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  • Christian Wolff

Handpollination of cocoa flowers

In November 2018, Göttingen-based agroecologists Dr. Thomas Cherico Wanger and Manuel Toledo Hernandez (meanwhile both at Westlake University of China) visited AMAP Brazil and Fazenda Bom Pastor for the first time. Together we wanted to discuss cooperation on cocoa research and outline project ideas. This was to be the start of the EAI project, but it could only be realized in 2022 due to the Covid pandemic. However, as we had already come together on site and didn't just want to plan theoretically, we decided to implement a small, exciting project that would only take a few months - from the cocoa blossom in November to the harvest of the cocoa fruit in the middle of the following year. All workers of AMAP were involved in this project and a lot of extra hours had to be worked over Christmas and New Year 2018/19. The work resulted in a scientific article that was published in October 2023.

In a field study, an attempt is being made to optimize yields by hand-pollinating cocoa flowers. Cocoa flowers are pollinated by wild insects. Ecological conditions for pollinators on plantations are crucial for pollination success. Nevertheless, even with good ecological conditions, there is a gap between realized yield and potential yield. This yield gap is reduced on conventional cocoa farms with synthetic fertilizers and pesticides; this is not possible with organic management and also harms potential pollinators and biodiversity.

The study could show that enhancing pollination through hand pollination in relation to shade canopy cover and grafting of high yielding varieties is a major driver of cocoa tree yield in agroforestry systems in Brazil. Hand pollination can increase the average fruit set by 331% and mature fruits by 300% with as little as 10% hand pollination, in contrast to natural pollination. The labor efforts for hand pollination would be ~5 min per tree to pollinate 10-30% of the flowers per tree.

Based on the findings the authors recommend three actions to achieve hand pollination benefits for cocoa farmers managing agroforests:

  • Enhance cocoa pollination by at least 10-30% flowers per tree

  • in selected high yielding grafted trees

  • growing under an average of 40-50% shade

This field experiment shows that hand pollination is an easy-to-use method to increase yields and improve the income of local cocoa farmers, particularly in agroforests under 40-50% canopy cover and thus creates win-win opportunities for high productivity and climate resilience/biodiversity conservation.

The monitoring of cocoa pollination in the EAI project is based on the results of this study and other previous work, and focuses on the pollinator ecology of cocoa.

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