Selection of new varieties of cocoa (Theobroma cacao L.) adapted to the effects of climate change in Côte d'Ivoire
Creators
- 1. Centre National de Recherche Agronomique (Côte d'Ivoire)
- 2. ex- Bioversity International (France)
- 3. Alliance Bioversity-CIAT (Italy)
- 4. Centre de Coopération Internationale en Recherche Agronomique pour le Développement (France)
Description
In Côte d'Ivoire, climate change is particularly evident in the lengthening of drought periods, which seriously affects the establishment and productivity of cocoa orchards. In addressing this challenge, breeders must maintain or improve tree productivity and bean technological quality. The objective of this work is to select new varieties of high-performance cocoa trees adapted to different agroclimatic zones.
The experimental design, which is based on the previous achievements of the CFC/ICCO/Bioversity (2004-2009) and FIRCA (2008-2011) projects, includes four agro-climatic zones (Bouaflé, Abengourou, Divo and Soubré) including two with rainfall deficit (Bouaflé and Abengourou). The planting material, planted in two plots per zone, is made up of 15 CNRA families common to each agro-climatic zone and 10 to 15 free progenies, selected in each zone by the cocoa producers for their superior agronomic and technological performance.
The traits studied concerned i) the production potential, ii) the adult vegetative vigor measured by the diameter at the collar of the trees, iii) the grain size evaluated by the weight of 100 dry cocoa beans, and iv) the field resistance to black pod-rot (caused by Phytophthora spp.), evaluated by the percentage of rotten pods.
The results showed that with the exception of field resistance to black pod-rot, a highly significant zone x family interaction (probability < 0.0001) was observed for the studied traits. In particular, the negative impact of drought on the weight of dry bean size has been highlighted. The study also allowed the selection of four families of promising hybrids for resistance to black pod disease in the field, and nine remarkable farmer-selected progenies for bean size. For most of the traits studied, six families of hybrids were ranked among the ten best families in all the study areas, thus highlighting the stability of these families for these traits, regardless of the water regime of the area. The interest of releasing these varieties of selected cocoa trees in production areas with low rainfall in Côte d'Ivoire was considered and discussed.
Keywords: climate change, agro-climatic zone, breeding.
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