Salicylic Acid as a Tolerance Inducer of Drought Stress on Sunflower Grown in Sandy Soil

Abstract

Agricultural water rationalization expressed in irrigating the plants below their requirements became a significant strategy in crop water management. However, reduction in crop productivity under low water supply is realized. Therefore, the current study aimed to diminish sunflower yield losses associated with deficit irrigation using salicylic acid (SA). During two seasons of 2019 and 2020 at El Nubaria region, El Behaira Governorate, Egypt, combinations of three irrigation regimes (100, 85 and 70% of crop evapotranspiration, denoted WR100%, WR85%, and WR70%, respectively), and three levels of SA (0.0, 0.5, and 1 mM. abbreviated as SA0.0, SA0.5, and SA1.0, respectively) on sunflower plants performance were evaluated. Treatments were arranged in a strip–plot design with three replicates. Findings revealed that treated sunflower plants with WR100% × SA1.0 contained the highest amounts of total chlorophyll and carotenoids as well as the lowest proline content. Seed yield of WR100% × SA1.0 treatment was higher than that of WR70% × SA0.0 by 109.7% in the first season and 125.9% in the second one. As averages of the two seasons, SA0.5 and SA1.0 lowered the reductions in seed yield from 21.0% to 15.8 and 14.4% as well as 46.2% to 40.8 and 40.1% under WR85% and WR70%, respectively, compared to the farmer common practice (WR100% × SA0.0). WR100% × SA1.0 for iodine value as well as WR100% × SA1.0 and WR100% × SA0.5 for seed oil % were recorded the highest. Application of WR100% × SA1.0 and WR100% × SA0.5 were the effective combinations for ameliorating water use efficiency. In conclusion, involving salicylic acid in irrigation programs of sunflower became a decisive action to save water and alleviate the yield losses resulting from drought stress.