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

Valerio Cirillo; Ida Romano; Sheridan L Woo; Emilio Di Stasio; Nadia Lombardi; Ernesto Comite; Olimpia Pepe; Valeria Ventorino; Albino Maggio

doi:10.3389/fpls.2023.1304627

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

Front Plant Sci. 2023 Dec 6:14:1304627. doi: 10.3389/fpls.2023.1304627. eCollection 2023.

Authors

Valerio Cirillo^#¹, Ida Romano^#¹, Sheridan L Woo^{2

3

4}, Emilio Di Stasio¹, Nadia Lombardi¹, Ernesto Comite¹, Olimpia Pepe^{1

4}, Valeria Ventorino^{1

4}, Albino Maggio¹

Affiliations

¹ Department of Agricultural Sciences, University of Naples Federico II, Portici, Italy.
² Department of Pharmacy, University of Naples Federico II, Naples, Italy.
³ National Research Council, Institute for Sustainable Plant Protection, Portici, Italy.
⁴ Task Force on Microbiome Studies, University of Naples Federico II, Portici, Italy.

^# Contributed equally.

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.

Keywords: Azotobacter chroococcum; Trichoderma afroharzianum; biostimulants; nutrient stress; tomato rhizosphere; water stress.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was carried out within the EU Horizon 2020 Research and Innovation Program — ECOSTACK (grant agreement no. 773554), the MIUR - PRIN 2017 PROSPECT (grant number 2017JLN833), National Biodiversity Future Center (NBFC — D.D. n.1034, 17/06/2022) and Agritech National Research Center and received funding from the European Union NextGenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR)—MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4—D.D. 1032 17/06/2022, CN00000022). This manuscript reflects only the authors’ views and opinions; neither the European Union nor the European Commission can be considered responsible for them.