EVALUATION OF SEVENTEEN MAIZE (Zea mays) POPULATIONS FOR TOLERANCE TO LOW NITROGEN IN NITROGEN DEFICIENT ENVIRONMENTS

Abstract

The problem of soil fertility in terms of nitrogen availability is a major constraint to the production of maize in the tropical rain forest due to continuous land use, leaching, erosion, volatalization among others. Maize is a crop that requires high quantity of nitrogen for optimum yield. For any meaningful maize production programme to be achieved, adequate and regular supply of nitrogenous fertilizer is required. This is not easily available due to high cost of nitrogenous fertilizer and the various bottle neck practices involved in the supply of fertilizer. Therefore, this research was carried out to evaluate seventeen selected maize populations for tolerance to low nitrogen in nitrogen deficient environments. Two field trials were carried out at Federal University of Technology, Akure, Teaching and Research Farm and Benin- Owena River Basin Development Authority Experimental Plot at Araromi, Akure North. Pre- planting soil tests were carried out at the two locations. The seventeen selected maize populations were planted at both locations in a Split plot arranged in Randomized Complete Block Design with four replications. The experimental area was 46m x 25m, plot size was 25m x 25m and the spacing of 0.75m x 0.5m was used. Data were collected on both agronomic and yield traits, which include; plant height, number of leaves, plant stand, number of days to pollen emergence, number of days to silk emergence, ear height, root lodging, stem lodging, plant aspect, number of plants at harvest, number of ears at harvest, ear aspect, ear rot, field weight, grain weight, rust, moisture content, yield and crop partial factor productivity. Data collected were subjected to analysis of variance using Minitab version 17 software, significant means were separated by Tukey test at 5% level of probability and GGE Biplot software was used for stability study. Analysis of variance carried out showed that there were significant differences among the genotypes for various parameters studied. Fertilizer treatment had no statistical significant effect on the yield in both locations, although there were slightly higher yield at the fertilized plots than the unfertilized plots. The comparably high PCV: GCV observed in most of the parameters suggests that the environment had much impact on the traits that control these parameters. Ranking of the seventeen maize populations on selected nine agronomic and reproductive parameters at FUTA shows that, TZPB Prol C 4 had the best performance from the rank of mean rank, while DMR-ESR-Y was the poorest. At Araromi, TZPB Prol C 4 also recorded the best result across the various parameters evaluated, while BR 9943-DMRSR-W had the poorest result as seen from rank of mean rank. From the ranking across locations, TZPB Prol C 4 was still the best genotype while BR 9943-DMRSR-W was the poorest. At FUTA, ear height, field weight and grain weight are components that have positive significant correlation on crop partial factor productivity. At Araromi, ear height, root lodging, ear aspect and moisture content had positive significant correlation with yield, while number of days to pollen emergence, root lodging, moisture content and yield had positive significant correlation with crop partial factor productivity. From the GGE Biplot analysis, TZPB Prol C4 was the genotype with highest yield and most stable. BR 99 TZL Comp 4 DMSRSR was the most unstable irrespective of fertilizer application and had the lowest yield.