How should Gastrodia elata tubers be selected for use as seed?
Gastrodia elata tubers that are undamaged, free of pests and diseases, and not deformed are best for cultivation as seed. However, when seed is in short supply, tubers with minor damage can also be used for cultivation as seed after treatment. The treatment method is: first cut away the damaged part with a knife or bamboo strip, sun-dry the cut surface until it no longer exudes sap, and then plant it; generally it will grow as normal.
When large white Gastrodia tubers are cultivated as seed, after 1 year they can become 1 large arrow tuber. When arrow tubers are cultivated as seed for asexual propagation, the "parrot beak"-like mixed bud at the top of the arrow tuber must be broken off, so that the arrow tuber will not produce an arrow (no longer bolt); this is called "arrow suppression." After arrow suppression, it should be air-dried a little so that the part where the bud was broken off can form a thin film (no longer leaking nutrient solution outward), and only then can it be planted; otherwise it is prone to rot. One year after planting, a de-arrowed arrow tuber can grow 3 to 5 large and medium white tubers and a small amount of millet-sized tubers.
Large white Gastrodia tubers can be processed into commercial tubers for medicinal use, and cultivating them as seed is not cost-effective, but some people have also used the arrow suppression method for arrow tubers to conduct bud suppression experiments on large white tubers (mainly to break apical dominance). The bud suppression method is the same as the arrow suppression method for arrow tubers: use a sterilized knife to cut out the young bud (because the buds of white tubers are small and cannot be broken off by hand). Each time a cut is made, sterilize the knife once, then expose the seed tuber body to sunlight briefly so that the sap oozing from the cut area dries into a thin film. Once the film has formed, do not continue drying it in the air; bring it back immediately and plant it. After planting, many bud eyes on the tuber body can successively sprout more new tubers; some of these grow into arrow tubers, some into white tubers, and some into small tubers. One large white tuber can produce several arrow tubers, white tubers, and many millet-sized tubers. In the spring 1975 harvest of Dongfeng Team 3, Dishuipu Commune, Ningqiang County, Shaanxi, there was one bud-suppressed white tuber originally weighing 20 grams that grew 8 arrow tubers (weighing 0.925 kg), 7 white tubers (weighing 0.15 kg), and 78 millet-sized tubers all over its body.
The number of arrow tubers and white tubers formed depends mainly on the supply of nutrients from Armillaria mellea and the degree of that supply. If the nutrient supply is sufficient, then more arrow tubers, white tubers, and millet-sized tubers will grow.