Genetic variability in nitrogen use efficiency of spring barley
Increasing costs of N fertilizers and the negative impact of excessive N on the environment have made improvement in nitrogen use efficiency (NUE) a desirable goal in barley (Hordeum vulgare L.) breeding. Seventeen replicated trials, each consisting of 15 to 20 genotypes, were performed across different environments in Alberta, Canada from 1998 to 2007 to determine genetic variability in NUE. Further, 25 genotypes were grown at six environments in 2007 for analysis of the pattern of genotypic variation for NUE. Analysis of variance revealed significant effects of genotype and environment on NUE. The majority of the phenotypic variation in NUE was accounted for by genotypic variance and heritability estimates for this trait ranged from 0.5 to 0.86. Genotypes H97097001001, H96014002, ‘Vivar’, and ‘Xena’, were superior in NUE, yielding 47 to 48 kg kg–1 N as compared to about 35 kg kg–1 N yield for the relatively inefficient genotypes. There was no clear distinction between two-rowed and six-rowed types in NUE, but rather significant differences were observed among genotypes within each spike-type group. Reduction in N fertilizer requirements in barley while maintaining yield may be achieved through breeding by targeting increased yield potential in association with higher NUE.