Application of Olive-Mill-Wastewater-Compost in Combination with Symbiotic Microorganisms Improves the Physiological, Biochemical Performance and Tolerance of Tomato (Solanum lycopersicum) Under Drought Stress.

Drought seriously affects the agro-physiological and biochemical functioning of plants by influencing the interactions between plants and symbiotic microorganisms. Therefore, the objective of the present study was to implement a management approach to improve tomato growth, and drought tolerance using arbuscular mycorrhizal fungi (AMF) (pure strain (M) and consortium (M′)), and/or plant growth-promoting-rhizobacteria (Actinomycetes (A) and consortium with two bacteria Z2 and Z4 (B), and/or Olive-Mill-Wastewater-compost (OMWW-compost (C)). The potential for changes in physiological (stomatal conductance, chlorophyll fluorescence, photosynthetic pigments) and biochemical (sugar, protein, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), phenols, and antioxidant enzymes) functioning in response to water stress was analyzed. Therefore, under 35% field capacity (FC), the application of AMF (M or M′)/PGPR (A and B) amended with compost stimulated biomass and improved stomatal conductance, chlorophyll and carotenoid contents and photosynthetic efficiency to a greater extent than in uninoculated and/or unamended plants. The compost application with double inoculation including M′A (CM′A) significantly improved sugar concentrations in leaves and roots by 34% and 30% as well as enhanced antioxidant activities notably catalase (CAT), polyphenoloxidase (PPO) peroxidase (POX) and superoxide dismutase activities of about 92%, 177%, 84% and 79%, respectively. The dual inoculation together with compost (CM′A) and (CM′B) resulted in a significant reduction of H₂O₂ contents by 14% and 13% and MDA by 93% and 92%, respectively. The application of locally produced compost with dual combinations of bacteria can overcome the challenges of water stress by improving the physiological, biochemical and tolerance of tomato. [ABSTRACT FROM AUTHOR]