Over time, the productivity of cacao trees diminishes, compelling farmers to either replace the older trees or cultivate new crops in different locations. Often, these new plantations are set up in portions of the forest that have been cleared to make room for fresh cacao trees. However, this practice incurs significant economic and ecological repercussions. A more sustainable solution is to graft productive and native cacao varieties onto the older trees that are already in place. A research team from around the globe, spearheaded by scientists from the University of Göttingen, discovered that cacao grafting is an effective method to revitalize cacao plants, enhancing their yield and profitability with minimal disruption to biodiversity. The findings are detailed in the Journal of Applied Ecology.
Cacao grafting involves inserting a shoot from a desirable variety into a mature cacao tree. By utilizing the established root system of the adult tree, this method quickly replaces the outdated tree canopy with new, vigorous branches. Although this technique has been employed for various crops for a long time, its effects on cacao production and biodiversity had never been rigorously tested together. Researchers from the Universities of Göttingen and Würzburg in Germany, alongside Bioversity International, collaborated with local farmers in Peru to study this approach. The focus was on grafting high-yield genotypes from the highly prized native variety, Cacao Blanco de Piura. “These native varieties have already led to a 45% increase in crop yield within just two years,” states Dr. Carolina Ocampo-Ariza from Göttingen University’s Agroecology group, who led the research. “This is excellent news for producing fine flavor cocoa, demonstrating the effectiveness of grafting to boost yields in a short time frame.”
In the initial six months following grafting, the researchers evaluated the diversity of arthropods, such as spiders, mites, and insects. “We were concerned that the diversity of arthropods on the new grafts would be lower since the large, mature tree crown with multiple branches had been removed,” explains Sophie Müller, a former MSc student at Göttingen University and co-leader of the study. “However, we actually observed that after a slight decline in diversity—particularly among predatory arthropods—the community rebounded quickly within just six months.” This resurgence is particularly beneficial for managing insect pests in cacao agroforests, as predatory arthropods can help reduce pest infestations.
“Our research confirms that grafting serves as a sustainable method to refresh aging cacao crops, helping to prevent agricultural expansion into tropical forests,” emphasizes co-author Professor Teja Tscharntke from Göttingen University.