Comparison of Shoot Regeneration on Different Concentrations of Thidiazuron from Shoot Tip Explant of Cowpea on Gelrite and Agar Containing Medium

Abstract

Cowpea (Vigna unguiculata L. Walp) is an important legume grown all over the world as grain crop, animal fodder, cover crop, gren manure and vegetable. The present study compares effects of agar and gelrite on micropropagation from shoot tip explant of two Turkish cowpea cultivars Akkiz and Karagoz using 0.15, 0.15, 0.35 mg/l Thidiazuron (TDZ), 3 g/l activated charcoal, 2 mg/l yeast extract with and without 1.25 mg/l Polyvinylpyrrolidone (PVP). To overcome problem of endogenic bacterial contaminations, all cultures contained 500 mg/l augmentin and incubated at 24 ± 2o C in 16 h light photoperiod for eight weeks. Therafter, all explants were transferred to MS medium for two weeks for shoot regeneration and elongation under same incubation and photoperiod conditions. The results showed that frequency of shoot regeneration increased with increase in TDZ concentrations in both cultivars on both agar and gelrite gelled medium. Both cultivars showed maximum mean number of shoots per explant in gelrite compared to agar gelled medium. Maximum number of 4.72 and 2.86 shoots per explant were recorded on MS medium containing 0.25 mg/l TDZ in cv. Akkiz and cv. Karagoz respectively. Hyperhydricity was recorded on some regenerated shoots, which was more prominant on agar. Agar gelled medium had greater shoot length compared to gelrite medium in both cultivars. Regenerated shoots were rooted easily on MS medium containing 0.50 mg/l IBA with regeneration of mean number of 4 secondary shoots on cv. Akkiz and 3 on cv. Karagoz. Rooted plantlets were successfully hardened in the growth chamber and subsequently established in the greenhouse; where they flowered and set seeds. The recorded survival rate of the plants was 100%. Plants looked healthy with no visible detecTab. phenotypic variations.