Detailed Explanation of Gastrodia Cultivation Techniques and Key Planting Management Points
Gastrodia is the dried tuber of the orchid family plant Gastrodia elata, also known as Chijian, Shuipu, Mingtianma, etc. It has effects such as calming the liver and extinguishing wind, dispelling wind and unblocking collaterals. It is mainly produced in Sichuan, Guizhou, Yunnan, Shaanxi, Hubei, Anhui and other provinces. It is now introduced and cultivated throughout the country.
(1) Morphological characteristics
Perennial herb, without roots, without green leaves, plant height 30 cm to 150 cm. The tuber is fleshy and thick, elliptical, pale yellow on the outside, with uniform rings, and membranous scales and inconspicuous bud eyes at the nodes. Those with a terminal red mixed bud are called jianma; those without an obvious terminal bud are called baima and mima. The stem is single, cylindrical, generally with 7 nodes, yellow-red, with white stripes. The degenerated small scalelike leaves are membranous, alternate, light brown. The raceme is terminal, with membranous bracts; the flowers are pale yellow-green, bisexual, with the perianth fused into a crooked tube and 5-lobed at the apex; the column is fused, the anther is 2-celled, block-shaped, at the apex, and the anther cap is hood-shaped; the ovary is inferior, and the stalk is twisted and yellow-brown. The capsule is oblong, light red, with 6 longitudinal sutures; the seeds are tiny and powdery, and when magnified 50 times, the seeds can be seen to be spindle-shaped or crescent-shaped. Flowering period May to June, fruiting period June to July, see Figure 4-3.
(2) Growth habits
Gastrodia prefers a cool and humid environment, is cold-tolerant, and fears high temperatures. Gastrodia has no roots and no chlorophyll to absorb and manufacture nutrients, so it must rely on Armillaria mellea to provide them. Armillaria mellea is a facultative fungus that often parasitizes or saprophytically lives in the tissues of tree roots and old trunks. It begins to grow at 6c to 8c, with soil moisture of 60% to 80%, and can grow normally at a temperature of 20c. The optimum growth temperature is 20c to 26c; growth is slow above 28c, and stops above 32c.
Gastrodia and Armillaria mellea have a nutritional symbiotic relationship. The Armillaria mellea rhizomorph invades the epidermal tissue of the Gastrodia tuber; the tip of the rhizomorph ruptures, the hyphae penetrate the cortical parenchyma cells, decompose and absorb the epidermal cells, and the hyphae continue to extend inward, then the hyphae are in turn decomposed and absorbed by the digestive layer cells of Gastrodia to supply Gastrodia's growth.
Gastrodia seeds have no endosperm, the embryo is undifferentiated, and they cannot provide a nutritional source for germination themselves. Under natural conditions, seed germination requires the participation of fungi in addition to the conditions required by ordinary green plants. The seeds begin to germinate in early May at 10c to 15c, but the germination rate is extremely low, generally 1% to 10%. Gastrodia grows best at 20c to 25c, and growth is inhibited above 30c. In spring, when the ground temperature at 15 cm reaches above 10c, the Gastrodia buds begin to sprout and begin to reproduce daughter tubers. Growth is rapid from June to July, slows in September, and enters dormancy in late October when the ground temperature drops below 10c. From seed to flowering takes 4 to 5 years.
(3) Cultivation techniques
1. Site selection and land preparation It is advisable to choose semi-shaded and semi-sunny gentle slope land and valley land rich in organic matter for planting. The soil should be loose loam, well-drained sandy loam or sandy soil, especially virgin land. The soil pH value of 5 to 6 is suitable. Avoid clay and waterlogged land, and avoid continuous cropping. In addition, air-raid shelters, mountain caves, basements and other places can also be used to grow Gastrodia.
2. Propagation methods Mainly use tuber propagation, and seed propagation can also be used.
(1) Tuber propagation: winter planting or spring planting. Winter-planted Gastrodia has a high inoculation rate and grows quickly; the time is November. Spring planting is in March to April. Before planting, the fungus bed must be well cultivated. Tree species suitable for Armillaria mellea growth are commonly those of the Fagaceae family, such as Qinggang, Quercus aliena, Quercus variabilis, and Mao su, etc. Broadleaf trees with thick bark, hard wood, and strong decay resistance are best. Saw the selected wood into 40 cm to 50 cm long wooden sticks, and chop the bark into fish-scale notches. In the selected plot, 2 to 3 months before planting, dig a pit 25 cm to 30 cm deep and 60 cm wide, with length determined by the terrain. Loosen and level the soil at the bottom of the pit, spread a layer of dry leaves or humus soil, and place one layer of treated new wooden sticks alternating with wood carrying Armillaria mellea (commonly known as fungus wood), with the distance between adjacent sticks 6 cm to 7 cm. Some broadleaf tree branches can be placed in between, and humus soil can be used to fill the gaps to prevent contamination by miscellaneous fungi. Then cover with soil 3 cm to 4 cm. Arrange the second layer in the same way, then cover with soil 10 cm. Keep the pit moist, cover with weeds to shade, cool, and retain moisture, so that Armillaria mellea grows normally, thus forming a fungus bed. Select tubers without disease spots, without freezing injury, and not rotting as seed tubers, sort them by size, and plant them separately. When planting, place the seed Gastrodia parallel in the furrows between the fungus sticks, close to the fungus sticks, fill the gaps with humus soil, then cover with soil 3 cm, so that the lower layer of fungus wood is not visible. Plant the second layer in the same way, finally cover with 10 cm to 15 cm, and cover with a layer of leaves and weeds to keep the soil moist. During overwintering, thicken the covering soil to prevent freezing injury.
(2) Seed propagation: Select jianma weighing more than 100 g, and plant them as they are collected according to the above method. When bolting, prevent sunlight exposure, and perform artificial pollination when flowering. Pollination can be done around 10 a.m. on a sunny day, when the edge of the anther cap slightly shows the flower. After pollination, cover the fruit spike with a plastic bag, and when a small amount of seeds spills from the lower fruits, collect them from bottom to top as they ripen. Because Gastrodia seeds have a short lifespan, the harvested capsules should be sown promptly. When sowing, take out the upper layer of fungus wood from the fungus bed, scrape away the soil on the lower layer of fungus wood, scatter moist fallen leaves on the lower layer of fungus wood, and press them slightly flat; evenly scatter the seeds on the leaves, cover with a thin layer of moist fallen leaves, then sow the second layer of seeds, cover with soil 3 cm, then cover with a layer of moist leaves, place the upper layer of fungus wood, and finally cover with soil 10 cm to 15 cm. If 10 fungus wood pieces per pit can be sown with 8 to 10 capsules, and each capsule has about 30,000 seeds, with proper planting, in the autumn of the second year a portion of jianma, baima, zimma, and a large amount of mima can be harvested, which can be used as seed tubers for tuber propagation.
3. Field management After planting Gastrodia, careful management is required, and trampling by people and livestock is strictly prohibited. Before overwintering, thicken the covering soil and add leaves to prevent freezing; during the high-humidity period from June to August, build a shed or intercrop tall-stalked crops for shade; before the rainy season arrives, clear the drainage ditches and promptly drain accumulated water to prevent tuber rot. In spring and autumn, necessary sunlight should be received to maintain a certain temperature.
4. Pest and disease control
(1) Rot disease: caused by various factors, commonly known as rot nest disease. Control methods: strictly select seed stems; strengthen water management in the field, so as to prevent drought, prevent waterlogging, and preserve soil moisture.
(2) White grubs: the larvae chew the tubers in the pit. Control methods: use light traps to kill adults; drench with 90% trichlorfon 800-fold solution and 75% phoxim emulsifiable concentrate 700-fold solution.
Other pests such as mole crickets, aphids, and ants also damage fungus wood and tubers, etc., and should be controlled as needed.
(4) Harvesting and processing
Large baima and jianma used as seed are harvested one year after planting; small baima and mima used as seed require 2 years after planting to harvest. Generally, digging is carried out in early winter or early spring. First scrape away the surface soil, take out the fungus wood, collect the Gastrodia, and grade it, then cover the gaps with leaves to let the mima continue growing. Aside from part of the jianma being reserved for seed propagation, it is processed for medicinal use together with baima.
The processing method is to wash the graded Gastrodia, steam it in a steamer for 10 to 20 minutes, until there is no white core, take it out and air-dry the surface moisture, then continue drying it over fire until dry. If it is large Gastrodia, it can be pierced with a needle so that the internal moisture is released outward, pressed flat when half-dry, stop the fire and let it sweat, then bake at 70c for 2 to 3 days until completely dry.