The Effects of Localized Heating and Ethephon Application on Cambial Reactivation, Vessel Differentiation, and Resin Canal Development in Lacquer Tree, Toxicodendron vernicifluum, from Winter to Spring

Resin canals serve as a natural feature with the function of a defense system against fungi, bacteria, and insects. Trees can form these canals in response to mechanical injury and ecological disturbance. Factors, such as plant hormones and temperature, influence cambial activity and cell differentiation. This study examined the effects of increased temperature and plant hormones on cambial reactivation, vessel formation, and resin canal formation using localized heating and the application of the ethylene generator ethephon to dormant stems of the Toxicodendron vernicifluum seedlings. Localized heating was achieved by wrapping an electric heating ribbon around dormant stems, while ethephon was applied to the bark surface. Treatment was initiated on 29 January 2021, including control, heating, ethephon, and a combination of heating and ethephon. Cambial reactivation and resin canal formation were monitored using light microscopy, and bud growth was recorded with a digital camera. Localized heating induced earlier phloem reactivation, cambial reactivation, and xylem differentiation, increasing the number of vessels. The application of exogenous ethylene delayed these processes. The combination of localized heating and exogenous ethylene application resulted in smaller vessels and larger resin canals. These results suggest that increased temperature plays a significant role in cambial reactivation and vessel formation in ring-porous hardwood and that ethylene affects vessel differentiation and resin canal development.