Introduction
Vegetative propagation of improved or selected cultivars is important to make Chinese jujube (Ziziphus jujuba Mill.) cultivation economically viable. Like many other deciduous fruit trees, jujubes are often propagated by grafting two genotypes or cultivars together. There are two parts necessary for grafting: the rootstock, used for the root system; and the scion, the chosen cultivar or variety.
For successful grafting there are five important requirements:
- The stock and scion must be compatible (usually different cultivars of the same species).
- The cambium layer of the scion must be placed in close contact with that of the rootstock. The cut surfaces should be held together tightly by wrapping, wedging or other methods to encourage rapid healing of the graft union. This is so water and nutrients can be supplied to the scion from the rootstock by the time the buds start to open.
- Grafting must be done at a time when the scion and rootstock are in the correct physiological stage. This usually means the scion buds are dormant while the cut tissues at the graft union are capable of producing callus tissue for healing the graft.
- Immediately after grafting, all cut surfaces must be protected from dehydration. This is done by covering with tape or grafting wax.
- Proper care must be given to the grafts for a period of time following grafting. If shoots are not removed from the stock below the graft this can inhibit the desired growth from the scion.
Propagating jujubes
Until recently Chinese jujube was propagated primarily by root suckers. More farmers in China now graft or bud onto seedling rootstocks. More than 95% of grafts take successfully if scion wood is coated with a thin layer of wax. Softwood grafting in early spring also gave success of 90%. Tissue culture has successfully been used for propagation but commercial production by this technique is still under development due to the requirements of high skill and expensive facilities. Attempts to root hardwood cuttings have generally failed previously, but there are some successful reports.