Growth and yield characteristics of dwarf off-types recovered from tissue-cultured bananas

Abstract

Dwarf off-types recovered from a tissue cultured line of banana cultivar New Guinea Cavendish (Mum sp., AAA Group, Cavendish subgroup) were used to quantify some of the changes associated with dwarfism, the most common off-type associated with tissue-cultured Cavendish bananas, and to determine the relative stability of the trait. The off-types were significantly (P<0.01) shorter than true-to-type plants and retained their dwarf stature over 5 generations. The dwarfs were characterised by small fruit with closer packing of the hands on the bunch. Choking, when the bunch fails to emerge fully from the plant, was a characteristic of the dwarfs but not observed in true-to-type plants. Dwarfism appears to be a relatively stable genetic trait and not a transient (epigenetic) change produced in vitro. By contrast, a thin-leafed off-type reverted to normal morphological characteristics 3-4 months after field establishment.