Detailed Explanation of the Key Cultivation and Management Techniques for Dendrobium nobile

Dendrobium nobile, an orchid family plant, also known as flat gold hairpin or hanging orchid. It is a perennial herb, 20-50 cm tall, with white aerial roots. The stems are erect, clustered, yellow-green, slightly flattened, grooved, and jointed. The leaves are alternate, sessile, narrowly oblong, with leaf sheaths clasping the stem. Racemes are terminal, bearing 2-3 small flowers; the flowers are white with a slight pale purple tint at the tip. The capsule is elliptical with 4-6 ridges; the seeds are very small. The flowering period is May to June, and the fruiting period is July to August. The stems are used medicinally; they are cold in nature and sweet in taste, with effects of benefiting the stomach and promoting fluid production, nourishing yin and clearing heat. They can be used to treat conditions such as yin damage with insufficient fluids, dry mouth and excessive thirst, and poor appetite with dry retching.

I. Site Selection and Land Preparation  For Dendrobium cultivation, a semi-shaded, semi-sunny environment should be chosen, with air humidity above 80% and winter temperatures above 0°C. The tree species should be live trees such as Huangjue trees, pear trees, and camphor trees, with thick bark, longitudinal grooves, high water content, dense branches and leaves, and thick trunks. Rocky areas should also be in cool, moist locations, with moss growing on the rocks and a small amount of humus on the surface. Before planting Dendrobium, the plot must first be prepared. The basic requirements are: when planting Dendrobium on large rocks, holes should be drilled on the rock surface with an awl at a spacing of 30 cm × 40 cm between plants and rows, with a hole depth of 5-10 cm, and a small drainage outlet should be made on the lower side of the rock surface to prevent water accumulation from causing basal rot; when drilling holes, the moss on other parts of the rock surface should be protected. When planting Dendrobium on small gravel, remove weeds and miscellaneous branches from the plot, reserve shade trees, and clear out excessive and overly dense small miscellaneous trees to help increase light penetration.

II. Propagation Methods Because Dendrobium seeds are extremely small, with about 20,000 seeds per capsule, they generally need to be cultured in a tissue culture room. In actual small-scale production, asexual propagation is commonly used, carried out in spring or autumn. Select plants 1-2 years old with good growth vigor, no pests or diseases, well-developed root systems, and many sprouts as stock plants. Pull them up by the roots, remove dead branches and broken stems, trim excessively long fibrous roots, keeping old roots at about 3 cm, and divide them into several clumps according to the number of stems. Each clump must have 4-5 stems to serve as planting material.

III. Planting Methods Dendrobium is best planted in spring (March-April) or autumn (August-September), with spring planting being more suitable than autumn planting. ① Rock-attached planting method. Choose shady, moist rock crevices or stone grooves under the forest where there is humus, wrap the roots of the divided small clumps of Dendrobium seedlings with cow dung slurry, and insert them into the rock crevices or grooves. When inserting, make sure they are firm to prevent them from falling. If cultivating on gravel, the method is to lay the seedlings flat on the gravel, then use stones to press down the middle and lower parts of the seedlings, leaving the base and top exposed, with the degree being that they do not move in the wind. When planting Dendrobium around the rock surface, a small hole can be drilled with an awl. Beforehand, 30:1 phosphate fertilizer can be mixed into fresh cow dung, add water and tread to mix; the moisture level should be such that no water remains in the finger gaps when squeezed by hand. Press the Dendrobium seedlings tightly against the small hole, and with one hand take the prepared cow dung and apply it to the middle and lower parts of the Dendrobium seedling stems, so that the seedlings firmly adhere to the rock. ② Tree-attached planting method. On relatively flat and thick trunks or branches, or at recesses, cut a shallow slit with a knife every 30-50 cm, and peel off some bark. Then fix the base of the prepared Dendrobium seedlings in the tree slits with bamboo nails or ropes, and smear cow dung slurry (made by mixing cow dung and mud evenly) on their roots and the surrounding bark grooves. To prevent wind shaking and rain washing, generally use bamboo nails to nail them firmly or use bamboo strips and other ropes to tie 2 loops to fix the Dendrobium fibrous roots and plants on the trunk or branch forks. When planting on trees, proceed from top to bottom.

IV. Field Management After planting Dendrobium, maintain moist air conditions and water appropriately, but strictly avoid overwatering; never allow water accumulation that causes root rot. No fertilization is needed at planting time. Starting from the second year after planting, topdressing should be carried out 1-2 times per year. The first is sprout-promoting fertilizer, applied around the Spring Equinox to Qingming; the second is warmth-preserving fertilizer, applied around the Beginning of Winter. Use cake meal, bean dregs, cow dung, pig manure, and fertile soil mixed with phosphate fertilizer and a small amount of nitrogen fertilizer, mix evenly, and then spread a thin layer around the roots. Because the root system of Dendrobium has a relatively poor ability to absorb nutrients, to promote its growth, during the growing period, foliar fertilization is often carried out every 1-2 months with 2% superphosphate or 1% potassium sulfate. Regardless of the cultivation method used for Dendrobium, fertilizer and water should be applied after the morning dew has dried, and application under the high temperatures of the midday sun is strictly prohibited; otherwise, it will seriously affect the normal growth of Dendrobium. After planting, weed twice a year: the first from mid-March to early April, and the second in November. In the high-temperature summer season, weeding is not advisable, so as not to affect the normal growth of Dendrobium. Every spring before sprouting or when harvesting Dendrobium, some old branches and dead branches, as well as overly dense stems and branches, should be pruned to promote new bud growth. After 5 years of Dendrobium cultivation, the plants have many sprouts, old roots die, the substrate rots, and pathogens infect, causing poor plant growth. Therefore, according to the growth situation, the clumps should be turned over, dead and decayed old roots removed, and division carried out for replanting elsewhere, so as to promote plant growth and increase yield and income.

V. Pest and Disease Control The main diseases commonly occurring during the growth and development of Dendrobium are: ① Black spot disease. This disease often occurs from March to May. Use 1:1:150 Bordeaux mixture or 1000-fold Duoling solution to prevent and control its development. ② Sooty mold. March to May is the main onset period of this disease. Use 50% carbendazim 1000-fold solution or 40% dimethoate emulsion 1500-fold solution for spray control 1-2 times. ③ Anthracnose. January to May is the main onset period of this disease. Use 50% carbendazim 1000-fold solution or 50% thiophanate-methyl 1000-fold solution by spray to prevent and control infection of new plants by this disease. The main pests currently found are: ① Dendrobium scale insect. Late May is the peak hatching period for this pest. Spraying with 40% dimethoate emulsifiable concentrate 1000-fold solution or 1-3 degree lime sulfur mixture gives better control results. For those that have formed shields but are few in number, control can be carried out by pruning old branches and leaves and burning them in a concentrated manner or crushing them to death. ② Snails. Mix bran with trichlorfon and scatter it in places where the pests frequently move for poison bait trapping; spray trichlorfon, deltamethrin, and other pesticides on the cultivation bed and surrounding environment, and quicklime can also be scattered.

VI. Harvesting and Preliminary Processing After 2-3 years of cultivation, harvesting can be done in all four seasons, but it is best to harvest before the plants sprout from the Beginning of Winter to Qingming. When harvesting, use scissors or a sickle to cut the old plants from the base of the stems, taking care to harvest old stems and leave young ones, so that the remaining young plants continue to grow, achieving the goal of planting once and benefiting for many years. Fresh Dendrobium can be used directly for medicinal purposes without removing leaves and fibrous roots. Alternatively, remove the fibrous roots and branches and leaves, and store in wet sand for later use. The traditional processing methods for dried Dendrobium are the water-blanching method and the hot-frying method.