Inoculation with a microbial consortium increases soil microbial diversity and improves agronomic traits of tomato under water and nitrogen deficiency

Abstract

Microbial-based biostimulants, functioning as biotic and abiotic stress protectants and growth enhancers, are becoming increasingly important in agriculture also in the context of climate change. The search for new products that can help reduce chemical inputs under a variety of field conditions is the new challenge. In this study, we tested whether the combination of two microbial growth enhancers with complementary modes of action, Azotobacter chroococcum 76A and Trichoderma afroharzianum T22, could facilitate tomato adaptation to a 30% reduction of optimal water and nitrogen requirements. The microbial inoculum increased tomato yield (+48.5%) under optimal water and nutrient conditions. In addition, the microbial application improved leaf water potential under stress conditions (+9.5%), decreased the overall leaf temperature (-4.6%), and increased shoot fresh weight (+15%), indicating that this consortium could act as a positive regulator of plant water relations under limited water and nitrogen availability. A significant increase in microbial populations in the rhizosphere with applications of A. chroococcum 76A and T. afroharzianum T22 under stress conditions, suggested that these inoculants could enhance soil microbial abundance, including the abundance of native beneficial microorganisms. Sampling time, limited water and nitrogen regimes and microbial inoculations all affected bacterial and fungal populations in the rhizospheric soil. Overall, these results indicated that the selected microbial consortium could function as plant growth enhancer and stress protectant, possibly by triggering adaptation mechanisms via functional changes in the soil microbial diversity and relative abundance.

Integrating Smart Greenhouse Cover, Reduced Nitrogen Dose and Biostimulant Application as a Strategy for Sustainable Cultivation of Cherry Tomato

“…He et al [37] reported that three species of Bacillus and one of Pseudomonas, inoculated either individually or in co-culture, promoted the growth and the uptake of N-depleted fertilizer of tomato plants, and co-inoculation with more microorganisms with complementary modes of action exerted an additive effect of growth promotion. Recently, Cirillo et al [38] showed how the simultaneous application of Trichoderma afroharzianum and Azotobacter chroococcum enhanced yield and alleviated the effects of combined water-nitrogen stress in tomato. Furthermore, the use of a plant-based biostimulant (sugar cane molasses with yeast extract by yeast autolysis) improved plant performances and fruit quality in tomato-grown plastic tunnels in Southern Italy at summer elevated temperatures [39].…”

Optimizing tomato seedling growth with indigenous mangrove bacterial inoculants and reduced NPK fertilization

“…Plant Growth Promoting bacteria (PGPB) are eco-friendly, low-cost natural resources that can be integrated to reduce the toxic effects of synthetic inputs and promote sustainable agriculture. PGP bacteria include different genera such as Agrobacterium, Rhizobium, Azospirillum, Azotobacter, Bacillus , and Pseudomonas ( Boleta et al., 2020 ; Rosa et al., 2022 ; Tounsi-Hammami et al., 2022 ; Cirillo et al., 2023 ; Gen-Jiménez et al., 2023 ). These bacteria can act as biofertilizers through various mechanisms, including nitrogen fixation, nutrient solubilization, ammonium production, siderophore production and hormone production.…”

Microbiome-Mediated Strategies to Manage Major Soil-Borne Diseases of Tomato

“…For instance, 'microbial inoculants' constitute a main strategy that inoculates specific beneficial microbiomes to the root zone to boost growth, nutrient, and stress tolerance in tomato plants [34]. Another tactic is engineering microbial consortia, which support plant health and provide disease resistance to root pathogens [35,36]. 'Biofertilizers' refer to the use of beneficial bacteria in tomato seeds, which promote plant growth [37].…”