Effect of drought stress and spraying of gibberellic acid and salicylic acid on the quantitative and qualitative yield of canola (Brassica napus)

Abstract

An experiment was conducted as split-split plot based on randomized complete block design (RCBD) with three replications during cultivation season 2017-2018 in Darreh-Shahr, Ilam Province. The experimental factors were four levels of irrigation as main plots including normal irrigation, cut of irrigation at stem elongation stage, cut of irrigation at the beginning stage of flowering, and cut of Irrigation at the beginning of the pod. Sub-factors included two levels of spraying and non-spraying of gibberellin hormone (100ppm) and salicylic acid (150 ppm), respectively. The comparison of mean effects of gibberellin showed that application of gibberellin resulted in highest saturated fatty acid while the plants receiving no gibberellin contained the lowest saturated fatty acid. The later drought stress occurred, the more significant was reduction in the oil percentage. The effect of drought stress on saturated fatty acid was significant but it had no significant impact on the unsaturated fatty acid. Both applications of gibberellin and salicylic acid increased the oil percentage and saturated fatty acid content. Results showed that normal irrigation with both uses of gibberellin hormone and salicylic acid produced the highest biological yield and the lowest dry matter was obtained in irrigation cutting at the beginning of podding stage without any spraying . The combined application of these two hormones increased seed oil content significantly. Finally, the findings indicated that the spraying of gibberellin and salicylic acid under drought stress significantly affected the yield in canola and when these hormones are applied at a suitable time they decrease the adverse effects of drought stress and increases oil yield.

Keywords

• saturated fatty acid
• drought stress
• grain yield
• canola
• gibberellin spraying