Biostimulant Potential of Trichoderma Spp. on the Vegetative Growth of Cocoa Seedlings in Nurseries in Côte d’Ivoire

Abstract

Cocoa tree (Theobroma cacao L.) plays a strategic role in Côte d’Ivoire’s economy and social life. However, the production of vigorous seedlings in nurseries is hampered by low nutrient availability in the soil and plant pathogens. This study aims to improve cocoa seedlings in nurseries through the use of a biostimulant based on Trichoderma sp. Isolates of Trichoderma sp. were obtained from the rhizosphere of cocoa trees in the localities of Agboville and Yamoussoukro. These fungal strains were characterised morphologically and their effects on the vegetative growth of cocoa seedlings were assessed. Twenty-five Trichoderma isolates were obtained and grouped into seven morphotypes. The effects of these isolates were assessed in terms of plant height, leaf length and width, as well as stem base diameter and number of leaves, over a 90-day period. The results show that inoculation with Trichoderma significantly improves all the parameters studied compared with the control plants. Treatments T3, T5 and T7 performed best, with a particularly marked response for T3. These results confirm the potential of Trichoderma sp. as a biofertiliser for improving the vigour of cocoa seedlings in nurseries.