Proliferasi Kalus dari Eksplan Hipokotil dan Kotiledon Tanaman Jarak Pagar (Jatropha curcas L.) pada Pemberian 2,4-D

The aim of this study was to develop an efficient method for the induction of embryogenic callus formation for in vitro propagation ofjatropha. Plant materials used were 30-days old in vitro seedlings, cut into hypocotyl and cotyledon (lower, middle and upper) sections.Medium used was MS composition supplemented with vitamins, 3% sucrose, 0.7% agar at pH 5.8 ± 1, and 2,4-D (0, 1, 2, 3, 4 dan5 mg l-1). Cultures were kept at temperature of 25 ± 1 0C with 50 μmol m-2 s-1 light intensity and 16-h photoperiod. The results indicated thatthe rate of callus formation depended on the source of explant, the application of 2,4-D, and the interaction of both. The fastest callusproliferation (2.33 days following initiation) was obtained on cotyledon explants cultured on medium without 2,4-D. The explant sourcesand 2,4-D concentrations also showed significant effect on the percentage of explant forming callus. The most callus formation (88.33%)was obtained on middle cotyledon cultured on 3 mg l-1 2,4-D, whereas the fewest (6.84%) was found on upper cotyledon cultured on mediumwithout 2,4-D. The colour of callus was dominated by white, light yellow, cream and brown with mostly compact structure, particularly onhypocotyl cultured on medium without 2,4-D. The texture of callus formed on hypocotyl treated with up to 4 mg l -1 2,4-D was dominatedby coarse appearance. In contrast, majority of callus proliferated on hypocotyl treated with 5 mg l -1 2,4-D or cotyledon treated with orwithout 2,4-D produced callus with smooth texture %.