Effective Methods for Adventitious Root Regeneration on Weeping Fig Stems

Abstract

When transplanting mature Ficus trees, the large root balls are expensive to treat, handle, and move. This study aimed to identify the optimal wounding method and auxin treatment for regenerating adventitious roots (ARs) from weeping fig (Ficus benjamina L.) stems to uptake additional water and to compensate for fewer absorption roots in the smaller root balls at transplantation. We adopted a two-factorial experiment involving the wounding methods (three-line cut (3LC) and rectangular peel (RP)) and auxin treatments (2000 mg·L−1 Indole-3-butyric acid (IBA), 2000 mg·L−1 IBA + 2000 mg·L−1 1-naphthaleneacetic acid (NAA), and 4000 mg·L−1 IBA). The rooting rate of each treatment, the mean root number, the length of the three longest ARs, and the dry weight of ARs in each wound were evaluated. The treatment combination using 4000 mg·L−1 IBA with RP13 (rectangular peel 1/3 the perimeter of the stem) consistently exhibited the best rooting results in 2019 and 2020. It had a 100% rooting rate, a mean of 18.5 roots, a 16.8 cm root length, and a 1640 mg dry weight in the wounds. All auxin treatments demonstrated a superior rooting ability as compared to water treatments. The RP method regenerated more roots than the 3LC method. Doubling the RP length to be 2/3 of the perimeter improved the rooting ability. The locations of ARs varied under different treatment combinations, with 4000 mg·L−1 IBA on RP13 demonstrating the most diversified distribution on four edges of the wounds. Thus, it is recommended to regenerate ARs from stems of F. benjamina trees.