Effect of sowing date on seed yield and yield components of canola (Brassica napus L.) cultivars in north Khuzestan conditions

Determination of optimum sowing date plays an important role in crop management and achieving the higher yield. To study the effectof sowing date on seed yield of canola cultivars, a filed experiment was carried out as strip split plot block arrangement in randomized completed block design with three replications in 2017-18 and 2018-19 cropping seasons at Safiabad Agricultural and Natural Resources Research and Education Center of Dezful, Iran. Vertical factors consisted of six levels of sowing date (23rd September, 07th October, 22nd October, 06th November, 21st November  and 06th December), and horizontal factors were seven canola cultivars (Agamx, Hyola4815, Hyola50, Hyola401, Safi6, Zabol9 and Zabol13). Results showed that high temperature, due to the delay in sowing date, during the silique stage and grain filling period led to a reduction in the number of silique per plant and seed yield. In 2017-18, mean comparison of sowing date × cultivar interaction effect revealed that the highest number of siliques per plant (513.5 silique.plant-1) belonged to Zabol-13 in 23rd September sowing date , and the lowest (88.5 silique.plant -1) to Zabol13 in sowing date 06th December. In 2018-19, the highest number of siliques per plant (713.67 silique.plant-1) was counted in 22nd October sowing date and Safi6, and the lowest (126.24 silique.plant-1) belonged to Hyola401 in 06th December sowing date. The highest seed yield (3244 kg.ha-1) belonged to Agamax in 22nd October sowing date in2017-18 cropping season. Hyola50 had the highest seed yield (2888 kg.ha-1) in 7th October sowing date in 2018-19 cropping season. Seed yield stability anlysis showed that Hyola50 had the lowest mean rank and identified with thehighest seed yield and yield stability in all sowing dates (except .22nd October) followed by Agamax and Zabol9, respectively. In conclusion, 23rd September - 06th November can be recommended as optimum sowing date window for canola production in the north Khuzestan conditions in Iran.