Genotypic Variability in Morphological and Physiological Traits among Maize Inbred Lines—Nitrogen Responses

Abstract

A better understanding of the physiological processes related to nitrogen (N) metabolism in maize (Zea mays L.) inbred lines is important for increasing the efficiency of breeding programs targeting low-N environments. This study analyzed the response to contrasting N availability of morphophysiological traits in a set of 12 maize inbred lines, from different origins (USA and Argentina) and breeding eras (from 1952 onward). Traits included in the analysis were related to canopy structure, light interception, shoot biomass production, and grain yield. Our results indicate that (i) the start of N effects on canopy size was more related to a threshold crop leaf area index (about 2) than to a given leaf stage (i.e., V n ), (ii) the light attenuation coefficient value was not affected by N availability, (iii) variations in kernel number per plant were explained by prolificacy (r 2 5 0.59), and (iv) differences in harvest index were related to kernel number per plant (r 2 5 0.77). The most important finding of our research was the detection in some inbreds of a particular response of kernel number to plant growth rate around silking, different from the general model established for hybrids. In these inbreds an additional effect of N availability was detected as reduced kernel set at a given plant growth rate under N deficient conditions (i.e., reduced reproductive efficiency). This result highlights the need of more research on reproductive sink development in this type of germplasm.

Multi-attribute responses of maize inbred lines across managed environments

“…Three-mode PCA allowed to improve our understanding of the genotype and G · E effects for multiple traits across a set of maize inbred lines and helped overcome the restrictions found when using univariate ANOVA (D'Andrea et al 2006). Although univariate ANOVA revealed the existence of significant G · E interactions, three-mode PCA allowed the description of the genotype-specific responses for multiple traits associated with the main environmental contrast, i.e., the G · Y interaction, contributing to the understanding of physiological bases of grain yield determination.…”

Timing and rate of nitrogen application influence grain quality and yield in maize planted at high and low densities

“…Spatial variability in optimal N rates is mainly due to variations in soil N supply and N uptake efficiency, rather than to variations in crop demand for N, and variable‐rate application of economically optimal N fertiliser rates increases net profit by an average of $ 38 per hectare 12. Reduction in N rate reduces grain yield by 43–74% and number of kernels per plant by 33–65% 13…”

Plant density and nitrogen effects on growth dynamics, light interception and yield of maize

“…Spatial variability in optimal N rates is mainly due to variations in soil N supply and N uptake efficiency, rather than to variations in crop demand for N, and variable-rate application of economically optimal N fertilizer rates increases net profit by an average of $38 ha -1 (Scharf et al 2006). Reduction in N rate reduces grain yield by 43-74% and number of kernels plant 71 by 33-65% (Andrea et al 2006). Increasing the plant density for short-season maize increases the cumulative intercepted photo-synthetically active radiation, which compensates for a short growing season to achieve high yield with substantially less irrigation (Edwards et al 2005).…”