Selection criteria in grass breeding. V. Performance of <i>Lolium perenne</i> genotypes grown at different nitrogen levels and spacings

Abstract

1. The yields and yield components are recorded for selected clones of Lolium perenne , grown at different levels of applied nitrogen (0, 200, 400, 600 and 800 lb. of nitrogen per acre per annum) and at two spacings (widely spaced plants and simulated monoculture swards). Four harvests were taken in each of the two years 1962 and 1963. 2. In both years there were significant and consistent differences between clones in their drymatter production per unit area, detectable at both spacings. A genotype x spacing interaction was detected only in 1962. A genotype x nitrogen interaction at some harvests was not found on annual totals.