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A new model to explain photoperiodism in African sorghum

Photoperiod sensitivity is a key adaptation of annual crop species in tropical regions. By this mechanism, their growth cycle can be tailored to climatic constraints, especially rainfall. The flowering date may thus be adapted to and independent of the sowing date, thus enabling the plants to avoid water stress at the end of the cycle along with biotic constraints. A new model that accounts for this mechanism has been developed within the framework of PhD thesis research at CIRAD.

Tapping teak diversity

Demand for teak is rising because of its resistance to degradation and aesthetic qualities. Asian natural forests from which this species originated are disappearing or now protected, so marketed teak comes mainly from plantations located in some 30 tropical countries worldwide. A study was carried out to assess how the environment affects teak tree growth and wood quality so as to ultimately be able to provide growers with planting material that will fulfil their specific needs.

Key factors determining the carotenoid composition in citrus fruit

Citrus fruits have an especially high carotenoid content. Carotenoids give them their colour, taste and many nutritional qualities. Findings of a series of studies carried out by CIRAD revealed a correlation between the carotenoid composition of different species and the structure of genetic diversity within the Citrus genus.

A method to improve plant selection accuracy

In arid regions, rainfall varies markedly between years, so it is especially hard to decide on the best varieties. The choice of the best varieties is generally based on multilocation trials lasting three years on average, which is too short to obtain varieties that would be well adapted to such unstable environments. A new method has been developed at CIRAD to improve selection efficiency and draw up recommendations tailored to each specific situation. This method can predict genotype x environment interactions on the basis of historical or simulated rainfall data in locations where the new varieties have not been tested.

Timber production in French Guiana: what is the impact on the evolution of forest tree species?

In the tropical rainforests of French Guiana, large trees of major commercial timber species, which are often the most reproductive, are cyclically eliminated in selective logging operations. In the long run, this can modify the demography and genetic diversity of populations of these species. CIRAD and partners have developed a forest dynamics model that integrates gene flows to study and predict such phenomena. This model, which can simulate different logging scenarios over periods of hundreds of years, should help to draw up decision-making guidelines to ensure sustainable timber production.