2. Generally, strong seedlings are cultivated in sunny beds, greenhouses, small and medium-sized arch sheds or greenhouses from late June to early February in the Central Plains of 65438+, and the seedlings need to be heated in areas with early seedlings or cold weather. At present, most tomato seedlings are raised by two-stage method, that is, when two leaves are combined, seedlings are raised, and after seedling separation, large seedlings are raised in large pots (10cm× 10cm) or sparse plants (10cm× 10cm). Measures to cultivate strong seedlings in the open field in spring include:
(1) Soak seeds to accelerate germination. Before sowing, put the seeds in warm water with a temperature of 50-55℃, keep stirring until the water temperature is about 30℃, soak them for 3-4 hours, take them out, dry the skin moisture, wrap them with clean wet cloth, and accelerate germination at 25-30℃ for 3-4 days.
(2) The nutrient soil used for seedling raising before and after seedling division must be carefully prepared. Six core soil samples, preferably loam, and four decomposed and crushed organic fertilizers (such as pig manure, chicken manure, etc.) were selected from field crop plots without pests and diseases. ), adding 65438+/-0 kg compound fertilizer of nitrogen, phosphorus and potassium per cubic meter, and then fully mixing. In order to prevent the spread of pests and diseases in the soil, 200 grams of "Chongchiling" and 100 grams of "trichlorfon" can be mixed per cubic meter. Put the prepared nutrient soil into the seedbed or bowl, water it and dry the surface moisture. You can sow seeds or divide seedlings.
(3) Sow in time and strengthen seedling management. The suitable sowing time is when more than 80% seeds germinate. After sowing, cover about 0.5cm of dry fine soil, not too thick. Temperature management at seedling stage has great influence on the growth and development of tomato. Tomato is a thermophilic crop, and the flower bud differentiation period begins with two leaves and one heart. If the night temperature at seedling stage is lower than 12℃ for a long time, it will affect flower bud differentiation and produce many abnormal fruits. Tomato seedlings can be managed at variable temperature, that is, the temperature is 28-30℃ during the day; The daytime temperature is about 25℃ from the first seedling stage to the first seedling stage, and the nighttime temperature of the whole seedling stage 15- 18℃ should not be lower than 12℃. The purpose of water and fertilizer management is to prevent seedlings from growing too vigorously. After the nutrient soil is prepared, no seedling fertilizer is applied in the whole seedling stage, and water is used as little as possible to avoid flooding. When the soil is dry, you can spray water or sprinkle fine soil on the bed surface to keep moisture. To cultivate strong seedlings, we should see more light, whether it is rain or shine, rain or snow, we should uncover the grass cover during the day and let the light shine at all times. We should also do a good job in the prevention and control of seedling diseases such as sudden lodging and sudden lodging. The standard of strong seedlings is: the stem is about 0.5cm thick, the leaves are 7-8, and the buds are big.
3. Careful soil preparation, timely early planting, selection of plots where solanaceous fruits have not been planted for 4-5 years, and deep ploughing in winter are beneficial to seedling growth and reduce pests and diseases. Careful soil preparation should be carried out about 7 days before planting, and foot fertilizer and water should be applied in combination with soil preparation. Generally, 667m2 of decomposed organic fertilizer (5-7m3 soil miscellaneous fertilizer, or 3-5m3 pig manure, cow dung, etc.) is applied. ) and 50-80 kilograms of NPK compound fertilizer, and at the same time, 2 kilograms of "Tujundan", 2-3 kilograms of "Ligenzha" or "thread control" are used to control soil-borne diseases and root-knot nematodes.
Timely and early planting can make open-field tomatoes bear fruit and come to market early in spring, and at the same time reduce the harm of virus diseases. Sowing can be done in the first half of April in the Central Plains. When sowing, it is necessary to choose big seedlings and strong seedlings first, which is the basis of early maturity. Planting adopts wide ridges (ridge width 1-2m), with 2 rows per ridge. 3,500-3,800 plants were planted in the self-capped early-maturing variety 667m2, and 3,000-3,500 plants were planted in the infinite-growing middle-late-maturing variety 667m2. When planting, it is necessary to damage the roots less and bring more soil, which not only has a high survival rate, but also shortens the slow seedling stage. Avoid flooding after planting, but pour the planting water into the pit. Plastic film mulching can be used 2-3 days before planting to improve the ground temperature.
4. Strengthen on-site management
(1) Intensive cultivation and soil culture can promote the robust growth of plants. In May and June, the temperature and ground temperature rose sharply. Tillage and soil cultivation can loosen soil and conserve moisture, reduce ground temperature, improve soil physical and chemical properties, and be beneficial to root growth.
(2) The water and fertilizer management method of timely watering and topdressing is to control first and then promote. Spring tomatoes grow fast and have high yield, which requires a lot of water and fertilizer, and adequate water and fertilizer is the guarantee of high yield. Before the first ear is set, the temperature is still very low, so water and fertilizer can be controlled to prevent vigorous growth. After the first ear of fruit is set, topdressing should be done in time. About 25kg NPK compound fertilizer should be applied to 667m2, or 500kg decomposed and crushed chicken manure, or fermented and crushed cake fertilizer 150kg. Water after ditching and burying. The second topdressing (667m2 diammonium phosphate 15kg, or 20kg NPK compound fertilizer) can be applied after the second ear fruit sets, and the third topdressing is required for the middle and late-maturing varieties after the second ear fruit is harvested. Watering in time every time topdressing, especially after May-June, when the dry-hot wind is serious, you can use deep wells to water at night to reduce the ground temperature, improve the microclimate, reduce viral diseases and promote the robust growth of plants.
(3) Unlimited early-maturing varieties with high cultivation density and flowering can be pruned separately; Thinning can be carried out by using self-capped varieties or infinite mid-late maturity varieties. The temperature of spring tomato is low in the early stage and high in the late stage, which is not conducive to pollination and fertilization, and it is not easy to set fruit, so artificial assistance is needed to protect flowers and fruits. You can spray flowers with tomato essence or dip them in 2.4-D solution.
(4) Strengthen the prevention and control of pests and diseases Spring tomatoes should pay attention to the prevention and control of virus diseases, especially during the high temperature and drought period from May to June, and the prevention and control of virus diseases should start from the time of planting. Every 7- 10 days, add "Jianzhibao 30ml ++ Kang Run No.2 2 2 tablets+Wanshuai 1 No.30g" to water 15kg, and at the same time, prevent and control the spread diseases such as aphids. Leaf mold, early blight and gray mold are more likely to occur in the early stage of low temperature, which can be prevented by spraying goodwill or Jianzhibao, and spraying "Lan Chao" or "Lvsujing" in time after onset has excellent effect. Attention should be paid to the prevention and control of powdery mildew in the late period of high temperature and drought, and anthracnose and other diseases should be prevented in time when it is high temperature and high humidity. The control effect of Lvsujing or krupa is excellent.