Genetic variability in s1 and s2 maize (Zea mays L.) inbred lines under drought and irrigated conditions

Abstract:

Understanding genetic variation and its potential utilization in breeding programmes is essential for exploiting genetic variability among species and among varieties within a species. In the present investigation, 200 S₁ inbred lines of maize (Zea mays L.) were developed through ear-to-row progeny selection and evaluated along with nine parental lines and 16 checks during the post-rainy season of 2012 to assess genetic variability for different traits under drought and irrigated conditions. The experiment was conducted in a 15 × 15 lattice square design with two replications. Subsequently, 80 S₂-generation selfed progenies, along with 12 inbred lines, three composite populations and five checks, were evaluated using a 10 × 10 lattice square design during the summer seasons of 2013–14 under normal and water-stress conditions. The analysis of variance revealed highly significant differences among genotypes for all 18 characters under drought conditions, whereas under irrigated conditions, 17 characters showed highly significant differences and one character showed a significant difference. Under drought conditions, high heritability coupled with high genetic advance as a percentage of the mean was observed for bulk cob weight, grain yield per plot, number of cobs per plant, anthesis–silking interval and number of kernels per row. Under irrigated conditions, high heritability coupled with high genetic advance as a percentage of the mean was recorded for bulk cob weight, grain yield per plot, cob length, number of kernels per row, number of cobs per plant, 100-seed weight and plant height. In the S₂ generation, the analysis of variance revealed highly significant differences for 17 characters, except relative water content at 60 and 90 days and number of kernel rows per cob. Under drought conditions, high heritability coupled with high genetic advance as a percentage of the mean was observed for grain yield per plot, bulk cob weight, anthesis–silking interval and grain yield per plant. Under non-stress conditions, highly significant differences were observed for seven characters, while four characters showed significant differences. High heritability coupled with high genetic advance as a percentage of the mean was recorded for grain yield per plot and bulk cob weight. These traits may therefore serve as useful selection criteria for improving grain yield in maize under both drought-stress and non-stress conditions.