Nursery substrates and provenances influence rooting performance of juvenile, single-node vine cuttings of Gnetum africanum Welw. (Gnetaceae)

Abstract

Gnetum africanum Welw. (Gnetaceae) is a forest vine that is highly valued for its leaves which are a source of food and income. Because wild populations are threatened by over-harvesting, there is an increasing need to cultivate the plant, which in turn entails a need for developing good quality planting material. This study investigates the effects of four provenances, four substrates and their interactions on rooting and shoot development of vine cuttings of G. africanum using the non-mist propagation system developed by ICRAF. Single-node, half-leafed vine cuttings were used and data on rooting and leaf production were collected monthly from the second to the fifth months. Rooting percentages were subjected to analysis of variance using logistic regression procedures in Genstat version 12. Provenance (P<0.001), substrate (P<0.001) and interaction between provenance and substrate (P<0.001) showed highly significant effects on rooting. Excel was used to determine rooting percentages, with the highest observed in fine sand on cuttings from Lekie- Assi (81%) and Boumnyebel (79%) which are high G. africanum exploitation areas in the Centre Region of Cameroon. Boumnyebel showed a signficantly higher shoot development than the other provenances. Fine sand and sharp sand can be recommended for rapid, low-cost production of G. africanum planting material. Key words: domestication, rooting substrate, non-mist propagator, vine cuttings