Genetic Variability, Heritability and Genetic Advance for Yield and its Related Traits in Maize (Zea mays L.) Inbred Lines as Influenced by Drought and Heat Stress Conditions in Sudan Savannah of Nigeria

Abstract

The experiments were conducted during the dry seasons of 2021 and 2022 at research farm of Kano University of Science and Technology Wudil and Farmers field at Dambatta Local Government Area, to evaluate the genetic analysis of maize inbred lines under combined drought and heat stress conditions. The parental materials comprise of eight inbred lines that were crossed in a partial diallel pattern. The 64 genotypes were arranged in a 99 lattice design with three replications at each location. Each plot consists of two rows 4 m long, with inter and intra row spacing of 75 cm x 25 cm respectively. Sowing was done manually in February 2022; two seeds per hill were sown 0.25 x 0.75m, with a seed bed of 2.5 x 2.5m (6.25m²) and later thinned to one plant per hill. Irrigation water was applied to field capacity once every week to all the conditions during the first 5 weeks (35 days) after sowing. The well- watered and stress conditions were separated from each other by 2.5m alley to prevent spill-over at the water stress sites during the period of imposed water and drought stress and at the beginning and end of each replication; non experimental lines were raised to minimize the edge border effects. The results of analysis of variance revealed that the genotypes exhibited highly significant differences for plant aspect, ear aspect, grain weight and grain yield across the two locations indicated the existence of sufficient genetic variability among the selected materials and scope for improvement in maize. High GCV and PCV was recorded in anthesis silking interval and grain yield showing high variability of the trait, while moderate GCV and PCV was observed for ear height, ears per plant, plant aspect and ear aspect indicating moderate variability among the genotypic trait. Other trait recorded low GCV and PCV. The result shows high heritability accompanied by high genetic advance as percent of mean (GAM) for as to 50% flowering and days to 50% silking which indicated the preponderance of additive gene action in controlling the traits. Hence direct selection of such characters would be effective in improving for the inheritance of the affected traits. Therefore trait could be improved through breeding method such as simple selection, single seed decent. Low heritability and GAM observed for other traits were influenced by non-additive gene effects for the inheritance of the trait and could be dependable for their improvement in maize.