Trichoderma species: biofertilizers and biocontrol agents for agricultural sustainability

Abstract

Modern agricultural practice is burdened with increasing caution related to the use of chemical inputs in the form of fertilizers and pesticides. These concerns have been followed by a growing interest in more ecological approaches to nutrient supplementation and disease control management. As an option, biofertilizers and biocontrol agents gather the scientific community, aiming to deeply explore and emphasize “the solutions from nature”. In that context, the objective of our research was to isolate Trichoderma spp. from different environments (agricultural, forest soil, and pine bark) and test their biocontrol and plant growth promoting potential. A total of 13 Trichoderma spp. were isolated, and confrontation tests were established with Botrytis cinerea, Fusarium graminearum, and Fusarium oxisporum. Biochemical characterization involved the assessment of several plant growth promoting characteristics (production of indoles, siderophores and enzymes). The confrontation test revealed different mechanisms employed in newly formed interactions. The mycelia of six Trichoderma isolates completely overgrew the tested pathogens, expressing very high antagonistic activity (≥75%), and emphasizing the competitive character of the isolates. The presence of an inhibition zone, a sign of antibiosis as a probable mode of action, was recorded within F. oxisporum interactions with several Trichoderma isolates. Biochemical characterization confirmed the production of cell-wall degrading enzymes (cellulase, β-glucosidase and N-acetyl-β-glucosaminidase) which are correlated to mycoparasitism. Biochemical assessments confirmed the plant growth promoting nature of Trichoderma isolates, which were capable of producing indoles, siderophores and enzymes involved in P cycle (phosphatase and naphthol-AS-BI- phosphohydrolase). The obtained results suggests several newly isolated Trichoderma spp. as effective plant growth promotors capable of expressing direct and indirect mechanisms of growth stimulation and acting as promising biocontrol agents against significant crop pathogens. Further analyses demand assessment of field conditions performance and deeper insight into the mechanisms involved in mutualistic interactions with plants and antagonistic interactions with phytopathogens.