Nitrogen uptake and utilization efficiency of European maize hybrids developed under conditions of low and high nitrogen input

Maize varieties with improved nitrogen(N)-use efficiency under low soil N conditions can contribute to sustainable agriculture. Tests were carried to see whether selection of European elite lines at low and high N supply would result in hybrids with differential adaptation to these contrasting N conditions. The objective was to analyze whether genotypic differences in N uptake and N-utilization efficiency existed in this material and to what extent these factors contributed to adaptation to low N supply. Twenty-four hybrids developed at low N supply (L x L) were compared with 25 hybrids developed at high N supply (H x H). The N uptake was determined as total above-ground N in whole plants, and N-utilization efficiency as the ratio between grain yield and N uptake in yield trials at four locations and at three N levels each. Highly significant variations as a result of hybrids and hybrids x N-level interaction were observed for grain yield as well as for N uptake and N-utilization efficiency in both hybrid types. Average yields of the L x L hybrids were higher than those of the H x H hybrids by 11.5% at low N supply and 5.4% at medium N level. There was no significant yield difference between the two hybrid types at high N supply. The L x L hybrids showed significantly higher N uptake at the low (12%) and medium (6%) N levels than the H x H hybrids. In contrast, no differences in N-utilization efficiency were observed between the hybrid types. These results indicate that adaptation of hybrids from European elite breeding material to conditions with reduced nitrogen input was possible and was mainly the result of an increase in N-uptake efficiency.