What are the methods to prevent early bolting in Angelica sinensis?
How do you prevent early bolting in Angelica sinensis? Please explain the methods. Angelica sinensis is native to high-cold mountain areas and is a low-temperature, long-day plant. In its individual development, the transition from vegetative growth to reproductive growth must go through two developmental stages: the vernalization stage (requiring a low temperature of 0-5°C) and the photoperiod stage (requiring a long day of more than 12 hours). Therefore...
How do you prevent early bolting in Angelica sinensis? Please explain the methods
Angelica sinensis is native to high-cold mountain areas and is a low-temperature, long-day plant. In its individual development, the transition from vegetative growth to reproductive growth must go through two developmental stages: the vernalization stage (requiring a low temperature of 0-5°C) and the photoperiod stage (requiring a long day of more than 12 hours). Therefore, artificial cultivation requires growing seedlings in the first year (raising seedlings), harvesting the roots for medicinal use in the second year, and allowing bolting, flowering and fruiting to collect seeds in the third year. However, in production practice, Angelica sinensis often bolts and flowers in large numbers during June to July of the second year of cultivation. In normal years the bolting rate is between 10-30%, and in severe cases it reaches more than 60%. In plants that have bolted and flowered, the parenchyma cells of the secondary xylem become lignified, and the ratio of secondary phloem to secondary xylem in the root changes from the normal 2:1 to 1:10. The fleshy root gradually becomes lignified and hollow, is highly fibrous, lacks oil and gas, and cannot be used medicinally. Therefore, preventing and controlling early bolting is an important technical measure for improving the yield and quality of Angelica sinensis. Based on the factors affecting bolting and flowering in Angelica sinensis, the following should be noted in production:
1. Select and retain good seeds. Under the same cultivation conditions, seeds set by plants that bolt and flower early generally have early-maturing traits and are prone to bolting and flowering. According to experiments, under the same conditions of seedlings and cultivation management measures, when seeds from plants that flowered and set seed in the second and third years were used separately to raise seedlings, the seedlings raised from seeds that flowered and set seed in the second year had an early bolting rate 30-40% higher than those from seeds that flowered and set seed in the third year, and bolted 10-15 days earlier. At the same time, the bolting rate of Angelica sinensis seeds is also related to seed maturity. Fully mature seeds have strong vitality and grow vigorously after planting, with a high bolting rate. Tender seeds have weak vitality; although they will not bolt early after sowing, their survival rate is low, their growth is weak, and their yield is low, making them difficult to use in production. Therefore, in order to improve seedling quality and reduce the early bolting rate, it is necessary in the current three-year-old seed production field to select and collect uniform seeds from plants with large roots, robust growth, somewhat late flowering, and moderate seed maturity (fish-belly white) for raising seedlings. Because the main stem and side branches of Angelica sinensis do not develop uniformly, in production it is necessary to cut off the main stem at the early bolting stage of the seed-retaining plants to promote uniform development of all branches, so as to obtain seeds meeting production requirements.
2. Sow at the right time, fertilize reasonably, and control seedling age and seedling weight. According to production practice: for Angelica sinensis seedlings to pass through the vernalization process, they not only need a certain low temperature but also need sufficient sugar content themselves, so tall, large seedlings are prone to bolting and flowering, while small seedlings have a very low early bolting rate. At the same time, seedling age also has a great influence on bolting. From the same batch of seeds, when seedlings are raised at different times and root weight is the same, seedlings with greater age have a higher early bolting rate. According to data from Taibai County, Shaanxi Province, when seeds collected from three-year-old plants were used to raise seedlings, if the seedling age was greater than 130 days, the early bolting rate reached more than 90%, while if the seedling age was less than 70 days, early bolting almost did not occur. However, if the seedling age is too young, the root weight of the seedlings is small, the survival rate after transplanting is low, growth is weak, yield is low, and benefits are poor. In order to control large seedlings and old seedlings and reduce the rate of early bolting and flowering, the sowing date should be appropriately delayed so that seedling age is controlled within 110 days and the weight of 100 seedlings is below 40 grams. In the later stage of seedling raising, appropriately increase the application of nitrogen fertilizer to raise the total nitrogen content of the plants and reduce the total sugar content of the plants, thereby inhibiting bolting and flowering.
3. Lower the storage temperature of the seedlings, reducing the storage temperature to below 0°C. Because the suitable temperature required for vernalization is 0-5°C, storing the seedlings frozen below 0°C keeps them in a dormant state and prevents them from passing through the vernalization stage, which can reduce their early bolting rate to zero.
4. Change the cultivation method, delay the sowing time, and replace seedling transplanting with autumn direct sowing to control early bolting.
In addition, planting density, climatic conditions, altitude, soil fertility and other conditions all have a certain influence on early bolting in Angelica sinensis. Drought, poor soil, sufficient light, low altitude, and low sowing density are all unfavorable to the vegetative growth of Angelica sinensis, and the early bolting rate is relatively high. Growers should manage strictly according to cultivation requirements based on the growth characteristics of Angelica sinensis, reduce the early bolting rate, and improve the yield and quality of Angelica sinensis.
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