Evaluating Three Pakistani Soybean Cultivars for High-Temperature Tolerance

Background: Soybean (Glycine max) is oil seed crop and grown world widely, It seedlings might encounter varying temperature conditions in both early and conventional soybean production methods. The suitable optimum temperature for soybean cultivation is 30/22 ºC. Methods and Results: Considering climate temperature changes in the world, a study was conducted to quantify the performance of three major Pakistani soybean cultivars at high temperature (HT; 40/25ºC) during the seedling growth stage. The performance was accessed in term of morphological features, biochemical parameters, antioxidant enzyme activity assays and expression analysis of stress related genes. For all parameters, leaf samples were collected at 32 Days After Sowing (DAS). The results showed that Germination Percentage (GP) was high in NARC-II and RAWAL-I with earlier Days to Flower Initiation (DFI) and Days to Maturity (DM) as compared to SWAT-84. NARC-II showed smaller Plant Height (PH), Number of Branches per Plant (NBP) and Pods per Plant (PP) as compared to other cultivars. Seed Yield, Total Soluble protein (TSP), and Total chlorophyll was recorded high for NARC-II as compared to other cultivars, while carotenoids content was also observed higher in NARC-II as compared to RAWAL-I and SWAT-84.Antioxidant enzymatic activity for POD and SOD activity was observed higher in SWAT-84 among cultivars. Relative expression of peroxidase (GLYMA_19G148800) gene and lipoxygenase (GLYMA_13G239000) indicates that NARC-II has the highest expression followed by RAWAL-I and SWAT-84. Conclusions: This is pilot study to explore tolerance of high temperature among the NARC-II, RAWAL-I and SWAT-84 cultivars.