Effect of integrated nutrient management on growth parameters and nodulation of Lentil (Lens culinaris M.)

Introduction

Lentils have been a nutritional mainstay for humans from the Pottery Neolithic period due to its early domestication in the Near East, when pottery was not yet developed (Ahmad et al., 2018) [1] . Lentil is a pulse crop that belongs to the leguminous or fabaceous family and is often grown during the winter months. They are well-known for their protein-rich grains, which have a wide range of culinary applications. Lentils are a key rabi pulse in India, predominantly grown in Uttar Pradesh, Madhya Pradesh, Bihar, West Bengal, Jharkhand, Rajasthan, and Assam (Malik et al., 2022) [9] . This crop yields less than other legumes because to its low care requirements, cultivation in poor quality soils, and dependency on rainfall (Singh et al., 2025) [17] . Nutrients have a direct impact on both the plant and the symbiotic nitrogen, significantly influencing lentil yield. The continued loss of soil nutrients has resulted in numerous nutritional deficits in a variety of crops, including lentils. Nonetheless, an overreliance on artificial chemical fertilizers has gradually led to significant environmental dangers, soil degradation, and lower agricultural production (Chaudhay and Pathak, 2024). Integrated nutrient management (INM) has been used in conventional agriculture for a very long time because soil plant systems have a low rate of nutrient turnover (Patel et al., 2026) [14] . Rhizobium is a soil bacteria that works in tandem with pulse crops to promote their development and productivity. It enters legume root hairs and forms root nodules where biological nitrogen fixation (BNF) occurs (Surya Kant et al., 2016) [19] . This natural nitrogen source significantly enhances plant growth indicators such as height, biomass, and branching. Treating pulse seeds with the right Rhizobium inoculam is a cost-effective and environmentally friendly way to improve soil fertility and reduce the need for synthetic nitrogen fertilizers (Amat et al., 2020) [2] . Vermicompost is an organic fertilizer filled with nutrients that helps plants grow by supplying easily accessible macronutrients, micronutrients, plant hormones, and beneficial bacteria that promote root development and biomass. Additionally, phosphate-solubilizing bacteria (PSB) are beneficial soil microbes that convert insoluble phosphorus molecules to plant-accessible orthophosphate by releasing organic acids and phosphatases. This procedure enhances phosphorus absorption, encourages root development, and improves overall plant health. Keeping these facts in view, this study is proposed to understand the impact of integrated nutrient management on the nodulation and growth parameters of lentil (Kumar, 2023) [7] .

Materials and Methods

The experiment was carried out at the Agricultural Research Farm, Rama University, Kanpur, Uttar Pradesh, during the Rabi season of 2025-26. The soil was sandy loam in texture, low in available nitrogen, medium in available phosphorus and potassium, and slightly alkaline. The variety Shekhar Masoor-2 (KLB-303) was sown at a seed rate of 45 kg/ha with a spacing of 30 x 10 cm. The experiment was laid out in a Randomized Block Design (RBD) with 8 treatments and 3 replications. The treatments were: T 1 (Control), T 2 (RDF 100%), T 3 (RDF 50% + Vermicompost 10 t/ha), T 4 (RDF 50% + Vermicompost 5 t/ha + PSB), T 5 (RDF 50% + Vermicompost t/ha + PSB + Rhizobium), T 6 (RDF 75% + Vermicompost 10 t/ha), T 7 (RDF 75% + Vermicompost 5 t/ha + PSB), and T 8 (RDF 75% + Vermicompost + PSB + Rhizobium). Biometric observations for growth parameters and nodulation were recorded at 30, 60, 90 DAS, and at harvest.

Result and Discussion

Plant height

Plant height was significantly enhanced by nutrient treatments across all growth intervals, with treatment T 8 (RDF 75% + Vermicompost + PSB + Rhizobium) consistently recording the maximum heights: 13.70 cm at 30 DAS, 18.25 cm at 60 DAS, 38.40 cm at 90 DAS, and 49.43 cm at harvest. Treatments T 7 (RDF 75% + Vermicompost 5 t/ha + PSB) and T 6 (RDF 75% + Vermicompost 10 t/ha) closely followed, ultimately reaching 47.68 cm and 45.72 cm at harvest, respectively. Conversely, the T 1 (Control) treatment consistently exhibited the shortest plants at every stage, progressing from a minimum of 12.23 cm at 30 DAS to 12.24 cm at 60 DAS, 24.58 cm at 90 DAS, and at harvest the smallest harvest height of 30.24 cm. The addition of vermicompost, PSB, and Rhizobium greatly increases lentil plant height by providing a consistent supply of critical macro-and micronutrients, as well as growth-promoting phytohormones. This symbiotic mixture enhances root development, biological nitrogen fixation, and phosphorus solubility, resulting in enhanced vegetative growth and strong canopy architecture. The similar results observed by Pandey et al. (2017) [13] and Fatima et al. (2018) [6] .

Number of branches

The number of branching was significantly enhanced by integrated nutrient applications, with treatment T 8 (RDF 75% + Vermicompost + PSB + Rhizobium) consistently producing the maximum number of branches per plant: 2.83 at 30 DAS, 3.96 at 60 DAS, 8.06 at 90 DAS, and 11.66 at harvest. Treatments T 7 and T 6 closely trailed this trend across all growth intervals, ultimately reaching 11.33 and 10.96 branches at harvest, respectively. In contrast, the T 1 (Control) treatment consistently exhibited the lowest branching rate, yielding minimums of just 1.66 at 30 DAS, 1.83 at 60 DAS, 5.50 at 90 DAS, and concluding with only 9.00 branches at harvest. These results are in close agreement with the findings of Mekuria et al. (2019) [11] , Samar and Kumar (2020) [16] and Begom et al. (2021) [4] .

Dry matter accumulation

Dry matter accumulation was maximized across all growth intervals under treatment T 8 (RDF 75% + Vermicompost t/ha + PSB + Rhizobium), which recorded 54.26, 276.56, 656.48, and 772.50 g m -2 at 30, 60, 90 DAS, and harvest, respectively. Treatments T 7 and T 6 closely followed this superior trend at every stage, culminating in harvest accumulations of 760.80 and 748.55 g m -2 . Conversely, the T 1 (Control) treatment consistently exhibited the poorest performance throughout the crop cycle, yielding the minimum dry matter of just 37.48 at 30 DAS, 216.20 at 60 DAS, 542.88 at 90 DAS, and terminating with 628.32 g m -2 at harvest. The combined application of vermicompost, PSB, and Rhizobium considerably stimulates vegetative growth and leaf area expansion, directly increasing the crop's net photosynthetic rate and seasonal dry matter accumulation. Furthermore, Rhizobium's symbiotic nitrogen fixation and PSB's improved phosphorus solubility work synergistically with the micronutrients in vermicompost to promote better dry matter distribution. This outcome strongly aligns with prior research by Tarek et al. (2021) [20] , Rakesh and Mehra (2022) [15] and Kumar and Singh (2023) [8] .

Number of days to 50% flowering and maturity

Integrated nutrient management significantly accelerated the crop's phenological development, with treatment T 8 (RDF 75% + Vermicompost + PSB + Rhizobium) achieving the earliest 50% flowering at 45.83 days and the earliest maturity at 109.33 days. This rapid progression was closely followed by T 7 (46.50 days to flowering; 110.66 days to maturity) and T 6 (48.33 days to flowering). In contrast, the purely inorganic T 2 (RDF 100%) treatment delayed flowering to 49.83 days and maturity to 115.66 days. The maximum duration for both parameters was consistently observed in the T 1 (Control), which took 57.50 days to reach 50% flowering and 123.23 days to mature, followed by T 3 which took 120.66 days to reach maturity. These findings mirror the results reported by Pandey et al. (2017) [13] and Math (2018) [10] .

Number of Nodules per Plant

The incorporation of organic manures and bio-fertilizers with chemical fertilizers significantly enhanced the nodulation process in lentil. The maximum number of nodules per plant was recorded in treatment T 8 (RDF 75% + Vermicompost + PSB + Rhizobium), which observed a value of 20.66. This was significantly followed by treatment T 7 with 20.16 nodules and treatment T 6 with 18.53 nodules per plant. The minimum number of nodules per plant was observed in the T 1 (Control) treatment, which recorded 12.06, followed by the T 3 with 14.16 nodules. Inoculation with Rhizobium and PSB promotes early root colonization and nodule formation by turning insoluble phosphorus into accessible orthophosphates, thereby meeting the high energy requirement necessary for vigorous biological nitrogen fixation. A matching trend was documented by Sonkarlay (2020) [18] , Aparna and Dawson (2022) [3] and Mounika et al. (2022) [12] .

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