Not Available

Not AvailableNot AvailableDepartment of Science and Technolog

Not Available

Not AvailableNot AvailableDepartment of Science and Technolog

Impact of Local Global Warming on Rainfall and Annual Cocoa Water Requirements in the Regions of Lôh-Djiboua and Gôh in West-central Côte d'Ivoire

Aims: To understand the role of the interannual variability of cumulative rainfall and maximum dry sequences in cocoa production in the Centre-Ouest, one of the cocoa basins in Côte d'Ivoire, in order to propose technical routes more adapted to current rainfall conditions. Study Design: Collection, analysis and processing of daily rainfall data collected by the rain gauges at Divo and Gagnoa stations. Location and Duration of Studies: Divo Cocoa Research Station of the National Center for Agricultural Research, between January 2017 and June 2019. Methodology: The rainfall regime of each locality was determined to assess the impact of rainfall changes on the seasonality of rainfall. The interannual variability of rainfall was studied from the reduced centred rainfall indices. The break years in the time series were detected at both stations from the Khrono Stat software. The interannual cumulative rainfall were analysed for each station and compared to the minimum threshold allowed for cocoa trees. The means of the maximum interannual dry sequences and their probabilities of occurrence were determined using the agrometeorological software called Instat + Version 3.37. Results: The rainfall regime in the area studied (west-central Côte d'Ivoire) has not been modified by the post-rupture rainfall recession as is the case in other parts of the country; it remains a bimodal system characterized by two rainy seasons and two dries during the year. The Divo and Gagnoa regions have been facing a general recession in rainfall since 1966 in Gagnoa and 1972 in Divo. However, the locality of Gagnoa has experienced an increase in rainfall since 2000. Most of the rupture detection tests identified rainfall rupture dates identical to those indicated by the interannual variability highlighted by the rainfall indices. In Gagnoa and Divo, the interannual cumulative rainfalls after the years of rainfall break are reduced compared to those before these rainfall accidents. This situation has led to an increase in the maximum interannual dry sequences in the departments studied. Conclusion: Local climate change has created difficult rainfall conditions after years of rainfall break for cocoa trees as their water needs are increasingly reduced, especially in Divo in Lôh-Djiboua where the downward trend in rainfall has been continuous since 1972. In Gagnoa since the beginning of this century, there has been a new wet period that allows rainfall to adequately meet the cocoa tree's water requirements

Assessment of genetic diversity and structure in cocoa trees (Theobroma cacao L.) in Cte d'Ivoire with reference to their susceptibility to Cocoa swollen shoot virus disease (CSSVD)

International audienceResistance to Cocoa Swollen Shoot Virus disease (CSSVD) is becoming an increasingly important criterion for selection of new cocoa cultivars in Cte-d'Ivoire, where the disease resurfaced since 2003. This virus can seriously affect the yield of trees with a loss of 25%, 1 year after infection, to around 100% 3 years after. In order to find tolerant plant material, 337 farm accessions have been collected on fields affected by CSSVD, according to the status of accessions potentially tolerant (APT) or susceptible (APS). Both phenotypic groups were genotyped using 30 microsatellite markers (SSR) in the presence of representative clones of the ten genetic groups of cocoa. This study revealed 214 alleles with the set of primer pairs used. The number of alleles per locus was between 3 and 16 with an average of 7.13 alleles per locus. The results showed a high contribution of genetic diversity within population (H (s) = 0.51) to the total genetic diversity (H (t) = 0.53) for the two studied groups. There was no significant difference between tolerant and susceptible groups (Fst = 0.05). These results suggest that APT could be a potential genetic reservoir for other traits of interest associated with virus resistance. The phylogenetic tree, as the STRUCTURE analysis of Ivorian cocoa population, showed a distribution of individuals following four groups marked by a high contribution of group 4 (Nanay, Maranon, Guiana) followed by group 2 (Criollo), and group 1 (Amelonado), and a lower contribution of group 3 (Iquitos, Purus, Nacional, Curaray, Contamana)

The genome of Theobroma cacao.

We sequenced and assembled the draft genome of Theobroma cacao, an economically important tropical-fruit tree crop that is the source of chocolate. This assembly corresponds to 76% of the estimated genome size and contains almost all previously described genes, with 82% of these genes anchored on the 10 T. cacao chromosomes. Analysis of this sequence information highlighted specific expansion of some gene families during evolution, for example, flavonoid-related genes. It also provides a major source of candidate genes for T. cacao improvement. Based on the inferred paleohistory of the T. cacao genome, we propose an evolutionary scenario whereby the ten T. cacao chromosomes were shaped from an ancestor through eleven chromosome fusions