Article The Induction of Adventitious Roots Regeneration before Transplanting Rootless Ficus elastica Heritage Tree Nelson Li 1 , Pei-Chun Tu 1 , Kuo-Chin Lo 2 and Yu-Sen Chang 1,* 1 Department of Horticulture and Landscape, National Taiwan University, Taipei 106, Taiwan;
[email protected] (N.L.);
[email protected] (P.-C.T.) 2 Treegarden Corporation, Neihu, Taipei 114, Taiwan;
[email protected] * Correspondence:
[email protected] Received: 31 August 2020; Accepted: 27 September 2020; Published: 30 September 2020 Abstract: Heritage trees carry both botanical and historical value for a city’s resilience and sustainability and hence are precious and unique. Their transplant is costly and very rare due to tremendous cost and 100% survival requirement by law. Rootless transplant is even more detrimental to the heritage tree due to removal of roots infected by brown root rot (BRR) before transplanting. This study examined the adventitious roots (AR) induction ability of the Ficus elastica Roxb. heritage tree infected with BRR. The experimental design considered three factors: root diameter (RD), wounding method (WM), and auxin solution on aerial roots under fractional factorial experiment in completely randomized design (CRD). There were four RD groups: RDI (RD < 2 cm), RDII (2 RD 4.3 cm), RDIII (4.3 < RD 22), and RDIV (RD > 22); three WMs: ≤ ≤ ≤ cutting off (CF), girdling (GD), and rectangular shape peeling (RP) of aerial roots; and three auxin solutions: 2000 mg L 1 IBA(Indole-3-butyric acid) (2B), 2000 mg L 1 IBA + 2000 mg L 1 · − · − · − NAA(1-Naphthaleneacetic acid) (2NB), and 4000 mg L 1 IBA (4B) plus water as control (C).