Chinese cabbage seedling cultivation can easily cause early bolting and loss of commercial quality. Not only can it not be marketed in the early spring, but it can also cause economic losses to the farmers. The reasons are caused by the abnormal climate and improper cultivation and management. Naturally there are varieties of improper selection and cultivation methods, as well as improper selection of the cultivation season. Comprehensive analysis leads to the following reasons for the phenomenon of early bolting. 1. Improper selection of varieties is the direct cause of premature bolting. We all know that Chinese cabbage requires different vernalization conditions than cabbage. Cabbage requires plants to grow to a certain size of vegetative species before they can cause bolting through vernalization, so the same site can even In the same greenhouse in different sowing dates, under the same management conditions, after passing through a cold, the seedlings sowed in advance were all bolted, and the seedlings sown in the later period were safe and intact. This phenomenon was called vernalization. The cabbage can be treated with low temperature from the beginning of the seed germination. It belongs to the seed vernalization type. Therefore, the seedling management of Chinese cabbage is far more demanding than that of cabbage. A slight oversight can cause premature bolting. However, the sensitivity to low temperatures varies from species to species, so the ability to resist bolting varies. In the past few years, the Chinese cabbages grown in spring have been commonly used by South Koreans, such as "Spring and Summer Kings", "Spring Yellow", "Yang Chun", "Jin Feng", "Strong", and "Cold Cold Ground". "General" and domestic "Lu Chunbai No. 1", these varieties have great differences in the ability to resist bolting, so the more northward cultivation should be selected varieties that have strong resistance to bolting. 2, the choice of sowing time is not appropriate, sowing and planting can easily lead to early bolting in front of said, cabbage is a seed vernalization type, if sowing too early, long seedling age, seedling period is in a long time low temperature conditions, easy Through the vernalization stage and bolting, especially in the face of multiple cold invasion, we must pay attention to the warming of the seedlings and heating, it was determined that the temperature management of Chinese cabbage shall not be less than 13 °C, if less than 13 °C, the seedlings received low temperature caused Bolted. In the winter of 1996, when temperatures were low in snow, a certain vegetable farmer in Tieling planted a “Harvest of the Spring and Summer†variety for a good harvest. In order to grab the morning market, the seedlings were raised in January and planted in a solar greenhouse in February. The growing trend was pleasant and tidy. As a result, 100% of the bolts were bolted without the ball. After receiving the claims from the seed management department, it was considered that the seeds were impure. January and February are the coldest months in China. Needless to say, in low temperature years, it is difficult to ensure that no bolting is done in normal years. Moreover, the response of any species to low temperatures has a certain range, and there is no absolute low temperature resistance, otherwise You can't harvest the seeds. The seedling age of Chinese cabbage should be about 30 days, and then it should be planted under suitable temperature management conditions. The selection of the growth period is generally suitable for early maturing varieties, short growing time, and easy management, morning market. However, the length of growth period is related to temperature, and it is generally cultivated in the cold season. The growth rate is slow, and it takes a long time, so there is a potential risk of bolting. If you cultivate at a slightly higher temperature. The growth period is significantly shortened. Therefore, the correct choice of sowing date and time to market is also a factor that cannot be ignored. 3. The selection of cultivation methods is irrational, and the growth and development conditions that have not been adapted to it have led to some farmers who have planted bolts for early colonization and early morning planting. They planted large seedlings very early and then planted them in open fields. Actually, they are in the growing time of large seedlings. It has passed vernalization. After the planting of the open land, we encountered the cold weather. When we saw the bulbous weed, we extracted it. This is a problem with the selection of cultivation methods. If the morning market, early breeding seedlings will be planted in the greenhouse with warming and insulation conditions, using plastic film and drip irrigation, both to prevent flooding to reduce the ground temperature, but also reduce water and reduce air humidity. In Shenyang, four types of cultivation can be adopted in stages to sow the plant and row out. Both warming greenhouse seedlings in the solar greenhouse colonization, solar greenhouse nursery colonization, solar greenhouse seedlings open small shed colonization, open-air cultivation and so on. 4. The cultivation and management techniques are not in place Any type of cultivation can not be separated from reasonable cultivation techniques. However, the focus here is on management technology. The temperature, water and fertilizer management and pest control technology after planting are not in place. Some vegetable farmers adopted large-scale fertilizer after the planting to promote the majority. As a result, the seedlings grow large and tender, and in small enclosed arches, the young seedlings are susceptible to freezing and can be easily roasted. As a result, the seedlings are damaged, which in turn affects the growth and development, and is susceptible to pests and diseases. Some seedlings at the seedling stage passed incomplete vernalization due to premature release, and the water and fertilizers did not keep up in the early stages of balling. The result was ball-wrapped moss, which also seriously affected commerciality. How to cultivate spring cabbage cabbage, avoid early spring bolting, prevent pests and diseases, the main technical measures are the following four aspects: 1. Select the appropriate varieties of the most used in our country most of the bolting species from South Korea and Japan, domestic Spring cabbage Chinese cabbage varieties have just started. Whether they are foreign or domestic varieties, there are obvious differences in the resistance to bolting between varieties. Different regions can choose different varieties and can not be generalized. In principle, the more cold regions should choose varieties with strong resistance to bolting. According to the test results in Shenyang, the order of resistance to bolting was Jinfeng? Strong? Spring yellow? High cold? Yangchun? Spring and summer Wang?chun spring? Lu Chunbai?. The "Jinfeng" and "strong" varieties have short center pillars and no bulges. They are more resistant to bolting and resistant to disease. The "yangchun", "spring and summer king", "spring general" and other varieties of the center column length, showing a triangular convex, resistance to bolting than the above varieties, and "Lu Chunbai No. 1" all bolted flowering and loss of commercial. Therefore, the selection of good varieties can fundamentally prevent and solve the problem of early bolting bolting in early spring. 2. Select the appropriate sowing time Each species has a certain degree of resistance to bolting and growth period, the general resistance to bolting strong long-term varieties can be sown early. Generally, it is appropriate to use seedlings for direct seeding and nutrition. The seedling age is guaranteed in about 30 days. Different cultivation methods have different sowing dates. Warming greenhouse seedlings The sowing date in the solar greenhouse is generally mid-February, but this method is very expensive and is rarely used. The seeding period of nursery sheds in solar greenhouses is generally raised in the middle or late February, and a small shed can be added to the shed to guarantee the availability of the market. The sowing date of the small greenhouse shed for greenhouse cultivation is generally at the beginning of March. This type of cultivation method has low investment and is listed early. It is commonly used. The sowing date of the film-mulching film covering live or open field seedling cultivation is generally in the mid-April of April. In this cultivation method, the temperature gradually increases in the later period, and the pests and diseases are heavier. According to the above situation, sowing is not good early or late. Premature temperature is low and it is easy to pass vernalization. Pre-extraction bolting occurs. It is too late, and the yield is low. After being listed, it is easy to get sick and the efficiency is poor. Therefore, the appropriate sowing date should be properly selected for high efficiency. 3. Choose a suitable cultivation method to determine a reasonable cultivation method based on the local climate characteristics. Taking Liaoning as an example, Dalian in the south of Liaoning, Tieling in northern Liaoning, Jinzhou in western Liaoning, and Dandong in eastern Liaoning have different temperatures in the same season. In the Tieling area, it is mainly protected, ensuring the safety during the seedling period. In Dalian, it is appropriate to raise the seedlings in advance or open the ground. In western Liaoning Province, it is possible to raise seedlings early, but it is also possible to prevent sprouting at high temperatures. Different cultivation methods have different nursery time. If the nursery time is too early, the plants cannot be planted in time, the seedlings will be too large, the seedlings will inevitably be controlled for a long time, and exposed to low temperature conditions. If the nursery is early and there is no corresponding protective measures when planting, that is, the selection of cultivation methods is not reasonable, it will also cause bolting. 4. Select appropriate management techniques After planting the seedlings, especially under protective measures, pay more attention to temperature and water and fertilizer management. In the early stage, the seedlings should be properly controlled and the ventilation should be strengthened. For example, a small arch shed in open field is used as an example. Generally, a small shed is used to cover a small number of days before it is covered. After the planting, the seedlings are poured and the seedlings are watered until they survive, especially after the end of April, at noon. The temperature is very high, it must be properly vented to ensure that the temperature within the arch shed not too high, with the outside temperature rise, you can make a hole in the lee place. When the external temperature stabilizes above 15°C in early May, when the seedlings have grown to be quite large and topped with small arches, the arches should be promptly removed, cultivating and weeding, topdressing, and falling off the film. After the seedlings adapt to the external conditions, watering and pesticides are used to strengthen field management, and later to promote growth, promote vegetative growth, and suppress reproductive growth. Generally, harvesting begins in mid-May.
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