EFFECT OF THIDIAZURON AND 6-BENZYLAMINOPURINE ON ADVENTITIOUS SHOOT REGENERATION FROM LEAVES OF 3 STRAINS OF MCINTOSH APPLE (MALUS X DOMESTICA BORKH) IN-VITRO

Regeneration of adventitious shoots from apple leaf segments of three strains of 'McIntosh' has been achieved using leaves from in vitro gro wn plants, Optimum levels of thidiazuron (TDZ) and 6-benzylaminopurine (BAP) for shoot regeneration differed among the strains. The optimum levels of TDZ were between 2 and 3 mu M. The optimum levels of BAP req uired for shoot regeneration varied according to the field growth habi t of each strain: 'Wijcik' (the most dwarf strain) regenerated best at a higher level of BAP (20 mu M) than 'Macspur' (intermediate, 16 mu M ) and 'McIntosh' (standard, 12 mu M). Leaf mid segments were the most likely to regenerate shoots. Most of the adventitious shoots originate d from cut areas rather than from leaf surfaces, It appears that BAP c oncentrations can be used to differentiate among strains of 'McIntosh' at both the proliferation and regeneration stage. (C) 1997 Published by Elsevier Science B.V.