Mycorrhizal Interaction between Companion Trees and Cocoa Trees (Theobroma cacao L.) in Traditional Agroforestry Systems in Côte d’Ivoire

Abstract

Aims: The effective use of companion trees in agroforestry systems could improve the health and productivity of cocoa trees by understanding the interactions they promote. This study aims to decipher the characteristics of arbuscular mycorrhizal communities in the roots and soil of cocoa trees and their companion trees to understand the interaction between these two types of trees. Methodology: Five mycorrhization parameters measured in cocoa trees and nearby companion trees were compared. These were, shared species diversity, number of spores, mycorrhization frequency, mycorrhization intensity and colonization intensity in the mycorrhized part of the root system. correlation tests between these parameters were also used to establish the link between the data. Results: The study identified 49 AMF species involved in the interactions between companion and cocoa trees. T. superba (64.28%) and B. mannii (62.5%) recorded the highest species diversity and spore numbers. The highest mycorrhization rates were found between T. ivorensis and cocoa. Statistical analysis revealed strong positive correlations for species diversity and spore numbers with specific companion trees. Based on the results, T. superba, B. mannii, and R. heudelotii are recommended for promoting mycorrhizal spore production, while T. ivorensis is suggested for high mycorrhization levels. Conclusion: The study of interactions thus disclosed strong links between all cocoa trees and companion trees on the basis of the 5 types of variables used to establish correlations. But, A. boonei, T. superba, T. ivorensis, T. heckelii, M excelsa, B. mannii, B. mannii and G. kola can be recommended in cocoa agroforestry systems as they have the most important mycorrhizal interactions with cocoa trees.