Detailed Explanation of Spring Open-Field Cultivation Techniques for Purple Cabbage

Purple cabbage has good cold tolerance, firm heads, bright color, strong adaptability, high yield, and good quality, with relatively high planting returns. It is suitable for open-field and protected cultivation, with a yield of generally 2500-3000 kg per mu. The key points of its spring open-field cultivation techniques are introduced as follows:

I. Raising Strong Seedlings

1. Variety selection. The early-maturing variety "Zaohong," introduced from the Netherlands and suitable for spring open-field cultivation, can be selected. Its leaves are purplish red, and its head is oval, with a single head weight of 0.75-1 kg. It takes about 65-70 days from planting to harvest.

2. Timely sowing. For spring open-field cultivation, seedlings can be raised under protection from mid-January to mid-to-late February, sowing dry seeds and using nutrient pots for seedling raising. Before sowing, water the nutrient soil thoroughly; after sowing, cover with 1.5 cm of soil. Then cover with film to promote strong seedlings and early growth.

3. Seedling stage management. The seedling age is generally 70-90 days, and it takes 20-30 days from sowing to the appearance of 2 true leaves. During the emergence stage, keep the daytime temperature at about 25°C, and the nighttime temperature at 15°C. After the seedlings emerge completely, lower the temperature to 20°C during the day and 10°C at night. It takes 45-60 days for seedlings to grow from 3 true leaves to 6-8 true leaves. Before planting, carry out low-temperature hardening, keeping it at about 15°C during the day and 7°C-8°C at night, gradually approaching open-field temperatures. The standards for strong seedlings are: 6-8 true leaves, short internodes, thick leaves, deep color, sturdy stems, and well-developed root systems.

II. Land Preparation and Fertilization

Purple cabbage likes fertilizer. For base fertilizer, generally apply 5000 kg of high-quality barnyard manure, 15 kg of diammonium phosphate, and 15 kg of potassium fertilizer per mu, then plow and harrow evenly with the soil before preparing the land and making beds. Generally, flat beds 1-1.2 m wide are made.

III. Planting

Open-field cultivation should not be too early, so as to avoid bolting before the plants are mature. Generally, planting is done after Qingming Festival in spring, when the temperature is stable above 6°C. Use the "water-stabilized seedling" method, and the amount of water should not be too large, so as to promote seedling recovery. The planting density is 50 cm x 50 cm in row and plant spacing, with 2500-2600 plants per mu. The planting depth should be such that the leaves remain above and the heart leaves are not buried in the soil. If improved plastic film mulching cultivation is adopted, it can promote early maturity and high yield.

IV. Field Management

Purple cabbage has a high fertilizer requirement. During the seedling stage, rosette stage, and head-forming stage, topdressing is applied 4-5 times in total. Among these, the rosette stage and head-forming stage have the greatest fertilizer demand and should be heavily fertilized. After seedling recovery, water once to help the seedlings recover. Then 10-15 days after seedling recovery, apply 15-20 kg of urea per mu with irrigation water. In the middle of the rosette stage, carry out the second topdressing, applying 15-20 kg of urea, 20 kg of diammonium phosphate, and 10 kg of potassium fertilizer per mu. From planting to the late rosette stage is 30-40 days. When the heart leaves begin to fold inward, it indicates that the head-forming stage has been reached. This period is when purple cabbage grows fastest and has the greatest growth amount, and it is also the period with the greatest demand for fertilizer and water. Therefore, during the head-forming stage, topdress 2-3 times in combination with watering, applying 10-15 kg of diammonium phosphate per mu each time. In the later stage, apply a small amount of chemical fertilizer. Especially before harvest, do not apply excessive fertilizer and water, so as to avoid head splitting.

Pang Qiujuan, Pingxiang County Agricultural Bureau