Response of Yield and Yield Components of Canola Cultivars to Different Seeding Rates in Dryland Conditions of Kermanshah Province

The study was conducted to identify the effect of seeding rates on yield and yield components of canola in dryland conditions of Kermanshah. For this aim an experiment was laid out during 2006-2008. Annual experiment was as factorial based on randomized complete blocks design (RCBD) with four replications. The factors were including two cultivars of canola Brassica napus var. Okapi and Brassica juncea var. Lethbridge and six levels of seeding rates 6، 8، 10، 12، 14 and 16 kg/ha. Results showed that there was not significant difference between two years for grain yield. Two cultivars had significant difference in grain yield، number of plant/m2، number of seed per pod، 1000-seed weight and plant height. The different seed rates for all traits except number of pod per plant had different significance. In Both genotypes with increasing seeding rates from 6 to 10 kg/ha we observed an increase in grain yield and then from 12 to 16 kg/ha seeding rates the yield was decreased. Undoubtedly the increase process did not constant، so that the rate of add in seeding rates not the same with grain yield increasing. The same results were obtained for number of seed per pod، however with increasing in seeding rates، number of branch per plant was decreased. As the interaction effect between genotype and seed rate for grain yield، number of plant/m2، number of seed per pod and 1000-seed weight was significant، based on mean comparison of this interaction effect for grain yield، the highest yield obtained from Okapi (1292 kg/ha) and Lethbridge (1330 kg/ha) at 10 kg/ha seeding rates، respectively.