Field trial to correlate mineral solubilization activity of Pseudomonas aeruginosa and biochemical content of groundnut plants

The excessive use of phosphorus (P) fertilizers increases crop production but can lead to P-induced zinc (Zn) deficiencies, making both nutrients unavailable to plants. Plant-microbe interactions, such as with Pseudomonas aeruginosa, can alleviate these constraints by solubilizing Zn and P in soil. A soil incubation study revealed that applying P. aeruginosa with farmyard manure (FYM) significantly increased Zn and P solubilization (6.86 mg/l; 14.83 mg/l) compared to control (3.15 mg/l; 13.67 mg/l). A field experiment evaluated the effects of P. aeruginosa on the biochemical composition of groundnut plants under five treatments. The T2, T3, and T4 treatments had the highest protein, carbohydrate, and chlorophyll levels, likely due to the heterogeneous activity of FYM and the mineral solubilizing ability of P. aeruginosa. Groundnut seeds from T3 (combined liquid inoculant and FYM) had the highest iodine (88.47 mg KOH/g), saponification value (195.56 mg KOH/g), and free fatty acid content (2.23 g oleic acid). The pH of the T3 soil decreased from 8.3 to 7.5, and significant increases were observed in electrical conductivity (from 2.88 to 0.30 dS/m), calcium carbonate (2.53-1.7%), organic carbon (0.39-1.91%), nitrogen (273.75-788.25 kg/ha), P (20.1-59.65 kg/ha), potassium (182.25-346.5 kg/ha), and Zn (1.53-7.24 mg/kg). The study suggests that the combined application of liquid formulants of P. aeruginosa with FYM is advantageous, as FYM supports microbial growth by providing essential nutrients for mineralization. Moreover, liquid inoculants formulated with polyvinylpyrrolidone as an osmo protectant demonstrated enhanced shelf-life and mineral solubilization, contributing to improved biochemical properties in groundnut plants.