YIELD PERFORMANCE AND STABILITY OF DROUGHT TOLERANT AND STRIGA RESISTANT THREE-WAY CROSS HYBRIDS OF MAIZE (ZEA MAYS L.) ACROSS SIX ENVIRONMENTS

Abstract

The possibility of hybrids to perform differently under varying environments due to the effect of genotype by environment interaction informed a multi-locational testing of 44 drought tolerant and Striga resistant (DTSTR) maize hybrids in six contrasting environments within Nigeria. This work was carried out to (I) evaluate the performance of 44 DTSTR maize hybrids across six contrasting environments, (ii) use the genotype and genotype by environment (GGE) analysis to determine stability of grain yield and the pattern of response of the DTSTR maize hybrids to varied environments, (iii) identify stable hybrids with superior yield performance in a group of environments or specific environment for yield performance stability and (iv) identify the best performing DTSTR hybrid(s) for possible release. The field trials were carried out in 2018 and 2019. The drought and irrigated trials at Ikenna were evaluated during the dry season (November, 2018 – March, 2019), while those at Mokwa and Abuja under Striga infested and non-infested conditions were evaluated during the main rainy season (June – October, 2018). Each trial was arranged in a 11 x 4 alpha lattice design with three replications. Data were collected on number of plant stands, days to 50% tasselling, days to 50% silking, anthesis-to-silking interval, plant height (cm), plant lodging, number of plant harvested, ear harvested, ear aspect, grain moisture (%), and grain yield (kg/ha).These data were subjected to analysis of variance (ANOVA), and mean were separated using Tukey Honestly Significant Difference Test. variance components, phenotypic and genotypic coefficients of variation, heritability in the broad sense and genetic advance were estimated. The GGE biplot model was also deployed to determine stability of grain yield and ultimately identify the best performing hybrid(s) in relation to grain yield and stability across environments. The results showed a wide range of variation among the hybrids as the genotypic effect was significant (p<0.01) for all characters evaluated except plant height. The environmental effect was also significant (p<0.01) for all characters studied. However, genotype by environment interaction were not significant for days to 50% silking, days to 50% tasselling, and plant height. The local check (G7), and some hybrids (G42, G39, and G40) consistently performed poorly across all test environments. Conversely, M1628-9 (G38), M1628-12 (G21), M1227-12 (G11), M1628-1 (G27), M1124-7 (G9), M1628-10 (G28), and M1628-4 (G33) were the best hybrids in terms of grain yield across the six environments. M1628-10 (G28) was identified by the GGE biplot as the best hybrid across the six environments as it was the closest to the ideal genotype. In the same way, E2 (Abuja-uninfested) environment was identified as the core test environment, being the closest to the ideal environment. Furthermore, the GGE biplot showed that the six environments belonged to three mega-environments with E1 and E5 in mega-environment I, E2, E4 and E6 in mega-environment II and E3 in mega-environment III. G28 is the best adaptable hybrid and E2 is the ideal test-site for effective selection of DTSTR maize hybrids in national regional tests. The study showed that environment played an important role in the grain yield performance of the DTSTR maize hybrids in the different agroecology. G28 can be evaluated for an additional year to confirm the consistency of its yield stability for release.