Investigation of relationship between yield and yield components of wheat under drought stress using multivariate analysis

In order to evaluate effects of drought stress on yield and some relevant traits of bread wheat cultivars, current study was carried out in the research field of Islamic Azad University of Karaj during 2006-2007. The irrigation schemes scheduled as main plots included the following: (T1) 40% moisture depletion throughout the growing season (control); (T2) 60% moisture depletion throughout the growing season; (T3) 80% moisture depletion throughout the growing season; (T4) no irrigation at stem elongation and continuing with adequate irrigation to the end; (T5) no irrigation from stem elongation to the end of the growing season; (T6) no irrigation at flowering and continuing with adequate irrigation to the end; (T7) no irrigation from flowering to the end of the growing season; and (T8) no irrigation from milk stage to the end; and 2 wheat cultivars [Marvdasht (V1), Chamran (V2)] as sub-plots. The simple correlation results showed that seed yield has a positive, significant correlation with the biomass, Harvest index, Plant height, 1000 grain weight and Spike numbers per square meter. According to results of principal component analysis an increase in the number of components was associated with a decrease in eigenvalues and its maximum at three factors which all together accounted for 70.87% of the total variation of grain yield.