Forcing and In Vitro Establishment of Softwood Shoots from Large Stem Segments of Woody Plants

Abstract

Softwood shoots can be forced from various lengths of large stem segments that have been removed from intact trees and shrubs. Many woody species have large numbers of latent buds and thus forcing may result in the production of many shoots. If the plants were originally propagated by seed, shoots that grow from lower sections may retain juvenile traits, such as ease of propagation. Forced leafy softwood shoots may either be rooted as stem cuttings or may be used as an explant source for in vitro studies and micro-propagation. This is relatively a newer technique and its potential for micropropagation has not been determined in many woody plants. Contamination of the explants taken from the softwood-forced shoots is perhaps a major limitation associated with forcing under mist or fog. This paper focuses on several aspects influencing softwood shoot formation taking few representative examples, e.g., Acer saccharinum (silver maple), Fraxinus pennsylvanica (green ash), Carya illinoensis (pecan) and Tectona grandis (teak). The results suggest that this technique holds a promise for micropropagation of many recalcitrant woody species.