The Influence of Plant Growth Modulators on Physiological Yield and Quality Traits of Sesame (Sesamum indicum) Cultivars Under Rainfed Conditions

Sesame is an important oilseed crop, and the crop yields frequently fluctuate as the crop is largely grown in rainfed and low-fertile lands. Limited water availability negatively affects many physiological processes and the final productivity of sesame. Limited work has been carried out in the past to understand the role of plant growth regulators (PGRs) in modulating sesame growth and development for optimum productivity. A field study was conducted under rainfed conditions to evaluate the response of foliar application of different PGRs such as hormonal-based gibberellic acid (20 ppm); chemical-based thiourea (500 ppm); chemical-constituting structural component-based ortho-silicic acid (380 ppm); and control (water-sprayed) on sesame cultivars: Swetha til, GT-10, TKG-22, and JCSDT-26. The PGRs foliar application was done at the vegetative (25-30 days after sowing), 50% flowering (40-45 days after sowing), and seed development (70-75 days after sowing) stages of the crop. The results revealed that application of different PGRs positively influenced the plant's growth, physiological, yield and quality traits; however, most effective results were obtained with gibberellic acid (20 ppm), followed by ortho-silicic acid (380 ppm), and thiourea (500 ppm) improved the morphological, yield, and yield-attributing traits. The interaction between PGRs and varieties was found significant and among the sesame cultivars, swetha til followed by JCSDT-29 was found most promising. The application of PGRs has significantly improved the plant height, leaf area, number of branches, capsules, seeds/capsules, seed yield oil content, and fatty acid content compared to the control by gibberellic acid, followed by ortho-silicic acid and thiourea. The interaction between PGRs and varieties was found to be significant, and cultivar Swetha til, a white-colored cultivar performed most superiorly among the different tested cultivars in terms of growth, physiology, yield as well and quality traits when treated with GA3 at 20 ppm. The seed yield was enhanced by 25-26%, 11-12%, and 6-7% with the application of gibberellic acid, ortho-silicic acid, and thiourea, respectively, over control. Considering the findings, it can be concluded that the application of PGRs (thiourea, ortho-silicic acid, and gibberellic acid) significantly enhanced the growth, physiology, yield, and quality of sesame under rainfed conditions; however, GA3 at 20 ppm was found most effective and may not only enhance the optimum productivity but also effective in improving the quality traits of sesame.