Schisandra chinensis asexual propagation and seedling raising: Rootstock method for green-branch cleft grafting
For the cultivation of rootstocks for green-branch cleft grafting, refer to open-field direct seeding for seedling raising. If the rootstocks are not dug out before winter arrives, pruning must be carried out before the ground freezes. Leave 3 to 4 buds on each rootstock and cut at about 5 cm, then water thoroughly with winter-protection water to prevent freeze damage and drying out. If the rootstock seedlings are to be planted out the following year, the seedlings can be dug out and stored in cellars or trenches, which is more beneficial for rootstock seedling management. When planting out the following year, they also need to be cut back to 3 to 4 buds to establish the trunk. Rootstock seedlings that overwinter in place should be irrigated promptly after the ground thaws the following year and given a topdressing of quick-acting nitrogen fertilizer to promote new shoot growth. Keep 1 to 2 new shoots per plant and remove all the rest, paying particular attention to removing underground horizontal runners sprouting from the base. When using rootstock seedlings for field planting and grafting, the general seedling planting method can be followed; ridge planting can be used to make grafting more convenient.
In central and northern Liaoning and various parts of Jilin, this can be done from late May to early July, but when grafting is late, the branches that grow in the same year are short; especially in areas with a short growing season, the shoots cannot fully mature in the same year after sprouting, so grafting earlier at the proper time is recommended. It is best to choose a cloudy day for grafting; rain after grafting is ideal, and on sunny days with relatively strong sunlight, grafting in the afternoon is more suitable.
When grafting, select robust new shoots growing from the rootstock. The retained length of the new shoot should be enough to have two leaves, with the cut about 1 cm from the base of the uppermost leaf, and the leaves on the rootstock are kept. To achieve better healing, minimize damage to the cells at the cut on the rootstock; the scissors must be sharp, or a single-edge razor blade can be used to cut it off.
For the scion, select robust new shoots and secondary shoots of a superior variety or strain. After cutting F, remove the leaves and keep only the petioles. The scion is best used immediately after being collected; if long-distance transport is needed, cooling, moisture retention and freshness preservation should be done well to increase the survival rate. When grafting, leave 0.5 to 1 cm above the bud and 1.5 to 2 cm below the bud, and cut the lower end of the scion into a double-bevel wedge about 1 cm
long on the right side, with the cut surface smooth and the angle small and uniform.
Split an incision in the middle of the rootstock, carefully insert the scion, and align the cambium of both the scion and the rootstock. When the thickness of the scion and rootstock is not the same, align one side, and leave about 1 mm of the scion's cut surface exposed, which helps healing. After grafting, tightly wrap the union with plastic film about 0.5 cm wide, exposing only the petiole and axillary bud on the scion. In relatively dry conditions, the union at the top of the scion is prone to water loss, which affects survival, so plastic film can be used to "cap" the top.
The grafting process requires attention: the rootstock should be relatively fresh and tender; rootstocks that are excessively lignified have a poor survival rate; the scion should be selected from semi-lignified branch sections, which favors survival; the plastic film at the union must be tied well, with no gaps, but it must not be tied too tightly; before grafting, and especially immediately after grafting, water thoroughly and keep the soil moist; after grafting, still repeatedly and promptly remove lateral buds and horizontal runners sprouting from the rootstock; after successful grafting, remove the plastic film at the proper time.