Synergistic effect of Adathoda vasica plant-derived biostimulant and PGPR on Zea mays L. for drought stress management

Drought is a significant abiotic stress that adversely affects the physiological and biochemical processes in crops, posing a considerable challenge to agricultural productivity. The present study explored the efficacy of plant-derived biostimulant (PDB) and plant growth-promoting rhizobacteria (PGPR) strains Pseudomonas putida (RA) and Paenibacillus lentimorbus CHM12) in the management of negative impacts of drought stress in Zea mays (maize). Adathoda vasica leaf extracts (ADLE) emerged as the most potent biostimulant of the seven evaluated medicinal plant extracts. The synergetic effect of ADLE and RA enhances plant vegetative growth (root length, shoot length, fresh weight and dry weight) as well as significantly modulates drought-induced oxidative stress, as indicated by higher chlorophyll content and increased sugar and phenolic levels and reduction of proline level. The expression of defence-related (ZmAPX, ZmSOD, and ZmCAT) and transcription factor (ZmNAC, ZmWRKY, and ZmMYB) genes further supported the beneficial effects of this synergism under drought conditions. Furthermore, metabolite profiling through GC-MS analysis showed significant alterations in metabolites such as glucose, galactose, mannose, hexopyranose, linolenic acid, hexadecenoic acid, and butanedioic acid when PDB and PGPR were applied together. Overall, the findings of the present study affirm that the combined application of plant-derived biostimulant ADLE and plant-beneficial rhizobacteria RA can effectively alleviate the adverse effects of drought on maize, providing an eco-friendly and sustainable solution for improving productivity under stress.