Selection Criteria for High Nitrogen Use Efficiency in Wheat (Triticum aestivum L.) Parents and their F1 and F2 Progenies

Developing nitrogen use efficient (NUE) genotypes of wheat could reduce crop N fertilizer requirement. However, selection for NUE alone can be difficult and less efficient than associating it with one or more of selection criteria. The aim of this study was to determine selection criteria for improving NUE in wheat genotypes and their F1 and F2 progenies under contrasting N environments. The results of this study indicated that high nitrogen uptake efficiency (NUPE), grain yield/plant (GYPP), grains/spike (GPS), spikes/plant (SPP), and grain protein content (GPC) of parents, high NUPE, GYPP, biological yield/plant (BYPP), GPC and GPS of F1's and high NUPE, harvest index (HI), BYPP, SPP, GPC and GPS of F2's have significant and strong correlation coefficients with high nitrogen use efficiency (NUE). It is observed that NUPE is commonly correlated with NUE in all studied genotypes (parents, F1's and F2's). Similarly, GPS is also strongly correlated with NUE. Moreover, SPP is strongly correlated with NUE in parents and F2's. A negative and significant correlation existed between NUPE and NUTE for parents under high-N (-0.82), F1's under high-N (-0.73) and low-N (-0.36) and F2's under high-N (-0.91) and low-N (-0.81). The traits NUPE, GYPP, SPP and GPS showed high heritability in narrow sense and could therefore be offered to wheat breeders for use in breeding programs as selection criteria for improving nitrogen use efficiency.