Mass Multiplication of Mature Trees of Gmelina arborea Roxb. Through ex vitro Rooting of Rejuvenated Bud Sprouts

摘要

Clonal multiplication of selected superior genotypes of Gmelina arborea is difficult owing to maturity related loss in adventitious root potential which constitutes a serious constraints in their ex situ conservation and mass multiplication for sustainable use. The present study reports a new procedure for optimizing adventitious rhizogenesis through rejuvenation in the parent material taken from mature trees. Miniature bud sprouts (1-1.5 cm long with 1-3 unexpanded leaves) produced on semi-hardwood shoot cuttings taken from 15 year old trees were evaluated in comparison with juvenile seedling cuttings, coppice shoot cuttings and semi hardwood cuttings. The cuttings were administered with a quick dip treatment for 30 sec of water (T1) or 5 mM (T2) and 10 mM IBA (T3) before planting and observations were recorded on various rooting parameters after 3 weeks. The mini-cuttings exhibited significantly superior adventitious rhizogenesis (94%) with about 2 and 4.7 times more rooting than seedling cuttings and semi-hardwood cuttings, respectively. The treatment of 5 mM IBA resulted in significantly superior adventitious rhizogenesis. The findings indicate rejuvenation of parent material in the procedure which may be employed for large-scale clonal multiplication and ex situ conservation of mature ortets of Gmelina arborea having desirable traits.