Evaluation of bio-stimulants on germination and early seedling vigor in soybean under stress

Abstract:

A recurring observation across soybean-growing regions is that early-season moisture stress during germination can reduce stand establishment by 20–40%, yet most seed treatment research focuses on fungicides rather than vigor enhancement. This research evaluated the effect of three bio-stimulants—humic acid (0.3%), seaweed extract (2%), and amino acid complex (0.2%)—applied individually and in combination as seed priming agents on germination, seedling vigor, and stress tolerance of soybean (cv. JS-335) under simulated moisture stress (−0.4 MPa PEG-6000) at Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal, during 2022–23. A completely randomized design with five treatments and four replications was used. The combination treatment (humic acid + seaweed + amino acid) produced the highest germination percentage (93.6%), root length (14.8 cm), shoot length (9.7 cm), and seedling vigor index (2294) under stress—representing 21.9%, 48.3%, 36.2%, and 68.4% improvement over the stressed control, respectively. Under non-stress conditions, the combination still outperformed the control by 12.4% in vigor index. These results show that multi-component bio-stimulant seed priming can meaningfully buffer soybean seedlings against early-season drought.