Causes of character degradation of Gastrodia elata and its control

The performance of hemp character degradation is that the yield of arrow hemp decreases, the individual becomes smaller and slender; the yield of rice flax and white hemp decreases greatly, ginger or light brown, the stress resistance is poor, and the original yield and characters can not be fully reflected. The reasons are generally as follows: 1. Multi-generation asexual reproduction. Generally, the phenomenon of degradation began to appear after 5-6 generations of asexual reproduction, but the degree of degradation was different when cultivated on different soils. The degradation of granite soil was slower, followed by yellow brown soil sandy soil parent material, shale or limestone weathering formation of acidic soil. 2. Continuous cropping. In general, the output was high in the first year and low in the next year, and decreased rapidly after 3-4 years. 3. Armillaria mellea degenerated. First, the adaptability and stress resistance decreased, and the fungal cord grew slowly; then the fungal cord was inelastic, fragile, and even turned into an empty shell. With the continuous increase of transfer algebra, Armillaria mellea formed a thick, long, many and branched brown-black fungal network on the fungus material. 4. Intensive deep cultivation. This method leads to the lack of oxygen in the growth process of Gastrodia elata, which leads to the decline of vitality. 5. Disease. Old seed hemp, old fungus and old nest are the most susceptible to disease, the light ones do not grow well, and the heavy ones do not harvest. 6. High temperature. Induced to accelerate the disease, resulting in poor growth of Gastrodia elata, the most obvious is the head of arrow hemp showed a "bottleneck" shape, rice hemp, small white hemp increased, rotten hemp increased. Control methods: ① is introduced from wild species and other places, especially from high to low places. ② screening and cultivation of high-quality Armillaria mellea, purification and expansion, lineage comparison, rejuvenation and reproduction, cultivation of high-quality bacterial materials, using high-quality loose culture materials as fillers and coverings. ③ changed the cultivation place and selected acid sandy loam to avoid continuous cropping. ④ adopts the technique of sexual reproduction. Sexual reproduction and asexual reproduction alternate, and the bulbs of sexual reproduction only grow for 4-5 generations. ⑤ application hybrids. ⑥ is strictly against diseases.