Effect of late season drought tension and salicylic acid on grain yield and canopy temperature of two rapeseed cultivars

In order to investigate the effect of salicylic acid (zero, 0.5, 1, 1.5 and two mM) on yield and canopy temperature of two rapeseed cultivars (Sarigol and RGS) under full irrigation and late season drought tension conditions, this research was conducted at Research Station of College of Agriculture and Natural Resources of Darab Shiraz University in 2013-14 cropping year. The experiment was as split split plots based on randomized complete blocks design with three replications. Results showed that all investigated factors including (terminal drought tension, salicylic acid and cultivar) had significant effect on pod length, grain number and grain yield. Both cultivars used in this research were highly sensitive to terminal drought tension at flowering date so that drought tension caused 40 percentage yield reduction in both cultivars. In RGS cultivar yield from 6780 kilogram per hectare in full irrigation conditions reduced to 3930 kilogram per hectare in terminal drought tension conditions. In both cultivars in full irrigation conditions one mM treatment and in tension conditions two mM salicylic acid produced the highest grain yield in rapeseed. Both cultivars had similar responses to drought tension and salicylic acid, but as a whole RGS cultivar produced higher yield (5354 kilogram per hectare) than Sarigol cultivar (4911 kilogram per hectare). Also, in both cultivars the application of salicylic acid reduced canopy temperature under drought tension conditions. In general, it can be concluded that although drought tension causes reduction in rapeseed growth and yield but the application of salicylic acid with the amount of two mM could alleviate 13 percent of yield reduction.