Abstract
Shortage of irrigation water at critical growth stages of maize is limiting its production worldwide. Breeding drought-tolerant cultivars is one possible solution while identification of potential genotypes is crucial for genetic improvement. To assess genetic variation for seedling-stage drought tolerance, we tested 40 inbred lines in a completely randomized design under glasshouse conditions. From these, two contrasting inbred lines were used to develop six basic generations (P1, P2, F1, F2, BC1F1, BC2F2). These populations were then evaluated in a triplicated factorial randomized complete block design under non-stressed and drought-stressed conditions. For statistical analyses, a nested block design was employed to ignore the replication effects. Significant differences (p≤0.01) were recorded among the genotypes for investigated seedling-traits. Absolute values of fresh root length, fresh root weight, and dry root weight lead to select two genotypes, one tolerant (WFTMS) and one susceptible (Q66). Estimates of heritability, genetic advance, and genotypic correlation coefficients were higher and significant for most of the seedling-traits. Generation variance analysis revealed additive gene action. Narrow-sense heritability [F2 ≥ 65; F∞ ≥ 79] revealed the same results. Generation mean analysis signified additive genetic effects in the inheritance of cob girth, non-additive for plant height, grains per ear row and grain yield per plant, and environmental for ear leaf area, cob length, grain rows per ear, biomass per plant, and 100-grain weight under drought-stressed conditions. For conferring drought-tolerance in maize, breeders can adopt the recombinant breeding strategy to pyramid the desirable genes.
Highlights
Maize (Zea mays L.), commonly known as corn, is a major staple consumed as food, feed, and raw materials in many industrial products worldwide
Breeding drought-tolerant cultivars is one possible solution while identification of potential genotypes is crucial for genetic improvement
Two contrasting inbred lines were used to develop six basic generations (P1, P2, F1, F2, BC1F1, BC2F2). These populations were evaluated in a triplicated factorial randomized complete block design under non-stressed and drought-stressed conditions
Summary
Maize (Zea mays L.), commonly known as corn, is a major staple consumed as food, feed, and raw materials in many industrial products worldwide. Maize is grown on an area of about 183 Mha with 1021 Mt production annually (http://faostat.fao.org/). Maize is highly productive under suitable environmental and better management conditions. It is very sensitive to drought and heat-stresses and may result in yield losses of 15-20% annually (Lobell et al, 2011). These yield losses depends upon stress severity, duration and occurrence at the crop stage. Droughtstress during V8 to V17 plant growth stages affects maize plant development, architecture, ear size and kernels
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