From waste to growth: tea residue recycling through Trichoderma's solid-state fermentation for tea cuttings

Abstract

Abstract Background Trichoderma is a widely recognized plant growth-promoting fungus (PGPF) that has been extensively utilized in various agricultural applications. However, the effects of Trichoderma on the growth of tea cuttings and the changes in the fungal community are still unclear. This study produced T. guizhouense NJAU 4742 (NJAU 4742) via solid-state fermentation using tea residue and evaluated its potential to promote the growth of tea cuttings. Results The optimal conditions for spore yield were determined as a 7:3 (w/w) ratio of tea residue to rice bran, a material thickness of 3 cm, an inoculum concentration of 15%, and an incubation time of 4 days, resulting in a spore count of 1.83×109 CFU/g. The application of NJAU 4742 spore products significantly increased the biomass of tea cuttings and influenced the fungal community composition. Moreover, the application of higher NJAU 4742 spore concentrations resulted in better growth performance, and the application of nursery substrate with 1×107 CFU/mL spores was the most economically viable option. Notably, among the top ten fungal genera with the highest relative abundances, Trichoderma showed a positive correlation with the fresh weight of tea cuttings, while the other nine genera exhibited a negative correlation. Conclusions This study showed that utilizing tea residue for solid-state fermentation of NJAU 4742 is a feasible approach, and the application of NJAU 4742 spores enhances the growth of tea cuttings by increasing the relative abundance of Trichoderma.