GIBBERELLIC-ACID DETECTION OF DWARF OFFTYPES IN MICROPROPAGATED CAVENDISH BANANAS

Detection of dwarf offtypes produced by micropropagation of Cavendish bananas (Musa spp.) cultivars New Guinea Cavendish and Williams was ac hieved by spraying gibberellic acid (GA(3)) solution (289 mu mol/L) on to deflasked plants and measuring various plantlet responses. The most useful identification criterion was elongation of the sheath of the f irst leaf to form after GA(3) application. Elongation of this structur e was about 2-fold greater in normal plants than observed in dwarfs. S imilar measurements taken earlier during in vitro culture or later dur ing plant establishment in soil were not as useful in discriminating b etween normals and dwarfs as the measurements made at deflasking. The similar GA(3)-induced elongation response of the dwarf offtype and tha t of the naturally occurring dwarf cultivar Dwarf Parfitt suggests tha t the mechanism for dwarfism could be the same in the 2 cases.