Nitrogen uptake and remobilization in maize hybrids differing in leaf senescence

Abstract

Maize (Zea mays L) is an important cereal crop with multiple purposes. Stay-green varieties have been considered a major progress in breeding for high yield. Nevertheless, few studies have been conducted to evaluate the influence of nitrogen (N) levels on N uptake, N remobilization in relation to grain yield and N concentration in stay-green versus early-senescing hybrids. Field studies were undertaken in P. R. China on an Ustochrepts soil to determine the effects of N levels and hybrid differing in leaf senescence on grain yield, N concentration, N uptake, N remobilization and residual N in vegetative tissues in 1996 and 1997. Results showed that ND108 (a stay-green hybrid) had greater yields than TK5 (an intermediate hybrid) and ZD120 (an early-senescening hybrid) under both high (225 kg N ha⁻¹) and low N supply (0 in 1997 or 45 kg N ha⁻¹ in 1996, respectively). ND108 took up more N than the two other hybrids. Grain N concentration of ND108 did not decrease significantly under low N compared to high N in 1997. However, in 1996 grain N concentration of ND108 decreased with reduced N supply, since post-silking N uptake was reduced by the shorter grain filling duration. N remobilization efficiency in vegetative tissue was higher in the early-senescening hybrid (ZD120) than in the stay-green hybrid (ND108). The N retained in the stover at harvest was much higher in ND108, which can lead to a deficit of soil N for the next crop when the stover is not returned to the field.