Effect of tillage system, planting method and nitrogen fertilizer rate on agronomic charachteristics and seed yield of oilseed rape (Brassica napus L.) cv. Dalgan in Guilan, Iran

To study the effects of tillage system, planting method and of nitrogen fertilizer rate on the agronomic characteristics and seed yield of rapeseed (Brassica napus L.) Dalgan oilseed rape cultivar, as the second crop after rice, a split factorial experiment in complete randomized block design with three replications was carried out in two cropping seasons (2016-2018) at paddy fields of Rice Research Institute of Iran, Rasht, Iran. In this experiment, three tillage systems (conventional tillage, minimum tillage, and no-tillage) were considered as main plots and two planting methods (direct and transplanting) and four rates of nitrogen (N) fertilizer (0, 100, 200 and 300 kg.ha-1) as factorial arrangement in sub plots. The results showed that conventional and minimum tillages in the transplanting method had the maximum seed yield (with the averages of 3458 and 3360 kg.ha-1, respectively). Transplanting method with 300 kg.ha-1 of nitrogen level had higher number of auxiliary branches per plant, number of siliques per plant, seed yield, and oil yield. Minimum tillage system with 200 kg.ha-1 of nitrogen with an average seed yield of 4144 kg.ha-1 had the highest seed yield. Based on the results of this experiment, minimum tillage system with 200 kg.ha-1 of nitrogen in both planting methods, direct seeding and transplanting, would be more suitable for oilseed rape production in Guilan region.