Selection criteria in grass breeding. IV. Effect of nitrogen and spacing on yield and its components

Abstract

1. The effects of applied nitrogen (0, 200, 400, 600, and 800 lb. per acre per annum) and spacing (widely spaced plants and simulated monoculture swards) on average yields and yield components of eight clones of Lolium perenne are reported for four harvests taken each year during 1962 and 1963.2. During both years, higher yields per unit area were obtained from swards than from spaced plants; the degree of difference varied from harvest to harvest.3. A greater effect of nitrogen on yield was detected in 1963 than in 1962, an effect especially marked in swards at lower rates of nitrogen application. A highly significant nitrogen x spacing interaction on yield was detected in 1963.