In order to study the reaction of fifteen maize hybrids to different levels of drought stress, and evaluate drought tolerance indices, an experiment was conducted in split plot arrangement using randomized compelet block design with four replications in Gharakhil(Ghaemshahr) Agricultural Station, in 2006. The main plots consisted of drought stress levels and sub-plots included maize hybrids. Six drought tolerance indices were calculated for grain yield. Under normal, mild and severe stress conditions, hybrid OSGT14 produced 9.445, 9.270 and 8.352 tha-1, respectively, while under most severe stress, hybred SPGT12 produced the highest grain yield(7.455 tha-1). Based on the highest correlation observed between grain yield and different indices, MP, GMP, Harm and STI, were suitable indices. Biplot analysis determined hybrids OSGT14, KSC710GT and
KSC-mog 84- 062, in group A, as tolerant hybrids and suitable for normal and stress conditions, and hybrids BGT10, KSC 708 GT, BGT15 and KSC712GT as susceptible hybrids. Cluster analysis based on different indices, divided hybrids under mild and severe stress conditions, into five, and under most severe stress into six groups. Indices MP, GMP, Harm and STI, identified hybrids OSGT14 and KSC710GT as tolerant, and BGT15 and KSC708GT as susceptible hybrids to drought stress, while, indices TOL and SSI showed KSC 720 and KSC700 as tolerant and KSC712GT and BGT10 as susceptible hybrids to drought stress. |