Effect of sowing time and seed rate in rapeseed relay intercropping before rice harvesting under climatical conditions of Amol

An experiment was conducted to evaluate effects of sowing time and seed rate onyield and yield components of rapeseed [(Brassica napus L.) cv. Hayola 401] in asplit plot based on randomized complete block design with 3 replications at researchfarm of Rice Research Institute of Iran – Deputy of Mazandaran (Amol) during 2007. Sowing times before rice harvesting at 3 levels (15، 10 and 5 days before riceharvesting) and seed rates at 4 levels (6، 9، 12 and 15 kg ha-1) were the treatments. Results of ANOVA indicated that sowing date had significant effect only on seednumber per pod. However، plant number per square meter and seed yield significantlyaffected by seed rates. Interaction effect of these factors (sowing time × seed) hadsignificant effect on pod number per main stem in which the highest amount of thistrait was belonged to the second and third sowing times with higher seed rates. Thehighest seed number per pod was belonged to 15 and 10 days before rice harvest andwith delaying of sowing date (5 days before rice harvest) the lowest seed number perpod was recorded. According to correlation analysis، plant number per square meternegatively correlated with seed yield، while the highest correlation was observedbetween seed number per pod and seed yield (r = 0. 51**).