What measures do tomatoes take to protect flowers and fruits?

In view of the problems existing in tomato production in greenhouse, such as heavy falling flowers, difficult fruit setting and many deformities, it is suggested that vegetable farmers focus on the following technical points in order to achieve the purpose of protecting flowers and fruits.

(1) temperature and lighting condition control

During the flowering and fruit-setting period of tomato, the required temperature is 20 ~ 30℃ during the day, and the optimum temperature at night is 15 ~ 20℃. When the temperature in the shed is higher than 30℃, the air should be released in time to prevent the fruit from being abnormal due to excessive temperature; When the lowest temperature in the shed drops below 15℃, the straw curtain should be covered in time to keep warm. For tomatoes in spring and autumn, because of the drastic changes in weather and temperature in spring and autumn, it has a great influence on the flowering and fruit setting of tomatoes, which is easy to cause falling flowers and deformed fruits, so it is necessary to control the temperature in the shed. But at noon in summer, the intensity of sunlight far exceeds the illumination intensity of 30,000 ~ 35,000 lux required for tomato growth. Too strong sunlight can cause sunburn, and shading with shading net can also reduce the light intensity, which is beneficial to the preservation of tomato fruits. In the morning and evening, the temperature in the shed is suitable for tomato growth, and the sunshine intensity is not strong, which is just suitable for tomato flowering and fruit setting. Therefore, vegetable farmers should not cover sunshade nets during these two periods.

(2) Fertilizer and water management

Tomato is a crop with a large amount of fertilizer, which needs more fertilizer during the whole growth period, and the demand for fertilizer will increase greatly during the flowering and fruit-setting period of tomato, so topdressing should be carried out on the basis of applying sufficient base fertilizer. The principle of topdressing is to apply it thinly before fruit setting, and then apply it again after fruit hanging, and topdressing in stages. The ratio of nitrogen to potassium should be coordinated. If tomatoes lack boron fertilizer, it will easily lead to poor flower organ development, which will lead to flowers without fruit. Therefore, boron fertilizer should be sprayed on the leaves in time one week before flowering to promote tomato flower bud differentiation and protect flowers and fruits. During the flowering and fruiting period of tomatoes, plants need more water for growth, especially tomatoes cultivated in summer, so we should pay more attention to watering to ensure uniform water supply. Generally speaking, from the seedling stage to the first ear, sit still and water less properly to prevent the plants from growing in vain, resulting in falling flowers and fruits. The first ear fruit expands, and the second ear fruit is set, so that the watering times are increased, and the young fruit is watered in time when it expands.

(3) Plant regulation

For tomatoes that are not self-capped, single stem pruning or double stem pruning can be used. Take single stem pruning, leaving about 7 ears of fruit per plant. The first ear can leave three fruits; From the second to the fifth ear, leave 3 ~ 4 fruits per ear and remove the excess. Wipe off the side buds and sparse flowers and fruits in time to keep the fruits large and even. Generally, 5 ~ 6 fruits are left per ear. When the fruit grows to about 2 cm in diameter, it is necessary to remove abnormal fruits and pests and keep 4 ~ 5 fruits. However, too much fruit must not be left in the first few ears of tomato, in case the fruit expands when the nutrition is concentrated, resulting in serious flowering and fruit drop in the upper part.

(4) Hormone regulation

In production, plant growth regulators can be used externally to adjust the hormone balance in tomato plants, so as to achieve the purpose of protecting flowers and fruits. Hormone regulation technology three points:

① There are two main points to be mastered in stippling: one is to master the accurate concentration. The concentration can be higher when the temperature is low, and lower when the temperature is high. The second is to master the correct method of use. At 8: 00 ~ 10: 00 on sunny days, dip a small amount of liquid medicine with a brush, point it on the newly opened female flower pedicel or gently smear it on the pedicel. If the temperature in the shed is low and there are few open female flowers, you can order flowers every 2 ~ 3 days; If the temperature is high and the female flowers are in full bloom, you can order flowers once every 1 day or every day.

(2) Pay attention to three problems: First, point flowers at the right time. When there are 2 ~ 3 bloom flowers in the first ear, you can start to order flowers. When the petals of female flowers are fully unfolded and stretched into a trumpet shape, it is appropriate to point flowers. It is easy to form hard fruit too early, and it is easy to crack fruit too late. The second is that flowers don't repeat. Compound key flowers are prone to abnormal fruit and hormone poisoning, leading to poor growth of growing points. Third, be careful when you order flowers. If the liquid drops on buds, leaves and growing points, it is easy to cause drug damage, leading to atrophy or necrosis of the affected area.

③ Combination of flower-spotting and daily management: First, combination of flower-spotting and fruit thinning. The first flower of each inflorescence is easy to produce deformed fruit, so it should be thinned before dipping the flower. If there are too many flowers per panicle, the abnormal flowers and extra small flowers should be thinned out, and generally only 5 ~ 6 flowers should be left. If you spend too much, it will not only be labor-consuming, time-consuming and medicine-consuming, but also bring inconvenience to fruit thinning. After fruit setting, choose 3 ~ 4 fruits with regular shape, uniform size and no pests and diseases. If there are too many fruit sets, it will often lead to different fruit sizes, reduced single fruit weight and reduced fruit quality. Second, the combination of flowers and fruit protection with other cultivation management. After the fruit is set, the growth speed of the fruit is accelerated.

(5) Pest control

It is necessary to release air and remove humidity in time, adjust the temperature and humidity in the shed, strengthen the management of water and fertilizer, do a good job in pest control, promote fruit ripening and improve fruit yield and quality. The main diseases that harm tomato flowers and fruits are early blight, gray mold, canker, stripe virus and so on. It is suggested that chemical control should be done well. Early blight and gray mold are fungal diseases, and chlorothalonil, thiophanate-methyl or carbendazim are preventive drugs. Canker is a bacterial disease, and agricultural streptomycin or copper preparations (DT, copper, etc. ) for drug prevention. To prevent virus diseases, we can spray moroxydine, copper acetate (virus A) and ningnanmycin, and at the same time pay attention to the application of imidacloprid or acetamiprid to prevent the occurrence of pests such as whiteflies and aphids, because it is easy to spread the virus.