Effect of irrigation cut on physiological characteristics and seed yield of canola cultivars under different sowing dates

In order to investigate some physiological characteristics and seed yield of canola cultivars under irrigation cut and different sowing dates, an experiment carried out as factorial split plot based on randomized complete blocks design with three replications at the research farm of Karaj Seed and Plant Improvement Institute during 2013-2014 and 2014-2015 cropping years. In the present experiment the sowing dates (October 7 and November 1) and irrigation cut (normal irrigation (control) and cut off irrigation from the pod formation stage to the next) as the main plots and 6 cultivars of canola included: SW102, HW1, HW2, BAL1, BAL4 and OKAPI (control cultivar) were assigned as subplots. The measured traits included chlorophyll content a, b and total, temperature of canopy, stomatal resistance, relative water content of leaf, biological and seed yield. The results indicated that the highest relative water content of leaf was related to SW102 cultivar and planting date of 7th October (91.64 moisture percent), under normal irrigation (88.87 percent moisture) and the lowest relative water content of leaf was related to planting date of 1st November and drought tension (78.59 percent moisture) for all cultivars indicated that drought resistance was high for all studied cultivars. The highest grain yield was related to two cultivars SW102 and HW1 by amount of 3876.9 and 3801.1 kilogram per hectare and planting date 7th October under normal irrigation (5060 kilogram per hectare). Considering the amount of seed yield on sowing date 1st November and normal irrigation 3114 kilogram per hectare and on sowing date 7th October and drought tension, was 3929 kilogram per hectare; as a result, we state that, the planting date was more important than the irrigation factor in our experiment in cold mild climates conditions.