Study of Effects of Drought Stress on Growth Stages on Grain Yield and Chlorophyl Amount of Leaves of 4 Spring Cultivars in Khorramabad Weather Conditions

In order to study the effects of different amounts of irrigation on grain yield and chlorophyl amount of leaves in growth stages of 4 rapeseed cultivares, an experiment was performed in the agriculture research station of Khorramabad in 2009-2010.The design was a split-plot with irrigation treatments as main plot in a randomized complete block design and cultivares as sub plots.4 irrigation periods included normal irrigation (as control) , cuting of irrigation from stem stage, irrigation cut from flowering stage and irrigation cut from poding stage. 4 cultivars included R.G.S003, sarigol, Option 500 and Hyola 401.The results showed that water deficiency stress had significant decrease on pod number in plant,weight of 1000 grain and decreased grain yield,grain oil yield,biological yield and harvest index of treatments to control consequently. Since limited irrigation water treatments to cause control increased water use efficiency, therefore these treatments can be used to economize water use. The comparison of 4 cultivares showed that in regard to pod number in m2 , pod number in plant, grain yield, biological yield, grain oil percent, and grain oil yield. Hyola 401 had relative superior to option 500,R.G.S003 and sarigol. In total , if water was limited, cutting of irrigation from poding stage in comparison to control and use of Hyola401 cultivar was favoured because grain yield and oil yield increased.