Is Datian County in Fujian Suitable for Gastrodia elata cultivation?
Temperature is the primary factor affecting the growth of gastrodia elata. Gastrodia elata likes to grow in an environment that is cool in summer and not too cold in winter. It is sensitive to temperature and directly affects the growth, yield and quality of gastrodia elata. The effective accumulated temperature of gastrodia elata from young rice hemp to arrow hemp is around 3800℃, and it is more commercialized around 4000℃. Generally speaking, when the ground temperature reaches above 12℃, gastrodia elata cells become active, and they can begin to digest and absorb Armillaria mellea as their own growth and expansion nutrition, and their vitality will increase with the increase of temperature. The ground temperature reaches 20~25℃, which is the optimum temperature for the growth of Gastrodia elata and Armillaria mellea, and the growth and development of Gastrodia elata is the fastest. When the soil temperature continues to rise above 30℃, the growth of Armillaria mellea and Gastrodia elata will be inhibited, and it is easy to produce "Aconitum-like" arrow hemp. Therefore, attention should be paid to heatstroke prevention and cooling in high temperature season. When the temperature is lower than 15℃, the growth rate of Gastrodia elata slows down, gradually stagnates and enters hibernation. Gastrodia elata is cold-resistant, so long as the soil temperature is higher than -4℃, it can overwinter normally. However, if the temperature is lower than -5℃, the tuber of Gastrodia elata will suffer from freezing injury and rot, which will affect its safe wintering.
Gastrodia elata (seed hemp) needs a certain low temperature dormancy in winter to germinate normally in spring. At the low temperature of 2~5℃, it takes about two months to get through the dormancy period. If the low temperature time is insufficient, the seed hemp will not germinate even if the germination conditions are suitable. The germination rate of seed hemp after dormancy release is also related to the low temperature conditions accepted during dormancy. The longer the low temperature treatment time, the faster the germination rate, and vice versa.
Wild gastrodia elata is generally distributed in areas where the annual precipitation is above 1000 mm, the air relative humidity is about 80%, and the soil water content is 50-55%. The climatic conditions in rainy and humid areas are most suitable for the growth of Gastrodia elata, especially in the peak season of June-August, when the nutritional accumulation of Gastrodia elata reaches its peak and more water is needed. Abundant rainfall during this period is the key to ensure the high yield of gastrodia elata. In September, the nutritional accumulation of Gastrodia elata entered the late stage and reached the physiological maturity. At this time, the soil moisture should be controlled below 40%. If there is too much rain, Armillaria mellea will flourish, invade new hemp, decompose gastrodia elata as nutrition, lead to tuber rot of gastrodia elata, and reduce yield or quality.
Because gastrodia elata is a non-green plant, the whole asexual reproduction process from planting to harvesting is underground, so the light has no direct influence on the growth and reproduction of underground tubers, but only indirectly affects the change of soil temperature. If gastrodia elata is planted in cold areas, increasing direct sunlight can increase the ground temperature. Gastrodia elata needs some scattered light after bolting (about two months), but strong light should be avoided. Strong direct light can cause sunburn, damage the stem of gastrodia elata, and easily lead to plant death. At the same time, direct sunlight will increase soil moisture evaporation, reduce soil moisture and affect tuber growth. So at this time, we should pay attention to building a shed to shade the sun and reduce direct sunlight. Strong winds are only harmful to gastrodia elata, which is bolting and flowering, and will break or blow down flower buds, affecting seed yield. Therefore, the unearthed flower buds should be protected against strong winds, such as kidnapping the unearthed flower buds.