56 



Development and Activities of Roots of Crop Plants. 



Marquis wheat and barley were scarcely less striking, the greater development 

 of the root system at Peru being consistent for all crops examined. Nor is 

 this difference correlated with height-growth, for the average height-growth 

 of the several crops at Lincoln during 1919 and 1920, especially when the 

 lowland plats are included, was not unlike that at Peru. Moreover, the 

 differentiation of root systems into a more or less distinctly shallow portion 

 and a more deeply penetrating one was much more marked at the latter 

 station. The root habit of the cereals at Lincoln was consistent during the 



years 1919 and 1920, both of which, except for a late, cold spring in 1920, had 

 growing-seasons very favorable for crop development. Just how much the 

 modification of the root habit at Peru was due to the drought which prevailed 

 during 1919, and how much it was affected by other factors, such as soil 

 textm-e, fertility, etc., will be further discussed when the 1921 root growth 

 at the several stations is compared in chapter 5. A summary of earlier inves- 

 tigations on the root development of crop plants in the true prairie may be 

 found in chapters 6 and 7 of " Root development in the grassland formation." 



