An-Najah Staff

Some factors involved in shoot elongation and leaf enlargement of adventitious apple shoots in vitro were investigated. A system was established to produce large numbers of adventitious shoots for this study. Leaves were harvested from proliferating cultures of three apple scion cultivars, cut into two segments, and plated onto three regeneration media. Adventitious shoots formed best on a modified Murashige and Skoog medium supplemented with thidiazuron (3 µM) and naphthaleneacetic acid (5.4 µM). Large (15+ mm width) leaves regenerated significantly better than smaller ones. The cut surface of the leaf segments produced the highest number of regeneration sites. Shoot proliferation medium with 6-benzylaminopurine (4.44 µM) and kinetin (13.95 µM) was significantly better than the other media for producing tall shoots and satisfactory proliferation. Leaf expansion was significantly improved when shoots were grown on proliferation medium with either 2-isopentyladenine or kinetin alone.