Integrated application of plant growth promoting rhizobacteria and biochar improves salt tolerance in eggplant seedlings

Authors: RAZİYE KUL

Abstract: A pot study was conducted to determine the effects of the combination of plant growth promoting rhizobacteria (PGPR) and biochar on the growth, physiological, and biochemical characteristics of eggplant seedlings under salinity stress. The greenhouse experiment included two salinity levels of NaCl [S0 (0 mM NaCl) and S1 (100 mM NaCl)], three biochar levels [B0 (non-biochar), B1 (5%) and B2 (10%)] and two PGPR [R0 (non-PGPR), R1 (combination of Bacillus megaterium TV-6D, Paenibacillus polymyxa KIN- 37, and Pantoea agglomerans RK92). Results showed that plant growth, relative leaf water content (LRWC), and chlorophyll content of eggplant seedlings decreased significantly, while malondialdehyde (MDA), hydrogen peroxide (H2O2), proline, sucrose and ABA content, and electrolyte leakage (EL) increased significantly with increase in salinity levels. Biochar and PGPR applications mitigated the negative influence of salinity stress on plant growth and physiological and biochemical characteristics of eggplant seedlings, enhancing chlorophyll content, plant nutrient element uptake, and antioxidant enzyme activity. The enhanced salinity tolerance due to biochar and PGPR applications could be associated with a significant reduction in Na and Cl uptake, MDA, H₂O₂ and EL and an increase in LRWC, chlorophyll content, antioxidant activity and plant nutrient element uptake. Therefore, it can be concluded that combining biochar and PGPR could be used to minimize the detrimental impacts of salinity stress conditions in eggplant seedlings.

Keywords: Salinity stress, PGPR, biochar, eggplant, physiology, biochemistry

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