40 



BULLETIN 1405, U. S. DEPARTMENT OF AGRICULTURE 



practically identical where the leafage was removed once (plant 1) 

 and where it was harvested twice (plant 2) in a season. Plant 3, 

 on the other hand (representing the removal of the herbage four 

 times in a season), shows a comparatively poorly developed root 

 system after a single season's treatment. The same general results 

 are seen in Nos. 1-A, 2-A, and 3-A, representing plants treated 

 for three seasons. Numbers 1-A and 2-A show practically the same 

 luxuriant root development, whereas No. 3-A shows a weak root 



system which is capable of absorbing only a relatively small quantity 

 of water and soluble salts and of storing little plant food. 



By assigning a value based as nearly as possible upon the calories 

 of the essential constituents of the roots, chemical index data are 

 derived which appear to show the relative quantity of food mate- 

 rials in the roots of average plants variously treated (fig. 16). In 

 mountain brome, the plants whose leafage was harvested four times 

 in a season for three successive years show an index figure of less 



