The Potential Evaluation of Mycorrhizal Inoculation on the Growth of Young Cocoa Plants (Theobroma cacao L.) Hybrid P7 x IMC67 in Greenhouse

This research aims to evaluate the effectiveness of mycorrhizal inoculation alone or in combination with biofertilizers on the growth of cocoa seedlings. The study was carried out in the greenhouse at the Station d'Expérimentations Agronomiques of the University of Lomé from December 2020 to May 2021 following a completely randomized design. Cocoa beans (hybrid P7 x IMC67) were sown on substrates inoculated with Rhizophagus aggregatum and Ben 10 strains at a single dose of 500 spores/pot or combined with two biofertilizers: FERTIPLUS (100 g/pot), AGROBIO (75 g/pot). The seedlings were monitored and their agronomic performance measured. The results show a good mycorrhization rate, 63.67% for R. aggregatum, 62% for Ben 10, 67% for R. agrgregatum + AGROBIO and 60.34% for Ben 10 + AGROBIO with mycorrhizal dependencies of 18.70%; 18.72%; 35.75% and 41.15% respectively. Furthermore, the results showed that the application of both mycorrhizal strains (R. aggregatum and Ben 10) alone or in combination with AGROBIO induced a significant increase (p < 0.05) in total fresh biomass, total dry biomass, height, colar circumference and number of leaves compared with the control. However, application of FERTIPLUS alone or in combination with the two mycorrhizal strains significantly (p < 0.05) depressed total fresh biomass, total dry biomass, height, crown circumference, taproot length and number of leaves compared with the control. This study shows that arbuscular mycorrhizal fungi provide important benefits to the plant, and can be used to improve the growth of young cocoa plants.