PHYSIOLOGICAL EFFICIENCY AND SEED YIELD OF SESAME AS INFLUENCED BY DIFFERENT PLANT GROWTH REGULATOR

Abstract

Sesame (Sesamum indicum L.) is an important oilseed crop cultivated in India since ages during kharif season. Excessive vegetative growth is observed under favourable environment and optimal moisture conditions, which resulted in lower capsule formation, reduced seed yield due to poor source to sink partitioning of photosynthates resulting in low yield and poor harvest index of the crop.  A field experiment was conducted during the Kharif season of 2025 at the Research Farm of the ICAR All India Coordinated Research Project (Sesame and Niger) Unit, College of Agriculture, Jawaharlal Nehru Krishi Vishwa Vidyalaya (JNKVV to identify environmentally acceptable and practically affordable plant growth regulator  that can modify plant growth suitably through growth retardants, stress-mitigating compounds and potassium nutrition  to improve assimilate production, partitioning and reproductive efficiency in sesame by improving the physiological efficiency of the crop to increase productivity of sesame. The experiment was laid out in a randomized block design (RBD) with three replications and eleven treatments comprising a control, salicylic acid, paclobutrazol, mepiquat chloride, chlormequat chloride and potassium chloride (KCl), applied either as a single spray at 60 days after sowing (DAS) or as split sprays at 45 and 60 DAS. Each foliar treatment was applied at a spray volume of 300 L ha⁻¹. The treatments included salicylic acid at 200 ppm at 60 DAS and 100 ppm at 45 and 60 DAS; paclobutrazol, mepiquat chloride and chlormequat chloride at 200 ppm at 60 DAS and 100 ppm at 45 and 60 DAS; and KCl at 2% at 60 DAS and at 45 and 60 DAS. Observations were recorded on plant growth attributes, physiological parameters, yield attributes and seed yield. Among the treatments, chlormequat chloride @ 200 ppm applied at 60 DAS (T8) consistently outperformed other treatments, combining the highest Leaf Area Index (3.18) at 60 DAS, Leaf Area Duration 53.55 m² days during 30–60 DAS and 64.20 m² days during 60DAS –maturity, Crop Growth Rate of 9.55 g m² day⁻¹ at 30–60 DAS and 19.90 g m² day⁻¹ during 60DAS – maturity, Net Assimilation Rate during 30–60 DAS varied from 6.67 g m² day⁻¹ (T4) to 7.32 g m² day⁻¹ (T3), however it varied significantly during 60 DAS - maturity and maximum NAR (9.78 g m2 day-1) was recorded under treatment T1, Light Transmission Ratio varied from 30.68 to 34.19%, energy interception varied from 65.81 to 69.32% while chlorophyll content varied between 46.93 (T1) and 55.72 (T8).  These improvements in physiological and yield attributes were reflected in the highest seed yield of 692.03 kg ha⁻¹, HI 32.44% and oil content 47.67% was recorded in T8, whereas higher biological yield 2514.34 kg ha⁻¹, was recorded under treatment T2. Application of PGRs significantly influenced seed yield and oil content in sesame. Among the treatments, Chlormequat chloride @ 200 ppm at 60 DAS @ 300 L ha -1(T8) proved to be most effective in improving seed yield, partitioning efficiency, and seed quality and found most effective for enhancing crop productivity.