Investigation of Yield and Its Related Morphological Traits Responses in Wheat Genotypes under Drought Stress and Irrigation Conditions

The objective of this study was to evaluate some morphological characteristics associated with grain yield potential on 20 bread wheat cultivars under two irrigation and drought stress conditions. The experiments were conducted at Research Farm of Agriculture College, University of Tehran, Karaj during 2001-2003. Twenty bread wheat cultivars were planted as subplots within each irrigation main plots in randomized complete block design with 3 replications. Drought stress was imposed at the end of flowering, and plants were re-watered when they showed signs of wilting, particularly during the morning. The results showed that the interactions between cultivars × year and cultivars × irrigation were significant for the grain yield. The cultivars showed significant differences in grain yield under drought stress condition in 2001-2003. Roshan, M-79-4 and Alvand in 2001-2002 and Azadi, Marvdasht and M-79-17 in 2002-2003 were most productive under drought stress condition, whereas C-79-12, MV-17 and Shahpasand in 2001-2002 and M-79-4, Roshan and Nicknajad in 2002-2003 performed visa versa. Correlation between grain yield and measured traits under irrigation condition was different from drought stress condition, suggesting that grain yield controlling mechanisms operate differently under these conditions. Drought stress caused a reduction in 1000 seed weight of cultivars. High 1000 seed weight and high grain number per ear were accompanied by high grain yield in drought stress and irrigation conditions, respectively. In the present study, clear relationship between grain yield and ear length was not observed.