The Latest Cultivation Techniques and Methods for Dendrobium officinale: A Tutorial

Dendrobium officinale, also known as Heijiecao (black-jointed grass), belongs to the genus Dendrobium in the orchid family (Orchidaceae) and is a precious wild medicinal plant. Its active components are mainly Dendrobium polysaccharides, dendrobine, amino acids, and others, among which the Dendrobium polysaccharide content is as high as 21.7%, which can significantly enhance the body's immune function and has effects such as nourishing the stomach and promoting fluid production, tonifying the kidney and boosting strength, nourishing yin and clearing heat, tolerance to hypoxia, anti-fatigue, and anti-tumor properties.

The methods of artificially cultivating Dendrobium officinale can be divided into two major categories: “wild-simulated cultivation” and “facility cultivation”. According to the different carriers chosen for cultivation, the cultivation methods can be further subdivided into: stone-attached cultivation, tree-attached cultivation, stone wall cultivation, rock wall cultivation, three-dimensional cultivation, pot cultivation, three-dimensional pot cultivation, seedbed ground cultivation, and so on. At present, the most widely used, efficient, and high-yielding method is “facility cultivation”. The modes of “facility cultivation” include: shade shed cultivation, solar greenhouse, balcony three-dimensional cultivation, indoor three-dimensional pot cultivation, and so on.

In areas south of the Yangtze River, Dendrobium officinale can be directly cultivated on tree trunks in forests, without the need for “facility cultivation”, building or using facilities to cultivate it, and the cost will be very low; in cold northern areas, one can use house balconies, abandoned vegetable greenhouses, etc., appropriately adjusted or modified into “facility cultivation”, using three-dimensional pot cultivation of Dendrobium officinale, without building new greenhouses, and the cost is also very low.

Environmental Requirements for Growing Dendrobium officinale

In “facility cultivation”, this refers to the internal micro-environment of the cultivation facility; in “wild-simulated cultivation”, it refers to the local climate environment, rather than requiring the climate of an entire province or region. There are the following main conditions:

1. Temperature: The survival temperature is -2-41°C, the growth temperature is 10-35°C, and the optimum growth temperature is 20-32°C. At high temperatures, such as in summer, the greenhouse must be shaded and ventilated, and frequent misting is needed to cool and maintain humidity; at low temperatures, such as in winter, insulation and heating are needed.

2. Humidity: Humidity needs to be adjusted accordingly with the temperature level. During vigorous growth, it is best to maintain the air humidity of the internal micro-environment of the cultivation area at 60%-90%. High temperatures require high humidity, and low temperatures require low humidity. During high temperature and high humidity, ventilation should be strengthened to prevent bacterial and fungal diseases.

3. Substrate: Cultivation requires the use of a substrate, and the substrate must keep the root environment easy to drain, easy to aerate, and full of gaps.

4. Water quality: The water used for watering Dendrobium officinale should be weakly acidic or neutral water.

5. Light: Adjust shading according to temperature and light, and during suitable growth, keep the shading degree controlled at 50-80%.

6. Ventilation: The cultivation site must have good ventilation conditions. Simply put, there are two major requirements: first, the cultivation micro-environment should be “warm, humid, and weakly lit”; second, the cultivation substrate should be “loose, aerated, and draining”.

Artificial Cultivation Methods for Dendrobium officinale

The site or carrier for cultivation and planting can be chosen from flat ground, hillsides, walls, rock walls, tree trunks, balconies, and flower pots, all of which are acceptable, requiring no water accumulation and easy drainage. When cultivating and planting, first spread a 3-5 cm layer of cultivation substrate, then plant the washed seedlings into the substrate just like planting tree seedlings. The cultivation substrate can be selected from: stones, limestone, tree bark, sawdust, discarded mushroom culture material, etc., mixed in a certain proportion; one can also choose humus soil formed from fallen leaves and branches under the forest mixed with stones in a certain proportion; or use some crop husks as the cultivation substrate.

Transplanting Dendrobium officinale

The natural reproduction rate of Dendrobium officinale is extremely low. Rapid mass propagation of Dendrobium officinale tissue-cultured seedlings through tissue culture has become an effective way to solve the seedling problem. Planting Dendrobium officinale tissue-cultured seedlings on raised beds allows misting and watering at any time and drainage of excess water at any time, so roots will not rot and seedlings will not die due to too much water, and it can ensure root ventilation and aeration, thus greatly improving the transplanting survival rate, which can reach more than 95%.

1. Hardening: Before transplanting, first move the bottle seedlings to a hardening room for 2~3 weeks of hardening, allowing the bottle seedlings to transition from a closed and stable environment to an open and changing environment and gradually adapt to the natural environment, until the bottle seedlings grow robustly, the leaf color is normal, the roots are more than 3 cm long, the fleshy stems have 3~4 internodes and 4~5 leaves, the leaf color is normal, the roots are more than 3 cm long, there are 4~5 roots, the root skin is white with green, there are no black roots, no deformities, and no variations.

2. Bottle removal: When taking the tissue-cultured seedlings out of the bottle, open the bottle stopper and gently take out the culture medium together with the small seedlings, place them neatly in a basin for washing, and place contaminated seedlings, bare-root seedlings, or seedlings with few roots separately. For normal tissue-cultured seedlings, first wash off the culture medium in tap water, especially the agar, to avoid root rot caused by moldy agar, then wash once more with fresh tap water. After the above washing, bare-root or few-root tissue-cultured seedlings also need to have their roots soaked in 100 mg/L ABT rooting powder for 15 minutes for rooting induction. After washing contaminated seedlings, soak the whole small seedlings in 1000-fold carbendazim for 10 minutes. Proper later management can effectively control the occurrence of contamination.

3. Preparation of the substrate: Suitable substrate must be selected for transplanting Dendrobium officinale tissue-cultured seedlings. The roots of Dendrobium officinale are aerial roots, with obvious aerophilic and shallow-rooted characteristics; therefore, the substrate is required to be loose, aerated, well-draining, not prone to mold, and free of hidden pathogens and pests. Sphagnum moss, limestone, crushed bricks, tree bark, wood shavings, fern roots, board edges, mushroom bran, wood bran, etc., can be selected as the transplanting substrate.

Field Management of Dendrobium officinale

1. Watering: If the air humidity is too low in the later stage after planting Dendrobium, water frequently to maintain humidity, and a sprayer can be used to water in the form of mist.

2. Topdressing: During the growing season of Dendrobium, attention should be paid to topdressing. A mixture of decomposed peanut cake, rapeseed cake, superphosphate, etc., added with river mud, can be spread at the roots. In addition, 0.05-0.1% potassium dihydrogen phosphate can be used for foliar topdressing.

3. Pruning: Before new buds sprout each spring, in combination with harvesting old stems, cut off the dead stems within the clump, and remove diseased stems, weak stems, and diseased roots. After 6-8 years of planting, depending on the growth of the clump base, turn over the clump and propagate again by division.

Pest and Disease Control of Dendrobium officinale

1. Dendrobium black spot disease: It harms leaves and causes them to wither, occurring from March to May. For control, spray 1-2 times with 50% carbendazim 1000-fold solution.

2. Dendrobium anthracnose: It harms leaves and stems, and affected leaves show brown or gray lesions, occurring from January to May. For control, spray 2-3 times with 70% thiophanate-methyl 1000-fold solution.

3. Dendrobium scale insect (Pinnaspis): It parasitizes the edges or undersides of plant leaves and sucks sap, with late May being the peak hatching period. For control, spray with the biological pesticide Haizheng Miechongling 4000-fold solution to kill them, or gather old branches with scale shells and burn them centrally.

Harvesting and Processing of Dendrobium officinale

1. Harvesting. Harvest before budding in late spring each year. When harvesting, cut off stems and branches that are more than three years old, leaving tender stems to continue growing.

2. Processing. Due to different varieties and commercial medicinal materials, there are two methods:

① Wash the harvested stems clean of mud and sand, remove the leaves and fibrous roots, separate them into single stems, put them into hot water at 85°C and blanch for 1-2 minutes, take them out, spread them on bamboo mats or a cement yard to sun-dry. When they are 50% dry, rub off the sheath membrane by hand, then spread them out to dry again, and pay attention to turning them frequently, until fully dry.

② Alternatively, put the washed Dendrobium into boiling water and blanch for 5 minutes, remove and air-dry, place on bamboo mats to sun-dry, turning 2-3 times each day, and when the stems become soft, rub them while drying, repeating many times until the remaining leaf sheaths are completely removed, then sun-dry until fully dry.