An efficient method for clonal propagation and in vitro establishment of softwood shoots from epicormic buds of teak （Tectona grandis L.）

摘要

Softwood shoots were produced from 40 cm long stem segments placed horizontally in flat trays containing sterilized sand under natural light or shade conditions for subsequent rooting and micropropagation studies in teak(Tectona grandis L.) . Higher number of shoots(6.17) per log was produced under natural light as compared to shade conditions. Forcing was also better in natural light as compared to shade in terms of shoot length,number of nodes or leaves. For rooting,2-4 cm long softwood shoots were excised and treated with either indole-3-butyric acid(IBA) or α-naphthyl acetic acid(NAA) at 0,1000,2000 or 3000 μmol·L-1 each or with combinations(1000 + 1000,2000 + 2000 or 3000 + 3000 μmol·L-1) and then placed in flat trays containing autoclaved sand at 25 ± 2oC in 16 h photoperiod at 35 μmol·m-2·s-1. After 28 days,softwood cuttings treated with IBA + NAA(3000 + 3000 μmol·L-1) had highest rooting percentage(89.3%) with 5.5 mean roots. Shoot apex and nodal explants of softwood cuttings were pretreated with 0.1%(w/v) ascorbic acid,boric acid,activated charcoal,citric acid,glutamine or polyvinylpolypyrollidone(PVP) for 24 h to remove phenolic compounds before surface disinfestation. Glutamine(Gl) and PVP were equally effective resulting in 60% establishment of shoot apices on MS medium supplemented with 10 μmol·L-1 6-benzylaminopurine(BAP) + 5 μmol·L-1 NAA. Using shoot apices,highest(42.80) number of multiple shoots with 54.33 mm shoot length were obtained on MS + BAP(8.8 μmol·L-1) + IBA(2 μmol·L-1) after 45 days. Shoots were successfully rooted and acclimatized to greenhouse conditions.