How to manage greenhouse vegetables after they enter the middle and late stage to improve quality and efficiency?

In terms of time, after the end of May, our greenhouse vegetables are basically in four periods: color change period, full fruit period, mature period and picking period, that is, the middle and late management period, and the management quality of these four periods is also an important period to determine the yield and quality of our greenhouse vegetables. In management, it is also different from the previous requirements. Therefore, during this period, management measures should be formulated around the growth characteristics of vegetables in the middle and late stage.

1. Growth characteristics of greenhouse vegetables in the middle and late stage

After entering the middle and late stage, the growth characteristics of greenhouse vegetables mainly include the following aspects:

Root system aging and seedling premature aging: when greenhouse vegetables enter the middle and late stage, the root system of vegetables will age and the absorption capacity of nutrients and water is not as good as before; In addition, the seedlings will appear old leaves and yellow leaves to varying degrees. Poor stress resistance and great environmental impact: in the middle and late stage, the stress resistance of vegetable seedlings will decline, which is the same as when we are old. It is a truth that the body's resistance is getting worse. Leaf senescence and functional decline: during this period, a series of problems such as yellowing, leaf curl and brittleness will appear from the old leaves, which will lead to the decline of leaf photosynthesis rate and pose a threat to the yield and quality of vegetables. Increased pests and diseases: During this period, the stress resistance of plants became worse, and the temperature and humidity in the shed increased, which created favorable environmental conditions for the occurrence of vegetable diseases. As a result, the condition became more and more serious. The peak period of organic nutrient transfer and reproductive growth: the middle and late period of vegetable growth is the most critical period. Because all organic nutrients will be transferred from leaves and seedlings to fruits during the four stages of color change, full fruit, ripening and picking, which is also determined by the characteristics of vegetables. When the external environment is unfavorable, organic nutrients will be transported to fruits. But the nutrients we are talking about here are organic nutrients, which refer to carbohydrates synthesized by leaves through photosynthesis, rather than mineral nutrients such as nitrogen, phosphorus and potassium. This is different. If the supply of organic nutrition is insufficient, the fruit will not swell and the quality of the fruit will not be good. Therefore, in the middle and late period of greenhouse vegetables, all our management measures revolve around how to ensure the sufficiency and operation of organic nutrition. However, the abundance of organic nutrition does not mean more fertilization. A large amount of fertilization at this stage will be counterproductive. The growth characteristics of vegetables in each period are different, and the management methods will be different. Therefore, when we know how to manage, we must understand why.

Second, the management points of greenhouse vegetables in the middle and late stage

After understanding the growth characteristics of vegetables in the middle and late stage, our management points should be carried out around these characteristics.

Rooting is the key: when greenhouse vegetables enter the middle and late stage, root aging will lead to premature senescence of plants. Therefore, doing a good job in this period is the key measure to prevent premature aging. Fertilizer control is the core: because the root system is aging, nitrogen, phosphorus and potassium cannot be used in large quantities during this period. No matter how much we use, the roots themselves can't absorb it. Therefore, fertilizer control is the core, and the use of nitrogen, phosphorus and potassium fertilizers should be reduced. In other words, if you want to raise roots well, you must control the amount of fertilization. As we all know, nitrogen, phosphorus and potassium are all inorganic salts, which have the characteristics of burning roots. The more they are used, the more serious the root damage will be. Vegetables need more organic nutrition in the middle and late stages, and mineral nutrition should decline at this time. It is necessary to strengthen leaf nutrition and protect leaves: the absorption capacity of roots is weak, the supply of nutrients in leaves should be strengthened, and leaves should be protected at the same time to make them slowly aging. If the senescence of leaves is delayed, the function of leaves will produce more hydrated compounds, thus ensuring the synthesis of organic nutrition. The temperature should be controlled well: because after entering the middle and late stage, the temperature has picked up. Therefore, the temperature management during this period must be done well, and vegetables should not be in the high temperature management stage for a long time. As our vegetable farmers know, when the temperature is high, the seedlings grow fast, but if the temperature lasts too long, the aging of the seedlings will also accelerate. Because each vegetable has its own suitable growth temperature, such as tomatoes, the most reasonable temperature for coloring period is 26 degrees Celsius, and if it exceeds 28 degrees Celsius, the quality will be affected. Pest control should keep up: as mentioned earlier, this period is also a period of high incidence of pests and diseases. Therefore, plant protection measures for disease prevention and pest control must also be in place. In the middle and later period of greenhouse, these five management tasks are the focus and core of management. Specifically, the management of each vegetable is carried out around these five management points.

Three, the specific management measures of different types of vegetables

Knowing the growth characteristics and management points of vegetables in the middle and late stage, we can formulate specific management measures for different types of vegetables:

1, tomato management measures in the middle and late stage

At this stage, tomatoes are just in the coloring period and harvest period. So the core of management is to turn the color evenly and keep the leaves from aging slowly.

Control the amount of nitrogen, phosphorus and potassium: In order to improve the quality, color change and taste of tomatoes in this period, it is not recommended to use all water-soluble fertilizers again in principle. In the early stage, the water-soluble fertilizer with low nitrogen, medium phosphorus and high potassium should be used at most once if the topdressing is less or the fruit is small. It is suggested that the ratio of nitrogen, phosphorus and potassium is about 6- 10-28. If topdressing is sufficient in the early stage, there is no need to topcoat water-soluble fertilizer. Bacon work should be strengthened: bacon work should be strengthened while controlling the amount of large elements. It is suggested that every water should be flushed with water, and the root system should be cultivated and fertilized to release the solidified nutrients in the soil and improve the utilization rate of fertilizer. Adjust the ratio of calcium and potassium: The purpose of adjusting the ratio of calcium and potassium is to promote coloring and fruit expansion. In other words, let the color change quickly. Organic potassium and chelated calcium can be sprayed on leaves to supplement organic potassium, promote coloring and prevent poor coloring; By supplementing calcium chelate, the problem of tomato fruit cracking can be prevented. Prevention and control of pests and diseases is the core: during this period, the most common diseases of tomatoes are higher fungal diseases gray leaf spot and leaf mold. However, this year's climate is special, and we should also do a good job in preventing late blight. It is suggested that the effective components of the medicament are difenoconazole+pyraclostrobin+Chunlei propamocarb, and these three components are combined to prevent diseases. Insect pests are mainly lice, and whitefly is a very serious pest on tomatoes. For whitefly, pesticides containing active ingredients such as pymetrozine+fenobucarb+dinotefuran can be selected for control. This scheme can only be used once, because the validity period can reach 12~ 15 days after one time. 2. Management measures of cucumber in the middle and late stage

At present, cucumber is in full bloom, that is, the full bloom of picking. Although topdressing is still needed during this period, in principle, the amount of fertilization should be reduced at full flowering stage. The core management work in the peak picking period is to use organic fertilizer to ensure cucumber yield.

Water and fertilizer management measures: Nitrogen, phosphorus and potassium water-soluble fertilizers should be used once every three times. It is recommended to use a balanced water-soluble fertilizer with the ratio of nitrogen, phosphorus and potassium of18-18, with a minimum of 5 kg per mu. For the remaining two times, it is not recommended to empty water, either raise roots or use organic water-soluble fertilizer to flush swollen melons. Foliage fertilizer: We pay attention to adjusting the ratio of calcium and potassium for tomatoes, and the foliar fertilizer for cucumbers is swollen melons. It is suggested to use small bottles of organic water-soluble fertilizers containing bioestrogens and chelated medium and trace element fertilizers. Pest control: two higher fungal diseases, target spot disease and anthracnose, are the main diseases of normal cucumber in this season. It is suggested that the effective components of difenoconazole+prochloraz+thiram+thiophanate-methyl should be selected for control. This year's climate is special, downy mildew and bacterial diseases are still quite serious, and the effective ingredients can be selected from Cyanazole+Chunlei? Propamocarb has no problem in preventing and controlling it. During this period, the pests of cucumber are mainly thrips, especially eggplant and pepper. For thrips, a drug containing emamectin benzoate+plant essential oil adjuvant can be selected as the effective ingredient, and sprayed around the evening to control thrips. Temperature control: It's not that cucumber can't be managed at high temperature now, but that there is a time limit for high temperature management. The longest high temperature management should be controlled within 7 days, which means that a week's high temperature management will reduce the temperature. During this period, the most suitable growth temperature of cucumber is 30~32℃, and the principle is not to exceed 34℃. 3. Management measures of melon in the middle and late stage

This is the first melon, and we are beginning to enter the stage of leaving two melons. The pollination of the second-crop melon is carried out after the first-crop melon expands, so the management of the second-crop melon should be strengthened after the first-crop melon is harvested.

Water and fertilizer management: In principle, we do not recommend NPK for melons in the second season. What should we use? For the first time, root fertilizer is applied with water; Second, in the second crop of melon expansion period, organic water-soluble fertilizers containing amino acids should be applied to strengthen organic nutrition.

Foliage fertilizer: the second crop of melon is coming, and the core is foliar fertilizer: first, protect the leaves and prevent them from aging; The second is to supplement calcium to prevent melon cracking. It is suggested that water-soluble fertilizers containing amino acids and chelated calcium should be sprayed on the leaves. Tomatoes adjust the ratio of calcium and potassium, and melons focus on calcium supplementation to prevent melon cracking.

Pest control: Powdery mildew is the main pest of melon in this period. If you want to keep the second crop of melon, you must thoroughly control powdery mildew, and you can choose the effective components of pyraclostrobin and hexaconazole for control. In this season, as the temperature rises, bacterial diseases such as Fusarium wilt will be no problem as long as there is enough ventilation. If powdery mildew has been particularly serious, it would be better to add plant essential oil additives to the previous agents.

4, eggplant, beans, peppers in the middle and late management measures.

These three crops all belong to vegetables with continuous flowering and fruit setting, so the management is similar. For crops that continue to blossom and bear fruit, it is still in the stage of continuous flowering and bearing fruit and high yield during this period. The management mainly focuses on the following aspects:

Flower promotion is the core: for vegetables that continue to bear fruit and blossom, flower promotion is more important than root cultivation at this period. In order to ensure the yield in the full fruit period, flower promotion is particularly critical. When watering, the water-soluble fertilizer with nitrogen, phosphorus and potassium content of about 12- 15- 13 can be applied at one time, which is different from other vegetable crops. Top dressing: Because the temperature is already very high, it is not recommended to use high potassium fertilizer, and balanced fertilization is needed. And after the temperature rises, you must remember to supplement calcium while using balanced fertilizer. It is suggested that the balanced water-soluble fertilizer with the ratio of nitrogen, phosphorus and potassium of18-18 should be 5 kg per mu and 2 kg of calcium chelate. During this period, the demand for fertilizer began to decline. There is no need to topdressing so much, but we must not give up the work of promoting flowers. Rooting: after the management of promoting flowering and topdressing of vegetables that continue to bloom and bear fruit. The next step is to raise roots. When watering and fertilizing, the principle is to water the flowers first, then use the balanced fertilizer for the second time, and use the root fertilizer for the third time, which is enough. Improve commodities: improve commodities, that is, improve brightness. Organic potassium+chelated calcium+micro-fertilizer in amino acids should be sprayed on the leaves once every 5-7 days, and can be sprayed 2-3 times according to the seedling situation. In this way, the gloss will be improved, and the goods will be fine, ensuring that you can sell more money. Moreover, it can also prevent some problems that are easy to occur at high temperature, such as eggplant and pepper, sunburn and navel rot, bulging beans or rat tails that are easy to appear in beans. 5. Management measures of leafy vegetables in the middle and late stage

Leafy vegetables, such as lettuce and celery, are relatively simple to manage in the middle and late stages. It is no problem to use high nitrogen, low phosphorus and low potassium when topdressing.

After understanding the growth characteristics and management points of greenhouse vegetables in the middle and late period, according to the above management measures for different types of vegetables, the commercialization of products will be greatly improved while achieving high yield.