Key Technical Points for Winter Planting and Management of Welsh Onion

Welsh onion (scientific name: Allium fistulosum L.var. giganteum Makion) is a type of onion and can be divided into four types: common Welsh onion, bunching onion, shallot, and cive. Welsh onion is pungent in taste and slightly warm in nature, and has the effects of inducing sweating and promoting yang; detoxifying and seasoning. It is mainly used for wind-cold common cold, aversion to cold with fever, headache and nasal congestion, cold pain in the abdomen, dysentery and diarrhea, worm accumulation with internal obstruction, insufficient lactation, and difficult urination and defecation. Welsh onion contains volatile oil, the main component of which is allicin, and also contains diallyl sulfide and calcium oxalate. In addition, it also contains fats, carbohydrates, carotene, vitamin B, C, nicotinic acid, calcium, magnesium, iron and other components. It is a perennial herbaceous plant, with cylindrical leaves that are hollow in the middle, fragile and easy to break, and green in color.

Morphological characteristics of Welsh onion

Root: The roots are white, fibrous, with few and short lateral roots. The number, length, and thickness of roots continuously increase with the increase in the total number of leaves produced by the plant. During the vigorous growth period of Welsh onion, the number of roots can reach more than 100.

Stem: The stem is extremely shortened, spherical or oblate, solitary or clustered, 1-2 cm thick, with a white, membranous outer skin that does not rupture. The upper part bears multiple layers of tubular leaf sheaths, and the lower part is densely covered with fibrous roots. After the growing point at the shoot apex differentiates into a flower bud, it will gradually develop into a flower stalk. The flower stalk of Welsh onion is stout, hollow, unbranched, and 30-50 cm long.

Leaf: The leaf consists of a leaf blade and leaf sheath. The leaf blade is long conical, hollow, green or dark green. A single leaf sheath is cylindrical. Multiple layers of nested leaf sheaths and the 4-6 young leaves wrapped inside them that have not yet emerged from the sheath form a club-shaped pseudostem.

Flower: Borne at the top of the flower stalk. Before flowering, the developing umbel is hidden within the spathe. In onion plants whose vegetative organs have fully grown, one inflorescence has 400-500 flowers, and can reach more than 800 in some cases. Bisexual flowers, cross-pollinated. Each flower has 6 tepals and 6 stamens. When the pistil matures, the style is 1 cm long. Ovary superior, 3 locules, 2 ovules per locule.

Fruit and seed: The fruit is a capsule, which easily splits when mature. The seed is shield-shaped, black, with 6 ridges and irregular dense wrinkles. The 1000-seed weight is 2.4-3.4 g.

Winter planting and management of Welsh onion

I. Transplanting and planting 1. Site selection and land preparation Select plots with deep available soil layers and convenient drainage and irrigation for planting winter Welsh onion. After the previous crop is harvested, plow 25 to 30 cm deep in summer in a timely manner, plow without harrowing, and sun-dry the clods. Sun-dry for as many days as possible to eliminate pathogens and weeds. 2. Planting time When the onion seedlings have grown for about 80 days, they can be planted in trenches. Generally, late August to before September 5 is suitable. 3. Trench digging A 12 cm wide and 35 cm long iron spade can be used to dig trenches, or a hoe can be used instead of a special iron spade. The trench spacing for winter Welsh onion is suitably 60 to 63 cm. If the trench spacing is too narrow, it is inconvenient for management and earthing up; if too wide, it wastes land. The trench depth is 20 to 25 cm. Apply decomposed farmyard manure at the bottom of the trench, 3000 kg per 1/15 hectare, and mix in 40 kg of three-element compound fertilizer. Use a spade or hoe to loosen the bottom of the trench so that the manure and soil are mixed evenly, which is convenient for absorption by Welsh onion and conducive to root development. The direction of the onion trenches can be north-south or east-west, with the former being best. 4. Seedling lifting and grading 1 to 2 days before lifting seedlings, water once to facilitate seedling lifting. The dug seedlings should be divided into large, medium, and small grades, and seedlings of different sizes should be planted separately to ensure uniform and strong seedlings and increase yield; otherwise, large seedlings suppressing small ones will lead to a low survival rate and low yield. 5. Reasonable close planting Both too dense and too sparse planting affect high yield. Every two onion seedlings form one clump, with 1.5 cm between clumps. Place the onion seedlings against the back of the onion trench, then cover with soil, with the suitable depth being not burying the heart leaf, that is, below what people call the "five-fork part," which means burying three-fourths of the white part of the onion is appropriate. Practice has verified that when planting onions, lifting seedlings, planting immediately, and watering immediately are beneficial for seedling recovery and result in high yield. II. Management after planting 1. Timely watering Water immediately after planting. The first watering should not be too heavy to prevent collapsing the onion trench. After 5 to 6 days, water again to help seedling recovery. After that, water once every 7 to 8 days to keep the soil moist regularly. After heavy rain, promptly drain the accumulated water in the trench to prevent root rot and seedling death from water accumulation. After "Frost's Descent," water once every 10 to 15 days. At "Winter Solstice," water again with one freezing water. 2. Formula-based topdressing Winter Welsh onion generally only needs topdressing 3 times. The first topdressing is carried out when the seedlings have recovered and begun vigorous growth. Apply 8 kg of urea and 8 kg of three-element compound fertilizer per 1/15 hectare. The second topdressing is carried out from "Cold Dew" to "Frost's Descent." The third topdressing is carried out from "Start of Winter" to "Light Snow," applying 20 kg of urea and 20 kg of potassium fertilizer per 1/15 hectare. In addition to topdressing, foliar spraying is also needed. Spraying ferrous sulfate, ammonium molybdate, copper sulfate, and manganese sulfate at a concentration of 1000 times can increase it by more than 10 percent. 3. Earthing up Each topdressing should be accompanied by one watering and one earthing up. Earthing up should be done so as not to bury the heart leaf, with the limit being not exceeding the "five-fork part," and should be lower rather than higher. Earthing up should be carried out when the soil moisture content is moderate and there are no mud clods, and care should be taken to avoid doing it when there is dew in the morning. When earthing up, also be careful not to damage the onion leaves and cause disease. III. Pest and disease control Winter Welsh onion has strong disease resistance, and almost no diseases have occurred. Spraying 500-times carbendazim or chlorothalonil 1 to 2 times for prevention is sufficient. The main pests include onion root maggots, onion thrips, and so on. After planting, in combination with the second watering, apply 2 kg of 90 percent trichlorfon per 1/15 hectare with the water to drench the roots, and the effect is good. Onion thrips can be controlled with 3000-times 2.5 percent deltamethrin emulsifiable concentrate.