High-crown grafting to increase low yields in Camellia oleifera

Tea oil camellia (Camellia oleifera) is a perennial evergreen shrub or small tree with multiple uses. Its seed oil contains rich bioactive compounds with powerful nutritional and medicinal values. To improve low seed yield in natural forests of this species, the new grafting technique of high-grafting and change-crown is being widely used. This usually has three grafting methods, inlay graft by separating bark (IGSB), bark xylem graft by cutting stock (BXGCS), and cleft graft (CG). In this research, we (1) investigated growth, development, fruit yield, and traits of trees after high-grafting and (2) tested effects of grafting methods (IGSB, BXGCS, and CG) and times (spring, summer, and autumn) on survival rates. Results indicated that sprouted scions flowered and set fruit in the third year after high-grafting, and grafted trees produced higher oil yields in the fourth year. Both grafting methods and times significantly influence grafting survival rates. The optimal grafting method for this species is BXGCS, resulting in a 77.4% survival rate in the summer. These results not only demonstrate that this new grafting technique is advantageous to improve low-yield trees, but also that grafting method and time affected survival rate, contributing to enhanced productivity.