Effects of sucrose on development of cultures of some accessions of Dioscorea spp

Abstract

The method of micropropagation was used to establish nodal cultures of D. rotundata, D. alata, D. praehensilis, D. dumetorum, D. esculenta and D. cayenensis on 6 ml or 8 ml MS medium supplemented with 2.5 μM kinetin. The cultures were incubated at 28ºC and 16 h photoperiod at 4500 Lux, on 3%, 5%, 7%, and 10% sucrose, with a sucrose-free medium as control in a CRD design. Generally, increase in sucrose concentration significantly (P≤0.05) enhanced the rate of survival and growth of the Dioscorea cultures. Mean shoot height and root formation were high-est in D. rotundata cultures on full-strength MS medium containing 10% sucrose compared to half-strength MS medium. However, 7% sucrose stimulated the highest rate of vigorous growth of healthy cultures, leaf formation and plantlet production among the Dioscorea spp. It also enhanced development of bud primordia to regenerate plantlets in D. rotundata meristem cultures. There was a positive correlation (r=0.983) between the rate of leaf production and shoot height. It was evident that 5% and 7% sucrose were more effective for culture development towards multiple bud, lateral and terminal bud differentiation in most of the Dioscorea spp as well as re-duced the duration for plantlet development and the demand for regular sub-culturing since the growth phase of cultures could be prolonged. However, D. esculenta cultures appeared to grow better on 3% sucrose than the other Dioscorea spp tested, suggesting that the optimum sucrose concentration required to initiate and establish culture differs significantly among various Dioscorea species.