Genetic Studies on Diversity Combining Ability and Heterosis for Drought Tolerance in Maize Zea mays L

Abstract

Drought tolerant genotypes are necessary in order to secure food security among newlinecrops. In the present investigation one hundred and thirty-three S5 inbred lines were newlineevaluated under two conditions i.e., non-stress and stress condition at two locations, newlineDharwad and Devihosur in randomized complete block design (RBCD). Water stress newlinewas induced by withholding irrigation one week before anthesis, such that plants have newlineto utilize residual moisture in the soil during flowering stage. Genetic diversity using newlinephenotypic traits was measured by using Mahalanobis D2 method. The lines were newlinegrouped into seven clusters under non-stress and elven clusters under stress condition. newlineCluster 8 under stress condition which recorded high intra cluster distance contained newlinemost of the drought tolerant inbred lines. Based on the per se performance, genetic newlinediversity and drought susceptible index fifteen promising drought tolerant lines namely newlineDIL-1, DIL-6, DIL-10, DIL-12, DIL-14, DIL-23, DIL-39, DIL-44, DIL-51, DIL-58, newlineDIL-60, DIL-64, DIL-78, DIL-80 and DIL-107 were selected. These selected lines newlinewere crossed in Diallel method II mating design to produce 105 direct crosses. The 105 newlinecrosses along with their 15 parents and three checks were evaluated under two newlineconditions non-stress and stress conditions. Combining ability study revealed newlinesignificant variation among additive and non-additive genes for all the fourteen traits newlineunder non-stress and stress conditions. The GCA/SCA ratio was less than unity for all newlinethe traits indicating predominant role of non-additive gene action such as dominance, newlineover dominance and epistasis in expression of these traits in both non-stress and stress newlinecondition. Overall pooled gca effects revealed DIL-1, DIL-10, DIL-78 and DIL-39 newlinewere promising inbred lines. Similarly, based on pooled sca effects hybrids DIL-12 × newlineDIL-51, DIL-23 × DIL-78, DIL-14 × DIL-60 and DIL-1 × DIL-44 were best newlineperforming. Grain yield was reduced by 56.57 % in stress condition (36.07 q/ha) than newlineunder non-stress condition (83.06 q/ha). Floweri