Low nitrogen tolerance in tropical quality protein maize (Zea mays L.): value of predictive traits

Abstract

In the tropics, maize (Zea mays L.) is often grown under low N conditions. Information on the respective role of N uptake and partitioning at anthesis in determining grain yield under low N is scarce. Senescence traits have been proposed as secondary traits to select for low N tolerance, but the stability of their association with yield under different environmental conditions has been rarely described. In the present study we analyzed the associationro between grain yield, N uptake and partitioning at anthesis, dry matter matter partitioning, and senescence traits during two seaons in QPM (quality protein maize) hybrids. Association between grain yield and N uptake at anthesis, when found, was mainly explained by a close relationship between grain yield and above-ground biomass. No relationship was found between grain yield and N partitioning at anthesis. In both seasons grain yield was significantly positively associated with ear to aboveground biomass and ear to tassel weight ratios. The magnitude of the correlation between grain yield and senescence traits highly depended on climatic conditions.