The Biopotential of a Wood-decaying Strain of Trichoderma harzianum for Protecting and Promoting the Sensitive Early Roots of Micropropagated Potato Plantlets and Reducing Transplantation Stress in an Aeroponic System

Minituber production in aeroponics is a growing trend in the potato seed industry for ensuring high-quality disease-free seed, as it requires vigorous, healthy plantlets to survive under stressful conditions. Fungi can assist plantlets endure stress, and there is a pressing need to explore various native fungi from an environmentally beneficial standpoint. In this study, three strains of Trichoderma harzianum were tested for their ability to protect the early roots of tissue culture–raised potato plantlets during hardening and to reduce transplantation stress in an aeroponic system. In the bioactivity results, strain TI21 isolated from decayed wood significantly improved root length by 42.7%, shoot length by 25.9% and biomass weight by 29.9% of tomato seedlings compared to control and demonstrated strong biocontrol activity (percentage) against four phytopathogens, including Sclerotium delphinii SCR5 (75.97 ± 8.06), Fusarium equiseti PTR3 (67.27 ± 5.11), Curvularia spicifera BLR4 (61.66 ± 2.98) and Alternaria alternata ALT10 (61.90 ± 4.58). Strains TI26 and TI27, isolated from rice rhizospheric soil, yielded no significant results. In potato-plantlet-hardening experiments, TI21 increased plantlet survival by 22.46%, 25.75% and 24.12%, compared to TI26, TI27, and control, respectively, by reducing root-rot caused by Sclerotium sp. and Fusarium sp. After 7 days of transplantation in aeroponic, TI21-treated plantlets had a significantly higher survival (90.5%) than control (77.6%), but there were no significant differences after 12 days, revealing that plantlets were much more susceptible to transplantation stress within the first 7 days of transplantation, which was overcome by TI21-treated plantlets. According to the findings, strain TI21 can be employed in micropropagated plantlets’ hardening to improve survival rates in aeroponic systems.