When do onions grow?

Onion, alias fire onion, onion, garlic onion, petaloid onion and ashilong onion, is a biennial herb of Allium in Liliaceae. Young leaves and bulbs are used as seasoning, and bulbs can also be used as pickling raw materials. Onions originated in Central Asia. Garlic is the main onion variety cultivated in Cuba and also cultivated in Japan. China grows more in the south, such as Guangzhou, and less in the north, but the catering industry is in great demand and needs to be introduced from the south.

1, botanical characteristics of fibrous roots. The stem is short and disc-shaped, and the leaves are composed of leaf sheaths and conical tubular leaves, which are inserted on the stem disc. Leaves are short and soft, generally 25 cm long, turquoise, with little wax powder. Strong tiller, can form bulbs, bulbs are oval, purple skin and white inside. A plurality of bulbs are densely clustered, the bases are connected, and the joint is extruded into an angle. This plant germinates in late spring with hollow stems and lilac flowers. There are no seeds in the south, and Beijing can get a small amount of seeds. Seeds are shield-shaped, such as onion seeds, black and shiny, and have germination ability for 2 years.

2, the requirements of environmental conditions, shallots like cold climate, strong cold resistance, heat resistance. Seeds and bulbs can germinate slowly at the low temperature of 3 ~ 5℃, and the germination speed will be accelerated when the temperature reaches above 65438 02℃. The optimum temperature for plant leaf growth is about 22℃. When the temperature drops to 10℃, the growth is slow, and when it is higher than 25℃, the growth is poor. Bulbs need a higher temperature of 20 ~ 26℃ in the growth and expansion period. Under the condition of long sunshine, higher temperature will promote the formation and expansion of bulbs. Therefore, in the warm areas of southern China, onions flourish in winter and spring, and form large bulbs before high temperature in summer. When the temperature is high in summer, the leaves turn yellow and soft, and the bulbs enter short-term physiological dormancy to spend the summer.

Welsh onion belongs to vernalization type, which needs a certain period of low temperature to bolting, and it takes about 50 days at about 5℃. Welsh onion has shallow roots and weak water absorption capacity, so it needs to keep the soil moist frequently, especially at the peak of leaf growth, but it is not tolerant to waterlogging. It has strong adaptability to soil and likes fertilizer, and is suitable for planting on fertile and loose loam with strong soil and water conservation fertility.

3. Cultivation techniques

1) Cultivation season According to the requirements of environmental conditions of shallots, the cultivation season is arranged. The seedling stage and leaf growth period of shallots are arranged in short sunshine and low temperature, and the bulb expansion growth period is arranged in long sunshine and high temperature. Therefore, open cultivation in warm areas in the south and protected cultivation in cold areas in the north are suitable for autumn planting, and bulbs or ramets are used for propagation, and planting is carried out in July-September. Planting in the open field in the north in spring, harvesting plants without bulbs in summer, or stubble on the spot and harvesting bulbs in autumn. You can also leave stubble in the open for winter and harvest young crops in the next spring, but you can't leave stubble for a long time, otherwise the bulbs will get smaller and smaller.

(2) Planting method

① Soil preparation and base fertilizer application: the root system of shallot is shallow and small, the soil preparation should be fine and flat, the base fertilizer should be decomposed and subdivided, and the application should be shallow and uniform. The amount of fertilizer applied depends on soil fertility. Generally, 37,500 ~ 75,000 kilograms of manure or compost is used per hectare, and 375 kilograms of calcium superphosphate is added. As a border, the width of the border is about 100 cm. The high or flat boundary depends on the conditions in different places.

② Planting density: Bulbs can be planted, with row spacing of 20cm and hole spacing of 10cm, with 2 ~ 3 bulbs per hole. Plant with ramets, the row spacing is 24 cm, the plant spacing is 18 cm, and one tiller seedling is placed in each hole. 225,000 seedlings per hectare.

(3) In the early stage of field management, intertillage and weeding should be done in time to loosen the soil and conserve moisture. After the plants begin to tiller, topdressing is combined with topdressing, watering and shallow soil cultivation. Keep the soil surface dry and moist. After each tiller seedling is harvested, it should be topdressing once, watering and shallow tillage.

(4) Prevention and control of pests and diseases There are few diseases of shallots, and sometimes rust occurs. Small white spots first appeared on the diseased parts of infected plants, and then the diseased spots were raised, showing orange to brown rust spots, and the disease was more serious when the air humidity was high. When the pathogen is infected, 0.8 baumeishi sulfur mixture should be sprayed for protection, and 50% amobam 500 times solution or 2% sodium sulfamate can be sprayed at the initial stage of the disease.

Insect pests, such as thrips and liriomyza sativae, are more likely to occur when it is dry and rainy and the temperature is high. When the insect population is found for the first time, low-toxic pesticides should be sprayed all over the field for control.

(5) It takes about 60 days from planting to collecting shallots. The harvest period of autumn planting is from September to May of the following year. When harvesting, leave 2 ~ 3 tillers in each hole to make the re-tillers grow, and harvest every 30 ~ 35 days. The yield of onion per hectare is 24000 ~ 30000 kg.

The rest of the plants were planted shallowly in the high ridge in March of spring. In May, onion leaves turn yellow and droop, and bulbs are harvested. After the onion seedlings are dried, hang them in a ventilated place for preservation.

Welsh onion doesn't bear seeds in the south. In the suburbs of Beijing, after overwintering in the open field in autumn, it bolts and blooms in late spring and early summer, and can be harvested in early June, but the seed harvest is very low. Seedlings grow slowly after sowing.

4. Due to different varieties and harvest time, the nutritional components and utilization rate of shallots are very different. Every 100g fresh sample of improved varieties contains 85g of water, 87.4mg of vitamin C, 435mg of potassium, 6.75mg of sodium, 42.2mg of calcium 187mg of magnesium and 5 1.9mg of phosphorus. Zinc 0.34 mg, manganese 0.78 mg, strontium 1.02 mg, and contains mercaptan, dimethyl disulfide, etc. , and contains prostaglandin A, which is rare in vegetables.

Generally, onions are used as seasoning, such as steamed fish with chopped green onion. Onions taste the best. Used for noodle soup, soup powder, etc. Cut the shallots into chopped green onions. When the noodles and powder are cooked, sprinkle with chopped green onion to stimulate appetite. Bulbs and green leaves of shallots can also be fried or pickled with meat. The sulfide contained in shallots has the function of lowering blood fat, which is beneficial to health if eaten regularly.