A Detailed Guide to Artificial Cultivation Techniques and Processing Methods for Gastrodia elata

Gastrodia elata is a parasitic herb whose underground tuber is an important medicinal material in great demand on both domestic and international markets. In the past, Gastrodia elata was produced by asexual propagation. Because Gastrodia elata was planted in few areas and easily degenerated, neither its yield nor its quality could meet demand. Using artificial sexual propagation allows for large-scale production, and the quality is good as well. Although Gastrodia elata is a herbaceous plant, it has no chlorophyll throughout its body and must parasitize Armillaria mellea to obtain nutrients. However, Armillaria mellea is a fungus that must also parasitize the bases of certain tree trunks, growing on the initially decaying sap it decomposes. Therefore, to artificially propagate Gastrodia elata, the relationship among these three must be well coordinated.

I. Cultivation of Armillaria mellea material: Wild Armillaria mellea should be used as the inoculum whenever possible. Armillaria mellea generally grows on fallen, half-rotted tree trunks and stumps at forest edges and stream banks, and in relatively moist soil rich in organic matter, and can be collected by hand for inoculation and cultivation. The tips of young hyphae are brownish-red and can serve as inoculation material. Smooth, thick, dark-red rhizomorphs on the surface are mature rhizomorphs with strong sprouting capacity and are good inoculation material. Those with a dark brown surface are old rhizomorphs and can also be used for inoculation. Those with a pure black surface are completely aged rhizomorphs and cannot be used for inoculation. Because new hyphae grow out from the cut ends of rhizomorphs, the collected rhizomorphs should be cut into small segments, each not too long, preferably 2-5 mm. To ensure the activity of the hyphae, the work must be done in a shaded and clean place, and contamination by foreign fungi must be avoided. Then, the hyphae are cultivated on wood segments. Tree species relatively suitable for Armillaria mellea reproduction should be chosen for the wood segments.

II. Cultivation of Gastrodia elata seeds: Freshly emerged wild Gastrodia elata can be collected as seedlings and cultivated in Armillaria mellea material until flowering, when hand pollination is carried out. The purpose of this artificial sexual propagation is to increase the fruit-setting rate of Gastrodia elata. The seeds are harvested in July-August and can then be sown in small pits. The small pits should preferably be 60-70 cm wide, about 100 cm long and 28-35 cm deep, with earthen ridges left between pits to facilitate the growth of the Gastrodia elata tubers in all directions. The optimum temperature for the vigorous reproduction and growth period of Gastrodia elata and Armillaria mellea is 20-25°C, and the optimum humidity is about 80%. Sowing can be timed according to local conditions.

III. Sowing Gastrodia elata seeds: First loosen the soil at the bottom of the pit and spread a layer of humus soil, then place the pieces of wood material on which Armillaria mellea has been cultivated, and fill the gaps with some broadleaf tree leaves. If only wood segments capable of cultivating Armillaria mellea mycelium are used, then finely cut wild rhizomorphs should be sprinkled on the peeled parts of the log segments. Then place the seeds on the wood material (or log segments) at a spacing of 6-8 cm, cover with a layer of leaves, sawdust or fine fibrous roots of herbaceous plants, and finally add the upper covering layer. The humidity of the pit should be maintained at 45-60% year-round. After 2-3 years, harvesting can be carried out; most is used for processing into Gastrodia elata medicinal material, and the rest can be kept as seed Gastrodia elata to continue expanding production.

IV. Harvesting and processing of Gastrodia elata: Gastrodia elata stops growing when the ground temperature reaches 10°C and enters dormancy, resuming growth only when the ground temperature rises above 10°C. Gastrodia elata harvested during this period is of the best quality and is called winter Gastrodia elata. Therefore, it is best to harvest and process it during this period. If one waits until the stem bolts and emerges from the soil, the quality gradually declines. When processing Gastrodia elata, first wash the outer skin with water, then rub with straw and scrape off the scaly coarse skin, and cut off the stem if there is one. At a ratio of 200 g of alum per 10 kg of Gastrodia elata, put it into boiling water and boil for 10-20 minutes. Alternatively, separate the large and small Gastrodia elata (to avoid uneven cooking) and steam them thoroughly in a steamer; when they are cooked or steamed until they soften when pinched and appear semi-transparent with no solid core when held up to the light, they can be taken out and flattened with a wooden board, sun-dried during the day, and dried at night on a heated brick bed or beside a coal stove, or dried over a low fire in an iron pot lined with a layer of paper. Gastrodia elata is generally dried over a charcoal fire; firewood is avoided to prevent blackening from smoke, and the fire should not be too large or too fierce, lest the tuber surface dry rapidly and become dry outside but wet inside. For large-scale drying, a rectangular drying stove 1 m high can be built, with an iron pot set in the stove, charcoal fire placed in the iron pot, and the charcoal fire covered with charcoal ash; then a long bamboo mat is placed on the stove, a gunny sack is spread on the bamboo mat, the Gastrodia elata is placed on it, and another layer of gunny sack is laid on top. Attention should be paid to turning it frequently so that the degree of drying is uniform. When it is half dry, it can be taken out; after the Gastrodia elata regains moisture and the internal water seeps outward, it is dried again, and this must be repeated three times to achieve complete dryness. If some sulfur mud balls are added to the charcoal - made by mixing 70-80% clay with 20-30% sulfur and adding water to knead into coal-ball shapes - for fumigation and drying, the Gastrodia elata can be made white and lustrous in color and can be prevented from insect damage. The processed Gastrodia elata should be wrapped well in white paper and sealed in non-toxic plastic bags, or stored in a porcelain jar with the mouth covered by a layer of clean thick paper, and kept in a dry place to prevent moisture and insect damage.