Evaluation of Drought and Heat Tolerance in Two Rapeseed (Brassica napus L.) Cultivars

To evaluate drought and heat stress tolerance in new rapeseed (B. napus L.) cultivars, an experiment was conducted at Agricultural Research Station of Gonbad in 2005-2007 cropping seasons. The experiment was arranged as split plots in a randomized complete block design with three replications in two conditions, i.e. supplemental irrigation and rainfed. Five dates of sowing: 06 Nov., 06 Dec., 06 Jan., 06 Feb., and 06 March were assigned to main plots and two rapeseed cultivars; Hayola401 and RGS003 were randomized in sub-plots. Results showed that, in stress and non-stress conditions, seed yield and oil content of Hyola401 hybrid was considerably more than RGS003. The mean seed yield of Hyola401 hybrid and RGS003 was 4455 and 3480 kgha-1 in non-stress conditions, 3718 and 2994 kgha-1 in drought stress conditions, 583 and 340 kgha-1 in heat stress conditions and 349 and 217 kgha-1 in drought+heat stress conditions, respectively. The mean of oil content of Hyola401 hybrid and RGS003 was 44.0 and 42.3% in non-stress conditions, 42.3 and 40.3% in drought stress conditions, 32.5 and 27.7% in heat stress conditions and 31.2 and 29.4% in drought and heat stress conditions, respectively. Considering stress tolerance indices, drought, heat and drought and heat stress tolerance of Hyola401 hybrid was more than RGS003. Therefore, for areas prone to terminal heat and drought stresses, Hyola401 hybrid is more suitable than RGS003, and is recommended.