THE MECHANISMS OF WOUND RESPONSE IN ACACIA-MANGIUM

Branches of 8-year-old trees of Acacia mangium Willd. from a plantatio n in Malaysia were wounded. After response periods from 1 to 4 weeks w ound-adjacent xylem was investigated by electron microscopy. Wounding induced the synthesis of dark-stained material in parenchyma cells wit h subsequent secretion through the pits into vessels and fibres. After four weeks many of them contained wall-attached layers of this materi al. Entirely filled vessels and fibres were not observed. As a second wound-associated process suberization of parenchyma cells contributes to the separation of wound-adjacent xylem tissue. Fungal degradation f requently occurred around the wound already three weeks after wounding . The effectivity of early wound responses in A. mangium appears low.