How to manage the heading period of Chinese cabbage

Chinese cabbage, biennial herb, 40-60 cm tall, often glabrous throughout, sometimes with a few bristles on the midrib below the leaves. Native to northern China, it is a leafy vegetable of Brassica in the cruciferous family, usually referring to Chinese cabbage; it also includes Chinese cabbage and cabbage, namely "cabbage" or "cabbage", a cultivated variety of cabbage. It is introduced to the south and cultivated in all parts of the north and south. It was introduced into Japan, Europe and the United States in the 19th century. There are many kinds of cabbages, including Shandong Jiaozhou cabbage, Beijing green white cabbage, green Tianjin sesame leaf cabbage, northeast big dwarf cabbage, Yutian cabbage, Shanxi Yangcheng big Maobian and so on. Cabbage is eaten with tender leaf balls, rosette leaves or flower stems. The cultivated area and consumption rank first among all kinds of vegetables in China.

Types of cabbage

Chinese cabbage subspecies can be divided into four horticultural varieties, namely loose leaf cabbage variety, semi-heading Chinese cabbage variety, cauliflower cabbage variety and heading Chinese cabbage variety.

According to the cultivation center and ecology, the varieties of heading Chinese cabbage can be divided into three basic ecotypes, straight tube type, oval type and head type. Five secondary types were produced from three basic ecotypes: flat head straight cylinder type, flat head oval type, cylinder type, straight tube flower heart type and flower heart oval type.

In addition to ecotype, cabbage varieties can also be divided into different types according to leaf bulb characters and growth period.

According to the number and weight of globular leaves, it can be divided into heavy leaf type, leaf number type and intermediate type. According to the core form of the leaf ball, it can be divided into three types: closed heart, flower heart or turning heart, vertical center and semi-closed heart. According to the type of dome, it can be divided into flat head, round head and pointed head. According to the hugging mode of the blade in the ball, it can be divided into folding, folding, twisting and hugging types. According to the growth period, it can be divided into very precocious, precocious, middle and late maturing types.

Growth habits of Chinese cabbage

The growth and development process of Chinese cabbage can be divided into two stages: vegetative growth and reproductive growth.

The vegetative growth stage can be divided into the following periods:

Germination period: from seed germination to unearthed, true leaf exposure is the germination stage. It takes about 3-5 days under suitable temperature and soil moisture conditions.

Seedling stage: from true leaves to 5-8 leaves to form the first leaf ring. Precocious varieties have 5 leaves at seedling stage, which takes about 12-15 days. There are 8 leaves in the seedling stage of late-maturing varieties, which takes about 17-18 days.

Rosette stage: after the end of the seedling stage, two more leaf rings form a rosette. The young heart leaves in the center of the plant begin to clasp, which is the characteristic of the end of the rosette. During this period, early-maturing varieties took about 20-21 days and late-maturing varieties about 27-28 days.

Heading period: from the heart leaf clasping to the leaf ball formation. It takes about 25-30 days for early-maturing varieties and 50 days for late-maturing varieties.

Dormancy period: the leaf ball is forced to go into dormancy because of the cold climate. In the areas with low winter temperature in Northeast China, Chinese cabbage can enter the reproductive growth stage under long sunshine after vernalization at low temperature, and the process can be divided into three stages: bolting stage, flowering stage and podding stage. The transition from vegetative growth to reproductive growth of Chinese cabbage generally requires a low temperature vernalization condition of 2-10 degrees Celsius and 10-30 days. Late-maturing varieties are more stringent than early-maturing varieties.

Chinese cabbage likes mild and cool climatic conditions, the suitable temperature for growth is in the range of 10-22 degrees Celsius, the growth is poor when it is higher than 25 degrees Celsius, and it cannot adapt when it is higher than 30 degrees Celsius. Slow growth below 10 degrees Celsius, growth pause below 5 degrees Celsius, can withstand light frost, can not bear severe frost. During the growing period of Chinese cabbage, sufficient light conditions are required to facilitate photosynthesis, accumulate more substances and promote heading. Because Chinese cabbage has a large number of leaves and large leaf area, and the leaf cuticle is very thin, water transpiration is very large, so sufficient water supply should be ensured during the growing period.

How to manage the heading period of cabbage?

The heading period of Chinese cabbage is a period in which the outer leaves of autumn Chinese cabbage grow slowly, the leaf heads grow rapidly, the daily growth is the largest, and the nutrients accumulate massively. The key points of management in this period are scientific watering and fertilization, keeping the soil moist and ensuring the healthy growth of Chinese cabbage.

Chase ball fertilizer

In the process of growth and development, when there is a certain number of outer leaves, Chinese cabbage enters the late growth stage of outer leaves and begins to enclose and bear balls. The heading period of autumn cabbage is from the beginning of heading to the compactness of leaf balls. Generally, it is 25-30 days for early-maturing varieties and 40-50 days for late-maturing varieties. The heading period can also be divided into:

One is the early heading stage, from curling to pulling, which requires 20 ℃-22 ℃ during the day and 10 ℃-12 ℃ at night, with more sunny days, sufficient light, high soil moisture and sufficient fertilizer, which is beneficial to the photosynthesis of outer leaves and root absorption.

Second, the middle heading stage, the early heading stage and the middle stage are the fastest growing period of the heart leaf, and 80% of the weight of the leaf ball is formed in these two periods.

Third, in the late stage of heading, Chinese cabbage continued to grow and the weight of leaf head was still increasing. Obtaining compact, white and tender leaf balls is an important economic character in the production of autumn cabbage. Therefore, special attention should be paid to improving the level of fertilizer and water management during the heading period, so as to ensure the normal growth of leaf balls and prevent the occurrence of pine balls, cracked balls, deformable balls and even non-heading balls. It can be sprayed with 500-fold solution of biotin, once every 10 times every 15 days, for 3 times in a row.

Fertilization should be mastered in the initial stage of heading after the application of heavy fertilizer, called "suction fertilizer". Application of ammonium sulfate or urea 10kg-15kg per mu, or application of dilute manure combined with irrigation about 1500 kg, or cake fertilizer 50kg-100kg, but cake fertilizer must be fermented and ripened. At the same time, calcium superphosphate and potassium sulfate each 7.5 kg-10 kg should be applied to promote the growth of leaf bulbs. In the middle stage of heading, combined with irrigation, a heart-filling fertilizer was applied once, and 10 kg-15 kg of chemical fertilizer or 1000 kg-1500 kg of human feces and urine were applied per mu to promote pelleting and compactness. the method of topdressing could be ditch application or deep application of digging pit.

Rational watering

Cabbage growing vigorously during the heading period, needs adequate fertilizer and water supply, generally needs to be irrigated 2-3 times, in case of dry weather, the number of irrigation will be increased. Pay attention to the first water to be gently irrigated to prevent sudden flooding to make the cabbage gang crack; the second water to follow closely to prevent the ground surface dry crack caused by root. The method of furrow irrigation should be used to make the water infiltrate slowly, which can not only ensure the water needed for the growth of Chinese cabbage, but also avoid too much water and encourage the occurrence of soft rot. Irrigation should ensure that there is no water accumulation in the ditch, no water on the ridge (border) surface, and no shortage of water absorbed by the root system. Stop irrigation 5-10 days before harvest to ensure that the storability of Chinese cabbage is improved.

Bundled vegetables

Bundling vegetables can protect autumn Chinese cabbage from frost injury, increase yield, reduce loss and facilitate storage. The bundling of vegetables is generally carried out 15 days before harvest, pick up the rosette leaves and hold the leaf balls, and bind them with sweet potato vines, millet stalks and other crop straws. After bundling vegetables, the photosynthesis of leaves is affected, and the yield is affected prematurely, and it is easy to suffer frost injury too late.

Timely harvest

When the average temperature of the day drops to 5 ℃, the Chinese cabbage leaves should be harvested in the first ten days of November, when the harvest is finished in Lesser Snow's solar terms.