Assessing certain root characteristics among provenances of Gnetum spp. in South West Cameroon: relevance for domestication and conservation.

Abstract

Gnetum africanum and Gnetum bulchozianum are two slow-growing, dioecious, and morphologically similar understorey lianas that are widely distributed in the humid tropical forests of West and Central Africa. Dwindling wild stocks of the widely consumed leafy vegetable are under persistent threat from deforestation, increasing demand and harvesting pressure. These factors militate in favour of domestication with recourse to vegetative propagation. The main objective of this study is to improve the species genetically based on a comparative assessment of rooting abilities among various provenances and ascertain implications for domestication and conservation. The experimental design was a completely randomised block. Twenty vines were randomly selected from each of five provenances and randomly assigned to 10 experimental blocks. Leafy stem cuttings extracted from the vines were inserted into a rooting medium of rotted saw dust. Rooting depth, number of roots and rooting percentage were parameters used in assessing rooting performance. Most of the variation in rooting characteristics was explained by within-provenance variability, highlighting the importance of clonal selection in genetic screening. The most variable quality trait and root length significantly differed (p < 0.05) among provenances. Furthermore, root length is an important predictor of sprout survival (r = 0.32), an important attribute in domestication. Key words: Gnetum, provenance, root characteristics, domestication, genetic improvement, conservation, South West Cameroon.