I. Bertling et F. Bangerth, CHANGES IN HORMONAL PATTERN OF THE NEW GROWTH OF SCLEROCARYA-BIRREA AFTER REJUVENATION TREATMENT WITH GA(3) AND HEADING BACK, Gartenbauwissenschaft, 60(3), 1995, pp. 119-124
Gibberellic acid (GA(3)) was injected into the stems of adult trees of
the African fruit tree species Sclerocarya birrea ssp. caffra to caus
e rejuvenation. Invigorated growth after such treatment in comparison
to control trees was visible after 14 days. Another tree, rejuvenated
by 'heading back', also showed growth invigoration. Histological analy
sis of shoots showed less xylem vessels in the shoots of the GA treate
d and the 'headed back' tree in comparison to control trees. Levels of
gibberellins, indoleacetic acid (IAA), abscisic acid (ABA), zeatin/ze
atin riboside (Z/ZR), and isopentenyladenosine (IPA) were determined i
n leaves and 'shoots' of the newly emerged tissues. In addition to the
expected large increase of GA(3) in the new flush, the concentrations
of IAA and ABA were also found to be greater in the 'shoots' of treat
ed trees. No significant difference could be detected in the cytokinin
pattern. Changes in hormonal pattern of GA(3) treated and the 'headed
back' tree were similar. There was a better rooting of cuttings from
treated rejuvenated trees.