Application of Humic Acid and Sulphur on the Vigour and Viability of Harvested Soybean Seeds with Active Compounds

Humus represents the outcome of organic matter decomposition facilitated by microorganisms. Humic acid compounds consist of constituents of humus that are extensively distributed across the Earth's surface. Sulphur is a crucial macronutrient in growth and developmental processes, swiftly recognized as the fourth primary plant nutrient, following N, P, and K. The research presented aimed to assess the impact of humic acid and foliar sulphur levels on the vigour and viability of harvested soybean seeds at the Agronomy Research Laboratory, The University of Agriculture Peshawar, during the Rabi season of 2022-2023. A randomized complete block design was chosen in three replications for the conduction of the experiment, which comprises two factors: humic acid levels (0, 3, 6, and 9 kg ha^1) and foliar sulphur levels (0, 4, 6, and 8 kg ha^1), including a control. The analysis of variance demonstrated significant differences among all parameters and their interactions. According to the experimental findings, the application of humic acid at a rate of 9 kg ha^1 resulted in a notable increase in germination (57.67%), seedling fresh (0.89 g) and dry weight (0.69 g), followed by positive yield responses under foliar application of sulphur. Results display the interaction of humic acid levels and foliar sulphur on bioactive compounds, exhibited potential activities in soybean seeds, including isoflavones (12 mg/100 g), saponins (16 mg/100 g), phytosterols (18 mg/100 g), as well as phytic acid (19 mg/100 g) and lectins (22 mg/100 g) in treated as compared to control. In conclusion, applying humic acid at a rate of 9 kg ha^1, combined with foliar sulphur at a rate of 8, is recommended to enhance the vigour and viability of harvested soybean seeds.