In vitro shoot apex micrografting of mature Acacia mangium

Abstract

Prospects for in vitro micrografting shoot apices of mature Acacia mangium trees were investigated with the use of 432 micrografts. Overall success rates of 51.5%s% were obtained for shoot apices ranging from 200 to 400 μm in length, and a short basal wedge of underlying tissues top-grafted in aseptic conditions onto 2-to-3-month old in vitro grown Acacia mangium seedlings. The successfully established micrografts displayed, however, substantial variability in terms of further scion elongation as 41% of these micrografts, or 21.2% only of the total amount of the micrografts performed, had resumed growth two months after micrografting. The elongated scions exhibited different types of morphology, ranging from juvenile-like type composed leaves to the predominant mature-like phyllode morphology. Side-grafting, a more difficult procedure to perform than top-grafting, or placing the micrografts for 2 weeks in darkness after grafting, did not improve the scores. Moreover, attempts to micrograft meristems (150–200 μm) resulted in 5% success only.