Response of Chinese potato (Colocasia esculenta, Araceae) to abiotic and biotic stress, and the effectiveness of treatment with the fungus Trichoderma harzianum.

Abstract

Climate change intensifies drought, which increases susceptibility to phytopathogens in several crops such as the Chinese potato (Colocasia esculenta). This species is cultivated in tropical areas mainly for the production of corms, which are affected by Fusarium oxysporum dry rot. Phytopathology treated with toxic chemicals, which highlights the biocontroller Trichoderma harzianum, which also helps reduce the effects related to drought in other crops. Therefore, the objective was to characterize the response of C. esculenta to drought and infection by F. oxysporum, and the effectiveness of treatment with T. harzianum. Greenhouse tests were carried out with three factors (F. oxysporum, T. harzianum and drought), each with two levels (presence and absence) (N=48). Plant growth was evaluated for 30 days, in addition to the relative chlorophyll content, maximum efficiency of photosystem II, water content (WC%), incidence and severity. It was obtained that abiotic and biotic stress decreases growth. Drought lowered photosynthetic efficiency, and both stressors reduced chlorophyll in plants not treated with T. harzianum. Stress decreased leaf and corm WC%, but this effect was reduced by the biocontroller. This fungus reduced the incidence of F. oxysporum, and the severity of foliar symptoms for both types of stress. In conclusion, abiotic and biotic stress differentially impacts C. esculenta, and T. harzianum tends to improve growth under stress. However, more studies are required to evaluate its benefit on productivity. This work is one of the first to describe the stress response of this crop, and highlights its importance for future technification plans.