EFFECT OF Trichoderma harzianum AND Trichoderma viride INFECTION ON THE NUTRITIONAL COMPOSITION OF Ipomoea batatas (SWEET POTATO) IN CALABAR, CROSS RIVER STATE

Abstract

Sweet potato is a tuberous root vegetable cultivated in tropical and subtropical regions of the world mainly for its high nutritional content. Symptoms observed on the crop has suggested it’s susceptibility to a wide range of pathogens including fungi. Due to high impact of infections on the nutritional content of the crop, this study is aimed at determining the effect of Trichoderma harzianum and Trichoderma viride on the proximate composition of I. batatas. Infected and non-infected tubers were collected and proximate analyses was carried out. Isolation of pathogens from infected tubers was carried out by surface sterilizing in 1% sodium hypochlorite solution for 60 seconds and then, segments of tissue (3mm³) from the margins of rotten tubers were cut out aseptically, and plated on petri dishes containing PDA and incubated at 28±1⁰C for three days. Developing colonies were scrapped and cultured on fresh PDA plates to obtain and identify pure cultures of pathogens. Nutritional composition of infected samples was determined by oven drying sliced, flat tiny pieces of symptomatic tubers at 60^oC, and subsequently ground into fine powder and analyzed. Results identified T. harzianum and T. viride as the causative agents of postharvest rot of potato tubers. Also, nutritional content of tubers infected with T. viride showed a decrease in the carbohydrate, crude protein, and crude fat content when compared with non-infected tubers. Proximate content analysis showed, carbohydrate content, crude protein, crude fat, respectively decreased as follows: from 18.28±0.15 to 12.18±2.15, 1.81± 0.07 to 0.15±0.45, and from 0.08± 0.18 to 0.02± 0.12. While T. harzianum depleted carbohydrate, crude protein, and fat respectively to 10.31±0.33, 1.20±0.01, and 0.02±0.50. Fungal infection was found to negatively impact proximate composition of the crop. Since healthy plants are better able to resist fungal infections, enhanced soil fertility and plant health through proper nutrient management and soil amendments was recommended.