Integrated use of biofertilizers and bio-stimulants for improved soil fertility in okra (Abelmoschus esculentus L.)

Introduction

Okra, scientifically identified as Abelmoschus esculentus (L.) Moench, is a vegetable plant from the Malvaceae family with a chromosome count of 2𝑛 = 130. It is predominantly cultivated in tropical and subtropical areas globally. This yearly plant, also known as 'lady finger' or 'bhindi,' originated in Tropical Africa. Due to its nutritional value, delicious taste, medicinal properties, and industrial applications, Okra has become popular across diverse populations. The fibrous pods of Okra contain round seeds that are harvested when immature for consumption as a vegetable (Gaikwad et al., 2021). The extensive use of chemical fertilizers has negatively impacted soil structure and microbial populations in the soil. Moreover, the application of chemical fertilizers results in issues like nutrient loss through nitrogen leaching and phosphorus fixation. The high costs of chemical fertilizers pose a challenge for small-scale farmers to afford these costly inputs promptly. Overusing inorganic fertilizers has led to decreased nutrient absorption and a decline in vegetable quality (Tyagi et al., 2016) [1] . Bio stimulants are increasingly recognized as beneficial modern farming methods used in agriculture worldwide. They contribute to improving crop quality, supporting crop health, and enhancing grower profitability. They provide effective solutions to tackle the challenges posed by the growing demand for food due to an expanding global population. The growth and yield of okra are influenced by various factors such as seed quality, nutrition, climatic conditions, and chemical substances like plant growth regulators that are used to induce changes in plants and impact growth by improving the natural growth regulation system from seed germination to aging. These substances help enhance the physiological efficiency of plants, including their photosynthetic capacity and the efficient distribution of assimilates by promoting the translocation of photoassimilates. The use of growth promoters can scientifically boost the productivity of okra. Biofertilizers typically contain microorganisms in either live or dormant forms that have diverse beneficial effects on plant growth. These microorganisms include nitrogen-fixing bacteria that convert atmospheric nitrogen into a usable form for plants, as well as microorganisms that solubilize phosphates and release potassium from insoluble sources (Nayak et al., 2019) [2] . Biofertilizers contribute to maintaining soil fertility by releasing growth-promoting substances and vitamins. These substances not only enhance agricultural production but also aid in disease control by acting as antagonists and suppressing soil-borne plant pathogens (Sharma et al., 2024) [3] . The presence of nitrogen-fixing, cellulolytic, and phosphate-mobilizing microorganisms in biofertilizers further enhances the diversity of plant nutrients in the soil (Singh et al., 2018) [4] .

Materials and methods

The materials and the methods adopted during the course of present investigation entitled "Effect of biofertilizers and bio-stimulants on soil parameters of okra (Abelmoschus esculentus L.) field" which was carried out during the year 2022-23 to 2023-24 under the climatic condition of Gwalior. The trial took place at the research farm of the College of Agriculture, R.V.S.K.V.V., Gwalior, located in Grid zone at a latitude of 26°

Soil analysis (before and after experiment)

The soil samples were collected from the depth (0-15 cm) of soil profile with the help of screw and tube auger to study the impact of various fertility treatment on soil properties of experimental site. Soil samples were collected from each experimental plot before and after the crop harvest. The samples were air-dried, oven-dried, granulated using a wooden mortar and pestle and then passed through a 2 mm sieve.

Results

An in-depth analysis of the information depicted in table 3

Discussion

According to the results, there has been an attempt to address a particular approach. It is evident from the data in tables 3 to 5 that the use of both biofertilizers and bio-stimulants had a considerable impact on various soil factors such as soil acidity, electrical conductivity, organic matter content, nitrogen availability, phosphorus levels, and potassium content. The lowest soil pH after harvest was found in treatment combinations T 21 (Azotobactor + PSB + KSB + Humic acid 4 %) and T 19 (Azotobactor + KSB + Humic acid 4 %) at 6.87, 7.17, and 7.02, while the highest soil pH after harvest was documented in T 1 (control) at 7.50, 7.80, and 7.65 for the first year, second year, and overall data.

The minimum soil EC post-harvest was noted in T 21 and T 19 at 0.20 and 0.17 (ds/m) for the first and second years, with T 21 recording the lowest soil EC in pooled data at 0.18 (ds/m). Conversely, the maximum soil EC after harvest was seen in T 1 at 0.25, It might be because Azotobactor plays an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is inaccessible to plants, and releasing it in the form of ammonium ions into the soil. Azotobacter have a full range of enzymes needed to perform the nitrogen fixation: ferredoxin, hydrogenase and an important enzyme nitrogenase. The introduction of efficient microbes (P solubilizers) in the rhizosphere has been found to increase the availability of phosphorus from both applied and native soil phosphorus. The microbial property of dissolving interlocked phosphates appears to have an important implication in agriculture. Humic acid comprises various components such as large molecules, water-repelling, water-attracting, and functional units. The water-attracting property of humic acid draws in hydrogen ions, enhancing the soil's ability to retain water. Humic acid present in organic matter, known as humus, like (HA), can greatly influence the soil's well-being and the growth of plants.

The results are in line with Kataki et al. (2023) [5] who conducted a research on the Arka Anamika Okra variety grown over two years in the summer season using nine different combinations of Azospirillum and PSB. The soil exhibited the highest quantities of accessible N, P, and K when treated with a mixture of Azospirillum and PSB (T 6 ) in conjunction with suitable compost. Soil health markers such as Microbial biomass carbon and the activities of enzymes (dehydrogenase and urease) significantly increased in soil treated with both Azospirillum and PSB together with optimal compost (T 6 ). Acid phosphatase activity was most notable in T 4 (PSB with optimal compost). Pawar et al. (2018) [6] conducted a study to investigate the impact of soil quality on Integrated Nutrient Management in Snowball-16 cauliflower variety. Azotobacter, Farm Yard Manure (10 t/ha), Recommended Dose of Fertilizers (120:80:40 NPK kg/ha), and Azospirillum (10 kg/ha) were all part of the experimental setup. According to the findings, the application of the highest INM dose-100% RDF + FYM + Azotobacter + Azospirillum-was linked to the highest levels of accessible nitrogen (265.66 kg/ha), available phosphorus (23.26 kg/ha), and available potassium (415.33 kg/ha). The treatment containing 75% RDF + FYM + Azotobacter + Azospirillum also displayed the highest organic carbon content (0.93%).

Conclusion

The present study demonstrates that soil fertility status under okra cultivation was influenced by the application of biofertilizers and biostimulants. Soil pH and electrical conductivity showed treatment-wise International Journal of Advanced Biochemistry Research https://www.biochemjournal.com variation, while organic carbon and the availability of nitrogen, phosphorus and potassium responded more favourably to integrated treatment combinations. Among the evaluated treatments, T 21 (Azotobacter + PSB + KSB + humic acid 4%) consistently recorded the most favourable values for the major soil fertility parameters. The pooled results showed higher pH (7.50), organic carbon (0.81%), available nitrogen (147.33 kg ha -1 ), available phosphorus (35.00 kg ha -1 ) and available potassium (142.45 kg ha -1 ), along with lower electrical conductivity (0.18 dS m -1

), compared with the untreated control. Overall, the findings suggest that combined application of nitrogen-fixing and nutrient-solubilizing biofertilizers with humic acid can improve important indicators of soil fertility under okra cultivation. Therefore, integrated use of Azotobacter, PSB and KSB with 4% humic acid may be considered a promising soil-fertility management approach, although further evaluation under different soil types, locations and seasons would be useful for wider validation.

Acknowledgement

AcknowledgmentWe wish to thank the Department of Horticulture, College of Agriculture, R.V.S.K.V.V., Gwalior, M.P. for kind support during the research work.

References

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14. How to cite this article: Nagar BL, Gupta PK, Yadav SS, Gupta G, Yadav A, Shivam. Integrated use of biofertilizers and biostimulants for improved soil fertility in okra (Abelmoschus esculentus L.). International Journal of Advanced Biochemistry Research. 2026;SP-10(9):1933-1937. doi: https://www.doi.org/1