Tomato growth estimulation by a microbial consortium

Abstract

Individually, strains of Trichoderma spp. And plant growth-promoting bacteria (PGPB) can be effective as biocontrol and crop growth promotion agents. However, combinations of different Trichoderma species with PGPB have been shown to be more effective than a single microorganism. Numerous studies point towards a synergistic interaction of this type of consortium, given that this combination enhances the benefits on plants. Thus, it is essential to harness this intricate network of natural interactions to create microbial consortia that substantially and consistently benefit plant growth and health, increase crop production and decrease the use of chemical compounds. The objective of the present study was to analyze the potential of the strains Pseudomonas putida PCI2 and Trichoderma harzianum ITEM 3636 to promote the growth of tomato plants under commercial field conditions and to eventually control diseases affecting this crop. The field assays were carried out in an organic production greenhouse, located in Tres Acequias (33°01 ‘33.2 “S 64°25’ 53.7”W), and in greenhouses intended for traditional tomato production, which were located in the 38eriphery of Río Cuarto (33°04’46.6”S 64°20’ 37.2”W), during the 2022-2023 production period. The following treatments were carried out: (1) Control without inoculation; (2) inoculation with PCI2; (3) inoculation with ITEM 3636 and (4) inoculation with PCI2 + ITEM 3636. At the time of transplanting, seedlings were inoculated by immersion of their roots in the corresponding suspension, at a concentration of 1 x 105 conidia ml-1 for ITEM 3636 and 1 x 106 CFU ml-1 for PCI2. In the organic greenhouse, with focus on the consortium inoculation treatment, we observed statistically significant increases in leaf area (74%) and number of fruits per plant (225%), compared to the controls. Also, we observed that the inoculated treatments were always in a more advanced phenological stage than the control treatment, which was left behind due to competition with weeds. Thus, inoculation also contributed to the rapid establishment of the crop. On the other hand, in the traditional production greenhouses, we observed that the consortium inoculation treatment caused statistically significant increases in leaf area (68%), internode length (28%), equatorial diameter of fruits (20%) and polar diameter of fruits (28%), compared to the control. No disease occurred in any of the greenhouses. PGPB and fungi such as Trichoderma are examples of microbial players within the rhizosphere that can enhance nutrient availability, modulate phytohormones, provide biocontrol, and improve biotic and abiotic stress tolerance in plants. We can conclude that inoculation of tomato roots with PCI2 + ITEM 3636 favored the growth, yield and health of tomato plants, compared to the controls, under two different production systems.