How to Achieve High Yield in Off-Season Welsh Onion Cultivation

Welsh onion is a type of onion and can be divided into four types: common Welsh onion, bunching onion, rakkyo, and tree onion. Welsh onion is pungent in taste and slightly warm in nature; it releases the exterior and unblocks yang, and counteracts toxins and improves flavor. 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, internal obstruction from worm accumulation, failure of lactation, and difficult urination and defecation. Welsh onion contains volatile oil, whose main component is allicin; it also contains diallyl sulfide and calcium oxalate. In addition, it contains fats, carbohydrates, carotene, vitamin B, vitamin C, niacin, calcium, magnesium, iron and other components. It is a perennial herb; the leaves are cylindrical, hollow in the middle, fragile and easily broken, and green in color.

Welsh onion is an essential item in the daily kitchen; in the north, Welsh onion is dominant. It can not only be used as a flavoring, but also prevent and treat diseases, making it truly a fine vegetable and good medicine. According to the length of the white pseudostem, it is also divided into two types. Welsh onion plants are tall, and the white pseudostem is pure white and sweet, and it is cultivated more in the north. Welsh onion is mostly used for pan-frying, stir-frying, deep-frying and quick-frying; the south mostly produces small onions, which are a common seasoning, also called scallions, and are generally used raw or in cold dishes. Common Welsh onion: many varieties, good quality, and large cultivation area. According to the length of the white pseudostem, it is further divided into long white pseudostem and short white pseudostem. The long white pseudostem type is spicy and thick; famous varieties include Liaoning Gaiping Welsh onion, Beijing High-Leg White, and Shaanxi Huaxian Valley Onion; the short white pseudostem type has a short, thick and fleshy white pseudostem; famous varieties include Shandong Zhangqiu Chicken-Leg Onion and Hebei Opposite-Leaf Onion. Bunching onion: leaf color is deep, the white pseudostem is pure white, tillering ability is strong, spicy taste is mild, and quality is good. Onion has the effects of benefiting the lungs and unblocking yang, inducing sweating and releasing the exterior, promoting lactation and stopping bleeding, and relieving pain and healing injuries, and is used for dysentery, abdominal pain, arthritis, constipation and other conditions. Onion has a unique spicy aroma, which comes from the volatile sulfide allicin, and can stimulate saliva and gastric juice secretion and increase appetite. The malic acid and phosphoric acid sugars contained in onion can excite nerves, improve and promote circulation, and release the exterior and clear heat. Eating onion often can reduce the accumulation of cholesterol on blood vessel walls.

How to Achieve High Yield in Off-Season Welsh Onion Cultivation

1. Variety selection:

For growing Welsh onion for off-season marketing, varieties with cold resistance, bolting resistance, heat resistance, disease resistance and excellent quality should be selected. Such varieties include Zhengyan Cold Onion, Nanhu No. 1 Welsh Onion, Zhangqiu Long White Stripe Welsh Onion, and Zhonghua Giant Onion Superior Line, etc.

2. Raising strong seedlings:

1. Arrangement of seedling raising and transplanting time:

For the first crop, raise seedlings from late June to early July, transplant in September, and market in March to April of the second year; for the second crop, raise seedlings in mid-September, transplant in March to April of the second year, and market in August to early September.

2. Selection of seedling-raising land:

Since the seedling-raising periods of both crops are almost entirely in the rainy season, plots should be selected that are flat, slightly higher in terrain, can be irrigated in drought and drained in waterlogging, and have not grown Welsh onion, onion, Chinese chives, garlic or other Liliaceae vegetables for more than 3 years.

3. Applying sufficient base fertilizer:

Because Welsh onion seedlings have short roots that penetrate shallowly into the soil and have a poor ability to absorb soil nutrients, to raise strong seedlings it is necessary to apply sufficient thoroughly decomposed organic fertilizer and a certain amount of phosphorus and potassium fertilizer. The specific method is: before plowing, apply 5000-6000 kg of thoroughly decomposed, finely crushed barnyard manure per mu (excluding chicken, duck, sheep manure and fresh human feces and urine), prepare the beds well, and before sowing broadcast 25 kg of sulfuric-acid-type three-element compound fertilizer.

4. Fine plowing and harrowing, making ridges and beds: To prevent underground pests from damaging seedlings, after the organic fertilizer is spread, poisoned bait should be broadcast once more. That is, use 5 kg of wheat per mu, fry it until yellow, then mix it evenly with 250 mL of diluted phoxim, seal and cover it for 3 hours, then broadcast it on the ground and turn it into the soil together with the organic fertilizer; this can kill many kinds of underground pests at once. The plowed land should be fully harrowed fine, harrowed firm, and leveled. Before making beds, first open the irrigation furrow on one side of the field, then make the beds. The net width of the bed is 1-1.2 m, the bed ridge is 20-23 cm wide and 8-10 cm high (after being trampled firm and scraped straight). After the bed is made, first broadcast 25 kg per mu of three-element compound fertilizer (each containing 15% nitrogen, phosphorus and potassium) in the bed, hoe it through and level it, then sow.

5. Sowing:

Use 3-4 kg of seed per mu. Either of two sowing methods may be chosen.

1) Drill sowing: Evenly broadcast the seeds on the leveled bed surface, then use a rake to lightly rake it over once, so that the seeds are fully mixed with the soil and shallowly buried in the soil, then water.

2) Covered-seed bed: After leveling, use a flat shovel to remove 1 cm of fine moist soil from the bed surface, then level the bed surface again. Water, and stop watering when the water in the bed reaches a depth of 6-7 cm. Sow after the standing water on the bed surface has infiltrated dry, then cover with fine soil about 1 cm thick. Seedlings from covered sowing have deep roots, many roots, are more drought-tolerant with more seedlings, and are robust. If shade can be provided to protect against storms and rain during seedling raising, the effect is even better.

After sowing, when manual operations can be carried out, spray herbicide while there is moisture in the soil. Use 100-150 mL of 33% pendimethalin (also known as pendimethalin, pendimethalin) per mu, diluted in 60-75 kg of water, and spray evenly on the ground. Keep the ground moist frequently; the effective period is 30-45 days.

6. Management during the seedling stage:

From full emergence to the 5-leaf stage, carry out thinning 1-2 times. Seedling spacing is 1-1.5 cm. Along with thinning, pull out weeds not killed by the herbicide. Control watering; do not water unless dry, to reduce the occurrence of “disease incidence” and “yellowed seedlings”. If the seedlings grow relatively thin and weak, appropriate topdressing can be applied along with watering. Apply 7.5-10 kg of urea per mu flushed with water. Apply once every 20 days, for a total of 2 applications. If continuous cloudy and rainy weather is encountered during the growing period, attention should be paid to preventing and controlling downy mildew and white blight to ensure strong seedlings.

3. Timely transplanting:

Summer-sown Welsh onion is transplanted in early to mid-September, and autumn-sown Welsh onion is transplanted in March to April of the following year. Row spacing is 80 cm, plant spacing is 1.5-2 cm, and transplanting is done by opening furrows (arranging the onions). Before transplanting, first strictly grade the onion seedlings, then carry out chemical treatment to eliminate root maggots (seedcorn maggot larvae) and ensure a full stand. The specific method is to soak the onion seedling roots in a 4000-fold dilution of 1.8% abamectin solution, or an 800-1000-fold dilution of phoxim solution, or a 3000-fold dilution of beta-cypermethrin solution for 2-3 minutes.

The transplanting furrow should not be opened too deep or too shallow. If too deep, the dead soil layer is unfavorable for root growth; if too shallow, later earthing up is more difficult. After the transplanting furrow is opened, the newly turned loose soil should be slightly compacted to prevent later collapse from crushing the onion seedlings. After the onion seedlings are arranged in the furrow, an appropriate amount of root-pressing fertilizer should be applied. Thoroughly decomposed barnyard manure is better as root-pressing fertilizer. Apply 5000 kg per mu mixed evenly with 25 kg of three-element compound fertilizer. While opening the next furrow, properly cover a layer of fine moist soil over the root-pressing fertilizer. The thickness should be such that the root-pressing fertilizer plus soil does not bury the onion heart (growth point); slightly compact and then finish.

Note! Newly transplanted onion seedlings must strictly not be watered, to prevent root rot causing massive seedling death. In case of heavy rain, make every effort to drain all accumulated water from the onion field. After seedling recovery, if drought occurs, an appropriate amount of water may be applied.

4. Field management:

After off-season Welsh onion is transplanted, it is exactly the period when the temperature is most suitable for Welsh onion growth; once the seedlings recover, they grow rapidly. Therefore, fertilizer and water management is an important link for high yield and good quality. Where root-pressing fertilizer has been applied as required, there will be no fertilizer shortage before the middle growth stage; as long as soil moisture is suitable, rapid and robust growth can be ensured. It is appropriate to maintain soil moisture at about 70% of saturated water-holding capacity. Water when dry, and after watering carry out timely intertillage and loosening of the soil, so as to preserve moisture and increase soil aeration, promote root development, and improve the ability to absorb water and fertilizer.

The length of the white pseudostem is determined by the amount of earthing up. Generally, off-season Welsh onion requires earthing up 3-4 times to ensure the white pseudostem reaches 70-80 cm in length. The thickness of each earthing up should be based on not burying the growth point (onion heart). For overwintering off-season Welsh onion, carry out one thick earthing up before the ground freezes, to reduce leaf withering as much as possible, accumulate nutrients, and ensure early regrowth after winter.

As growth speed accelerates and leaf mass greatly increases, the plant's demand for soil nutrients rises sharply. To ensure high yield, topdressing must be carried out in time. Topdressing can be done in combination with watering. Apply 15-20 kg of urea per mu each time. Broadcast it along the furrow, then shallowly hoe to bury the fertilizer, to prevent the fertilizer from concentrating at the lower end of the field with the water during irrigation, so as to achieve balanced fertilization. It is best to additionally apply a certain amount of phosphorus and potassium fertilizer, which has a significant effect on increasing Welsh onion yield and improving Welsh onion quality.

5. Timely harvest:

For overwintering off-season Welsh onion, the harvest time can be decided according to market conditions. To ensure quality, it is best to harvest and market before bolting and when the onion bolt (scape) is relatively small; those raised in September can be harvested and marketed in August of the second year when market conditions are relatively good.

6. Pest and disease control:

1. Insect pests:

Thrips damage onion leaves, piercing and sucking the leaf mesophyll within the leaves and producing small white spots. Control method: spray with 1000-fold dilution of 20% carbosulfan, or 2000-fold dilution of 10% imidacloprid, or 1000-fold dilution of 2.5% spinosad. When spraying, add an adhesive to increase the amount of pesticide liquid adhering to the onion leaves and effectively kill the pests.

2. Diseases:

Downy mildew mainly damages leaves and is prone to occur when air humidity is too high. Control method: in the early stage of disease, spray with 600-fold dilution of 75% chlorothalonil wettable powder, or 800-1000-fold dilution of 50% copper metalaxyl wettable powder, or 500-fold dilution of 64% oxadixyl mancozeb wettable powder. Spray once every 7-10 days, for 2-3 consecutive sprays.

White blight, also called white tip disease, mainly damages leaves and can occur at the seedling stage and adult plant stage. Control method: in the early stage of disease, spray with 500-fold dilution of 77% copper hydroxide wettable powder, or 800-fold dilution of 72% cymoxanil wettable powder, or 1000-fold dilution of 69% dimethomorph mancozeb wettable powder. Spray once every 7 days, for 2-3 consecutive treatments.