GENERATION MEAN ANALYSIS OF DROUGHT TOLERANCE IN WHEAT (TRITICUM AESTIVUM L.)

Abstract

To evaluate the genetic background of quantitative criteria of drought tolerance in wheat, six generations of a cross between the varieties of Plainsman and Cappelle Desprez were grown in a randomized complete block design with three replications in the greenhouse of the College of Agriculture of the University of Tehran in 1997. Genetic variation was found for yield potential (Yp), stressed yield (Ys), excised leaf water retention (ELWR), relative water loss (RWL), relative water content (RWC) and harvest index (HI) under water stress conditions. High heterosis and heterobeltiosis were observed in the F1 hybrid for Ys, HI and spike yield index (SYI). Genetic analysis exhibited overdominance in the inheritance of Ys, RWL, ELWR, HI, biomass and SYI, while RWC and Yp were controlled by the additive type of gene action. High narrow-sense heritability estimates were shown by ELWR, biomass and SYI. The high genetic advance for ELWR, RWC, HI and SYI indicated that direct selection could be effective for these traits. The epistatic effects (additive × additive=[i] for Yp, Ys and RWL, additive × dominance=[j] for ELWR, and dominance × dominance =[l] for RWL) were found to be outstanding.