Abstract

Genetic improvement of a crop is highly depended on the abundance of genetic variation present within the crop populations. High genetic advance and high heritability estimates presents the most suitable condition for selection of which heritability estimate is employed by breeders in allocating resources necessary to effectively select for desired traits and to achieve maximum genetic gain with little time and resources. Based on this, ten open pollinated low nitrogen tolerance maize genotypes were tested during the cropping season of 2016 to 2017 at Teaching and Research farm, Landmark University, Kwara State, Nigeria to estimate the genetic variance, heritability, and expected genetic advance of 12 maize population for grain yield and its component characters. The 10 low N maize populations and 2 checks were evaluated under two different nitrogen regimes 90kg and 30kg of N/ha classified as high N and low N respectively. The study revealed lower phenotypic variances (σ2p) and PCVs relative to genetic variances (σ2g) and GCVs for all the studied characters, suggesting the low influence of environmental factors in the expression of these characters. High degree of genotypic coefficient and phenotypic coefficient of variance, heritability and genetic advance were recorded for grain yield, anthesis silk interval, husk cover, plant height, ear height, plant aspect, days to silking and days to pollen shed. Further, lowest value of interval between days to anthesis and silking was obtained by BR 9928-DMRSR LN C1. Highest maize grain yield was recorded by varieties TZLCOM1C6LNC I (6.19 t/ha) and Sint Marzocalarga (5.26 t/ha) under high N and low N respectively. These two maize genotypes can therefore be suggested for the future maize grain yield improvement programmes in low and high nitrogen soil condition in the tropic.