Response of six winter rapeseed hybrids to drought stress at different planting dates

The present study was conducted to determine the responsesof six winter hybrids of rapeseed(Brassica napus L.) to drought stress at different planting dates. A factorial split plot experiment was conducted in a randomized complete block design with three replications in two years (2014-2015 and 2015-2016) in Karaj Research Field Station, Seed and Plant Improvement Institute, Karaj, Iran. Experimental treatments included irrigation (normal and non-irrigation at flowering stage) and planting date in two levels including October 1 and November 1 in main plots, and Canola hybrids (Triangle, Brutus, Gabriella, Natali, Danob and Marathon) in sub plots. The results showed that the effects of planting date, irrigation and hybrids on plant height, stem diameter, number of pods per plant, number of seeds per pod, 1000 seed weight, grain yield and biological yield were significant. Planting delay caused 40% reduction in grain yield and 54% increase in seed number per pod. Also, non-irrigation at flowering stage decreased 25%, 30% and 24%, of number of pods per plant, number of grain per pod and grain yield, respectively. Natali hybrid had more yield than the other hybrids in both planting dates and therefore it is recommended to cultivate in Karaj weather conditions to achieve maximum yield. Lastly, October 1 date of cultivation of is proposed as the best date for cultivating in Karaj climate conditions for examined hybrids.