In order to investigate the effects of sowing different dates on some physiological traits and yield of rapeseed plant, three sowing dates (7, 17 and 27 October) as three separate experiments were carried out in randomized complete block design (RCBD) with three replications. The experiments were conducted in Eslamabad-e Gharb Agricultural Research Station in 2014-2015 crop year. In per experiments, eighth cultivars containing OPERA, KARAJ3, L72, SW102, KARAJ1, OKAPI, GKH3705 and GKH2624 were studied for different traits. The studied traits were leaf chlorophyll content, amount of protein and soluble carbohydrates of leaf, peroxidase enzyme activity, membrane lipid peroxidation, grain and biological yield. Results showed that delay in sowing in all cultivars induced a significant decrease in amount of chlorophyll content, amount of soluble proteins of leaf, grain and biological yield and increased amount of membrane lipid peroxidation and soluble carbohydrates in water and alcohol. The most suitable sowing date was 7th October among studied sowing dates, so that sown plants in this date (with average of 3314 kg/ha) produced more grain yield about 74% compared to sown rapeseed plants in 17th October (with average of 869 kg/ha). Also in comparison of cultivars was observed that there was significantly different among cultivars for different characteristics and effect of sowing date on these traits. Among studied cultivars, KARAJ3 had the highest grain yield in sowing date 7th October.
