Evaluation of biogenic Nano-sulphur for improving growth, reproductive development and yield in soybean (Glycine max L.)

Introduction

Glycine max L. Merrill, or soybean, is a significant oilseed and protein crop grown all over the world. It is prized for its superior oil and protein and is used extensively for industrial, food, and feed applications. As a legume, it also uses biological nitrogen fixation to support sustainable cropping systems. However, deficits in certain nutrients, especially sulphur, which is essential for protein synthesis, enzyme activity, photosynthesis, nitrogen metabolism, and biological nitrogen fixation, frequently limit soybean yield. Additionally, sulphur is necessary for the synthesis of amino acids that include sulphur, which enhances the growth and quality of seeds. The risk of sulphur insufficiency in agricultural soils has increased due to intensive cropping and insufficient sulphur replenishment, whereas the effectiveness of conventional sulphur fertilisers depends on their supply, particle size, soil conditions, and synchronisation with crop demand. Nanotechnology offers a promising approach for improving nutrient-use efficiency through Nano-fertilizers possessing high surface area and enhanced reactivity, potentially facilitating greater nutrient availability and utilization. Nano-sulphur has therefore emerged as a potential alternative sulphur source for crop production. Foliar application can further improve nutrient delivery by supplying sulphur directly to aerial tissues during critical vegetative and reproductive stages. Biogenic Nano-sulphur is of particular interest as an emerging Nano-enabled nutrient technology because biologically derived Nanoparticles offer potential advantages in terms of environmentally compatible production and agricultural application. Previous studies have reported beneficial effects of sulphur and Nano-based nutrient application on the growth and productivity of oilseed crops. Despite these advances, field-based information on the response of soybean to different concentrations of foliar-applied biogenic Nano-sulphur remains limited.

Therefore, the present investigation was undertaken to evaluate the influence of foliar-applied biogenic Nanosulphur on growth, reproductive development and yield attributes of soybean under field conditions.

Materials and Methods

The field experiment was conducted during the kharif season of 2025 at the Research Farm of the All India Coordinated Research Project on Weed Management, Dr. PDKV, Akola, Maharashtra, India. Soybean variety 'PDKV Amba' was grown in a Randomized Block Design (RBD) with four replications. Seeds were treated with Vitavax @ 2 mL kg⁻¹ seed and sown at a seed rate of 60 kg ha⁻¹ with 45 × 5 cm spacing. The gross plot size was 3.60 × 4.00 m and the net plot size was 2.70 × 3.80 m. Six nutrient-management treatments were evaluated comprising an absolute control (T₀), General Recommended Dose of Fertilizer (GRDF) (T₁), GRDF + soil application of bentonite sulphur @ 30 kg S ha⁻¹ at sowing (T₂) and GRDF + foliar application of Nano-sulphur @ 25, 50 and 75 ppm at 30 and 45 days after sowing (DAS) designated as T₃, T₄ and T₅, respectively. GRDF was applied to the respective treatments, bentonite sulphur was applied at sowing and Nano-sulphur was applied as foliar spray at 30 and 45 DAS. Growth, reproductive and yield attributes were recorded following standard field procedures. Plant height and number of branches plant⁻¹ were recorded at 30, 45 and 60 DAS using five representative plants selected from each net plot. Plant height was measured from the base to the tip of the youngest fully expanded leaf and expressed in centimetres, while primary branches were counted and expressed as number plant⁻¹. At harvest, the number of pods plant⁻¹ and seeds pod⁻¹ were determined from the selected plants. The crop from each net plot was harvested, dried and threshed and seed yield was recorded as kg plot⁻¹. The data obtained for different observations were subjected to analysis of variance appropriate for a Randomized Block Design. Treatment means were compared using the standard error of mean [SE(m)±] and critical difference (CD) at the 5% level of significance.

Results and Discussion

Plant height was significantly influenced by sulphur treatments at 30, 45 and 60 DAS. At 30 DAS, the maximum plant height was recorded with T₂ (30.07 cm) followed by T₅ (29.87 cm), whereas T₀ recorded the minimum (23.95 cm). At 45 DAS, T₅ recorded the highest plant height (61.20 cm) followed by T₄ (59.27 cm), T₃ (58.42 cm), T₂ (56.67 cm) and T₁ (50.67 cm), while T₀ recorded 40.67 cm. At 60 DAS, T₅ remained superior (66.70 cm) followed by T₄ (64.15 cm), T₃ (63.25 cm), T₂ (59.52 cm) and T₁ (52.32 cm) with the minimum value in T₀ (45.67 cm). The enhanced plant height under T₅ may be attributed to improved sulphur availability and utilization during active vegetative growth, supporting protein synthesis, photosynthesis, enzymatic activity and nitrogen metabolism.

Conclusion

The present investigation demonstrated that foliar application of biogenic Nano-sulphur in combination with GRDF significantly improved the major growth, reproductive and yield attributes of soybean. Among the treatments, GRDF + foliar application of Nano-sulphur @ 75 ppm at 30 and 45 DAS (T₅) was the most effective recording the highest plant height at 60 DAS (66.70 cm), branches plant⁻¹ (5.20), pods plant⁻¹ (39.90)and seed yield plot⁻¹ (2.55 kg). Thus, foliar application of biogenic Nanosulphur @ 75 ppm at 30 and 45 DAS along with GRDF emerged as the most promising treatment for enhancing soybean productivity under the conditions of the present study. Further multi-season and multi-location evaluation is warranted to confirm its consistency and wider agronomic applicability.

Acknowledgement

AcknowledgementThe authors gratefully acknowledge the All India Coordinated Research Project on Weed Management, Dr. PDKV, Akola for providing field facilities and technical support during the kharif, 2025 experiment. The authors also acknowledge the concerned research units and laboratories of Dr. PDKV, Akola for their support during the investigation.

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