1. Select good varieties of tomato cultivation in spring field should choose high-yield, high-temperature and high-humidity, high resistance to virus disease and root-knot nematode-resistant varieties, those who require early maturity should also choose medium-early maturity or self-capped type varieties, such as Jinfen No.2, Jinfen Early pink, etc .; selected late-ripening infinite varieties with long picking period are required. Base tomato cultivation should also choose thick-skinned and hard-meat-resistant varieties. Fandu 80, Fandu Golden Crown King, Xinxing No.2, Fandu Rookie, Fandu Pioneer, Yuxing 1887, Red General, Tianwang Superstar, Yuxing 2298, etc. selected by Henan Agricultural University Yuyi Seed Industry are suitable for spring Open field cultivation.

2. Cultivation of strong seedlings In the central plains of late January to early February, impotence, greenhouses, small and medium-sized arch sheds or greenhouses are used for seedling cultivation. In areas where seedlings are raised earlier or the weather is cold, seedlings need to be warmed. At present, tomato seedlings mostly adopt two-stage seedling cultivation method, that is, seedlings are divided when the two leaves of the seedlings are centered, and after the seedlings are divided, large bowls (10cm × 10cm) or sparse plants (seed spacing 10cm × 10cm) are used to grow large seedlings. Cultivation measures for spring field cultivation include:

(1) Soak seeds in 50-55 ℃ warm water before soaking to promote germination. Stir continuously until the water temperature is around 30 ℃ and soak for 3-4 hours. After removing, dry the epidermal moisture and wrap with a clean wet cloth. Germinate at -30 ° C for 3-4 days.

(2) Nursery nutrient soil used before and after seedling preparation must be carefully prepared, and 6 core soils of field crop plots without pests and diseases are selected. Loam is preferred, and organic fertilizers (such as pig fertilizer, Chicken dung, etc.), and add 1kg of N, P, K compound fertilizer per m3 and mix well. In order to prevent soil-borne diseases and insect pests, 200 g of "stubble spirit" and 100 g of "trichlorfon" can be evenly mixed per m3. The prepared nutrient soil is placed in a seedbed or a bowl, and the surface water is dried after being watered, and the seedling can be sown or divided.

(3) Sowing at the right time. Strengthen seedling management. When more than 80% of the seeds to be germinated are exposed, it is the appropriate time for sowing. After sowing, cover the dry fine soil with about 0.5cm, and do not cover the soil too thick. Temperature management at seedling stage has a great impact on tomato growth and development. Tomato is a high-temperature crop. The flower bud differentiation period begins with two leaves and one heart. For example, if the night temperature at the seedling stage is lower than 12 ℃ for a long time, it will affect flower bud differentiation, and there are many deformed fruits. Tomato seedlings can be managed by temperature change, that is, seeding to seedlings with a temperature of 28-30 ° C during the day; seedlings to planting at a temperature of about 25 ° C during the day, and the night temperature of the entire seedling period is 15-18 ° C, which cannot be lower than 12 ° C. Water and fertilizer management is to prevent the growth of seedlings. After the nutrient soil is matched, no seedling fertilizer should be applied throughout the seedling period. Minimize watering. Avoid flooding with large water. When the soil is dry, spray water on the bed or sprinkle fine soil to protect it. . Cultivate strong seedlings to see more light, no matter it is sunny, rainy or snowy, the grass must be exposed during the day and the light is always transmitted. It is also necessary to do a good job in controlling seedling diseases such as catastrophic and blight. The standard for strong seedlings is: stem thickness about 0.5cm, 7-8 leaves, with large flower buds.

3. Careful land preparation, timely planting and selection of plots that have not been planted with solanaceous fruits for 4-5 years, and deep turning in winter, which is conducive to seedling growth and reduce pests and diseases. About 7 days before planting, meticulous land preparation should be carried out, combined with applying ground fertilizer and watering. Generally, 667m2 of organic fertilizer (5-7m3 of soil mixed fertilizer, or 3-5m3 of pig dung, cow dung, etc.), 50-80kg of nitrogen, phosphorus, and potassium compound fertilizer, and 2kg of "bendam", "ligan sand" or "Line treatment" 2-3kg to prevent soil-borne diseases and root-knot nematodes.

Prompt planting in time can make the tomato in spring dew field bear fruit early and market in the morning, and at the same time can reduce the virus disease damage. The Central Plains can be planted in early to mid-April. When planting, first pick large and strong seedlings, which is the basis of precocity. Planting uses wide ridges (ridge width 1-2m), 2 rows per ridge. Self-capped early-maturing varieties of 667m2 were planted at 3500-3800 plants, and infinitely growing mid-late maturing varieties of 667m2 were planted at 3000-3500 plants. When planting, less root injury and more soil are needed, which not only has a high survival rate, but also shortens the slow seedling period. After planting, avoid flooding with large water. Cover with mulch for 2-3 days before planting to help raise ground temperature.

4. Strengthen field management

â‘  Cultivate and cultivate the soil, promote the robust growth of plants. The temperature and ground temperature increase sharply in May-June. The soil can maintain soil retention, reduce ground temperature, improve soil physical and chemical properties, and promote root growth.

â‘¡ Watering and topdressing water and fertilizer management method is to control before and after. Spring tomatoes grow fast, have high yields, require large amounts of water and fertilizer, and sufficient water and fertilizer is a guarantee for high yield. The temperature is still low before sitting in the ears, so you can control water and fertilizer to prevent growth. * Fruit topdressing should be carried out in a timely manner after the ears are seated. 667m2 of N, P, K compound fertilizer is about 25kg, or 500kg of rotten and crushed chicken manure, or 150kg of fermented and crushed cake fertilizer. After the second ear is settled, a second top dressing (15 kg of 667 m2 of diammonium phosphate, or 20 kg of N, P, and K compound fertilizers) can be performed. The middle and late maturity varieties need a third top dressing after the second ear is harvested. Watering should be done in time for each topdressing, especially after entering into May-June, dry hot wind is severe. You can use deep well water to irrigate the ground in the evening, in order to lower the ground temperature, improve the microclimate, reduce virus disease, and promote the healthy growth of plants.

â‘¢ Pruning and flower-preserving results: Infinite-type early-maturing cultivars can be single-pruned with large cultivation density; self-capped varieties or infinite-medium-late maturing cultivars can be used with double-dried pruning. Spring tomato's low temperature in the early stage and high temperature in the later stage are unfavorable for pollination and fertilization, and it is not easy to set fruit. You can use tomato spirit spray or dip flowers with 2.4-D solution.

â‘£ To strengthen the prevention and control of pests and diseases of spring tomatoes, we must attach great importance to the prevention and control of viral diseases, especially during the high temperature and drought period from May to June. The viral diseases are serious. The prevention and control of viral diseases should start from the time of planting. Jianzhibao 30ml + Kangrun No. 2 2 tablets + Wan Shuai No. 1 30g "against water 15kg once to prevent and control aphids and other pests that spread the disease. Early low temperature, leaf mold, early blight and gray mold are more likely to occur. It can be sprayed with good intention or Jianzhibao to prevent it. Spraying "blue tide" or "lusujing" in time after the onset have excellent results. In the later period of high temperature and drought, attention should be paid to the prevention and control of powdery mildew. In high temperature and high humidity, timely prevention and treatment of diseases such as anthracnose, Lu Sujing or Corumba have excellent control effects.

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Trauma Cannulated Screw

Cannulated screw is a common internal fixation device in orthopedic surgery.

Working process

During the operation, the Kirschner wire with the hole matching the hollow screw is first drilled into the bone of the fracture site, and then the hollow screw is screwed into the fracture site through the guidance of the Kirschner wire. Finally, the Kirschner wire is pulled out to complete the fixation of the fracture site. In many cases of fracture of the neck and femur, the healing cycle is long, and it usually takes about 30 months to remove the cannulated screws. At this point, the bone and the surface of the cannulated nail are closely connected and firmly connected in the nail path, which leads to defects easily generated by conventional nail removal methods, causing secondary injury at the fracture healing site and causing pain to the patient. Percutaneous cannulated screw internal fixation for femoral neck fractures has the advantages of small trauma, good healing, low rate of femoral head necrosis, and good stability.

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