Effect of biofertilizers and nano-fertilizers for enhancing seed yield and its quality parameters in off season soybean (Glycine max. L.)

Introduction

Soybean [Glycine max (L.) Merill], often hailed as the "Golden Bean" or "Miracle Crop", stands as the world's most economically significant leguminous species (Kumar et al., 2013) [14] . Its unique position in global agriculture stems from its dual-purpose utility as both a high-protein pulse and a premier oilseed. In India, soybean cultivation has seen substantial growth since its introduction in 1977, with the country now ranking fifth globally in production, contributing 14.98 million tons in 2023 (Anon., 2025a). The crop's nutritional profile is peerless among edible legumes, containing approximately 40-42% protein and 20% edible oil (Gopalan et al., 1989) [7] . Beyond quantity, the quality of soybean protein is noted for being rich in essential amino acids like lysine and tryptophan-often deficient in cereals-making its biological value comparable to animal-based proteins (Cowan, 1973; Quayam et al., 1985) [5,19] . Furthermore, its healthpromoting properties, including its role in reducing risks of coronary heart disease and osteoporosis, have solidified its status as a functional food (Oyvind et al., 2006) [17] . Despite this potential, a critical research problem persists: Indian soybean productivity remains stagnated at an average of 1179 kg/ha (Anon., 2025b). This yield gap is primarily driven by the rapid physiological deterioration of seed vigor, exacerbated by environmental sensitivity and poor storage capabilities (Calvinoa et al., 2003 and Tatic et al., 2012) [3,24] . The crisis is further intensified by erratic climatic shifts; unseasonal rainfall during the kharif harvest frequently compromises seed integrity, making the production of high-quality planting material a recurring struggle for farmers. Consequently, off-season (summer) seed production has emerged as a vital contingency strategy to ensure a resilient and high-quality seed supply chain. To resolve these productivity barriers, this study proposes a multi-pronged solution through integrated nutrient management. By leveraging biofertilizers like Rhizobium and Phosphorus Solubilizing Bacteria (PSB), we can naturally augment root development and nitrogen fixation (Prakash, 2001 and Saxena et al., 2013) [18,21] . When coupled with the precision of nanotechnology-which facilitates the synchronized, slow release of nutrients-we can drastically improve nutrient use efficiency (Meena et al., 2021 and Jyothi and Hebsur, 2017) [16,12] . Given the urgent need for robust seed material, the present study was undertaken to examine the synergistic effect of biofertilizers and nano-fertilizers on enhancing the seed yield and quality parameters of off-season soybean.

Materials and Methods

Two different experiments were carried out during Summer 2025 at the Seed Testing Laboratory, Department of Seed Science and Technology, JAU, Junagadh for laboratory experiment and Sagdividi Farm, Department of Seed Science and Technology, JAU, Junagadh for field experiment. Genetically pure seeds of variety Gujarat Soybean-4 (GS-4) were obtained from Department of Seed Science and Technology, College of Agriculture, Junagadh Agricultural University, Junagadh. In the investigation, two factor were assessed: the seed treatment of biofertilizers [S 1: (Rhizobium), S 2: (PSB), S 3: (KMB), S 4: (ZSB), S 5: (SOB) and S 6: (NPK consortia)] and nano-fertilizers foliar spray: [F 1: (4% Nano Urea), F 2: (Nano DAP) and F 3: (Nano Zn)] along with absolute control. The experiment was conducted with three replications at 45 × 10 cm spacing, with a gross plot size of 27 × 20 m² and a net plot size of 25 × 18 m². All the seeds are treated with different biofertilizers solution at dose of 10 ml/kg of seeds as per treatments combination and dry at room temperature The sowing of seeds was done on 18th February, 2025. Foliar applications were administered twice, at 30 and 45 days after sowing (DAS). The treatments consisted of Nano Urea and Nano DAP applied at a concentration of 5 ml/L, while Nano Zn was applied at a rate of 5 g per 15 L of water. The laboratory germination test was conducted as per ISTA (ISTA, 2015) [9] procedure by adopting between paper method. 100 seeds in four replications were taken at random from the seed lot of each treatment, placed uniformly on germination paper and kept in the control environment, where the temperature was maintained at 25 ± 0.50°C with 85 per cent relative humidity. The final counts were made on the 8 th day of the germination test for normal seedlings and germination was expressed in percentage. Ten normal seedlings were selected randomly from the germination paper (B.P) on final day of counting germination and root and shoot length were measured from the tip of primary root to the tip of shoot. The mean root and shoot length were expressed in centimeters. Seedling length was measured by adding root and shoot length in centimeters. To record seedling fresh weight ten seedlings were counted, cut free from their cotyledon and weighted while still moist. Their weights were recorded in milligram. These seedlings were kept in a hot air oven for 24 hours at a temperature of 100℃ (Gupta, 1993) [8] . The weight of the dried seedlings was recorded and expressed in milligram. Seedling vigour index-I and II were computed using following formula suggested by Abdul-Baki and Anderson and mean values were expressed in the whole number. Vigour index I = Germination (%) × Seedling length (cm) Vigour index II = Germination (%) × Seedling dry weight (mg) The laboratory data were analyzed statistically adopting the procedure described by Cochran and Cox. The following parameters were recorded for the field study: days to 50% flowering, days to maturity, plant height at maturity (cm), number of clusters per plant, number of pods per plant, number of pods per cluster, number of seeds per pod, number of seeds per plant, biological yield per plant (g), seed yield per plant (g), test weight (g) and harvest index (%). Five selected plants were tagged from each replication treatment for recording observations. The mean of five plants for each character was used for statistical analysis. Observations were recorded at the maturity stage of plant growth on all the quantitative characters. The experimental data was analyzed statistically by adopting a randomized block design (Factorial) described as per the standard methods. A randomized block design (Factorial) ANOVA was used to assess treatment effects (Chochran and Cox, 1957) [4] .

Results and Discussion

The results of laboratory observations are depicted in Figure 1 [15,22,23] . The superior efficacy of PSB is attributed to its ability to solubilize native and applied insoluble phosphorus through the production of organic acids. This enhances phosphorus availability, which is critical for robust root development and overall plant metabolism. While the NPK consortia performed at par due to its synergistic action in providing multiple nutrients, Rhizobium showed a comparatively lower response; its primary role in nitrogen fixation alone may not sufficiently meet the balanced nutrient requirements of the crop during critical growth stages. Similarly, irrespective of seed treatments, foliar spraying resulted in significant differences across all parameters. Nano DAP (F 2 ) foliar spray achieved significantly higher results for plant height (23.24 cm), clusters per plant (9.98), pods per plant (25.68), pods per cluster (3.31), seeds per pod (2.66), seeds per plant (69.50), biological yield (12.59 g), seed yield (6.82 g), test weight (10.41 g) and harvest index (54.50%). It also reduced the time to 50% flowering (37.61 days) and maturity (99.00 days) compared to other treatments (Khemshetty et [13,26,20] . The superior performance of Nano DAP in enhancing seed yield and its attributes is due to its role in promoting faster and more uniform nutrient uptake. By stimulating cell division and elongation, Nano DAP encourages more vigorous flowering, fruit set and seed development, ultimately resulting in bolder seeds and higher yield, germination and vigour indices. In contrast, Nano Urea and Nano Zn address only specific nitrogen or micronutrient needs, making their individual effects more limited. Consequently, the balanced nutrition provided by Nano DAP leads to enhanced dry matter partitioning and superior crop productivity. The interaction between biofertilizer seed treatments and nanofertilizer foliar applications was statistically non-significant for seed yield and most yield attributes, with the specific exception of the number of clusters per plant. This lack of interaction suggests that the individual effects of seed treatments on the studied characters are independent of the foliar spray applications and vice versa; the two factors do not influence each other's physiological impact for the majority of parameters. However, for the number of clusters per plant, a significant interaction was observed, indicating that both factors exert a mutual influence on this particular character. Furthermore, the contrast analysis between the absolute control and the remaining treatments revealed significant differences across seed yield per plant and all associated attributes. The absolute control consistently recorded the lowest values for all studied parameters when compared to the mean of all other treatment combinations. These findings align with those of Jaga and Sharma (2015) [10] , underscoring the necessity of external nutrient supplementation through biofertilizers or nano-fertilizers to achieve optimized crop productivity. The results of laboratory observations are depicted in Figure 1 and Table 4 and5. Irrespective of the nano-fertilizer foliar spray application, seed treatment with biofertilizers significantly influenced all studied seed quality parameters. Specifically, seeds treated with PSB (S 2 ) recorded significantly higher values for germination (86.56%), shoot length (4.43 cm), root length (3.93 cm), seedling length (8.36 cm), seedling dry weight (304.78 mg), seedling vigour index I (724.88) and seedling vigour index II (26442.67). Similarly, in the case of foliar spraying, the application of Nano DAP (F 2 ) resulted in significantly higher germination (89.22%), shoot length (4.51 cm), root length (4.13 cm), seedling length (8.64 cm), seedling dry weight (315.72 mg), seedling vigour index I (770.70) and seedling vigour index II (28185.06) (Dalvi et al., 2021; Javed et al., 2023 and Thakur et al., 2024) [6,11,25] . Statistical analysis further revealed that the interaction effect between biofertilizer seed treatments and nanofertilizer foliar spray applications was non-significant for these seed quality parameters, suggesting that each factor acted independently. Furthermore, the contrast analysis of the control vs. all other treatments showed a significant difference across all seed quality parameters studied, confirming the efficacy of the tested nutritional interventions over the absolute control.

Conclusion

The findings revealed that seed treatment with PSB and foliar spraying with nano DAP significantly enhanced days to 50 percent flowering, days to maturity, plant height, various yield components and quality parameters. The interaction between different seed treatments and foliar spraying treatments was not statistically significant except for the number of clusters per plant, which recorded a substantial difference. This indicates that seed treatment of biofertilizers and foliar spraying of nano-fertilizers had independent effects on most traits. These seed treatments provide a cost-effective and environmentally sustainable alternative to conventional chemical inputs, making nutrients easily available for the plant. Since PSB and Nano DAP are highly efficient and promote targeted nutrient delivery, their use can optimize input costs while enhancing productivity. Overall, looking at the result, it could be suggested that soybean seeds treated with PSB and foliar spraying of Nano DAP will give a higher seed yield and its quality parameters independently. Future studies should assess their long-term impact on soil health, microbial activity and crop yield while exploring their integration with eco-efficient farming practices and validation across agroclimatic regions.

Acknowledgement

AcknowledgementsThe authors thank the College of Agriculture, Junagadh Agricultural University, for providing the necessary infrastructure and resources.

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