Productivity of Blackgram (Vigna mungo L.) Influence by Biofertilizers and Variable Sources of Nutrients

Blackgram (Vigna mungo L.) is one of the important pulse crop grown in India which belong to the family “Leguminoseae”. Blackgram is reported as originated in the India (De Candolle 1886). It is commonly referred to by various regional names, including ‘urad bean,’ ‘black gram,’ ‘minapapappu,’ and ‘udad dal’. Blackgram is a protein rich food. It contains 48.0% carbohydrates, 22.3% protein, 154 mg calcium, 9.1 mg iron, 1.4 g fat, 0.37 g riboflavin and 0.42 mg thiamine in per 100 g (Asaduzzaman et al., 2010; Narayanan et al., 2017; Selvakumar et al., 2012). Black gram (Vigna mungo L.), is a highly nutritious legume that offers a wealth of health benefits and integral part of human diets, particularly in South Asia. This pulse is rich in essential nutrients, making it a valuable source of protein, dietary fiber, vitamins and minerals (Raveena et al., 2024). In India, it is mostly grown in summer and rainy seasons, covering an area of 4.2 million hectares with total production of 2.34 million tonnes and average productivity of 557 kg ha^-1 during 2020-21. Madhya Pradesh is the largest producer of blackgram, accounting nearly for 21 percent of the total national production, followed by Andhra Pradesh (15 %), Uttar Pradesh (13 %) and Maharashtra (11 %) (2020-21). In the case of area, the share of Madhya Pradesh was 24 per cent, followed by Uttar Pradesh (10%) and Maharashtra (7%) area shares of major blackgram growing states during 2020-21. Among the major producing states, productivity is highest in Andhra Pradesh (915 kg ha^-1), followed by Jharkhand (879 kg^-1) during 2020-21 (Anonymous 2021). Black gram’s roots lie in the Indian subcontinent; its cultivation has now extended to various parts of the world. The crop is extensively grown in countries like India, Bangladesh, Sri Lanka, Myanmar and Thailand, where it forms an essential part of the diet. Additionally, its popularity is spreading to regions in Africa, the Americas and even Australia due to its adaptability to diverse agro-climatic conditions.
       
Blackgram is a legume crop, which means that it can form a symbiotic relationship with Rhizobium bacteria to fix atmospheric nitrogen (Das et al., 2014; Sadiq et al., 2023; Yamini and Anilkumar, 2023. However, if the soil does not contain the right strain of Rhizobium bacteria, blackgram plants will not be able to fix nitrogen efficiently. They are living microorganisms that can fix atmospheric nitrogen, solubilize phosphorus and promote plant growth (Kumar and Patil 2024, Choudhary et al., 2025; Gautam et al., 2022). Biofertilizers can help to ensure that blackgram plants have the necessary Rhizobium bacteria to fix nitrogen and grow well (Hepsibha et al., 2024; Kavitha and Srimathi, 2022; Patel et al., 2022). Biofertilizers play an important role in blackgram (Vigna mungo L.) cultivation (Vinutha et al., 2023; Tiwari et al., 2017). In addition to Rhizobium bacteria, other biofertilizers that can be used for blackgram include phosphate-solubilizing bacteria (PSB) and plant growth-promoting rhizobacteria (PGPR) (Kumar et al., 2022; Satyanandam et al., 2022). PSB can help to make phosphorus in the soil more available to blackgram plants (Tyagi and Singh 2019; Porpavai et al., 2022). PGPR can promote plant growth by producing plant hormones, suppressing pests and diseases and improving nutrient uptake.

The experiment was conducted at Agronomy Research Farm, Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, India, during Kharif season 2023 and 2024. The field was well levelled, having good soil conditions. Geographically, Ayodhya (Kumarganj) falls in a subtropical climate and is situated at 26°47" North latitude and 82°12" East longitude with an altitude of 113 meters above mean sea level. Soil of the experiment field was classified as silt loam in texture with alkaline reaction (pH 8.1) low in organic carbon (0.25%) and available nitrogen (190 kg ha^-1), medium in phosphorus (14.5 kg ha^-1) and potash (238.1 kg ha^-1). The experiment was laid out in a factorial randomized block design, two factors (biofertilizers and variable source of nutrients) with three replications. The three treatments of biofertilizers are viz. B₁: PGPR (Seed treatment @20 g kg^-1 Seed), B₂: PSB (Seed treatment @20 g kg^-1 Seed) and B₃: PGPR + PSB (Seed treatment each @20 g kg^-1 Seed). The levels variable source of nutrients viz. N₀: Control, N₁: 100% RDF (Inorganic Fertilizer), N₂: 75% RDF + Vermicompost @ 1 tonne ha-1, N₃: 75% RDF + Enriched FYM @ 2 tonne ha^-1 and N4: 50% RDF+ Vermicompost @ 1 tonne ha^-1 + Enriched FYM @ 2 tonne ha^-1. The recommended dose of NPK was 20:60:30 kg ha^-1. Sources of nitrogen, phosphorus and potassium were urea, single superphosphate and muriate of potash, respectively. The blackgram variety “Shekhar-2” was sown at a spacing of 30 cm x 10 cm with a seed rate of 25 kg ha^-1. The growth characteristics and yield attributes were recorded as per the different stages of the crop growth. The seed and stover yield (kg ha^-1) was recorded from the net plot area of each treatment. All the observations are statistically analyzed, following Gomez and Gomez’s (1984) method, with the significance tested at p<0.05. Standard error of the mean (SEm±) and critical differences (CD) values were provided for computing mean differences.

Growth characters
 
The pooled data over two years clearly indicated that the growth parameters of black gram were significantly influenced by the application of biofertilizers and different sources of nutrient at 45 and 60 days after sowing (DAS) (Table 1 ). Among the treatments, seed treatment with PGPR + PSB (@ 20g kg^-1 seed each) consistently recorded superior plant growth, reflected in greater plant height (24.32 cm at 45 DAS and 49.29 cm at 60 DAS), a higher number of primary branches (3.41 and 5.90 per plant), Leaf Area Index (3.33 and 4.70) and dry matter accumulation (3.10 and 7.76 g plant^-1) compared to other biofertilizer treatments.


       
Similarly, the use of variable nutrient sources also exhibited significant effects on plant growth. The treatment comprising 50% RDF+ Vermicompost @1 tonne ha^-1 + Enriched FYM @ 2 tonne ha^-1 outperformed other nutrient combinations, particularly at 60 DAS, where it resulted in maximum plant height (51.93 cm), number of primary branches (6.52 plant^-1), Leaf Area Index (4.93) and dry matter accumulation (8.27 g plant^-1). At 45 DAS, the highest plant height (25.05 cm) was observed under 100% RDF (inorganic fertilizer) alone, though the combined organic treatment proved more effective at later stages of growth. However, number of primary branches (3.57 plant^-1), leaf area index (3.46) and dry matter accumulation (3.19 g plant^-1) were observed highest at 45 DAS in 50% RDF+ Vermicompost @1 tonne ha^-1 + Enriched FYM @ 2 tonne ha^-1.
       
Overall, the results suggest that integrating biofertilizers with organic nutrient sources enhances black gram growth, potentially reducing the reliance on full doses of inorganic fertilizers while sustaining plant vigor and biomass accumulation. Biofertilizer is crucial work in soil solubilized nutrients, uptake and increased nutrient use efficiency; similar results were found (Meena  et al., 2021; Sarwade et al., 2023; Sangothari and Radhamani 2024). These findings underscore the importance of integrating biofertilizers in agricultural practices to enhance soil fertility and crop yield. Future studies should explore the long-term effects of these treatments on soil health and sustainability.
 
Yield attributes and seed yield
 
The pooled results over two years clearly demonstrate the beneficial effects of biofertilizers and variable source of nutrients on the yield attributes and yield of blackgram (Table 2). Significant improvements were recorded in key yield components such as the number of pods per plant, pod length, number of seeds per pod, grain weight per pod, grain yield, stover yield and harvest index.


       
Seed treatment with a combination of PGPR + PSB (Seed treatment each @ 20 g kg^-1 seed) showed remarkable enhancement in plant performance, leading to a higher number of pods (32.87 plant^-1), pod length (5.93 cm), seeds per pod (5.31) and grain weight (0.239 g). This treatment also translated into superior grain yield (1,365.71 kg ha^-1) and stover yield (2,690.94 kg ha^-1) along with an improved harvest index (33.61%). These findings align with the observations reported by Kumar and Kumar (2022) and Menariya et al., (2024), highlighting the synergistic role of biofertilizers in improving nutrient uptake and plant productivity.
       
Furthermore, the combined application of 50% RDF+ Vermicompost @1 tonne ha^-1 + Enriched FYM @ 2 tonne ha^-1 outperformed other nutrient treatments. This integrated approach resulted in the highest recorded values for number of pods (33.87 plant^-1), pod length (6.05 cm), seeds per pod (5.57), grain weight (0.251 g), grain yield (1,492.68 kg ha^-1), stover yield (2,921.82 kg ha^-1) and harvest index (33.80%). The improvement under this treatment can be attributed to the combined effect of balanced nutrient supply from both chemical and organic sources, leading to better soil health and sustained crop growth. This might be due to enhancement in growth and yield parameters as well as uptake of nutrients by the crop. Obviously, the cumulative effects of these parameters might have contributed to the increased grain yield potential of the crop. Similar findings might be due to Geetha and Velayutham, 2016; Rekha et al., 2013; Kumar et al., 2023). Therefore, with regard to kharif black gram cultivation, PGPR + PSB (seed treatment each @ 20 g kg^-1 seed) were found to be the most promising treatment in order to increase the black gram yield. These organic sources, such as enriched farmyard manure and vermicompost provided a substantial amount of nutrients to the soil. This increased nutrient availability led to a higher conversion of carbohydrate into protein, subsequently contributing to the elaboration of protoplasm and cell wall materials, thereby increasing cell size. This morphological expression was evident in terms of plant height, the number of branches plant^-1 and ultimately, greater dry matter accumulation. It is noted that cellulose, being a highly persistent component, requires an extended period for the decomposition of blackgram crop. As a result, the blackgram crop benefited from the residual nutrients, leading to improved growth and increasing the yield of blackgram. The results were in confirmation with the findings of Sangothari and Radhamani (2024), Rohan et al., (2022), Ramesh et al., (2016).

On the basis of experimental results (pooled two-year values), it was concluded that the application of bio-fertilizers (PGPR + PSB) was found to better the growth and yield of blackgram, remarkable increase in plant height, number of primary branches, leaf area index, plant dry weight, yield attributes, seed yield and stover yield. Among the variable sources of nutrients, the application of 50% RDF + vermicompost @ 1 tonne ha^-1 + enriched FYM @ 2 tonne ha^-1 (N4) was found better to achieve higher growth, yield attributes and yield of blackgram. Therefore, with regard to kharif black gram cultivation. PGPR + PSB (seed treatment each @ 20 g kg^-1 seed) with the application of 50% RDF + vermicompost @ 1 tonne ha^-1 + enriched FYM @ 2 tonne ha^-1 was found to be the most promising treatment combination in order to increase the black gram yield.

All the authors acknowledge and thanks Department of Agronomy, Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya for their guidance and support.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All experimental procedures and handling techniques were approved by Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced for conducting study, data collection, analysis, decision to publish, or preparation of the manuscript.