Impact of Culturable Endophytic Bacteria on Soil Aggregate Formation and Peanut (Arachis hypogaea L.) Growth and Yield Under Drought Conditions

The profile of endophytic bacteria in groundnut and their potential contribution to the reduction of drought stress are incompletely understood. Therefore, the current study is concentrated on examining the groundnut-culturable endophytic bacterial diversity, which has practical implications for reducing drought stress. Polyethylene glycol (PEG 6000) was used to identify the osmotic stress-tolerant bacterial isolates, and 51 strains were selected based on their tolerance. Fourteen potential bacterial strains with drought alleviation capacity and plant growth-promoting properties were selected and their identity was confirmed using 16S rRNA analysis. These isolates were positive for 1-aminocyclopropane-1-carboxylate deaminase, ammonia, minerals solubilization, and indole acetic acid. When applied to the groundnut seeds under water deficit conditions, the bacterial consortium (A. deltaense AMT1/Rhizobium sp. (N-Fixer) Caballeronia zhejiangensis BPT9 (PSB), Burkholderia dolosa BPT8 (KRB), and Bacillus safensis BPT6 (Drought-Mitigating Isolate)) increased the peanut germination by 91%. Soil application improved the aggregate formation. Further testing was carried out in the pot culture, where bacterial consortium improved the shoot length, root length, relative water content, chlorophyll content, nodule number, oil content, and kernel yield at 75% Water Holding capacity (WHC). Moreover, the treatment with bacterial consortia further stimulated the drought-protective mechanisms and resulted in higher efficiency of nitrogen, phosphorous, potassium uptake, electrolytes leakage, and soil enzymes such as dehydrogenase and alkaline phosphatase at 75% WHC. Microbial consortia inoculation controlled groundnut water absorption, photosynthetic performance, and stress metabolites, reducing drought-induced damage; hence, it is believed that endophytes have potential application in the improvement of yields of crops.