Effects of Tiller Removal on Spring Barley

Abstract

Barley (Hordeum vulgare L.) plants normally produce tillers, many of which do not survive to bear grain. Three field experiments were conducted to test whether tillers compete with the main shoots for resources under field conditions. The specific objective was to assess whether mechanical removal of tillers influenced crop and main shoot yield, yield components, and water use under two watering regimes (rainfed only and rainfed plus supplemental irrigation). The experiments were conducted at three locations in different years. In all experiments tiller removal tended to reduce grain yield on a unit area basis. However, in two experiments the decrease in spike number resulting from tiller removal was partly offset by an increase in the grain yield of main shoots for both watering regimes. Specific main shoot yield components enhanced by detillering were kernel number per spike and mass per kernel. Main shoots also initiated more spikelet primordia per spike when tillers were removed. Tiller removal resulted in only a small reduction in the amount of water evapotranspired. These results are consistent with the hypothesis that tillers compete with the main shoot early in its development, reducing its inherent productivity. Genotypes that produce relatively few tillers may be preferred to optimize main shoot productivity and yet maintain the compensatory ability needed for successful production in most environments where barley is commercially grown.