Detailed Explanation of the Layering Method for Asexual Propagation of Cornus officinalis
Cornus officinalis, also known as Zaopi, Yaozap, Shuzap, and the fruit peel after pit removal is called Shanyurou or Yurou, is a woody Chinese medicinal herb unique to our country, with wide uses, and its medicinal value, economic value and ornamental value are all very high. It has long been a scarce medicine in domestic and international pharmaceutical markets, and in recent years, due to increased export volume, the price has risen to 140--180 yuan per kilogram. For many years, Cornus officinalis has been propagated by seed seedling cultivation, and from sowing to fruiting often requires 8-10 years. Even with careful management, vigorous plants still need about 7 years to bear fruit. Foping County, Shaanxi Province, is one of the three major cultivation base counties for Cornus officinalis in the country. After more than 10 years of exploration by the author and scientific and technological workers, the use of asexual propagation methods--layering, not only maintains the excellent traits and characteristics of the selected mother plant, but more importantly can make Cornus officinalis bear fruit earlier and achieve rapid growth and high yield. Self-rooted seedlings cultivated by layering on 10--15-year-old mother plants can bloom and bear fruit after two years, bearing fruit 6--8 years earlier than seed-grown seedlings, and the fruit is large, thick-fleshed and of high quality. The characteristic of Cornus officinalis layering is that the water and nutrients needed before rooting can be supplied by the mother plant, rooting is reliable, the method is simple, and the survival rate is high. Layering can be carried out from after fruit harvest in autumn, or after the soil freezes in spring before the young buds sprout.
1. Layering methods
1. Ground layering. Select 10-15-year-old robust trees free of pests and diseases, early fruiting, high yielding and of excellent quality as mother plants. Take branches near the ground, 2-3 years old, about 1 cm in diameter and 100--150 cm high, twist, press and bend them to the ground, or parallel to the ground, cut the shady side of the branch (that is, the part close to the ground) to a depth of 1/3 into the xylem (do not cut through the center, to prevent breaking the branch), then bury the branch in soil that has been previously plowed and applied with organic fertilizer, or after ring-barking, fix the buried part, compact and press it firmly with soil on top, and leave the tip of the branch exposed above the ground. This treatment can promote rooting at the pressed part. Fibrous roots can form after half a year.
2. Air layering. This method is suitable for tall Cornus officinalis trees whose lower parts do not easily sprout branches. The method is to select 2-3-year-old branches, cut or ring-bark the base of the branch to be layered, with a peeling width of 2-3 cm, then fill a split bamboo tube or clay pot with moist soil and bury the layer in the middle, often keeping the soil in the bamboo tube or clay pot moist. After rooting, cut it off from the lower end where roots have formed for planting.
2. Management after layering
After layering, the soil moisture content should be maintained, preferably at 60%-80% of maximum water-holding capacity. In addition, the soil permeability near the layered part is also very important. If it is poorly structured clay or sandy loam, it should be improved. In addition to applying sufficient base fertilizer at the time of layering, applying a small amount of decomposed organic fertilizer in the following spring can promote vigorous growth of the layered seedlings.
3. Field planting
In late autumn of the second year after layering (before the leaves fall, using the leaves for photosynthesis to manufacture and transport nutrients for its roots) or in the third spring, the part connecting the layer to the mother plant can be cut, and the separated self-rooted seedling can be lifted out with soil and planted in a selected plot by digging a hole according to the prescribed method.