Abstract

This experiment was carried out to study the effect of drought stress on physiological growth indices of winter rapeseed cultivars in Karaj, Iran using split-plot design with three replications to study the effect of drought stress on oil yield of winter rapeseed cultivars. The main-plot factors included: Four levels of irrigation regimes (control = no drought stress, irrigation interrupted during the flowering stage, irrigation interrupted during the silique formation stage and irrigation interrupted during the seed filling stage) while the sub-plot factor included three cultivars (Zarfam, Okapi and Licord) of winter rapeseed (Brassica napus L.). The results showed that total dry matter (TDM), leaf area index (LAI), relative growth rate (RGR) and crop growth rate (CGR) were highly significantly different among the rapeseed cultivars, whereas, drought stress had effects of practical significance on TDM, LAI, RGR and CGR. The results also showed that the highest TDM, LAI, RGR and CGR were obtained from the cultivar, Zarfam under no-drought condition. The findings firmly established that the drought stress sorely reduces physiological growth indices of winter rapeseed cultivars under conditions of Karaj in Iran.

Key words: Drought stress, physiological growth indices, winter rapeseed cultivars.