first or middle of Au- 

 gust. The second period is that in which the vegeta- 

 tive growth is checked, the plant diverting its energies 

 to the production of fruit from the previously stored 

 material. 



During the first period the mean daily temperatures 

 increase rapidly. Throughout the greater part of this 

 period cotton requires a very warm or even hot atmos- 

 phere, provided there is suflBcient humidity in the atmos- 

 phere to prevent excessive transpiration. It is also de- 

 siralble that the daily range in temperature should be 

 uniform during this first period; otherwise the vegetative 

 growth is hkely to be checked. ' 



In the second period the temperature decreases rapidly 

 and there is usually a greater range of temperature be- 

 tween day and night. This is very favorable to the 

 maturing crop as it serves to check the vegetative growth 

 and induce fruiting. It is highly important that the 



