Assessment of qualitative and quantitative yields of different spring rapeseed (Brassica napus) genotypes in response to sowing season and date in Karaj region

Rapeseed duo to having genotypes spring and autumn and adaptation to weather conditions as the point hope for provide edible oil of country is the required. Two separate experiments were set up as split-plot in a RCBD design with three replications in two fall and winter seasons during two years (2014-2015 and 2015-2016) at the research field of Seed and Plant Improvement Institute to investigate the effect of sowing season and date on the quantitative and qualitative yields of rapeseed genotypes in Karaj, Iran. In this study, the main plots were sowing dates of 7, 17, and 27 October in fall sowing and sowing dates of 9 and 19 February, and 1 March in winter sowing and sub-plots consisted of genotypes of RGS003, Dalgan, Zabol10, Hyola401, and Hyola4815. Grain and oil yields of rapeseed genotypes were 4330 and 1840 kg ha-1 in fall sowing, respectively, while these traits were decreased by 43.3 and 46.6% when rapeseed genotypes were planted in winter season, respectively. The highest grain and oil yields (5033 and 2202 kg ha-1) belonged to 7 October in fall sowing, while 9 February had the highest grain and oil yields (2996 and 1248 kg ha-1) in winter sowing. In general, the Dalgan genotype is recommended for cultivation due to suitable agronomic traits such as number of silique per plant, number of grain per silique, silique length, 1000-grain weight, as well as high grain and oil yields in cold temperate regions with arid and semi-arid climates such as Karaj, Iran.