A Detailed Guide to the Latest Grafting Methods and Technical Points for Jujube Trees
Red date, also known as jujube, large jujube, etc., is a deciduous small tree of the genus Ziziphus in the Rhamnaceae family, growing in mountainous areas, hills or plains below 1700 m in altitude. Propagation is mainly by division and grafting, and some varieties can also be sown. Grafting jujube trees generally mostly uses bark grafting, cleft grafting, side grafting and budding. Let's take a look at the jujube grafting methods together below!
Bark grafting
Bark grafting is a type of scion grafting, and it is suitable after the jujube tree has sprouted, during the period when sap flow is vigorous and the bark is easy to peel. The grafting method is simple, fast, and the survival rate is higher than other grafting methods. Select a smooth area of the rootstock bark and cut off the rootstock, then on one side of the cross-section cut a small slit about 0.5 cm from top to bottom through the bark down to the xylem, and peel back the bark to form a triangular opening. At the lower end of the scion, 2-3 cm from the lower cross-section, use a knife to cut downward at a slant, making the cut surface horseshoe-shaped, with the slant exceeding the pith. On the opposite side of the slant, cut another small short cut surface 2-3 mm long at the lower end, forming a sharp straight-line point to make insertion into the bark easier. Insert the long cut surface of the prepared scion along the xylem into the bark through the already-cut triangular opening of the rootstock (the long cut surface of the scion closely contacting the xylem of the rootstock), leaving 1 mm of cut surface above the cut surface, commonly called “white exposure”, to promote growth of callus tissue, then use plastic film to wrap the rootstock cut and the union with the scion completely and tightly, preventing air from entering, and grafting is complete. If the scion has not been wax-sealed, use thin plastic film to wrap the scion tightly.
Cleft grafting
Cleft grafting is a type of scion grafting, also called large grafting. The grafting time can be earlier than bark grafting, carried out when the bark is not yet easy to peel but the sap has already begun to flow. It can be used for grafting young seedlings in nurseries or for top-working large trees. For grafting young seedlings in nurseries, first clear away weeds and useless root suckers around the young seedlings. Cut off the rootstock seedling close to the ground, then dig down about 10 cm of soil to expose the thicker, smooth part of the root crown, use scissors to cut the rootstock cross-section, and split the rootstock vertically along the center of the cross-section with a cut 2-3 cm long. Then quickly cut the scion from 2-3 cm above the lower end downward into a smooth double-sided wedge-shaped cut surface, thick on top and thin at the bottom. If the scion is thinner than the rootstock, one side of the cut surface is slightly thinner than the other, with the main bud on the thin side. Then quickly insert the prepared scion into the split opening of the rootstock, leaving 1-2 mm of cut surface at the upper end of the scion cut surface, commonly called “white exposure”, so that the cambium on the thicker side of the scion aligns with the cambium of the rootstock (if the rootstock and scion are the same thickness, the cambium on both sides of the bark of the rootstock and scion can be aligned). Then use plastic film to wrap the rootstock split and the union with the scion evenly and tightly to help retain moisture. If the scion has not been wax-sealed, use thin plastic film to wrap the entire scion tightly to prevent water loss.
Side grafting
Side grafting is also a type of scion grafting, and the suitable grafting time is the same as cleft grafting. When grafting, cut off the rootstock, and along the rootstock cross-section cut a slanted split opening in the rootstock, with a depth exceeding half the rootstock diameter but not exceeding 2/3, otherwise it is prone to wind breakage, forming a slanted cut reaching the xylem. The scion cutting method is basically the same as cleft grafting, except that the scion cut surface should be cut with one side slightly longer and one side slightly shorter. When grafting, insert the prepared scion into the slanted cut of the rootstock, with the long cut surface facing inward and the short cut surface facing outward, so that the cambium of the bark of the scion and rootstock aligns. The other steps and requirements are the same as cleft grafting.
Budding with wood
Budding with wood is carried out in spring after the rootstock sap begins to flow. At a smooth area at the base of the rootstock, use a budding knife to make a horizontal cut on the rootstock down to the xylem, with a length about 1/3 of the rootstock diameter, and about 1 cm below the cut use the knife to cut a shield-shaped piece connected to the cut. Remove the wood piece. It is best to use a scion similar in thickness to the rootstock. Make a horizontal cut 3 mm above the main bud, with a length the same as the horizontal cut on the rootstock, then below the bud use the knife to cut a shield-shaped bud piece, the same size as the shield-shaped piece of the rootstock. Insert the bud piece into the shield-shaped cut of the rootstock, align the cambium of the bud piece with the cambium of the shield-shaped cut of the rootstock, wrap tightly with plastic film strips, leaving the main bud of the scion exposed in the middle, and budding with wood is complete. If the scion bud piece is smaller than the rootstock shield-shaped cut, align the upper cut and the cambium on one side of the scion with the upper cut and the cambium on one side of the rootstock, then wrap tightly with plastic film strips leaving the main bud exposed.
Bud grafting
1. Bud grafting time: Bud grafting is generally the method of using the current year's main bud for grafting after the main bud has formed in the growing season, also called T-shaped budding. If using the previous year's scion, budding can also be carried out in spring after the jujube tree has sprouted. Because it is difficult to take a bud piece with the complete vascular bundle, budding with wood is generally used, also called chip budding. Rootstocks that survive grafting before July can have the rootstock cut above the grafted bud, and can still grow into a mature grafted seedling in the same year. Rootstocks that survive grafting after August should not have the rootstock cut in the same year, otherwise the grafted seedling will find it difficult to overwinter due to low lignification, and the rootstock should be cut before sprouting the following spring.
2. Collection of scion wood: Generally use the current year's jujube shoot, cut off the secondary branches on the main bud and the leaves on the main bud, keep the petiole, then wrap well with a wet cloth to retain moisture for later use. The collected scion wood should not be stored for long at room temperature and should be used as soon as collected. If longer storage is needed, it should be placed in a refrigerated container at about 5°C.
3. Grafting method: At a smooth area of the rootstock, use a budding knife to make a horizontal cut down to the xylem, then from the middle of the horizontal cut cut a small vertical slit downward to form a T-shaped cut. To take the bud, use a sharp budding knife to make a horizontal cut about 3 mm above the main bud of the scion, down to about 1/3-1/2 of the scion diameter, then below the bud about 1 cm from the bud lift and cut upward to connect with the upper horizontal cut. Pinch the bud piece tightly with your hand and gently remove it, take out the grafted bud and quickly insert it into the cut of the rootstock, align the horizontal cut of the grafted bud with the horizontal cut of the rootstock, wrap tightly with plastic film leaving the main bud and petiole exposed. If after 7 days of grafting the petiole still remains green or falls off at a light touch, it indicates that the grafted bud has survived; otherwise, graft again.