A proposed selection criterion for drought resistance across multiple environments in maize

Abstract

Drought resistance is a complex quantitative trait, involving interactions of many metabolic pathways related to stress-resistant genes. Identification of a standard evaluation assay has been the most pressing problem for selection of drought-resistant genotypes and ultimately for elucidating the internal genetic mechanisms. A field phenotypic investigation was performed on more than 20 morphological traits and grain yield and its components for 201 Chinese common inbred maize (Zea mays L.) lines under water deficit in seven environments. An integrated selection criterion for drought resistance was proposed and used to identify drought-resistant maize genotypes. In it, six traits including grain yield, ear number per plant, kernel number per ear, plant height, anthesis–silking interval and degree of leaf curling were chosen as the most relevant factors related to drought resistance, as determined by statistical analysis. The integrated selection criterion was highly correlated with grain yield under both well-watered and water-stressed regimes, and was also highly correlated with other commonly used selection criteria. Moreover, for 128 (63.7%) inbred lines the evaluation result with this criterion was consistent across more than three environments thus avoiding the effect of genotype–environment interaction, though stress level between the different environments largely fluctuated. There were 43 inbred lines evaluated for drought-resistance and most were bred during 1990–2000. The criterion will be useful to identify excellent drought-resistant genotypes in future maize molecular breeding programs.