MICROBIAL INOCULATION INDUCED ENHANCEMENT OF PLANT GROWTH, NODULATION, ENZYME ACTIVITIES, NUTRIENT ACQUISITION, AND PRODUCTIVITY OF BLACKGRAM (VIGNA MUNGO L. VBN 8): A MULTIVARIATE PERSPECTIVE

Abstract

Pulses are integral to Indian agriculture and human nutrition, particularly for the predominantly vegetarian population, owing to their high protein content and capacity for biological nitrogen fixation. Among pulse crops, blackgram (Vigna mungo L.) is widely cultivated across diverse agro-climatic regions; however, its productivity remains relatively low due to poor soil fertility, marginal growing conditions, and inadequate nutrient management. The excessive and indiscriminate use of chemical fertilizers has further contributed to soil degradation, nutrient imbalance, and declining nutrient-use efficiency, emphasizing the need for sustainable nutrient management strategies. Biofertilizers offer an eco-friendly and cost-effective approach for improving nutrient availability, soil fertility, and crop productivity while reducing dependence on chemical fertilizers. The present study evaluated twelve elite microbial inoculants for their effects on the growth, nodulation, biochemical and enzyme activities, nutrient uptake, yield, and nutrient-use efficiency of blackgram under field conditions. Field evaluation demonstrated the consistent superiority of Azospirillum lipoferum AZ204, Azospirillum brasilense CW903, and Rhizobium leguminosarum BMBS P47, which markedly improved plant growth, nodulation, grain yield, nutrient uptake, and nutrient-use efficiency compared with uninoculated controls. AZ204 exhibited superior overall performance, particularly in grain yield, nitrogen and phosphorus uptake, and nutrient-use efficiency, whereas CW903 showed pronounced effects on phosphorus related traits and yield attributes. BMBS P47 performed strongly in nodulation, nitrogen uptake, and nitrogen-use efficiency. The cumulative effectiveness of these microbial inoculants was further confirmed by multivariate analysis, which showed that growth, yield, and nutrient-related characteristics significantly contributed to treatment discrimination. These outcomes demonstrate the potential of specific microbial inoculants as viable biofertilizers for blackgram production, particularly AZ204, CW903, BMBS P47, PSB 1, KRB 9 and ZSB 15.