Although improved nitrogen (N) use is a desirable goal of maize breeders, little is known about its inheritance. Thus, our objectives were to investigate the inheritance of several plant traits related to N use and to examine the relationship of these traits to grain yield. Fifteen single-cross hybrids produced from a diallel set of crosses among six inbred lines were grown at Champaign, Illinois, USA, in 1992 and 1993. Plants received either no supplemental N (low N) or an N rate considered sufficient for maximum yield (201 kg N ha-1, high N). While significant hybrid variation was detected for all traits, the correlation with yield depended on the N supply. Harvest index, kernel number, N accumulation, and N utilization efficiency were all positively correlated with grain yield when plants were grown at low N, while only biological yield and N accumulation were correlated with yield at high N. Changes in harvest index, kernel number, and N utilization efficiency were most closely related to N-induced increases in yield. With minor exceptions, the mean squares for general and specific combining abilities (GCA and SCA) were significant for all measured traits at both levels of N. Based on the magnitude of difference between these mean squares, the majority of genetic effects were associated with GCA, indicative of additive genetic effects. Identification of traits related to high yield at low levels of N and the elucidation of their inheritance have important ramifications in maize breeding programs attempting to develop more N efficient genotypes.

English

9802|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection