Applications of Trichoderma in plant growth promotion

Abstract

Trichoderma species are widely reported as plant growth promoters. This trait is isolate rather than species specific with individual isolates exhibiting varying degrees of plant specificity. Increased root and/or shoot biomass is the most common expression of growth promotion but changes in plant morphology and development are also reported. Growth promotion can be highly variable due to several limiting factors including crop type, growing conditions, inoculum rate and formulation type. Many Trichoderma bioinoculants are now commercially available with strain mixes becoming increasingly common due to their greater consistency of performance. Various mechanisms have been proposed to explain growth promotion including control of minor pathogens, enhanced nutrient uptake, increased carbohydrate metabolism and photosynthesis, and phytohormone synthesis. There is strong evidence for a role for microbe-produced indole acetic acid (IAA), although it is most likely that Trichoderma stimulates growth by influencing the balance of hormones such as IAA, gibberellic acid and ethylene.