RADIATION USE EFFICIENCY BY MAIZE HYBRIDS OF THE MEXICAN HIGH VALLEYS

Abstract

The interception and use of solar radiation by maize (Zea mays L.) at canopy level, are two processes that directly influence the production of biomass and grain yield. The aim of this work was to study the effect of planting date, population density and nitrogen doses on intercepted radiation (IR), radiation use efficiency (RUE) and grain yield of highlands maize hybrids. The experiments were carried out in the 2008 Spring-Summer season in Toluca, México. Three maize hybrids (‘H48’, ‘H50’ and ‘Condor’), two sowing dates, (intermediate (4/11/08) and late (30/04/08), two nitrogen fertilization levels (30 and 180 kg N ha^-1) and two population densities (6.25 and 9.25 plant m^-2) were evaluated. For each combination of planting date and N level, an experiment was carried out under a split plot design with three replications, assigning the population density to main plots and hybrids to subplots. Results indicated that agronomic management practices and the genetic potential of hybrids significantly influenced (P ≤ 0.05) on radiation use efficiency and grain yield of these highland maize hybrids. When N doses and population density increased the intercepted radiation by the plant canopy also increased, and this enhanced the growth conditions for setting a larger number of grains per unit area. Grain yield of the three hybrids was explained by number of grains per unit area rather than by average grain weight. The hybrid ‘Condor’ produced a larger number grain per area unit.