Response of Commercial Cultivars and New Lines of Oilseed Rape to Delayed Sowing Conditions in Mazandaran

To evaluate the effect of delayed sowing dates on phenological traits, yield components and seed yield of spring oilseed rape genotypes, a split plot experimental design with three replications was carried out at Mazandaran Agricultural and Natural Resources Research and Education Center during 2010-2011 and 2012-2013 cropping seasons. Four sowing dates of 19, 29 October, 8, 18 November were considered as the main plots and five genotypes of Zafar, Sarigol, L7, L4 and Hyola 401 as sub plots. The results of combined analysis of variance showed significant effects of sowing date, genotype and their interaction on all characteristics except 1000-seed weight. Delay in planting resulted in a significant reduction of seed yield and its components. Positive and significant correlation of seed yield with duration of flowering, days to maturity, number of pods per plant, number of seeds per pod, 1000-seed weight and harvest index showed that high levels of these traits in early sowing dates had increasing effects on seed yield. Among the genotypes, Zafar and Hayola 401 had high mean values of seed yield in all sowing dates and therefore had priority for planting in delayed sowing dates.