What are the key techniques for high-yield cultivation of Gastrodia elata?

Gastrodia elata is a rare and precious medicinal herb unique to China. Due to the sharp decline of wild resources, supply is tight and prices are high. In recent years, the area of artificial cultivation has continued to expand, and many places have taken Gastrodia elata cultivation as an industry for poverty alleviation and prosperity, achieving good results. Many farmers have embarked on the road to prosperity by growing Gastrodia elata. Huang Xiang, a villager of Awang Village, Huangnihe Town, Fuyuan County, successfully introduced Gastrodia elata from Guizhou for trial planting in 1996. By the end of 2002, he had led more than 400 surrounding farmer households to grow Gastrodia elata, with an area of 25,000 sq m and a fresh Gastrodia elata output of more than 200,000 kg. Through years of Gastrodia elata cultivation, a set of cultivation experience has been developed. It is summarized below for reference by Gastrodia elata growers.

I. Strictly control the three key passes

(1) The seed pass. The quality of Gastrodia elata seeds and the strength of their growth vigor are the key to high and stable yields of Gastrodia elata. In vegetative propagation, generally after 3-4 generations of planting, the seeds degenerate, growth vigor weakens, and yield drops sharply. Therefore, after 3-4 generations of Gastrodia elata cultivation, the seeds must be replaced to ensure that the seed characteristics do not decline and to achieve the goal of high and stable yields. At present, sexual reproduction technology for Gastrodia elata is becoming increasingly mature. Gastrodia elata seeds can be produced through sexual reproduction, which plays a role in purifying and rejuvenating Gastrodia elata and ensures high and stable yields.

(2) The Armillaria mellea pass. Due to the particularity of Gastrodia elata growth, the entire growth process of Gastrodia elata cannot be separated from Armillaria mellea; only then can it survive and reproduce and achieve relatively high yields.

First, increase the amount of wood used to create a growth advantage for Armillaria mellea, inhibit the growth of miscellaneous fungi, and ensure that Gastrodia elata growth has a sufficient nutrient environment. During cultivation, it is strictly forbidden to use old fungus sticks infected by miscellaneous fungi or those from which miscellaneous fungi have been removed after infection, so as to prevent re-contamination. Wood must be filled in firmly to prevent gaps between pieces of wood, which can accumulate water on rainy days and easily become infected by miscellaneous fungi. For wood, choose broadleaf trees with hard wood that does not rot easily, so as to ensure long-term growth of Armillaria mellea and its supply of nutrients to Gastrodia elata.

Second, supply fungi reasonably. The symbiosis between Gastrodia elata and Armillaria mellea is not passive. Under artificial conditions, it is entirely possible to change passive nutrient supply into scientific nutrient supply and rational fungus supply. In autumn, October-November, Gastrodia elata is in a dormant state. When Gastrodia elata is planted during the dormant period, Armillaria mellea can grow at temperatures above 5°C. When spring temperatures rise above 15°C, Gastrodia elata begins to sprout, and Armillaria mellea has gradually grown and combines with Gastrodia elata to supply nutrients, so Gastrodia elata will not starve and will grow well.

(3) Strictly control the temperature and humidity pass. As Gastrodia elata changes from wild to artificial cultivation, its growing environment undergoes relatively large changes. This generally manifests as excessively high temperatures during the dormant period of Gastrodia elata, shortening the dormant period and causing degeneration of seed characteristics. Generally, during the dormant period (November to February of the following year), the temperature should be controlled at 2-5°C and the humidity at about 30%; in the early growth stage (March-April), the temperature should be 15-20°C and the humidity about 40%; during the vigorous growth period (May-September), the temperature should be controlled at 22-25°C and the humidity at about 50%. In the early stage, greenhouses or plastic film mulching can be used to raise ground temperature, first to prevent frost damage and second to increase temperature and promote the production of Armillaria mellea. During the vigorous growth period of Gastrodia elata, plastic film mulching should generally not be used, because outdoor temperatures can fully meet the growth needs of Gastrodia elata. If greenhouses or plastic film mulching continue to be used and the temperature inside the film exceeds 28°C, first, Gastrodia elata will stop growing, and second, it may cause Gastrodia elata to rot, affecting yield. If cultivated in a greenhouse, after the indoor temperature exceeds 28°C, the greenhouse should be ventilated or shaded with straw mats, or watered inside the greenhouse to lower the temperature.

II. Pay attention to three links

(1) Gastrodia elata cultivation must implement crop rotation. Gastrodia elata and Armillaria mellea produce large amounts of harmful substances during growth and respiration. If Gastrodia elata continues to be planted in the same place, it will cause a sharp reduction in Gastrodia elata, or even total crop failure.

(2) The Gastrodia elata cultivation site should avoid places with foul odors. Armillaria mellea is an aerobic fungus. Planting Gastrodia elata in places with foul odors is unfavorable to the growth of Gastrodia elata and Armillaria mellea and affects the yield of Gastrodia elata.

(3) When Gastrodia elata is planted in field corners, rainfall is relatively heavy in the rainy season, which exactly satisfies the characteristic of Armillaria mellea liking large amounts of water. This can easily cause "nutrient backflow," leading to "fungus absorbing Gastrodia elata" and the occurrence of "nest rot." Therefore, special attention must be paid to rain shielding and ditch dredging for drainage, so as to create a reasonable symbiotic environment for Gastrodia elata and Armillaria mellea. Methods for identifying moisture: first, appropriately plant some tall-stalk crops beside the Gastrodia elata, such as sunflowers. In summer and autumn, they both shade and cool the Gastrodia elata and can also detect soil moisture, namely: when the tall-stalk crops begin to wilt, it indicates that the soil moisture is insufficient; another method is to scrape away the surface soil, grab a handful of soil, and squeeze it into a ball in the hand; if it can scatter when dropped on the ground, it indicates that the soil moisture is relatively suitable.