Spring is the peak season for growing vegetables in greenhouses, and it is the key period for obtaining high yields. The analysis of agricultural experts shows that although it has entered spring now, the activities of cold and warm air are frequent, and the temperature changes a lot. If vegetables want to obtain high yield, the management should pay attention to the following points: Disclaimer: Some articles on this website are transferred from the Internet. If third party legal rights are involved, please inform this website to deal with them. phone
Preparation of Fenebute
1. Prepare the first intermediate
Benzaldehyde and ethyl acetoacetate into ethanol, stir at room temperature under the catalysis of organic alkali reaction with filter cake filtration after 45 ~ 50 h, after the completion of the filter with ethanol elution filter cake, dry cake solids, then ethanol filtrate concentrated to a quarter of the original volume, to cold, concentrate filtering alcohol washing, solid, merging two solid is the first intermediate; The mole ratio of benzaldehyde, ethyl acetoacetate and ethanol is 1:2.5 -3:12-15.
2. Prepare the second intermediate
The first intermediate is added to the mass concentration of 20% sodium hydroxide solution, and the reaction is stirred at 85-90°C for 2-5 hours. After filtration, the filter cake is used for filtration. After filtration, the filter cake is washed, the filtrate is combined and cooled, and the filtrate is cooled by stirring for 3h. Solid second intermediate; The mass ratio of the first intermediate to the sodium hydroxide solution is I: 1.8-2.0;
3. Prepare the third intermediate
The second intermediate was dissolved in pure acetic anhydride solution for reflux 3 ~ 5h. After the reflux, the acetic anhydride was concentrated and dissolved with toluene. After the dissolution, ammonia water was added, and the reaction took place at 60_65°C for 1 ~ 1.5 h. Filtrate, wash and dry the precipitated solid to get the solid third intermediate; The mass ratio of the second intermediate, pure acetic anhydride solution, toluene and ammonia water is 5:1-1.2:0.5-0.8:0.5-0.8;
4. Prepare Finebute
The third intermediate was dissolved in 25% sodium hydroxide solution and cooled to _5°C ~ 10°C. After cooling, sodium hypochlorite was added slowly within 15-20min for 1h reaction, followed by ice bath reaction of 0.5 ~ 1.5 h and water bath reaction of 0.5 ~ 1.5 h. Finally, the temperature was gradually increased to 60 ~ 80°C for 1-5 h, and the reaction was cooled again after completion. After cooling, hydrochloric acid was added in the ice water bath to adjust the PH to 2, and the decolorization was stirred at room temperature. After filtration, sodium hydroxide was added in the ice water bath to adjust the PH to 6-7, and the cooling was stirred for 2 hours. The mass ratio of the third intermediate, sodium hydroxide solution and sodium hypochlorite is 1.0:0.8-1.0:1.0-1.1.
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The weather is getting warmer, and the management of greenhouse vegetables should be changed. After the weather is getting warmer, the vegetables grow faster and the branches and leaves gradually expand, which reduces the ventilation and light transmission between the rows of the plants, especially the lower part of the plants is prone to form a closed and small environment, which affects the coloring of the fruits and leads to Disease occurs. Therefore, as the outside temperature rises, the management of vegetables must be changed accordingly.
It is necessary to control the temperature as well as the temperature, especially the night temperature. It is recommended to ventilate early when the weather is normal. If the ventilation is not timely, the temperature of the greenhouse above 33 ° C will cause poor fruit setting. When the temperature of the greenhouse drops to about 20 ° C, the ventilation openings should be closed in time to control the night temperature to 13 ～ 15 ° C. In this way, it is not only beneficial for the photosynthetic products produced by the leaves to be transferred and distributed during the day, for root cultivation, tree promotion, and fruit attack, but also to increase the temperature difference between day and night and control the growth.
Second, we must remove the reflective film and properly shade the back wall. After the Qingming Festival, the natural lighting conditions in the shed can fully meet the needs of vegetable growth, and the reflective film should be removed in time to avoid sunburn. With the warmer weather, excessive heat storage on the back wall of the greenhouse will also cause excessive night temperature, and the plant ’s nutritional consumption will be greater. Therefore, it is recommended to grow legumes on the back wall of the greenhouse, so that it can make full use of the space in the greenhouse and weaken the heat storage capacity of the rear wall.
Strengthen the management of fertilizer and water, raise roots and promote trees. As the external temperature rises, the air temperature and ground temperature in the shed will gradually increase. Therefore, we must strengthen the management of fertilizers and water in order to raise roots and promote the trees, which will result in long leaves and increase the yield of vegetables.
First, we must change the type of fertilizer applied. Humic acid fertilizers and biological fungus fertilizers have little effect on ground temperature and light root injury after application, but their nutrient content is relatively low, which is difficult to meet the nutrient requirements for rapid plant growth after warming weather. Therefore, water-soluble high nitrogen and potassium fast-acting fertilizers should be used mainly, and the dosage is 8-10 kilograms per mu. In addition, when there are many sunny days, the sunlight is sufficient, and the concentration of carbon dioxide gas in the shed decreases rapidly. It is necessary to supplement the carbon dioxide gas fertilizer in time.
Second, we must change the watering method. After the weather warms, the water demand for vegetables has increased greatly. Note that the interval between watering and fertilizing is shorter than the low temperature season. Generally, watering is carried out every 10 days or so. It is best to use a combination of large water and small water for watering.
Pruning and pruning in time, adjusting the shape of the plant, cucumber, loofah, etc., must pick leaves and fall in time. In order to prevent the upper and lower leaves from overlapping after falling, it is necessary to remove the old leaves from the lower part before falling, and then fall after the wound is dry. In order to prevent the invasion of pathogenic bacteria from the injured stems, spraying can be performed by mixing 600 times solution of chlorothalonil with 4000 times solution of agricultural streptomycin after falling.
After each picking of peppers, sweet peppers, etc., the side branches on the main branch are promptly removed, and the inner leaves and branches are removed to prevent the plants from closing between rows. (Dingxing)
The temperature is unstable, and defense and remedial measures need to be strengthened in the near future. The persistently unstable temperature and long-term low temperature weather have a great impact on vegetable growth and seedling cultivation. Therefore, vegetable farmers should take active actions and adopt effective defense measures technically to deal with the impact of cold weather on vegetables.
The effects of low temperature on seedling growth mainly include insufficient light, low ground temperature, slow emergence of vegetables, weak growth, and severe cataplexy; the effects on transplantation are mainly delayed planting period, prolonged seedling period; growth and development process The main effect is that the growth potential is weak, the flowering, fruit setting and marketing period will be postponed. When the frost damage is severe, the plants will be directly frozen to death.
In early spring, you should make preparations for cold protection according to the changes in weather, and prepare films and grasshoppers in advance. Before the cold and cold weather arrives, cover the film in time and set up a small arch to keep warm. Seedlings can be sprayed with 0.04% Yunda-120 (brassinolide) + 0.3% potassium dihydrogen phosphate or poured a small amount of water in a sunny day before the cold and cold weather bursts out, which has a significant effect on improving the cold resistance Effect. When the weather improves, timely fertilize and uniformly seedlings, and strengthen the management of fertilizer and water at the seedling stage and comprehensive control of plant diseases and insect pests. The seedlings are subjected to low-temperature refining before planting to improve the resistance, cold resistance and disease resistance of the vegetables themselves. The eggplant fruits are 5 to 7 days before planting. The temperature is controlled at 22 ° C to 26 ° C on a sunny day and 8 ° C to 12 ° C at night.
Early spring vegetable transplanting should be covered with mulch in time to keep a small arch shed to keep warm. Pay attention to the weather forecast, spray antifreeze on the leaf surface before the low-temperature freezing injury. The formula is to add 50 grams of urea, potassium dihydrogen phosphate, and brown sugar to each 15 kg of water. Spray once.
Cultivate soil in combination with cultivating before low-temperature freezing damage. The depth of soil cultivation is 5-10 cm, which can loosen soil, increase soil temperature, and protect roots.