INFLUENCE OF GROWTH-REGULATORS AND CARBON-SOURCES ON CALLUS INDUCTION, GROWTH AND MORPHOGENESIS FROM LEAF TISSUES OF PEACH (PRUNUS-PERSICA L BATSCH)

Leaf segments of Prunus persica (L.) Batsch 'Elberta Queen' were colle cted from in vitro-grown proliferating shoots and cultured onto a basa l medium containing half-strength Murashige and Skoog (MS) salts, Stab a vitamins, 30 gl(-1) sucrose and 6.5 gl(-1) Difco-bacto agar. The inf luences of six growth regulators supplemented at three levels (5, 10 a nd 15 mu M) on callus induction were investigated under light conditio ns (16 h photoperiods). For all growth regulator treatments, caulogene sis was observed along cut margins of leaf explants. Among cytokinins tested, thidiazuron (TDZ) induced compact green calli, 6-benzyladenine (BA) and zeatin induced small calli, and kinetin failed to induce cal lus. For auxin treatments, both dicamba and 2,4-D induced friable whit e to yellowish calli. In another experiment, leaf explants collected f rom greenhouse-grown 'Bellaire' and in vitro-grown 'Elberta Queen' wer e cultured onto the basal medium supplemented with a wide range of TDZ concentrations (3 to 23 mu M). Caulogenesis was optimum for both geno types at TDZ concentrations of 8 to 13 mu M, while higher TDZ levels r esulted in necrosis of leaf explants. In a third experiment, the influ ence of glucose, fructose, and sucrose on caulogenesis was investigate d. Leaf explants grown on media containing glucose developed a higher frequency of green and compact calli than those grown on either fructo se or sucrose.