Pollination biology of coffea kihansiensis (rubiaceae), an endemic wild coffee species in kihansi gorge forest, Tanzania
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Date
2018
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Sokoine University of Agriculture
Abstract
The Kihansi wild coffee. Coffea kihansiensis. is an endemic coffee species found in the
understory of the Kihansi gorge forest in Tanzania. In this study, pollination biology of C.
kihansiensis was assessed. The aim of the study was to understand the relationship between
the flower biology of C. kihansiensis and its insect pollinators. Specifically, the study
investigated flowering patterns, floral dimensions, insect visitors, pollinators, floral rewards
and breeding system. A systematic sampling design was employed and three C. kihansiensis
populations were used as sampling blocks. Data were collected through direct observations.
direct counts, measurements and experiments. Flowering in the species exhibited a bing-bang
(mast) flowering pattern and was observed to occur from mid-December through to January
following short rains. C. kihansiensis flowers were visited by a wide range of insects
belonging to 44 species. Bees of various species were the most abundant insect visitors on the
flowers and appeared to be the most effective pollinators of C. kihansiensis. Flowers typically
offer pollen and nectar to insect visitors. Insect visitors* frequencies were higher in the
morning than in the afternoon and evening, and were associated with the timing of pollen and
nectar release. Irrespective of species, insect visitation was higher in morning, at 1100 hr.
Fruit set was high in cross pollinated flowers. The low fruit set in the absence of pollinators
might be interpreted as an adaptation to low pollinator visitation rate or pollen limitation. The
self-incompatibility index (1SI) was estimated to be 0.72. Results from hand-pollination and
the ISI value show that C. kihansiensis is partially self-incompatible, able to reproduce
through both selfing and outcrossing. It showed that pollinators play important role in
enhancing the productivity of C. kihansiensis. The above findings imply that in situ
conservation of C. kihansiensis must focus on monitoring the species, its insect pollinators and
conservation and management of its natural habitat.
Description
A dissertation submitted in partial fulfillment of the requirements for the degree of master of science in ecosystems science and management
Keywords
Coffea kihansiensis, Rubiaceae, Pollination biology, Wild coffee species, Kihansi gorge forest, Tanzania