The Effect of Drought Stress on Yield, Yield Components and Seed Oil Content of Three Autumnal Rapeseed Cultivars (Brassica napus L.)

Water deficiency has adverse effect on vegetative and reproductive stages of rapeseed. Hence, the objective of this field experiment was to examine the effects of irrigation intervals on yield, yield components and oil seed content of three autumnal rapeseed cultivars. An annual field experiment was conducted on a sandy-loam soil at the Islamic Azad University, Maybod Branch in 2006-2007. A split-plot experiment carried out in RCBD with four replications. The irrigation intervals were placed in the main plots including: I1: 7 days, I2: 10 days and I3: 14 days and Okapy, Zarfam and Sarigol cultivars were as subplots. Planting date was September 2006. Fertilizer was applied based on soil testing for all treatments. Irrigation treatments were applied on March 2007 after rosette stage and plant were harvested on July 2007. The following measurements were carried out: seed yield, the number of lateral branches, plant height, the number of siliques per plant, the number of seeds per silique, 1000-seed weight and seed oil content. Base on results, there were significant differences in seed yield between the irrigation intervals and cultivars. The I1 and I2 treatments produced a significantly higher seed weight than I3. Sarigol and Zarfam produced a significantly higher seed yield than Okapy. The irrigation intervals and cultivars were not significant on seed oil content. On the I1, I2 and I3treatments seed oil percentage were 37.58%, 38.38% and 35.93%, respectively and on the Sarigol, Zarfam and Okapy were 37.58%, 37.58% and 35.51% respectively. It is concluded from the present study that 7 days interval and Zarfam cultivar produced the highest seed yield.