With the continuous development of science and technology, colorful "Chinese cabbage" has been successfully cultivated in Shaanxi and is being popularized in a large area. This bright yellow or orange Chinese cabbage is not only beautiful in appearance, but also crisp and tender in texture and excellent in taste, and its nutritional value is much higher than that of traditional Chinese cabbage. The content of total carotene is about 5 times higher than that of ordinary Chinese cabbage, and the content of vitamin C is about 60% higher than that of ordinary Chinese cabbage. Today, people are demanding more and more food, and it will be more popular than traditional Chinese cabbage.
Second, biological characteristics.
1, root Chinese cabbage is a shallow root system, with two rows of lateral roots on the main root, and many branches on the main root and lateral root, forming a dense absorption network. Although the root system of Chinese cabbage is developed, it mostly grows horizontally, and the main root groups are distributed in the root layer 30 ~ 35 cm away from the surface.
2. The vegetative growth time of stems, shortened stems, internode segments, one leaf per node, and immature axillary buds. In the reproductive growth stage, the flower stem is 60 ~ 100 cm high, and many branches can occur on it.
3. The branches and leaves of leafy Chinese cabbage have the following characteristics: two cotyledons, two opposite leaves, kidney-shaped leaves and two basal leaves, opposite leaves, cross perpendicular to cotyledons, oblong leaves, also known as raw leaves; The middle leaves are inserted in the middle of the shortened stems, including seedling leaves and lotus leaves. Leaves alternate, wide, with obvious warping and no obvious petiole. Terminal leaves are alternate and inserted at the top of shortened stems to form terminal buds.
4, flowers, fruits and seeds racemes, complete flowers, calyx, petals are four, cross arrangement. Petals yellow or light yellow. There are nectaries at the base of filaments, which belong to cross-pollinated crops. The fruit is silique, which cracks longitudinally when it matures.
Third, the main varieties and characteristics
Chinese cabbage is the original ecological vegetable in China, and it is also the most important vegetable variety in our daily life. Its variety is rich, only a few vegetables can compare with it. According to statistics, there are more than 1000 local varieties of Chinese cabbage in China, and new varieties are constantly emerging, so I won't go into details. According to the varieties, it can be divided into three kinds: Chinese cabbage, green cabbage and green cabbage, and according to the different growth periods, it can be divided into spring cabbage, summer cabbage and autumn cabbage, that is, early, middle and late ripening.
Proper planting of Chinese cabbage in spring can effectively adjust the supply in early summer and off-season, increase the variety of colors in the market, and is of great significance to the annual vegetable supply. But the length of spring varies from place to place, and it is often difficult to accurately predict climate change. The period really suitable for Chinese cabbage growth is short, and the temperature changes from low to high in spring, which meets the needs of reproductive growth of Chinese cabbage, but is not suitable for nutritional growth. Therefore, if the cultivation of Chinese cabbage in spring is not handled properly, it will often bring a series of difficulties and problems.
Summer cabbage, also known as early-maturing Chinese cabbage, has strong heat resistance and short growth period, and it only takes about 55 ~ 60 days from sowing to harvesting. Sow in the middle and late July to August, and harvest in the middle of September to 10. Because the growing season of Chinese cabbage in summer is in a hot and dry season, it is necessary to water more to prevent all kinds of pests and diseases. Aphid, jumping headland, tomato diamondback moth, tomato diamondback moth and other pests are more serious. Soft rot is the most harmful disease. If you don't harvest in time, stop watering 5 ~ 7 days before harvesting, and 80% or 90% of the seeds can be harvested and put on the market, otherwise the harm of soft rot will be aggravated.
According to the growth and development law of Chinese cabbage and the requirements of environmental conditions, autumn Chinese cabbage is sown later, usually after sowing in beginning of autumn to avoid the high temperature in late summer and early autumn, and its growth cycle is longer. Generally speaking, the seedling period is from autumn to the white dew, the heart-filling period is from the autumnal equinox to the early winter, the rosette period is from the white dew to the autumnal equinox, and the heart-filling period is from the autumnal equinox to the early winter. Generally, vegetables should be harvested in time at the beginning of l 1, that is, when the lowest temperature in beginning of winter drops to about zero. When there is no severe frost climate, measures can be taken to shelve vegetables and promote package, and the date of cutting vegetables can be postponed appropriately.
Although it can be planted in stages, Chinese cabbage actually has a suitable growth cycle. Generally speaking, planting period: the average monthly temperature suitable for planting is 15 ~ 18℃, the highest is 2 1 ~ 24℃, and the lowest is 7℃. Germination period: Generally, it germinates quickly and robustly at 20 ~ 25℃, but it germinates quickly at 26 ~ 30℃ but the seedlings are emaciated, and it does not grow well above 30℃. Seedling stage: the suitable temperature is 22 ~ 25℃, and it can also be adapted to 26 ~ 30℃. Rosette period: the average temperature 17 ~ 22℃ is the most suitable, too high leaves grow white and too low leaves grow slow. Nodulation stage: the optimum temperature is 12 ~ 22℃. Enclosure period: it is easy to be frozen below -3℃. Storage: the temperature is 0 ~ 2℃, the relative humidity is 85% ~ 90%, the temperature drops below -2℃, and the Chinese cabbage is frozen.
Four. Nutritional and medicinal value
Chinese cabbage has high nutritional value and contains protein, fat, dietary fiber, moisture, potassium, sodium, calcium, magnesium, iron, manganese, zinc, copper, phosphorus, selenium, carotene, nicotinic acid, vitamin B 1, vitamin B2, vitamin C and trace element molybdenum. Chinese cabbage is a vegetable that people eat all year round, because it is rich in nutrition, delicious, diverse in methods and resistant to storage. [Next Page]
Chinese cabbage also has certain medicinal effects. "Compendium of Materia Medica" says that Chinese cabbage "produces fluid to quench thirst, is non-toxic and beneficial to the stomach." Chinese medicine believes that Chinese cabbage is sweet in taste and flat in nature, and has the effects of nourishing stomach, diuresis, relieving fever and relieving annoyance. Can be used for treating common cold, fever and thirst, bronchitis, cough, dyspepsia, constipation, dysuria, chilblain, ulcer bleeding, alcoholism and hot sore. Because of its low calorie, it is also a good supplementary food for obese and diabetic patients. It contains trace element molybdenum, which can block the generation of carcinogens such as nitrosamines in human body and is a good anticancer product.
V. Storage and preservation
At present, most Chinese cabbages in northern China are stored by stacking, burying and cellaring. Although the method is simple and the cost is low, the loss is too great and the shelf life is limited. If stored in cold storage, due to suitable humidity, temperature and other conditions, the storage period can be greatly extended, the loss is small, and the quality of vegetables on the market is also good. When storing Chinese cabbage, the optimum storage temperature is 0℃ and the relative humidity is above 98%RH. The optimum storage conditions of heading Chinese cabbage are 0℃, relative humidity 95- 100%RH, and it can be stored for about 1.5 ~ 2 months. Injured cabbages and diseased leaves must be removed at harvest, and ethylene cannot exist in storage environment. The storage period can be extended if it is stored under 1% anoxic condition.
At present, Chinese cabbage is mainly stored in ventilated warehouses and cellars, and some are piled on the ground or buried underground. However, no matter what kind of storage, there will be rot and cliques. Rot is caused by microbial infection. There are two reasons, one is illness in the field, and the other is improper temperature and humidity. Therefore, in the process of storage, it is necessary to strictly select and eliminate diseased plants, improve storage conditions in time, maintain air circulation, strengthen disinfection and anti-corrosion measures, and inhibit microbial activities. Abscission is a physiological phenomenon, which is the abscission layer formed by the roots of leaves. It is closely related to storage conditions. If the temperature drops to a level that can weaken the respiratory intensity, shedding will be reduced. Therefore, it is particularly important to reduce shedding and control temperature. In short, we must pay attention to the organic combination of temperature, humidity and ventilation when storing Chinese cabbage. When the vegetable market is stacked with herringbone scaffolding, a certain amount of soil can be laid on the open space on the edge of the house or the flat roof platform of the cement house, and the stacking position can be determined to the north, demarcated with ropes, dug into a row, and ditched on both sides. Leave 2 feet of space between the sidewalk and the ditch. Tie a herringbone shelf with bamboo poles or tree sticks, tie two rows of brackets with bamboo poles (or tree sticks) at the bottom of the shelf, and then put the selected Chinese cabbage on the brackets. After stacking Chinese cabbage, cover the pile to prevent rain and snow and keep warm. Plastic film materials and vegetable trees are separated into small shelves by bamboo poles or small tree strips, which can not only prevent the water vapor rake on the plastic film from rotting and deteriorating on vegetables, but also ventilate. Use straw bags or curtains to tie the doors at both ends of the pile to open and close the ventilation and check the quality. Strengthening management is the key to realize the organic combination of temperature, temperature and ventilation. Winter focuses on cold, antifreeze, rain and snow. Generally, the optimum temperature is 0 ~ 26℃ and the relative humidity is 85 ~ 90%. If the temperature drops below -3℃, Chinese cabbage will rot and deteriorate due to freezing. It is necessary to close two stacking doors in time to prevent freezing. When it rains and snows continuously, it is necessary to clear the snow in time, drain the accumulated water, and open the door for ventilation at noon to prevent vegetables from rotting and deteriorating due to high humidity. After beginning of spring, rain protection and warmth should be given priority to. When the temperature rises above 3℃, open the door for ventilation during the day and close the door for cold protection at night. If the temperature rises above l0℃, open the door wide at night and let the cool wind blow in, which not only regulates the temperature and humidity, but also makes the air fresh and reduces the reproduction of germs. Wholesale and retail markets can also use hanging storage, that is, each vegetable root is left about one and a half inches, tied with twine or lead wire, and placed on the beam or wooden frame of the warehouse. In this way, air circulation is less affected by temperature, humidity and bacterial infection, but because the air is unobstructed, water is easy to evaporate. In order to avoid the rapid diffusion of water in branches and leaves, a bag can be placed outside each ladder from the root down, and the bag mouth can be loosely tied, which has a certain effect on regulating temperature and humidity and ventilation.