Evaluation of Drought Tolerance Indices for Screening Some of Corn (Zea mays L.) Cultivars under Environmental Conditions

Abstract

In order to study the effect of drought stress on eight cultivars corn (Zea mays L.), an experiment was conducted in a factorial experimental on the basis of randomized complete block design under two irrigated conditions during 2010-2011 cropping season. Twelve drought tolerance/resistance indices including stress tolerance index (STI), stress susceptibility index (SSI), tolerance index (TOL), geometric mean production (GMP), mean production (MP), yield index (YI), yield stability index (YSI), drought resistance index (DI), relative drought index (RDI), stress susceptibility percentage index (SSPI) and modified stress tolerance (K1STI and K2STI) were calculated based on grain yield under drought and irrigated conditions. Yield in stress and non-stress conditions were significantly and positively correlated with STI, GMP, MP, YI, TOL, DI, RDI, YSI, SSPI, K1STI, and K2STI and negatively correlated with SSI. Yield in stress and non-stress conditions were significantly and positively correlated with STI, GMP, MP, YI, TOL, DI, RDI, YSI, SSPI, K1STI, and K2STI and negatively correlated with SSI. Screening drought tolerant cultivars using ranking method, three dimensional plots discriminated cultivars ‘KSC720’, KSC 710GT and ‘KSC 700’ as the most drought tolerant. Cluster analysis classified the cultivars into three groups i.e., tolerant, susceptible and semi-susceptible to drought conditions. In general, Results of this study showed that among drought tolerance indices STI, YI, SSPI, K1STI, and K2STI can be used as the most suitable indicators for screening drought tolerant cultivars and ‘KSC720’, KSC 710 GT and ‘KSC 700’ had the highest tolerance to drought in our studies condition.