Hand Pollination under Shade Trees Triples Cocoa Yield in Brazil's Agroforests

Agricultural diversification can enhance climate resilience, biodiversity conservation, and livelihood in global farming systems. Diverse agroforestry systems with cocoa have been shown to provide all these benefits, but the often-lower yields compared to monocultures limit agroforestry adoption by smallholder farmers. Cocoa yield is pollination-limited, and here, we quantified the effect of hand pollination in cocoa on fruit set, fruit abortion or cherelle wilt, pest and diseases, and number of mature fruits. Experiments were conducted in Bahia, Brazil, along a shade gradient from low [10-30%] to high [70-100%] canopy cover and with cocoa trees grafted with highyielding varieties. We found on average 331% fruit set, and 300% mature fruit increase (i.e. ripe pods) per tree by enhancing pollination by hand as little as 10% of the flowers/tree, compared to the control (i.e. with only natural pollination). Fruit set, fruit losses, and mature fruit development linked to hand pollination was higher in low compared to highly shaded cocoa areas. We found 31% higher fruit set and 37% higher number of mature fruits in grafted than un-grafted trees. Further, when comparing efforts invested in hand pollination, minimum labor (-5 min/tree to pollinate 10-30% of the flowers/tree) led to a 871% fruit set and a 750% mature fruit increase under low canopy cover, and intermediate labor (-15 min/tree to pollinate 40-60% flowers/tree) to a 629% fruit set under high canopy cover. As -5-15 min/tree hand pollination can substantially enhance fruit set and number of mature fruits in low as well as high shade management, we recommend performing hand pollination particularly in agroforests under 40-50% canopy cover to create win-win opportunities for high productivity and climate resilience. Future research should focus on the wide range of agroforestry, tree grafting and innovation strategies in all major production regions to capture the long-term variability of hand pollination as a basis to scale-up hand pollination for sustainable cocoa production globally.