POLLINATION OF Coffea arabica L. AND ASSOCIATED AWARENESS OF POLLINATION SIGNIFICANCE AMONG FARMERS IN KIAMBU DISTRICT, KENYA.

Abstract

Kenyan coffee (Coffea arabica L.) is rated among the best quality coffee produced worldwide. Unfortunately, there has been a decline of coffee production and inadequate pollination may be among the contributing factors. This was the first study in Kenya to investigate on the pollinators of coffee in organic and conventional farms, the role of natural floral resources as alternative floral resources, importance of pollination in improving coffee yield and cup quality, efficiency of various pollinators of coffee and pollination knowledge among coffee farmers. In total, bees from 63 families were recorded as the pollinators of coffee with a record of 60 species in the organic farm and 24 species in the conventional farm. Bee abundance and diversity in the organic and conventional farms was significantly different (P<0.05). During the study, Andrena a rare bee species was collected from the organic farm and it has not been previously described in Kenya. A total of 42 plant species represented in 19 plant families formed natural floral resources in coffee farms. The organic farm recorded all the 19 plant families and 40 species. The conventional farm had 25 plant species from 14 families (Appendix 4). A highly significant relationship (P<0.0001) existed between natural vegetation richness and bee richness. This study provided evidence that coffee requires pollination for high yields, heavy berries and high cup quality. Significant differences (P<0.001) existed between percentage fruit set, fruit retention (t= 49.258, P<0.0001), berry weight (P< 0.001) and average cup quality (P<0.001) between autogamy and different pollination levels. Open pollination which encompassed pollinators, wind and autogamy produced the best quality coffee while the lowest quality was recorded from autogamy. Peak foraging time of bees coincided with the time of high nectar volume and average nectar sugar concentration. There was a positive significant correlation (P<0.01) between the average time taken on a flower and the number of flowers of the same plant foraged on and a negative significant relationship (P<0.05) between percentage flowering and number of flowers foraged on in the same plant. This suggests pollination limitation during mass flowering in the study area and efforts should be made to enhance pollinator numbers during mass flowering. Among the sampled bee species solitary bees Patellapis (Zonalictus spp.) and Lasioglossum spp. deposited higher numbers of pollen coffee grains while Apis mellifera L. had the highest number of non coffee pollen hence the former could be more efficient pollinators of C. arabica. Significant differences occurred between A. mellifera and Patellapis zonalictus (p<0.001) and A. mellifera and Lasioglossum spp. (P<0.001). This finding calls for enhancement of diverse populations of solitary bees for more efficient pollination. Coffee farming was dominated by males (84%) with only 16% female farmers. Male farmers had a higher pollination knowledge index than female farmers but the differences in this knowledge were not significant (p>0.05). The differences in pollination knowledge between the different education level groups were also not significant (P>0.05). This indicates that education on pollination issues should be done across all education levels across both genders. This study concludes that biotic pollination is important in enhancing yields and quality of coffee and that A. mellifera is not the most efficient pollinator of coffee. Pollination knowledge among farmers is limited and outreach systems and extension services should be used to disseminate this knowledge.