Multivariate elucidation of soil-microbial-physiological interactions under bio-organic nutrient modules in kiwifruit (Actinidia deliciosa A. Chev.)

Organic formulations are emerging as sustainable and eco-friendly solutions for enhancing crop production and promoting long-term agro-ecosystem resilience. The present investigation was carried out on kiwifruit cv. ‘Allison’ under mid-hill conditions of Himachal Pradesh. The study aimed to assess the influence of integrated nutrient management modules comprising organic manures, biofertilizers (UHF-Jeevanu Khad) and Jeevamrit-based formulations on plant physiological traits, soil physico-chemical and chemical properties, and microbial activity. A field experiment, laid out in a randomized block design (RBD) with seven treatments and three replications, revealed significant improvements in physiological parameters, specifically, chlorophyll content, photosynthetic rate, stomatal conductance and transpiration rate, which collectively enhanced overall plant metabolic efficiency. Among the treatments, the combination of 75% recommended dose of fertilizers (RDF) and 25% UHF-Jeevanu Khad significantly enhanced soil macronutrients, namely N, P and K by 17.75, 20.58 and 19.78%, respectively, over their sole application, along with notable improvements in micronutrients (Fe, Zn, Mn, Cu), indicating improved nutrient dynamics. Microbial populations, including bacteria, fungi and actinomycetes, increased substantially under organic inputs, indicating enhanced microbial activity in the rhizosphere, which may improve root-microbe interactions and nutrient cycling. Multivariate statistical analyses including principal component analysis (PCA) and heatmap cluster revealed strong associations among microbial, nutrient and physiological traits, with the treatment comprising 75% RDF combined with 25% UHF-Jeevanu Khad, and the treatment involving RDF at 800:600:800 g N:P:K per vine forming distinct, high-loading clusters. Correlation analysis showed significant positive relationships between available nitrogen and photosynthetic rate (r = 0.983), stomatal conductance (r = 0.964) and chlorophyll content (r = 0.958), indicating close linkage between nutrient availability and plant physiological performance. Additionally, multiple regression analysis (R2 = 0.9938) identified available nitrogen and photosynthetic traits as dominant predictors of yield. The integration of organic manures, biofertilizers and Jeevamrit-based formulations with recommended fertilizers enhanced soil fertility, microbial activity and plant physiological performance, thus supporting sustainable kiwifruit production in mid-hill regions. These findings underline the importance of combining organic and microbial inputs with conventional practice to improve nutrient cycling, plant health and productivity.