44 



Plant Physiology' 



the other hand, it is especially necessary under the dry 



conditions which 

 prevail in that region 

 to have a deep surface 

 mulch. It is of inter- 

 est to note that under 

 these circumstances 

 shallow cul t i va tion 

 early and deep culti- 

 vation later has 

 proved the most satis- 

 factory method. 



Kafir corn and sor- 

 ghum produce roots 

 of the same general 

 type and distribution 

 as those of corn, but 

 the former are tough 

 and fibrous and the 

 laterals are beset with 

 numerous, fine, feed- 

 ing roots which are 

 to be found between 

 the main laterals and 

 the surface. The up- 

 per eighteen inches of 

 soil is very completely 

 filled with these fine 

 roots. Moreover, the 



FIG 9. Root-system of a potato grown to 

 maturity in a deep, narrow box. [After 

 Rotmistrov.J 



GTOWS late in 



the season, and the 



