Effect of Tillage Systems and Rice Residue Management on Morphological Traits and Yield of Winter Rapeseed (Brassica napus L.) as Second Crop after Rice in Rasht

In order to evaluate the effects of tillage systems and rice residue management on morphological traits and yield of winter rapeseed (Brassica napus L.) as second crop after rice in Rasht, a factorial experiment was conducted using randomized complete block design with 3 replications at Rice Research Institute of Iran (RRII, in 2003-2004 and 2004-2005 growing seasons. The experimental factors were tillage systems at 3 levels (T0: no tillage, T1: minimum tillage and T2: conventional or complete tillage) and rice residue management at 2 levels (R0: without residue and R1: with residue). The evaluated traits were time of flowering initiation, days to maturity, plant height, secondary branches number per plant, height of the lowest pod bearing branch, pod length, grain yield and dry weight of weeds (20 and 40 days after planting). The results of this experiment showed that there was a significant difference between tillage systems in terms of all the evaluated traits except pod length. Rice residue management had significant effects only on initiation of flowering, days to maturity and dry weight of weeds (40 days after planting). In addition, none of the traits showed significant response to the interaction of evaluated factors. The highest amount of grain yield with average of 2278 kg.ha-1 was related to conventional tillage system without residue treatment and the lowest amount of this trait with average of 1342 kg.ha-1 was obtained from no tillage system with residue treatment. Conventional tillage system treatment showed no significant difference with minimum tillage in terms of grain yield. Based on economical analysis, it seems that the minimum tillage treatment with or without residue have some advantageous compared with conventional tillage system which justifies its application.