Impact of conjunctive use of organic manure, chemical fertilizers and seed bio-priming on growth and yield of lentil crop (Lens culinaris M.)

Introduction

Lentils (Lens culinaris M.) are a member of the Leguminosae family and are considered pulse crops. Among the most seasoned and nourishing crops cultivated during the rabi season. To a large degree, it can with stand harsh winters and frost. It needs cold temperatures when growing vegetatively and warm temperatures (18 to 30°C) when it reaches maturity. Additionally, lentils display better adaptability to low-water soil conditions, requiring less water and demonstrating increased resilience to drought stress compared to other crops (Sehgal et al., 2021) [6] . In India, lentil seeds are referred to as "the poor man's meat" and "masoor" due to its great nutritional value, which includes fiber, carbohydrates, vitamins A and B, potassium, iron, and low amounts of fat and salt. Mainly eaten as dry seeds, it is a good diet for humans. Lentils are one of the most important edible grain legumes in terms of a balanced and healthy diet. Namba-Santiago et al. (2023) [5] suggested that the grain of lentils is rich in protein, vitamins, fiber and minerals. Lentil leaves a N-rich soil for the crop planted after it via biological N fixation; however, root nutrients such as N, Ca, P, and K remain in the soil root zone as a result of decomposition (Ahmad et al., 2022) [1] . For sustainable agriculture, the amount of organic matter is important for soil fertility, protection, and sustainability. With a 44% and 18% share of global production, respectively, Canada dominates global lentil production, followed closely by India (Food and Agriculture Organization, 2021). The data from 2021-22 reveals that Rajasthan holds the top position as the leading pulse producer in India, boasting an annual production of 4364.74tonnes. Organic manure promotes microorganism those are beneficial to plant growth because they fix certain nutrients, which lasts in soil until consumed by the plants. The organic manures, improves the organic carbon in soil on its application (Khan et al., 2010).

Organic carbon performs additional functions of increasing soil organic matter content, and CEC, enhance biological activity, improves soil structure (Uwah and Iwo, 2011). Low productivity of lentil may be ascribed to many reasons such as inadequate and imbalanced fertilization and prevalence of suboptimum soil moisture condition. The lentil crop shows good response to phosphorus fertilization (Muhammad et al., 2002) [4] . Rhizobium and phosphate solubilizing bacteria are known to enhance the productivity of the crop as they increase the availability of soil nitrogen and phosphorus (Elsayed, 1999). Phosphorus is one of the macronutrients required for biological growth and development. Among the major nutrients phosphorus is considered to be one of the major limiting nutrient elements in pulse production in India, particularly in acid soils of North Eastern India, including Manipur. Phosphorus plays a vital role in cultivation of legumes as it directly enhances grain formation, stimulates early formation and growth of roots, improves nodulation, seed yield and seed crude protein content (Singh et al., 2014) [7] . Bio-priming of seed is a wonderful approach to meet the demand of chemical free food for ever increasing population. Bio-priming of seed uses microbial inoculants of plant growth promoting rhizobacteria and fungi. It is an ecofriendly strategy using selecte1d microorganism which produces substances for growth promotion and pathogen inhibition. Presently, seed treatment with biological inoculants is being used as a substitute to synthetic chemical pesticides and fertilizers in agriculture for plant and soil health improvement. Using biocontrol agents with priming agents for seed treatment over simple seed coating has potential advantages and serves as a better strategy of managing many seed and soil-borne diseases. In this study, our main objective was to contribute to the sustainable agricultural production of our region in particular, and our country in general, with practices that are more protective of human health than chemical fertilizer applications, by capturing the benefits of organic fertilization in our region.

Materials and Methods Experimental Site and Duration

The field experiments were conducted during the Rabi seasons of 2021-2022 and 2022-2023 at the Nidharia,Agricultural Research Farm, Shri Murli Manohar Town P.G. College, Ballia, Uttar Pradesh, India. The experimental site is located at 25°0.76′ N latitude and 84°0.12′ E longitude, at an altitude of 59 m above mean sea level. The region falls under a sub-tropical climate, with hot summers and cool winters. The average annual rainfall of the district is about 648 mm, mostly received during July to September.

Experimental Design and Treatments

The experiment was laid out in a Randomized Block Design (RBD) with 11 treatments and three replications. Each plot measured 5.0 m × 3.0 m. The treatments consisted of different combinations of recommended dose of fertilizers (RDF), organic manures, seed bio-priming with plant growth-promoting rhizobacteria (PGPR), and boron spray.

Crop Variety and Sowing

The lentil variety Pusa L-4717 was used in both seasons. Seeds were sown at a rate of 30 kg ha⁻¹, maintaining a spacing of 30 cm × 10 cm with a sowing depth of 3-5 cm. Sowing was done manually using a khurpi.

Treatment Details

 T₁: Control  T₂: 100% RDF  T₃: 75% RDF + Vermicompost @ 5 t ha⁻¹  T₄: 75% RDF + Press mud @ 5 t ha⁻¹  T₅: 75% RDF + Fly ash @ 5 t ha⁻¹  T₆: T₃ + Seed bio-priming with PGPR + 0.

Application of Organic Manures and Fertilizers

Organic manures (vermicompost, press mud, and fly ash) and chemical fertilizers were applied three days before sowing as per treatment schedule. Representative samples of organic manures were analyzed for their nutrient content to ensure precise nutrient application.

Seed Bio-Priming

Seed bio-priming was carried out for treatments T₆ to T₁₁ using Rhizobium culture (10 g kg⁻¹ seed) and phosphate-solubilizing bacteria (PSB) (10 g kg⁻¹ seed). The treated seeds were shadedried and sown immediately. Bio-priming was done to enhance seed germination, root nodulation, and early crop vigor. Grain and stover samples were oven-dried, ground, and analyzed for N, P, K, and S using standard digestion and estimation techniques.

Growth

Results and Discussion

Effect of Treatments on Germination and Seedling Growth

The results revealed that germination percentage and early seedling growth parameters were significantly influenced by the integrated use of organic manures, chemical fertilizers, seed biopriming (Table 1). Among the treatments, seed bio-priming with Rhizobium and PSB in combination with organic amendments recorded higher germination percentage compared to control and sole RDF treatment. Vermicompost + seed-biopriming recorded the maximum germination percentage. Improved germination may be attributed to enhanced microbial activity, better nutrient solubilization, and production of growth-promoting substances by PGPR during early growth stages. Similar findings were reported by Elsayed (1999) and Singh et al. (2014) [7] in lentil. Seedling dry matter accumulation was significantly higher in integrated treatments 75% RDF + Vermicompost @ 5 t + ha⁻¹ Seed bio-priming with PGPR + 0.5% B spray (T9) at flowering and(T6). The increase in dry matter might be due to improved nutrient availability and better root development under integrated nutrient management.

Effect on Yield Attributes

Yield-attributing characters such as number of pods plant⁻¹, number of filled pods, pod length, and pod width were significantly affected by different treatments (Table 4). Integrated nutrient management treatments outperformed control and RDF-only treatments.

The highest number of pods plant⁻¹ and filled pods was observed under T₉, followed by T₆ and T₁₀. The improvement in yield attributes may be attributed to enhanced nutrient uptake, balanced nutrition, and better translocation of assimilates due to boron application at flowering stage. Boron plays a vital role in pollen viability, flower retention, and pod formation. The superior performance of boron-applied treatments supports earlier findings that boron application enhances reproductive growth and seed setting in pulses (Singh et al., 2014) [7] . 5). The highest grain yield was recorded under T₉, which was statistically superior to control and 100% RDF but at par with T₆.

Compared to control, grain yield increased substantially under integrated treatments, indicating the positive role of organic manures and bio-priming in sustaining crop productivity. Vermicompost-based treatments recorded higher yields than press mud and fly ash, possibly due to better nutrient synchrony and improved soil physical properties. Stover and biological yields followed a similar trend, suggesting that integrated nutrient management improved overall biomass production. Reduction of chemical fertilizers by 25% without yield penalty highlights the sustainability of the approach.

Conclusion

The results clearly demonstrated that conjunctive use of organic manures, chemical fertilizers and seed bio-priming significantly improved growth, yield attributes, and yield of lentil. The superiority of vermicompost-based treatments indicates its effectiveness in improving nutrient availability and soil health. Reduction of chemical fertilizers by 25% along with organic and biological inputs not only maintained yield but also improved soil fertility, making the production system more sustainable. These findings are in agreement with earlier reports emphasizing the role of integrated nutrient management in pulse crops.

References

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