Morpho-physiological traits associated with maize crop adaptations to environments differing in nitrogen availability

Abstract

The use of genotypes with improved performance for nitrogen (N) capture and use would be of great benefit through reducing production costs and pollution risks in maize cropping. The identification of morpho-physiological traits responsible for a better behavior in a target N environment is useful for cultivar selection, and become crucial for maize breeding improvement. This study analyzed, in a set of Argentinean commercial hybrids of maize, the grain yield (GY) variability in response to soil N availability at several locations representative of the main maize production region of Argentina during 2003–2004 growing season. The objectives of this work were to: (i) detect environmental groups for GY responses, (ii) identify morpho-physiological traits that were associated to winner genotypes in each detected environmental group, and (iii) assess genetic correlations between those traits. To generate more variation in soil N availability two N-fertilizer rates were applied in each experimental site (0 and 250 kg N ha −1, except for Balcarce where only 250 kg N ha −1 was tested). Morpho-physiological traits included in the analysis were related to N and radiation capture, use and partitioning, plant architecture, and leaf senescence. Grain yield components were also included. As expected, environment (E) effect explained the higher portion of GY variation (i.e., 82%), but genotype (G) and G × E interaction (GE) also significantly contributed (i.e., 9% each). Three environmental groups for GY were identified according to N availability. Morpho-physiological traits related to resource capture, use, and partitioning during the post-silking period are proposed as desirables for broad adaptation. In turn, a high N partitioning to grains after silking was associated with good hybrid behavior under high N availability and warm climate. On the other hand, a better grain yield performance when N became more limited appeared strongly related to an efficient canopy to sustain resource capture up to maturity. More studies are required in a wide range of environments to confirm identified traits and underlying physiological mechanisms. Nevertheless, our findings highlight the existence of differences in ideal plant-type for environments differing in N availability to be considered in maize breeding programs.