The aim of the BOLERO project is to develop phenotyping tools, predictive models, and low-cost breeding strategies to create rootstocks with enhanced tolerance to climate change, particularly focusing on coffee and cocoa crops. To reach this objective, WP4 is focusing on developing a method for fast and low-cost breeding and test it in low-input coffee and cocoa farming systems.

In Nicaragua, CIRAD, Nicafrance Foundation, Nestlé,  the National Autonomous University of Nicaragua (UNAN Matagalpa), and local farmers partnered on this initiative,  to create a resilient and diverse cocoa population.

First, they built a factorial design including 4 males crossed with 8 females. The male parent genotypes: IMC-67, Pure Criollo, Pure Amelonado (Catongo), and Clon 3, were carefully selected for their genetic characteristics. Complementing these, the female clones including ICS-1, ICS-39, ICS-95, TSH-565, CCN-51, UF-667, CRE-6, and EET-95, were chosen to create a diverse genetic pool.

Precision was key in the pollination process, where cocoa plants were meticulously selected based on maturity and flowering stage. Female plants were protected from outside pollination, ensuring the integrity of each cross. Pollen collection was done with care to preserve its viability.

Grafting was a pivotal stage in the project. It was performed using the previously created families as rootstock. Following a meticulous protocol, cacao clone CATIE R1 scions were grafted onto 6-month-old rootstock. The success of grafting, with a rate of 60%, marked a significant milestone in the project's timeline.

Post-grafting, once the scion successfully merged with the rootstock, the plants were transferred to the fields, in plots varying in sun exposure and fertilizer levels. Over the next 18 months, temperature, rainfall, and plant health will be monitored, with each plot analyzed for root system traits using machine-learning and NIR Spectroscopy on cocoa progenies, to assess performance and adaptation to different farming conditions.