Detailed Explanation of Key Techniques for Greenhouse Cultivation of Crown Daisy
Crown daisy (Chrysanthemum coronarium L.), also known as tonghao, penghao, haocai, juhuacai, tanghao, haozigan, haozi, and tonghuacai (called ecai and yicai in places such as Fujian), is an annual or biennial herbaceous plant of the Asteraceae family, with alternate leaves that are long and pinnately lobed, and yellow or white flowers that closely resemble those of the wild chrysanthemum. The achenes are ribbed, and the plant grows two to three chi tall. The tender stems and leaves are edible and can also be used as medicine. In ancient China, crown daisy was a delicacy of the imperial court, so it is also called emperor's vegetable. Crown daisy has the fresh aroma of mugwort and the sweet fragrance of chrysanthemum. According to ancient Chinese herbal texts, crown daisy is sweet and pungent in flavor, neutral in nature, and non-toxic, with the effects of “calming the mind, nourishing the spleen and stomach, resolving phlegm and fluid retention, and benefiting the intestines and stomach." It is cultivated for ornamental purposes in gardens throughout China. Wild plants are found in Hebei, Shandong, Shijiazhuang in Hebei, and other places.
Crown daisy is also called penghao and haozigan, and because its flowers closely resemble wild chrysanthemums, it is also known as juhuacai. The stems and leaves of crown daisy can be eaten together. Crown daisy has the fresh aroma of mugwort and the sweet fragrance of chrysanthemum, and is praised for being fresh, fragrant, tender, and crisp. It generally contains a full range of nutrients, and its carotene content in particular exceeds that of ordinary vegetables, being 1.5 to 30 times that of cucumber and eggplant.
Crown daisy contains a variety of amino acids, so it has the effects of moistening the lungs, tonifying the liver, stabilizing mood, and preventing memory decline. Crown daisy also contains crude fiber, which helps intestinal peristalsis and promotes defecation, thereby achieving the purpose of relieving constipation and benefiting the intestines. Crown daisy is rich in vitamins, carotene, and other nutrients, and its fragrant odor can resolve phlegm and relieve cough. Crown daisy contains protein and relatively high amounts of mineral salts such as sodium and potassium, which can regulate water metabolism in the body and eliminate edema. Crown daisy also contains a volatile essential oil, as well as substances such as choline, and has the effects of lowering blood pressure and nourishing the brain.
How is crown daisy cultivated in a greenhouse?
1. Variety selection: Crown daisy has large-leaf varieties and small-leaf varieties, and greenhouse cultivation mainly uses small-leaf varieties. Small-leaf varieties are relatively cold-tolerant, have a strong aroma, fine tender branches, fast growth, and early maturity, with a growth period of 40 to 50 days.
2. Land preparation and fertilization: Use 2500 to 5000 kg of high-quality farmyard manure, 50 to 100 kg of superphosphate, and 50 kg of ammonium bicarbonate per mu, apply them evenly on the ground, then deep-plow twice to thoroughly mix the fertilizer with the soil. After raking level, make beds 1 to 1.5 m wide, then rake the inside of the beds level again and lightly tread once to prevent sinking after watering.
3. Sowing at the appropriate time: In northern regions, sowing can be done from early October to mid-November. If sown in a greenhouse before Minor Snow, it can be harvested during the Spring Festival.
Sowing rate: 1 to 2 kg per mu.
Seed treatment: 3 to 5 days before sowing, soak the seeds in 30°C warm water for 24 hours, rinse them, drain them, let them dry briefly, put them into a clean container, and place them at 15 to 20°C for germination. Rinse once daily with warm water, and sprouts appear in 3 to 5 days.
Sowing: Whether sowing dry seeds or germinated seeds, both broadcasting and drilling can be used. For drilling, open furrows 15 to 20 cm apart in beds 1 to 1.5 m wide, with a furrow depth of 1 cm, water with a kettle in the furrows, scatter seeds in the furrows after the water seeps in, and then cover with soil. For broadcasting, first take 0.5 to 1 cm of soil from the surface of every other bed and place it in the adjacent bed, rake the bed surface level, water thoroughly, and broadcast the seeds after the water seeps in; then evenly cover with the removed soil to a thickness of 1.5 cm.
4. Greenhouse management:
Temperature: After sowing, the temperature can be slightly higher, at 20 to 25°C during the day and 15 to 20°C at night, and seedlings emerge in 4 to 5 days (germinated seeds) or 6 to 7 days (dry seeds). After emergence, the temperature in the shed should be controlled at 15 to 20°C during the day and 8 to 10°C at night. Be careful to prevent high temperatures. When the temperature exceeds 28°C, ventilate to cool it down. Above 30°C is unfavorable for growth, as photosynthesis decreases or stops, growth is affected, and leaves become thin and small, fiber increases, and quality declines. The minimum temperature should be kept above 12°C. Below this temperature, attention should be paid to cold protection and cold-proof facilities should be added to avoid freezing injury or death.
Water and fertilizer: After sowing, keep the ground moist to facilitate seedling emergence. After emergence, generally do not water, to promote root growth downward. High humidity and low temperature easily cause damping-off disease. When the seedlings grow 8 to 10 leaves, choose clear and warm weather to water once, and apply fertilizer once together with watering, applying 15 to 20 kg of ammonium sulfate per mu. Water 2 to 3 times during the growth period, and note that each watering should be done on a clear day, the amount of water should not be too large, and the relative humidity should be kept below 95%. When humidity is high, ventilate at noon on a clear day when the temperature is relatively high to remove moisture and prevent disease.
When the seedlings are 3.5 cm tall, thin them to a spacing of 3.5 cm between plants and rows. Water less during the seedling stage, and keep the soil moist during the middle and late growth stages. After thinning, final thinning, and each harvest, apply 10 to 15 kg of urea per mu.
After emergence, properly control water. After 6 to 8 leaves, strengthen management, control the temperature at 18 to 22°C, and keep the soil moist to promote growth.
Chemical weed control: After sowing and before sprouting, weed promptly. You can use 0.25 to 0.5 kg of 25% nitrofen per mu mixed with 60 kg of water and spray evenly with a sprayer (stir the liquid frequently during application to prevent the chemical from settling and affecting the effect), or mix the required chemical with 25 kg of fine soil (or fine sand) and scatter it evenly in the field. Note that after application, do not water for 2 days and do not hoe for 7 days. At sowing, water enough to moisten the soil at the bottom. Water once to ensure uniform emergence when seedlings are about to emerge, and cultivate and weed promptly after emergence.
5. Harvesting: There is one-time harvesting and staged harvesting. One-time harvesting is cutting close to the ground 40 to 50 days after sowing, when the seedlings are about 20 cm tall. Staged harvesting has two methods: one is thinning harvest, and the other is cutting while retaining 1 to 2 side branches. After each harvest, water and fertilize once to promote the sprouting and growth of side branches. After 20 to 30 days, another cutting harvest can be done. The yield from 2 harvests is 1000 to 1500 kg per mu.
6. Pest and disease control:
Downy mildew: It occurs easily when the temperature is suitable and humidity is high. Field and greenhouse temperature and humidity management should be strengthened. When the disease occurs, spray with 500 times dilution of 90% fosetyl-aluminum wettable powder, 400 times dilution of 64% sandofan wettable powder, or 500 times dilution of 58% metalaxyl-mancozeb wettable powder, spraying once every 5 to 7 days for 2 to 4 consecutive sprays.
Viral disease: It is mainly spread by aphids, and the disease is severe when aphids outbreak. Control of viral disease mainly relies on eliminating aphids, reducing insect population density, and reducing transmission vectors. In the early stage of the disease, spray a mixture of virus A at 500 times dilution, monopotassium phosphate at 300 times dilution, and triacontanol at 0.5 to 1 mg/kg. When spraying, first mix the above 3 agents thoroughly, and ensure uniform spraying.
Damping-off: In greenhouse cultivation of crown daisy, it is mainly spread by the flow of water. It is more likely to occur when the temperature in the greenhouse is low, humidity is high, sowing is too dense, and light is insufficient. Maintain suitable temperature in the greenhouse and pay attention to ventilation and dehumidification. Control moisture during the seedling stage, and promptly remove diseased plants when found. For greenhouse cultivation, soil disinfection should be carried out. The method is to loosen the soil 2 to 3 weeks before sowing and sprinkle 100 times dilution of 40% formalin, applying about 3 kg of the liquid per sq m, then cover with plastic film for 4 to 5 days, remove the plastic film, loosen the soil again, and sow after 2 weeks. When central diseased plants are found, spray 500 to 600 times dilution of 75% chlorothalonil, 500 times dilution of 70% mancozeb, or 800 to 1000 times dilution of 25% ridomil. These agents should be used alternately, spraying once every 5 to 7 days for 3 to 4 consecutive sprays.