Influence of carbon source on in vitro tuberization and growth of white yam (Dioscorea rotundata Poir.)

Abstract

The response of white yam (Dioscorea rotundata Poir.) nodal cuttings to eight different carbon sources (sucrose, glucose, mannose, maltose, galactose, fructose, lactose, and sorbitol) at two concentrations (3 and 5%) in modified Murashige and Skoog medium was investigated. The number of nodes per plant (NNP), plantlet fresh weight, number of leaves per plant (NLP), percentage tuberization, number of micro-tubers per plant (NTP), and micro-tuber weight per plant (TWP) were significantly different among the carbon sources (P < 0.01). There were no significant differences in terms of micro-tuber weight per tuber and plant dry matter content. In terms of NNP and NLP, fructose, glucose, mannose, and sucrose at 3 and 5%, and sorbitol at 5% were comparable. However, nodal cuttings were unable to produce tubers in media containing sorbitol. All the explants cultured in 5% sucrose, 5% fructose, and 3 and 5% mannose produced micro-tubers. The NTP ranged from 0.9 (3% mannose) to 1.8 (5% sucrose), while 5% glucose gave the highest TWP, followed by 5% sucrose. The best carbon sources for in vitro tuberization were sucrose and fructose.