Prediction of Lignin and Suberin Deposition in Boundary Zone Tissue of Wounded Tree Bark Using Accumulated Degree Days

Abstract

The phellogen of cultivated apple, sweet cherry, and peach trees was wounded at regular intervals beginning in early May and ending in late Aug. 1983. Bark tissue supporting the wounds was excised, sectioned, treated with phloroglucinol + HCl, and examined under a bright field to determine the extent of lignification. The same sections were examined under ultraviolet epi-illumination to determine the extent of suberin deposition in the boundary zone tissue formed from cells present at the time of wounding. Mean daily temperature, time post-wounding, and accumulated degree days (base = −5°, 0°, 5°, and 10°C) were used to predict the percentage of wounds lignified and suberized. A segmented quadratic equation incorporating accumulated degree days (base = 0°) was the best model for predicting lignification for the 3 species and for suberin deposition in peach and sweet cherry.