evaluation of oil, protein and grain yield of canola cultivars in different planting date in yasouj region

determination of the response of differentcrop varieties to environmental variables from planting to harvest is one of the fundamental pillars of agriculture planning to achieve maximum yield and desirable quality. changing planting date by effect on vegetative and reproductive growth period and balance between them, will affect yield and product quality. in order to study the responses of four winter canola cultivars to different planting dates a factorial experiment was carried out in randomized complete block design with four replications in 2008-2009 at the research field of agricultural research station of yasouj. planting date in four levels with ten days intervals from september 12 as a first factor and four winter canola cultivars (zarfam, okapi, elite and slm-046) as second factors were used. results showed that cultivars responses to different planting date in traits of number of pods per plant, biological yield, grain yield and oil yield were significant. the highest number of pods per plant (91), grain yield (5231 kg/ha) and oil yield (2227kg/ha) were belonged to elite cultivar in earlier panting date (september 12) and the lowest of these traits were belonged to slm-46 cultivar with forty days delay in planting (october 12). delayed planting decreased seed oil percent and increased seed protein percent. delayed planting decreased the grain and oil yield of zarfam cultivar lower than other cultivars