# Fungi of the _Trichoderma_ Genus: Future Perspectives of Benefits in Sustainable Agriculture
## 5 Application of _Trichoderma_ Fungi in Promoting Plant Growth
### Increasing the Availability of Nutrients
virens_ solubilized phosphorus in the range of 2.1-152.2 \(\mathrm{\SIUnitSymbolMicro g}\)/mL. [PERSON] et al. [143] documented that isolates of _T. harzianum_ and _T. virens_ increased the phosphate concentration in lettuce leaves by 1.2 and 1.9 g/kg dry weight, respectively. In turn, [PERSON] et al. [149] reported that two strains of _Trichoderma_ sp. isolated from the Amazon rainforests showed the ability to dissolve calcium phosphate at 82.6% and 90.3%. Moreover, these isolates produced organic acids such as lactic acid, fumaric acid, citric acid, isometric acid, and phytic acid during solubilization. The treatment of soybeans with the analyzed strains increased the dry weight of leaves and rootsand plant growth. The phosphorus absorption efficiency of the tested soybeans was in the range of 111.2-156.1% and 81.7-140.6%, respectively. [PERSON] et al. [150] also reported that the production of organic acids is one of the mechanisms responsible for the release of phosphorus ions, which appear to be inaccessible to plants in most soils. According to [PERSON] et al. [151], indole-3-acetic acid production and phosphate solubilization by _T. harzianum_ significantly stimulated the growth of tomato seedlings. The analyzed isolates produced auxins at the level of 13.38-21.14 \(\mathrm{\SIUnitSymbolMicro mL}\) and dissolved calcium phosphate at the level of 215.80-288.18 \(\mathrm{\SIUnitSymbolMicro mL}\). Plants treated with these strains increased leaf area, steam length, and fresh and dry weight of shoots and roots by 87.3-140.9%, 22.7-42.1%, 226.4-332%, 53.91-135.6%, 50-196.1%, and 166-400%, respectively, compared to the control. _Trichoderma_ fungi also increase the availability and uptake of magnesium ions, which are the main components of mRNA and chlorophyll synthesis enzymes [21], and potassium ions, which induce the activity of enzymes involved in respiration and photosynthesis, and regulate the osmotic potential of plants cells. The treatment of plants with these microorganisms also leads to an enhancement in their organisms of calcium ions, which participate in the signaling and metabolic processes of cells and the formation of the mitotic spindle [141]. In addition, _Trichoderma_ sp. has the ability to increase the availability of micronutrients, such as copper, zinc, and manganese ions, which affect crop size and plant nutrition [58; 79; 148]. These observations are confirmed by the studies of [PERSON] et al. [152], which show that _T. asperellum_ increased manganese concentration in wheat grains by 7.01 mg per kg and copper concentration by 0.51 mg per kg of grain. [PERSON] et al. [153] reported that the treatment of soil and tomato seeds with _T. harzianum_ significantly increased the concentrations of calcium, magnesium, potassium, and phosphorus in the roots and shoots of the analyzed plants. Similarly, [PERSON] et al. [143] noted that isolates of _T. harzianum_ and _T. virens_ enhanced potassium and calcium concentrations in lettuce leaves by 7.9 and 11.6 g/kg dry weight and 1.2 and 1.7 g/kg dry weight, respectively, compared to the control.