Moses Tita Njoya, Dieter Wittmann, Mathias Schindler:
Effect of Bee Pollination on Seed Set and Nutrition on Okra (Abelmoschus esculentus) in Cameroon


1University of Bonn, Agricultural Sciences & Resource Management in the Tropics and Subtropics (ARTS), Germany
2University of Bonn, Institute of Agricultural Zoology and Bee-Biology, Germany

The study was conducted from June 2004 to August 2004 at the out sketch of Yaounde (Cameroon). Okra (Abelmoschus esculentus), Malvaceae, is a native of West Africa. It has a considerable economic importance because the seeds and pods are used for food. Hand and insect pollination of okra flowers gave seed sets varying between 73-84% per pod which differ significantly (p < 0.05) from that of the bagged flowers (spontaneous self pollination) which just rendered 57% seed sets per pod. An increase of 10.3% in seed sets from cross pollination over forced-self pollination and a 16% increase in seed sets was recorded from forced-self pollination over spontaneous-self pollinated flowers. Noteworthy, that a fecundated seed contains 91.55#5g nitrogen whereas an unfecundated seed has only 2.65#5g nitrogen; this means that a fecundated seeds contains 35 times much more nitrogen. As a consequence, cross-pollinated flowers rendered more fecundated seeds; with 311.15#5g more nitrogen per carpel than seeds from spontaneous-self pollinated flowers with more unfecundated seeds. An increase of 754.15#5g carbons and 192.25#5g of nitrogen per carpel were noted comparing seeds from forced self-pollinated flowers with those from spontaneous self"=pollinated flowers. This demonstrates the need for cross"=pollination in the okra garden to achieve optimum yields both in both seed quality and seed sets. Observation of 829 individual bees of at least 4 different species visiting okra flowers indicates that Megachile sp. had more contacts with the stigma upon landing (56.1%), thus, it possibly does cross pollination. Halictus spp. are considered potential pollinators for self"=pollination, as they frequently roll on the anthers and consequently on the stigma of the same flower (86.3%) before taking off. Xylocopa sp. is a pollen thief, as it visits okra flower just to collect pollen but does not aid in pollination. Apis mellifera is mainly a nectar collector in okra flowers.

Keywords: Bee pollination, nutrition, Okra (Abelmoschus esculentus), seed set


Contact Address: Moses Tita Njoya, University of Bonn, Agricultural Sciences & Resource Management in the Tropics and Subtropics (ARTS)53177, Bonn-Badgodesburg, Germany, e-mail:
Andreas Deininger, November 2005