Key Technical Points for Improving the Survival Rate and Yield of Sexual Propagation of Gastrodia elata

Tuyan is one of the main Gastrodia elata production areas in Hubei, with wild Gastrodia elata widely distributed, and both the climate and soil within its boundaries are suitable for sexual propagation of Gastrodia elata. Combining local environmental conditions and based on practical experience, the author has summarized the key techniques for sexual propagation of Gastrodia elata suited to the local natural environment.

1. The quality and quantity of fungal inoculum are the foundation for ensuring the germination and growth of Gastrodia elata seeds

(1) The germination rate of Gastrodia elata seeds depends on the quality and quantity of the seed germination fungus. Practice has shown that sowing Gastrodia elata with No. 8104 seed germination fungus mixed in gives a high germination rate and fast germination speed. According to the author's experimental results, each hole (0.5 sq m) used 0.5 kg of germination fungus leaves and 10 Gastrodia elata fruits; sowing was done on June 5, and on July 6 inspection showed that the Gastrodia elata seeds had already germinated into protocorms, with an average of 7 protocorms growing from each fungus leaf bearing Gastrodia elata seeds, and about 15 in the most productive cases. This proves that a sufficient amount of vigorous germination fungus leaves can ensure mass germination of Gastrodia elata seeds. To ensure that the germination fungus remains vigorous, the number of generations of the fungal inoculum used must be strictly controlled, and rejuvenation must be carried out continuously. Sowing the germination fungus inoculum in the field and then isolating it back from the Gastrodia elata protocorms is the most effective way to keep the performance of the germination fungus stable.

(2) The inoculation rate of Gastrodia elata protocorms and the yield of Gastrodia elata depend on the quantity and quality of Armillaria mellea. The sowing amount of Armillaria mellea is mostly two bottles per hole. The author's practice has proven that the amount of Armillaria mellea should be increased; the methods of increasing it are, first, using large amounts of fine tender branches, and second, propagating Armillaria mellea branches in advance. Each hole uses on average more than 4-5 kg of fine tender branches, chopped into short sections of about 8 cm with slanted cuts, and 1-2 months before sowing, 2 bottles of Armillaria mellea inoculum are mixed in evenly and covered with sand or sandy soil to develop fungus branches. Using fungus branches at sowing time gives fast fungus development and a high inoculation rate, avoiding losses caused by insufficient Armillaria mellea. Three keys must be grasped regarding the quality of Armillaria mellea. First, fast growth speed; second, dense branching (branching at about 1 cm); third, robust growth. The mountainous areas in our city where wild Gastrodia elata grows have large amounts of wild Armillaria mellea, and collecting seed once a year (pure culture obtained by tissue isolation) can maintain the excellent species characteristics of Armillaria mellea. For introduced stock, "Jing 234" can be used, which gives high yield when mixed in for cultivating Gastrodia elata.

2. Strictly grasping the sowing season is another key to the success of sexual cultivation of Gastrodia elata

In the suitable growing areas for Gastrodia elata in our city, the altitude ranges from 300 m to 2000 m. In areas from 300 m to 800 m, sowing should be completed in early June, and it is best to advance it to April; from 800 m to 1200 m, sowing should be completed before mid-June; from 1200 m to 1500 m, sowing should be completed before the end of June; from 1500 m to about 2000 m, sowing should be completed in early July. Sowing at the right time or more than 1 month in advance can raise the success rate to 100%, while delaying the sowing period by 10-20 d may reduce the success rate to 50% or even lower; we have had painful lessons in this regard. If the sowing period is too late, the main dangers are, first, pests and diseases, and second, high temperatures causing the death of the germination fungus.

3. The selection of the cultivation environment is the third key to the success or failure of cultivation

For indoor cultivation, choose basements, air-raid shelters, earthen houses, etc. where the summer temperature does not exceed 28°C and ventilation is good; for outdoor cultivation, choose forest land or artificial shade sheds with terrain facing east or north but not west, and with a cool, shady, and humid climate; the soil should be sandy soil, oily sandy soil, or humus soil, and of course clean sand is best.

4. Adopt sowing and management methods suited to local conditions

At present, the sexual cultivation areas for Gastrodia elata in our country mainly use sand cultivation, but most mountainous areas in our city have soil but no sand, making open-field cultivation, especially cultivation in mountain forest land, quite difficult, and conventional methods are hard to succeed with. The author has developed an imitation-wild open-field cultivation technique suitable for local mountain cultivation. The soil in the mountainous areas of Hubei is characterized by mostly oily sandy soil, muddy sandy soil, and humus soil, without the yellow sand found in the Hanzhong area; the places where wild Gastrodia elata grows are not sandy soil, but usually weathered muddy sandy soil and humus soil. This kind of soil has a relatively high water content, usually above 45%, reaching about 70% after rain, and the surface tends to harden, with aeration conditions not as good as the yellow sandy soil in Hanzhong. This is the greatest characteristic of the soil ecology in our area. Another characteristic is that our area has slightly higher rainfall than the Hanzhong production area, and the soil retains moisture and resists drought relatively well, which is the main reason for the vigorous growth of wild Gastrodia elata. Based on these characteristics, cultivation methods cannot simply copy the advanced experience of others. The key points of the imitation-wild sexual cultivation technique for Gastrodia elata studied by the author are: 1. Single-layer planting, planting only one layer of Gastrodia elata seed mixed with fungus; 2. Armillaria mellea logs on the lower layer, Gastrodia elata seed on the upper layer. In the hole, first place the fungus logs, fill fine branches between the logs, then scatter fungus branches, then scatter the fungus-mixed Gastrodia elata seed, and then scatter some Armillaria mellea branches on the surface; 3. Sow shallowly and cover with soil shallowly. Because the local soil has a high water content and poor aeration, deep sowing and thick covering are not suitable; the fungus logs are basically placed on the ground surface, the hole is filled with fine soil plus leaves or humus soil, and the soil cover does not exceed 10 cm, and the soil is covered in 2 stages: at sowing time, cover with soil plus leaves to about 7 cm, and after the seeds germinate (about 30-45 d), add more soil to preserve moisture and prevent high temperatures; 4. Adopt rain-sheltering measures suited to local conditions. The greatest danger in mountain cultivation is none other than rainstorms flooding the holes. In addition to using terrain for drainage and flood prevention, cover the hole surface with sufficient leaves. On top of that, cover with the following rain-sheltering materials: mountain grass bundles, covered in a flower-like shape like a hat to shelter from rain; wheat bran, covering one layer can keep rain from wetting it; bundles of wheat straw or rice straw, covered in a cone shape; branches and leaves tied into bundles for covering. All of these can achieve the purpose of sheltering from rain and preserving temperature without affecting aeration. However, it should be noted that only the sowing layer is covered, with gaps left around for water intake; a small amount of rainwater seeps in from around, which can keep the hole moist, while excess water seeps into the fungus logs and humus soil layer in the hole and cannot soak the fungus-mixed layer. Because the relationships among aeration, drainage, waterlogging prevention, moisture preservation, and temperature preservation are handled well, Gastrodia elata can be grown well even without sand. This technique is suitable for promotion and cultivation in mountainous areas.