Detailed Explanation of Key Points for High-Yield Cultivation Techniques of Eucommia ulmoides

Eucommia ulmoidesIts bark is used as medicine, sweet in taste and warm in nature. It enters the liver and kidney meridians. It has the effects of tonifying the liver and kidneys, strengthening bones and muscles, and preventing miscarriage. It is used for lumbar pain due to kidney deficiency, weakness of bones and muscles, bleeding during pregnancy, restless fetus, and hypertension. The main producing areas include Hubei, Shaanxi, Anhui and other provinces and regions.

I. Morphological characteristics: A deciduous tree, 10-12 m tall. The branches, leaves, bark, and fruit peel contain rubber, and after breaking, many silvery-white filaments appear, hence the common name "chasi pi" (tearing-silk bark). The bark is gray, the branchlets are light brown, with small and obvious lenticels. The buds are nearly ovate, with scales. The leaves are alternate and have short petioles. The leaves are elliptical or elliptic-ovate, 6-13 cm long and 3.5-7 cm wide, with a long acuminate apex, a rounded or broadly cuneate base, and serrate margins, sometimes slightly hooked. The flowers are unisexual, dioecious, without perianth, opening before the leaves in spring or at the same time as the leaves, and borne at the base of the small leaves. The male flower bracts are spoon-shaped and obovate, with 6-10 stamens, linear anthers, and very short filaments; the female flowers have short pedicels, a narrow and long ovary, and a forked style at the apex. The samara is flat and thin, long elliptical, with a notch at the apex. There is 1 seed.

II. Propagation of seedlings: Most use seeds for sexual reproduction. However, in areas lacking seed sources, using asexual propagation is also a shortcut with small investment, quick results, and the ability to obtain high-quality, robust seedlings. Seven rapid seedling-raising methods by asexual propagation are introduced here.

Root cutting propagation: Using the thicker roots pruned off when lifting seedlings, cut them into 7-10 cm long segments. First use a wooden awl slightly thicker than the root segment to make holes in the seedbed, then insert the lower end of the root segment into the hole, with the thicker end slightly exposed above the ground. Water once each day before sunrise and in the evening. After 40-60 days, new seedlings grow from the callus tissue at the cut surface or from buds on the bark of the root segment.

Root layering propagation: Eucommia ulmoides roots have a strong sprouting ability. From March to April each year or after the beginning of autumn, according to the growth direction of the Eucommia ulmoides roots, scrape open the surface layer, select finger-sized root strips, cut and wound the root bark with a knife, and mound soil over the wounded area. Later, new roots and new seedlings grow from the wounded parts. After the seedlings grow to more than 60 cm, cut the roots, dig up the seedlings, and transplant them to the forest land for planting.

Bending-tree seedling propagation: In March of spring, for a clump of Eucommia ulmoides with two or more stems, except for leaving one main trunk, cut the other stems halfway through from the stump, and open a small ditch 16 cm deep on the ground, with the length depending on the tree. Then slowly bend the tree down into the soil ditch, cut a notch every 20 cm, and mound soil (leaving the notches and the tree tip exposed). After two months, shoots grow from the notches and produce fibrous roots. The following year, dig them up with the fibrous roots, cut them off, and they can be transplanted.

Stump seedling propagation: After a Eucommia ulmoides tree is cut down, many new shoots sprout from the stump. In April of spring, cut several notches with a knife at the places where the shoots are close to the stump, then mound soil over the stump. In the same year, many fibrous roots grow at the notches, and the following year they can be taken off with roots for transplantation.

Air layering propagation: During the two periods of March to April or June to July each year, select branches on the tree that are 2-3 years old and about 1 cm in diameter, cut wounds in the bark with a knife, then use plastic film or a bamboo tube split in half filled with fertile soil to wrap the wounded part of the branch, then tie it firmly with rope to prevent loosening, and keep it moist regularly. After about 30 days, new roots grow from the wounded treated part. After 60 days, cut off the branch below the tying place and move it to the forest land for planting.

Dormant branch cutting: Select annual robust branches free of pests and diseases, cut them in April, then cut them into small segments 15 cm long with 3-4 lateral buds retained, place the lower part into a 100 ppm ABT rooting powder solution, soak for 2 hours, then take them out, first make holes in the seedbed with a wooden awl, and insert the branches into the bed surface. Then spray water once in the morning. Generally, rooting can occur in 40-60 days. After that, strengthen topdressing and weeding management. After one year, they can be transplanted, with a survival rate of more than 95%.

Softwood cutting: From June to August, select robust current-year branches, cut them into small segments with 3 lateral buds, do not remove the leaves of the terminal bud on each small segment, then immediately place them into a 100 ppm ABT rooting powder solution, soak for 1-2 hours, and insert them into the seedbed using the same method as for dormant branches, with the upper leaves exposed. Then build a shade shed with 90% shade above the seedbed. In the first month, water once each morning and evening, but after the root system forms, gradually reduce spraying, yet the bed surface must be kept moist. For softwood cuttings, morning is the best time to carry them out. It has the characteristics of a high survival rate and fast rooting.

Trunk-cutting rapid-growth technique: Under the same conditions and land preparation method, for Eucommia ulmoides planted, a comparative experiment in November of the first year showed: the new stems of trunk-cut plants reached 1-1.5 m in height, and some even reached 2.5 m, while the ground diameter of non-trunk-cut Eucommia ulmoides increased only slightly; for Eucommia ulmoides planted for 2 years, the plant height of trunk-cut ones generally reached more than 2 m, with a ground diameter of 3.5 cm, while the height increase of non-trunk-cut ones was less than 30 cm, and the ground diameter generally reached only about 2 cm. Because the root system of newly transplanted young trees of non-trunk-cut Eucommia ulmoides is not well developed, their growth vigor is weak, while trunk cutting after planting has an obvious effect on accelerating the rapid growth of young Eucommia ulmoides trees.

Method of trunk cutting: After preparing the land, plant the Eucommia ulmoides seedlings from December to January of the following year, and in February (before the new buds sprout), cut off the main trunk of the Eucommia ulmoides seedling at 3-10 cm above the ground, then insert the cut stem at the original place as a marker. It can sprout in mid-April, more than 15 days earlier than non-trunk-cut plants.

After many years of experiments, it was found that planting seedlings in the first year and cutting the trunk in the following year is better than planting and cutting the trunk in the same year; cutting the trunk at the base is better than cutting at a high position. However, management must be done well. When the sprouts on the seedling stump grow more than 30 cm, multiple leader shoots and buds should be removed in time, and only one main bud should be selected as the trunk for cultivation. But in the same year, the base of the newly retained main trunk should not be removed in spring and summer, to prevent excessive upper leaves from causing the treetop to droop and the trunk to bend. In the second and third years after planting, the attached branches, diseased branches, and slanting branches on the lower part of the main trunk can be gradually pruned off, which is beneficial for the main trunk to grow straight and relatively thick and strong.