RESPONSE TO SELECTION FOR YIELD AND STEM BORER RESISTANCE IN TWO RECIPROCAL MAIZE (Zea mays L.) POPULATIONS

Abstract

Field experiments were carried out at the Teaching and Research Farm of the Federal University of Technology, Akure, Ondo State, and the research stations of the International Institute of Tropical Agriculture, IITA in Ibadan, Oyo State and Ikenne, Ogun State respectively. This study evaluated the response to selection for yield and stem borer resistance in two reciprocal maize populations. The experiment, laid out in a randomized complete block design with four replications was conducted across the three locations.Plants in experimental plots were artificially infested with egg masses of Sesamia calamistis and Eldana saccharina. Data were collected for agronomic and stem borer damage traits and analysis of variance (ANOVA) was computed separately for the genotypes in each location and then combined across environments using SAS 1999 software package. Response to selection and mid-parent heterosis were determined for individual environments and across environments. Combined mean squares across the genotypehad significant differences (P ≤ 0.05) for days to 50% silking, plant height, plant aspect, husk cover, field weight,leaf feeding damage and stalk breakage parameters.Similarly, the environments showed significant differences (P ≤ 0.05) for all traits except dead heart. Genotype by environment interactions were not significant (P > 0.05) for all traits except plant aspect, husk cover and stalk breakage parameters.Positive responses were recorded for days to 50% silking, plant height, plant aspect, field weight, grain yield, stem tunneling and leaf feeding across the three locations. For the maize populations, selection for grain yield was effective in hybrid TZBR Comp 2-W x TZBR Comp 1-W (13.92) and TZBR Comp 1-Y (47.61) populations in Ibadan. TZBR Comp 2-W (42.74) and TZBR Comp 1-Y x TZBR Comp 2-Y (31.03) recorded the highest gains in Akure. At Ikenne, TZBR Comp 2-W and TZBR Comp 2-Y recorded highest gains from selection (10.38 and 19.95). Results from this study showed no significant(P > 0.05) correlation between grain yield, dead heart and stalk breakage in Akure, Ibadan and Ikenne. However, positive correlation was observed between grain yield and stem tunneling in Ikenne while significant negative correlation existed between grain yield and leaf feeding damage in Ibadan and Ikenne.Days to 50% silking showed significant correlation with stem tunneling (-0.24), leaf feeding damage (0.37) and stalk breakage (-0.28) in Akure while plant height correlated with dead heart (-0.19) in Ikenne, stem tunneling (0.21) in Akure, leaf feeding damage (-0.55) in Ikenne and stalk breakage (0.25) in Akure. It was thus concluded that the reciprocal recurrent selection method was effective for improving the two reciprocal maize populations in this study for grain yield and stem borer damage traits