The effect of seed pre-treatment on the germination of garcinia kola, heckel,

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Garcinia kola Heckel, is an important chewstick non-timber forest species in West Africa. Its exploitation for use as chewsticks has resulted in the decline of its perpetuation in the forests of Ghana. Artificial regeneration has been less successful due to an unusually long period required for seeds to germinate. A study was therefore conducted to find the effect of standard seed pretreatment methods on the germination of the seeds and further identify the type and cause of dormancy in the species. The pretreatment methods used were manual removal of testa of the seeds and soaking some and leaving some unsoaked, storage at different temperatures, soaking in water at different temperatures and periods, soaking in ethanol for different periods and treatment with potassium nitrate, a germination stimulant. All the treatments were compared with a control. Soaking the seeds in ethanol for 1 hour and 2 hours enhanced germination over the control. The germination percentages of control treatment, 1hour and 2 hour ethanol treated seeds were 51 % to 87 % and 92 % respectively in 244 days whilst removal of testa without soaking gave a percentage germination of 89 % in 221 days, thus reducing the germination time by about 10 months. Removal of testa with soaking, soaking in boiling water as well as hot water was rather detrimental to the seeds. Intact seeds soaked in water for different duration failed to enhance percentage germination and time to complete germination. Extracts from the seed tested on lettuce seeds to determine its effect as dormancy causal factor significantly depressed germination of lettuce seeds (P=0.05). The extracts were analyzed by dissolving in ethyl acetate, spotting and separating on both Paper and Thin Layer Chromatography. The Rf values of the resulting spots having been compared with standard Rf values indicated the probable presence of resorcinol, coumarin and galactose.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of the Degree of Master of Philosophy, 1999