Evaluation of planting dates effects on growth, phenology and seed yield of spring rapeseed varieties

In order to the evaluate the effect of planting dates on phenological traits, plant height, pods per plant and seed yield of rapeseed spring varieties, a split-split plot experiment based on randomized complete block design with four replications was conducted during 2 years at Agriculture Research Station of Baykola, Mazandaran, Iran. Treatments were planting dates (September 29, October 9, October 19, October 29 and November 8) as main plot and sub-plots were three cultivars (Hyola401, Option500 and RGS003. All the traits were affected by planting date and variety. The mean values of seed yield of Hyola401, Option500 and RG 003 were 3274, 2898 and 3040 kg ha-1, respectively and Option500 and RGS003 had not statistically significant difference. Non significant interaction effects of planting dates and varieties for seed yield indicated that yield reduction of the varieties in late planting dates had similar trend and Hyola401 and Option500 had the most and the least seed yield, respectively. Seed yield reduction at late planting date was related to insufficient vegetative growth before flowering stage. Significant positive correlation between plant height and number of pods per plant was the main reason that in late planting date reduction of plant height imposed reduction of pods per plant and finally seed yield was decreased.