Comparative leaf growth and grain yield responses of hybrid and open-pollinated maize genotypes to nitrogen fertilizer application

Field experiment was conducted at the Teaching and Research Farm of the Faculty of Agriculture, University of Ilorin, Bolorunduro (8 29'N, 4 35'E) in the southern Guinea savanna of Nigeria, to compare the leaf growth and grain yield responses of hybrid and open-pollinated maize genotypes to nitrogen fertilizer application. Extension growth of leaves at nodes 5 to 15 on the plant was measured at 4 day intervals from emergence until maximum length of each was attained. Rates and duration of leaf extension at each node were determined from linear regression of leaf length against the chronological time in days after planting. Grain yield and yield components were determined at maturity. Application of N fertilizer had greater effects on leaf growth and hence on grain yield than the genotype effects. Grain yield increased with increasing N application due to enhanced leaf growth in both the hybrid and open-pollinated maize cultivars, thereby confirming the importance of leaf growth on grain yield of cereal. Positive correlation was obtained between grain yield and leaf extension rate (LER) and the final leaf length, while extension duration showed inverse relationship with grain yield. The results of this study therefore suggest that for the full advantage of hybrid over the open-pollinated to be achieved, leaf growth of the hybrid maize has to be improved. Keywords: Leaf growth, grain yield responses, nitrogen application, maize genotypes. Agrosearch Vol. 8 (1&2) 2006: pp. 13-2