Relationship between seed desiccation sensitivity, seed water content at maturity and climatic characteristics of native environments of nine Coffea L. species

A broad variability for seed desiccation sensitivity, as quantified by the water content and the water activity at which half of the initial viability is lost, has been previously observed within nine African coffee species. In order to investigate if these different degrees of desiccation sensitivi ty correspond to an adaptive trait, additional data, such as the duration o f seed development and seed water content at maturity, were measured for th ese species, and the relationships between these parameters and some climat ic characteristics of their specific native environments were investigated. Since flowering in all coffee species occurs only a few days after the mai n rainfall marking the end of the dry season, simulations could be made, ba sed on the continuous sequences of rainfall data compiled in databases of n ine climatic stations, chosen for their appropriate location in the collect ing areas. The simulations revealed a highly significant correlation betwee n the duration of seed development and that of the wet season. Consequently , mature seeds are shed at the beginning of the following dry season. Moreo ver, the mean number of dry months that seeds have to withstand after shedd ing was significantly correlated with the parameters used to quantify seed desiccation sensitivity. By contrast, seed moisture content at maturity was not correlated with the level of seed desiccation tolerance. All these res ults are discussed on the basis of more detailed descriptions of the natura l habitats of the coffee species studied.