Application of Trichoderma spp. at different times on the growth and nutrition of grafted dwarf cashew seedlings

Trichoderma species are widely recognized for promoting plant growth and improving plant nutritional status. This study aimed to evaluate the effects of Trichoderma longibrachiatum (LPPC299) and Trichoderma asperellum, applied at different times (at sowing, after grafting, and combined application), on the growth and nutrition of grafted dwarf cashew seedlings ‘BRS 226’. The experiment was conducted in a completely randomized design with seven treatments and ten replicates. At 120 days after germination, growth-related mechanisms, biometric parameters, dry matter production, and plant nutritional status were evaluated. The LPPC299 isolate applied after grafting promoted a significant increase in stem diameter and leaf nitrogen content, while combined applications increased stem diameter. T. asperellum mainly enhanced leaf area and leaf dry matter. Total biomass production and most nutrient contents did not differ significantly among treatments. The isolates did not produce indole-3-acetic acid; however, they were able to solubilize calcium phosphate and produce siderophores in vitro, independently of application type and timing. It is concluded that the effects of Trichoderma are isolate-dependent, with LPPC299 being the most promising isolate for improving the performance of grafted dwarf cashew seedlings.