This PhD proposal is about strategies minimizing harmful effects of climate changes and at the same time optimizing fruit production of Parkia biglobosa and Vitellaria paradoxa ssp. paradoxa in Burkina Faso. Both species are traditional multipurpose parkland species enjoying great popularity among the rural population due to their fruits and highly prized seeds. Neither species have been domesticated although breeding programs have been started. Knowledge concerning the pollination biology is scarce although it is a very important area due to the fruits and seeds being in high demand. According to models of expected climate changes the climate will become drier, and one risk is that the amount of pollinators will drop due to less availability of water and food (i.e. nectar, pollen, and fruits). The project will analyse the present situation both in the northern and southern parts of Burkina Faso, in order to examine the influence of the drier climate in the north. Honeybee colonies will be placed near some of the trees and their impact on fruit production will be studied. Furthermore, the influence of the kind of pollination (amount of pollen and/or degree of outcrossing) will be studied with regard to seed oil content of V. paradoxa and seed protein content of P. biglobosa. The degree of outcrossing will be determined by DNA-analysis.
Completion Report - summary:
We are providing new knowledge of the efficient pollinators of two important species of fruit trees in Burkina Faso, and this knowledge can be very important in terms of optimising fruit set.
• P. biglobosa depends on animal pollinators
• P. biglobosa is pollen-limited (even in the wetter site)
• Honey bees can compensate bat-pollination (both sites)
• If the climate becomes too dry (2012, northern site) many of the pollinated flowers abort as small fruits
• V. paradoxa depends on animal pollinators
• Stingless bees and solitary bees can partly compensate honey bee-pollination in terms of fruit set
• Flowers pollinated by stingless bees and solitary bees resulted in fruits with the same seed weight and germination time as the honey bee-pollinated flowers
• Fruit set in the open treatment was positively correlated with the number of honey bee colonies within 900-1,000 m from the given tree
• Fruit set in the semi-open treatment was positively correlated with presence of stingless bee colonies in the trunk of the tree.