How can coriander be grown in summer for high yields?
How can summer coriander cultivation achieve high yields? Please give guidance. Coriander prefers cool conditions; growth slows when the temperature is above 20°C, and stops when it is above 30°C. Therefore, cultivating coriander in summer is quite difficult, and the following supporting cultivation techniques must be mastered. 1. Choose varieties: choose ones that are drought-tolerant, fast-growing and slow to bolt...
How can summer coriander cultivation achieve high yields? Please give guidance
Coriander prefers cool conditions; growth slows when the temperature is above 20°C, and stops when it is above 30°C. Therefore, cultivating coriander in summer is quite difficult, and the following supporting cultivation techniques must be mastered.
1. Choosing varieties
Choose varieties that are drought-tolerant, fast-growing and slow to bolt, such as purple-stem coriander, Beijing coriander, North China large-leaf, American large-leaf coriander, Thai heat-tolerant large-grain coriander, etc.
2. Seed treatment
In summer, temperatures are high and moisture in the soil evaporates quickly. In order to achieve early and complete emergence, the seeds must be carefully treated before sowing: first crush the fruit coat, then soak the seeds to promote germination. The seeds can be soaked in cool water for 4-5 hours, then placed in a cloth bag and hung in a well 30 cm above the water surface. Soak the bag in water once a day to replenish moisture. After 7-10 days, sow once the seeds show white sprouts.
3. Soil preparation and fertilization
Choose soil that is fertile, retains water and nutrients, is easy to drain and irrigate, is well ventilated, and has not grown coriander for more than 3 years. Apply 4000 kg of cow manure per mu, deep-plow the soil 20-25 cm, break up the clods, rake the land level, and make flat beds 1-1.5 m wide and 7-8 m long.
4. Sowing carefully
Broadcasting is best, with a seeding rate of 3 kg per mu. Before sowing, water the beds thoroughly; after the water has seeped in, mix the seeds with sand, broadcast evenly, and cover with 1-2 cm of fine soil. After all sowing is complete, press once to preserve soil moisture. After sowing, lightly rake and pat firm, cover with straw to retain moisture and help the seedlings emerge. On the second day, depending on soil moisture, water lightly once in the morning and once in the evening. After that, keep the soil moist until emergence. Seedlings emerge about 7 days after sowing; once most of the seedlings have emerged, remove the covering.
5. Field management
After emergence, set up small arched frames 60-70 cm high and cover them with shade netting to prevent scorching sun and rain erosion. Remove the shade netting in the evening to allow ventilation. The plants grow slowly in the early stage, and the principle for fertilizer and water management is: do not water unless dry, water little in the early stage and more in the later stage; the amount of topdressing depends on the fertility of the soil, mainly nitrogen fertilizer (human and livestock manure and urine, urea). Coriander seedlings grow slowly and are prone to being choked by weeds, so weeds should be removed promptly.
6. Pest control
Summer-sown coriander has relatively few insect pests. The main diseases include damping-off at the seedling stage, viral disease at the adult stage, anthracnose and leaf spot. About 5 days after emergence, spray once with 3% polyoxin wettable powder at 800 times dilution; afterward, spray once every 7 days with polyoxin at 600 times dilution, for a total of 2-3 sprays, which can prevent damping-off, anthracnose and leaf spot. Shading and other methods can be used to avoid yield loss from high temperatures; use insect-proof netting and spray 20% imidacloprid wettable powder 20 g mixed with 50 kg of water on the leaves to control aphids, thereby reducing the occurrence of viral disease.
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