Pollination ecology of upper amazon Cocoa and breeding substrates of Cocoa pollinators in the Ejisu-Juabeng District of the Ashanti Region, Ghana
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Date
2015-02-23
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Abstract
Cocoa plays important role in the economy of Ghana as it is the second foreign exchange earner after gold. Lives of 800,000 farmers and their families depend on it. Although it has enjoyed a consistent growth Ghana’s cocoa yields per hectare are still low by international standards. This is probably because cocoa pollination which has for a very long time been relegated to the background in the scheme of cocoa production. The study was undertaken at Kubease in the Ejisu-Juabeng district using ten farmer managed farms around the Bobiri Forest. It involved a study of the ecological importance of floral phenology of the Amazon cocoa which forms about 58% of cocoa varieties in Ghana; a survey of insects in the cocoa ecosystem to establish their pollinator status; the relative importance of the breeding substrates in the cocoa ecosystem was also investigated; and the contribution of natural pollination to cocoa production. Results indicated that cocoa trees exhibited seasonally-related phenological patterns of flowering and fruit-set involving overlapping cycles under both intrinsic and extrinsic control. Significant (P<0.001) differences in the monthly floral production existed between the study farms. Optimum floral production occurred at temperature 22.5 oC, light intensity 91.8 Fc, and rainfall of 141.1 mm per month; however, rainfall could be the most critical factor in the floral phenology. Flower stability was affected by seaons and pollination. 2721 insects belonging to 36 species and 7 orders found in the ten farm plots. About 52.81% did not visit the cocoa trees; 10.4% insects were found on the cocoa trees. The ceratopogonids visited (F1, 30 = 28.79, P <0.05) more than other insects. Only midges could carry 60.1 ± 13 pollen. Population of midges was significantly (F = 0.65, P<0.05) greater under rotten banana pseudostem than the other substrates. There were significant diferences between the number of seeds of naturally pollinated and that of artificially pollinated fruits of small size pods (P< 0.04), medium size pods (P< 0.01) and the large sized pods (P<0.01). The study therefore demonstrated that cocoa has a specialised pollination mechanism, in which pollinators belong to just one pollinator class. Rotten banana pseudo stem preferred substrate implying that it might have provided a more condusive breeding microhabitat for the ceratopogonids. Natural pollination could contribute to cocoa productivity.
Description
A thesis submitted to the Department of Wildlife and Range Management
Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the degree of Doctor of Philosophy, 2012