Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Changes in hormonal pattern of the new growth of Sclerocarya birrea after rejuvenation treatment with GA3 and "heading back".

Abstract

Methods of rejuvenating shoots of adult trees of the African fruit tree species S. birrea subsp. caffra were examined in southern Africa for the production of material from which cuttings could be taken. Following injection of GA3 into the stems, invigorated growth was visible after 14 days. A tree headed back to a stump plus 2 branches also showed growth invigoration. Histological analysis of shoots showed fewer xylem vessels in the shoots of GA-treated and headed-back trees than in control trees. Concentrations of gibberellins, IAA, abscisic acid, zeatin/zeatin riboside and isopentenyladenosine were determined in leaves and shoots of the newly emerged tissues. In addition to the expected large increase of GA3 in the new flush, the concentrations of IAA and ABA were also higher in the shoots of treated trees. No significant difference could be detected in the cytokinin pattern. Changes in hormonal patterns in GA3-treated and headed-back trees were similar. Cuttings generally rooted poorly, but those from GA3-treated trees rooted better than those from control trees (6 and 3 rooted cuttings, respectively, out of 20 cuttings).