What are the main causes and control methods of bolting of spring sowing Chinese cabbage? What are the main points of cultivation techniques?

Chinese cabbage, also known as "heading Chinese cabbage", "cabbage", "yellow bud white", "gum cabbage" and so on, is called "Shaoxing vegetable" in Cantonese. It is widely planted in our country. So what are the main causes and control methods of bolting of spring sowing Chinese cabbage? What are the key points of countermeasure cultivation techniques?

What are the main causes and control methods of bolting of spring sowing Chinese cabbage?

First, the reasons:

1. The temperature in spring is low and lasts for a long time

Chinese cabbage belongs to seed vernalization type crop. After seed germination, it can accept low temperature vernalization and enter reproductive growth (that is, begin bolting). After general seed germination, it can pass through vernalization stage after 10 to 20 days under the condition of less than l0~l2 ℃, resulting in early bolting, which brings serious losses to production.

2. Improper cultivation and management

The immature bolting of cruciferous crops appears in the production every year, but the performance is different. The proper cultivation and management has a great influence on immature bolting, sometimes even decisive. Cultivation and management measures have a great influence on early bolting. If the spring Chinese cabbage is planted too early and the temperature is too low, the leaf bud can not be fully formed, which will promote the early formation of flower bud and immature bolting. On the other hand, cabbage and radish seedlings are too old, or too much fertilizer and water after planting, which makes them reach vernalization ahead of time, which is also easy to lead to early bolting.

3. The strength of winter character of varieties.

Under the condition of the same weather and cultivation management, the varieties with strong winterness bolted less and the varieties with weak winterness bolted more.

II. Preventive measures

1. Select superior varieties

The strength of winter character of varieties, that is, bolting tolerance, is an important index when selecting varieties. Generally, the temperature is on the low side, so the varieties with strong winter nature should be selected.

2. Strictly abide by the operating rules

Agricultural production must be scientific and cannot be done entirely on the basis of experience, because experience is formed under certain environmental conditions, and experience can have disastrous consequences when the environment changes. Therefore, we must strictly sow time and do a good job in fertilizer and water management.

4. Inhibit or promote the growth of bolts.

For bolting fields, such as spring Chinese cabbage, if bolting has just appeared, spraying anti-bolting thickening agent and paclobutrazol can be used to inhibit the growth of bolting, or straw rope binding can be used to promote bolting. If the Chinese cabbage is long, the culture tube should be strengthened to promote the growth of the Chinese cabbage, because the Chinese cabbage bolt is fresh and delicious, so it can become a light vegetable variety from April to May, thus certain economic benefits can be obtained. In addition, such as spring radish, if the radish has been initially formed, it can be bolted off, so that the radish can continue to grow and form a certain yield.

4. Catch up with the next season in time

Crops should destroy seedlings and clear gardens as soon as possible and plant the next crop as soon as possible to make up for the loss of fields where bolting is particularly serious and there is no reserved value.

What are the key points of cultivation techniques of spring sowing Chinese cabbage?

I. sowing period

This year is a cold year, the sowing time is more than 5 days later than usual, and the sowing began after March 1.

II. Variety selection

Must choose a generation of strong winter cabbage hybrids, such as the four Seasons Crown, Crown, Sub-Zero, Liangqing.

III. Soil preparation and fertilization

Avoid continuous cropping of Chinese cabbage, it is best to choose rotation with melons, legumes, onions and garlic, eggplant fruits and food crops, and choose fields without root swelling disease. During soil preparation, organic fertilizer 2000~2500kg and calcium phosphate fertilizer 40kg were applied per mu as base fertilizer and bio-organic fertilizer 40~60kg as middle layer fertilizer. Fields with sour soil should be treated with quicklime 50~100kg per mu. Generally, the bed is made by 2m to 2.1m with trench.

Third, sowing seeds

Plastic film mulching and direct seeding were used, and the row spacing was 40 × 35cm. Sow 3-4 seeds per hole, and the seed amount per mu is about 60g. Pay attention to pouring out the seedling water to ensure the whole seedling.

IV. Field management

The main results are as follows: 1. Seedling setting: after emergence, the seedlings were fixed for the first time at 2 Mel 3 tablets, 2 seedlings in each hole, and 1 seedling in each hole at 4 Mel 5 leaves.

2. Fertilizer and water management: generally topdressing twice, applying 10 kg urea, 10 kg potassium sulfate per mu in rosette stage, 10 kg urea, 10 kg potassium sulfate, 10 kg urea and 12 kg potassium sulfate per mu at the beginning of heading.

In terms of water management, sufficient bottom water should be poured before sowing to facilitate seedling emergence. The water demand in seedling stage is less, but the root system is shallow and the absorptive capacity is weak, so small water should be watered frequently. The water demand in rosette period is large, so the amount of irrigation should be increased, and it is appropriate to air-dry and rheumatism. The heading period is the period when the most water is needed, and the soil should be kept moist.

Prevention and control of diseases and insect pests

The main diseases of Chinese cabbage are soft rot, black spot, root swelling and so on. The main pests are Plutella xylostella, Pieris rapae, cabbage borer and so on.

1. Soft rot, black rot and bacterial angular spot disease are serious under the condition of high temperature and high humidity. It can be sprayed with 72% agricultural streptomycin 4000 times, or 90% streptomycin soil (neophytomycin) soluble powder 4000 times, or 30% copper succinate (DT) wettable powder 800mm 1000 times.

2. Black spot disease can be treated with 69% enylmorpholine ·manganese zinc (Anke manganese zinc) wettable powder 500 times 600 times, or 50% isobarbamide (prohydantoin) wettable powder 1000 times liquid, or 80% mancozeb (Sanderson) wettable powder 600 times liquid spray.

3. Disease-resistant varieties were selected for root swelling disease, seeds, seedling beds and planting holes were disinfected, rotation was carried out, planting in diseased fields was avoided, organic fertilizer was applied, lime was applied to adjust acidity and alkalinity, and cultivated in deep ditch and high border in rainy season. After two true leaves and colonization survived, the roots were irrigated with the following agents: ① 75% chlorothalonil wettable powder 800 × 1000 times, ② 50% carbendazim wettable powder 800 × 1000 times, ③ 30% carbendazim water 800 × 1000 times, ④ 70% methyl thiophanate wettable powder 1000 times.

4. Plutella xylostella, Plutella xylostella and Chilo suppressalis are controlled by microbial preparations such as Spodoptera exigua virus, Plutella xylostella virus, Beauveria bassiana and Bacillus thuringiensis. Or use chemical pesticide spray such as 2500 times of 5% fluazuron EC, 1500 times of 5% fluflubenzuron EC, or 1000 times of 50% phoxim EC. It can also be sprayed with matrine, azadirachtin, permethrin and bifenthrin.