Key Technical Points for Topdressing Management in Onion Cultivation
I. Selecting Superior Varieties In production, purple-skinned varieties such as Ziyu No. 1, Ziyu No. 2, Zixing, and Shuanghuanhong can be selected. These varieties have the characteristics of strong pungency, high yield, excellent quality, and suitability for export. These varieties generally yield about 5,000 kg per mu, and high-yielding plots can reach 7,500 kg per mu. II...
After onions are transplanted, root growth occurs first, followed by aboveground growth, and only after the aboveground part has grown fully does the plant enter the bulb enlargement growth stage. According to the growth and development characteristics of onions, doing a good job of topdressing by stages is one of the keys to high onion yields.Fertilizer for seedling recovery:
15-20 days after transplanting, apply fertilizer for seedling recovery to supplement nutrients for continued root growth and at the same time prepare for the aboveground growth that will soon begin. Apply 5-6 kg of urea per mu, broadcast it, and then water to facilitate absorption and utilization.
Fertilizer for plant development:
30 days after transplanting, when vegetative growth has intensified, topdressing for plant development should be applied to ensure the needs of functional leaf growth in the aboveground part. This is because the size of the leaf vegetative mass is very closely related to the size of the later bulb; promoting leaf growth in the early stage lays the foundation for bulb enlargement growth in the later stage. It is mostly nitrogen fertilizer, with 5-6 kg of urea and 5 kg of potassium sulfate applied per mu.
Fertilizer for promoting bulbs:
After the plant has 8-10 tubular leaves, the bulb begins to expand, and fertilizer for promoting bulbs should be applied once. This fertilizer should focus on the middle stage of bulb enlargement growth. When the bulb has just begun enlargement growth, too much nitrogen fertilizer should not be applied. If nitrogen fertilizer is applied excessively in the late stage of bulb enlargement growth, "late greening" will occur and affect harvest. Apply 5-7 kg of urea and 8 kg of potassium sulfate per mu. During the bulb enlargement growth period, potassium deficiency will not only reduce yield but also have a certain effect on the storability of the product.