This study determined whether in vitro storage of Khaya senegalensis clones could delay their maturation and increase their capacity for adventitious rooting. Forestry trees display the desired traits of high adventitious rooting, rapid stem growth and long internodes when they are propagated from juvenile rather than mature explants. In vitro storage has the potential to maintain the juvenility of clones during the period of clonal field selection but there is little empirical evidence to show that in vitro storage delays clonal maturation. This study assessed the maturation of 20 clones that had been stored for 12 months using two different methods: (1) as ex vitro stock plants in the nursery; or (2) as shoots in vitro at 25°C. K. senegalensis proved amenable to vegetative propagation, with high rooting percentages (76±4%) and adventitious root numbers (5.2±0.4) from the cuttings of nursery-stored stock plants. However, storing shoots in vitro for 12 months provided higher rooting percentages (89±2%) and adventitious root numbers (6.3±0.5). These results demonstrate that K. senegalensis clones did undergo significant maturation in the nursery and that in vitro storage delayed their maturation. In vitro storage is, therefore, an effective method for clonal archiving that minimises investments in water, fertiliser, pesticide and space while providing planting stock with the juvenile-phase characteristics required for forestry plantations.
Relation
Journal of Plant Sciences / Vol. 8, No. 2, pp.31-38