evaluation of physiological and qualitative characteristics of rapeseed cultivars(Brassica napus L.) in irrigation-off and change of planting date conditions

This experiment was conducted as factorial split plot in randomized complete block design with three replications for two years (2015-2016 and 2016-2017) in Karaj region. Irrigation includes regular irrigation (irrigation after 80 mm evaporation from Class A evaporation pan) and irrigation-off from the silique stage onwards in the main plots and planting date including the 5th of October and the 5th of November and rapeseed cultivars including Tasillo, Elvis, Neptune And okapi (control) were factorially divided into subplots.Based on the results, the highest amount of chlorophyll in both planting dates (October 5 and November 5) with values ​​of 1.59 and 1.88 mg / g fresh leaf weight and in normal irrigation conditions were assigned to Elvis cultivar. . The results showed that irrigation-off increased leaf proline and ion leakage of the studied cultivars while the relative leaf water content decreased. Elvis cultivar had the highest grain yield in earlier planting date (October 5) and in normal irrigation with an average of 3346.67 kg / ha.The highest percentage and yield of oil were 45% and 1349 kg of Elvis cultivar in the first year, respectively, in normal irrigation conditions, and the lowest amount of these traits was obtained from Tasilo cultivar in the irrigation-off on the 5th of October. The highest amounts of linolenic acid, static acid, rosaric acid and grain glucosinolate were 5.9, 3.36, 0.34, 32.78%, respectively in irrigation-off conditions and later planting date (November 25). Elvis cultivar was superior to other cultivars in terms of chlorophyll content, higher percentage of oil and fatty acids and less grain glucosinolate, which are considered as important and useful criteria for tolerance to dehydration stress of rapeseed.