Physiological and Ecological Studies on the Clipping of Herbage Plants. : 1. Relation between stubble, root starvation and shoot regrowth by clipping in Italian rye grass.

Abstract

Relation between photosynthetic (leaf) and reserving (stubble and root) organ after clipping in Italian rye grass was studied. Parallel with advancing new top growth after clipping, a rapid reduction in quantity of stubble and root reserves took place, especially greater reduction occuring in the stubble. Thus 1-2 weeks elapsed before sufficient photosynthetic tissue was produced to enable carbohydrate production in excess of those required by current growth. Close correlations were found between the regrowth of photosynthetic tissue after the clipping and the accumulation of stubble, root reserves at the time of clipping. In the cooler climates stubble-root reserves at the time of clipping was more abundunt and the new shoot growth immediately after the clipping was more rapid than in the warmer climate. And the decreasing of dry weight, percentage of carbohydrate and nitrogen of root-stubble after clipping was more rapid at the higher temperature than the lower one. The nitrogen contents of stubble and root were relatively unaffected by clipping, although nitrogen level was kept always higher in the clipping plants than in the unclipping. In the new shoot growth the nitrogen level increased, and reached maximum about 1∼2 weeks after clipping.