Paclobutrazol improves physiological traits and seed yield in sesame genotypes under rainfed Pothwar conditions

Climate change is increasing temperatures and causing drought conditions, along with fluctuations and unpredictable rainfall patterns, which are reducing crop yields. In the rainfed Pothwar region, sesame productivity is further constrained by terminal drought and heat stress, yet the potential of plant growth regulators such as paclobutrazol (PBZ) to mitigate these effects in sesame genotypes remains largely unexplored. To investigate the effect of paclobutrazol (PBZ) concentrations on the yield and physiological traits of sesame genotypes under rainfed conditions of the Pothwar region, experiments were conducted at two locations: NARC-Islamabad and URF-Koont, Chakwal. The study included ten exotic genotypes and two indigenous varieties and was carried out over two years, 2020 and 2021. Paclobutrazol was applied as a foliar spray, with treatments consisting of T 0 = Control without paclobutrazol, T 1 = 150, T 2 = 300, T 3 = 450, and T 4 = 600 mgL -1 paclobutrazol were employed. Results indicated that PBZ significantly enhanced physiological characteristics, and all variables examined (genotypes, locations, and PBZ concentrations). With the lowest intercellular CO 2 concentration, the sesame genotypes PI-175907 and PI-154304 had the highest relative water content (RWC), SPAD value, leaf area, net photosynthetic rate, transpiration rate, stomatal conductance, proline content, epicuticular wax content, and maximum seed yield. In both years of the experiment, PBZ treatments at 600 and 450 mgL -1 had the highest RWC, SPAD value, net photosynthetic rate, transpiration rate, stomatal conductance, proline content, epicuticular wax content, and seed yield. However, the PBZ concentration reduced the leaf area and intercellular CO 2 concentration. Regarding environments, NARC-Islamabad generated highest transpiration rate, intercellular CO 2 concentration; however, the URF-Koont produced the highest seed yield with the highest RWC, SPAD value, leaf area, transpiration rate, stomatal conductance, proline content and epicuticular wax content. Therefore, it is concluded that paclobutrazol could dramatically improve physiological characters while increasing economic returns through better seed productivity. Based on the findings, the genotypes PI-154304 and PI-175907 with paclobutrazol level 450 mgL −1 may be suggested for cultivation in Pothwar farming community under rainfed conditions, with improved physiological characters as well as enhanced growth and yield.