Sharing High-Yield Cultivation Experience of Yellow Onions

Yellow onions, with their high yield, good quality and attractive color, are exported to Japan, Russia and other countries, and have become an important way for farmers in Weifang, Jinan, Tai'an and other areas to get rich. The high-yield cultivation techniques for yellow onions are summarized as follows:

1. Select good varieties and cultivate strong seedlings.

1. Adapt to local conditions and select good varieties: Onion is a green-body vernalization-type vegetable, and improper variety selection can easily cause bolting in early spring, resulting in reduced yield and declined quality. In recent years, most yellow onion varieties planted in Shandong come from Japan and the United States. Tests over several years have proven that American varieties have weaker winter hardiness and are prone to bolting in early spring; among Japanese varieties, "O?P Yellow" and "Fuji Eisei" have the strongest winter hardiness, and their bulbs are round, with good color, high yield and good quality. Each bulb weighs about 300g on average, with the maximum reaching more than 500g, and the average yield per 666.7 sq m (mu) is 5000kg

2. Sow at the right time and cultivate strong seedlings: Because onions emerge slowly, the soil should be finely prepared before sowing. Generally, apply 5000kg of decomposed organic fertilizer and 30kg of nitrogen, phosphorus and potassium compound fertilizer per 666.7 sq m, plow deeply and rake level, and make flat beds 1.2m wide and 15-20m long. The suitable sowing period for yellow onions is September 10-15. If sown too early, the onions grow too much before winter and are prone to bolting in early spring; if sown too late, the seedlings are too small and are prone to dying during overwintering. Before sowing, water the seedbed thoroughly, broadcast dry seeds after the water infiltrates, then cover with 1-1.5cm of soil. Use 1.5kg of seed per 666.7 sq m, which can be transplanted to 10-12 mu.

3. Seedling management: Seven to eight days after sowing, the seedlings emerge completely. After emergence, water once lightly, and water again after 15-20 days to promote seedling growth. After that, keep the soil moist. At the same time, along with watering, apply 15kg of urea per 666.7 sq m. Afterwards, adjust fertilizer and water management according to seedling growth, and control the seedlings so that at transplanting time they have 3-4 leaves and a pseudostem diameter of 0.6-0.8cm.

2. Transplant at the right time and plant at a reasonable density

1. Prepare the soil and make beds: Onion is a shallow-rooted crop, so loose and fertile sandy loam should be selected for planting. Along with deep plowing, apply 7000-10000kg of decomposed organic fertilizer and 50kg of nitrogen, phosphorus and potassium compound fertilizer per 666.7 sq m, level and harrow finely, and make flat beds 1.2m wide (the bed can also be made according to the width of the mulch film) and 15-20m long, then cover with black mulch film, which helps keep warmth and moisture and also avoids weed infestation.

2. Plant at the right time and at a reasonable density: The suitable planting time for yellow onions is November 1-10. For ease of management, seedlings should be graded at planting: those with a pseudostem diameter of 0.6-0.8cm are first-grade seedlings; 0.4-0.5cm are second-grade seedlings; seedlings below 0.4cm and above 0.8cm should be removed. The planting density is 15cm×18cm. When planting, first make holes in the mulch film with a bamboo pole or steel bar, then insert the seedlings into the holes. Do not transplant too deeply; it is appropriate to bury the small bulb and prevent the seedling from floating when watered, about 1.5cm or so. Otherwise, spindle-shaped bulbs will appear, affecting marketability.

3. Fertilizer and water management after planting.

After planting and seedling recovery, inspect the plot promptly, and replant as early as possible where seedlings have floated, to ensure a full stand. Around "Minor Snow", water once with freezing water. When the seedlings turn green in late February and early March of the following spring, apply 20kg of urea per 666.7 sq m along with watering to promote seedling growth and development; in late April and early May, apply another 30kg of nitrogen, phosphorus and potassium compound fertilizer to promote full bulb expansion. During this period, water promptly according to soil moisture, keeping the soil alternately dry and moist. At the same time, remove weeds on bed ridges and in the field promptly to avoid weed infestation.

4. Pest and disease control.

1. Diseases: The main diseases of yellow onion are downy mildew and purple blotch. Control methods: in late April or at the early stage of disease occurrence, spray with 58% Ridomil 600-fold solution or 80% Daconi M-45 wettable powder 400-600-fold solution, once every 7 days for 3 consecutive sprays, which can achieve good control effects.

2. Insect pests: The main insect pests damaging onions are root maggots, beet armyworm and thrips. To control root maggots, broadcast 3-4kg of 10% profenofos granules per 666.7 sq m when preparing the soil before planting. September-October is the peak season for beet armyworm, so control should be carried out promptly at the seedling stage. Use 5% beet armyworm killer 1000-fold solution and spray from 6-8 a.m. In late April and early May, spray with 10% imidacloprid 2500-fold solution, once every 7 days, 3 consecutive sprays, to achieve thrips control.

5. Harvest at the right time and store properly.

Stop watering 7-10 days before harvest. Generally, in early June, after 2/3 of the pseudostems have fallen over, harvest on a sunny day, and never let them be exposed to rain. After harvest, handle gently to avoid mechanical injury, then place in a ventilated and shady place to dry. After the outer three layers of skin have dried, grade and sell according to export standards.