Detailed analysis of incurable diseases during flowering period of tomatoes in greenhouses (二)

5. Five major causes and countermeasures for falling flowers

(1) The temperature is too high or too low: the temperature is too high or too low will cause the defects of the flower organs, which will cause the flowers and fruits to fall. Data show that tomatoes will cause a lot of flower drop when the night temperature is lower than 15℃ or higher than 22℃, and the daily temperature is higher than 35℃.

Countermeasures: The temperature during the flowering period should be controlled so that the daytime temperature is about 28°C, not more than 35°C, and the night temperature is about 20°C, not more than 22°C. When the temperature is too high, it is recommended to use shading nets or cooling agents for cooling. However, in the morning and evening, the temperature in the shed is suitable for tomato growth, and the sunshade net should be removed in time. When the lowest temperature in the shed drops below 15°C, straw curtains should be covered in time for heat preservation.

(2) Vigorous growth of plants: The high temperature and humidity of the greenhouse can easily lead to vigorous growth of plants, which will eventually cause flower and fruit drop, especially in rainy weather, which will increase flower and fruit drop. It mainly occurs on the 1-2 spikes, so pay attention to control.

Countermeasures: First of all, to reduce the temperature and humidity in the shed, widen the temperature difference between day and night, we can adopt shading nets, increase the discharge of bottom wind, and water frequently. Second, we must control the amount of nitrogen fertilizer. Control the prosperous growth again to increase the fruit set rate.

(3) Improper soil and air humidity: Too much or too low moisture will cause flowers and fruits to fall. If the soil moisture is too much, it will easily cause excessive growth, resulting in falling flowers; if the lack of moisture causes soil drought, it is easy to cause the formation of a separation layer, resulting in a large number of falling flowers and fruit.

Countermeasures: During the flowering and fruiting period, the soil moisture content should be maintained at about 75%, and timely ventilation and dehumidification should be provided to reduce the air humidity and keep the relative humidity of the air at about 60%. Pay attention to frequent irrigation with small water, not flooding with large water, to prevent the roots from being "fried" by the ground temperature and the cold well water, which may cause physiological diseases such as yellow leaves.

(4) Improper plant adjustment: The first 2-3 ears of tomatoes retain too much fruit, which leads to the enlargement of the concentrated nutrient supply and the serious flower and fruit drop in the upper tribe.

Countermeasures: It is recommended to adopt single stem pruning, leaving more than 5 ears of fruit per plant. The first ear fruit can leave 3 fruits; after the second ear fruit, 3-4 fruits per ear are left, and the excess is removed. Wipe off the side buds and thin the flowers and fruits in time to keep the fruits large and even. It is also necessary to supplement nutrients in time, concentrate nutrient supply, and prevent serious flower and fruit drop in large areas.

6. Reasons for flowering but not fruit setting and countermeasures

Symptoms:

The specific manifestations are: some tomatoes have only a small amount of fruit per panicle, or some flower buds are not fully differentiated, some flowers only differentiate into sepals, but not well differentiated pistils, stamens and pollen, and some flowers may be yellowish in color Or it is white, and some flowers may fall without a little bit.

Main harm:

After the tomatoes can’t hold the flowers, it will cause the tomato plants to grow too vigorously and vegetatively grow, the leaves will be large and thick, the stems will grow tall, and the nutrients will be absorbed. As a result, the nutrients absorbed by the reproductive organs such as flowers and fruits will be reduced. Will be greatly reduced, reproductive growth will be insufficient, resulting in the flower buds can not differentiate normally, thereby affecting the normal growth of tomatoes. That is to say, the situation of "prosperous trees without fruit set" appeared.

Cause Analysis:

The main reasons for this situation are as follows:

(1) Excessive vegetative growth. The reasons for its formation are as follows:

① The temperature is too high. The temperature in the greenhouse is high, especially when the night temperature is high, the tomatoes will grow quickly, the stem joints are fast, the joints are long, and it is not easy to set fruit.

② Improper supply of nutrients. If the tomato is applied with too much fertilizer, especially nitrogen-containing fertilizer, it will make the plant absorb too much nutrient, and the plant will easily grow too vigorously.

③ Hormonal effects. Farmers now use fast-acting foliar fertilizers, which may contain certain growth-promoting hormones. If they are used too many times, tomatoes will grow too fast, resulting in unbalanced nutrition and excessive growth of plants.

(2) High temperature affects flower bud differentiation: According to the research results, tomatoes encounter high temperature during the flower bud differentiation period, which will affect the normal differentiation of tomato flower buds, and the occurrence of inflorescence abortion and fruit failure or failure to complete normal pollination. Abnormal development of flowers or fruits.

Responses

(1) Temperature management. The temperature in the shed should not be too high. During the day, it should not exceed 30 degrees Celsius. If the temperature is 35 degrees Celsius for more than 2 hours, it will affect the flower bud differentiation of tomatoes. It is usually 12 to 14 degrees Celsius at night, especially the temperature should not be too high at night, otherwise stems will appear. When the stalk is elongated, it is easy to fall flowers. The temperature in the greenhouse can be lowered by spraying clear water in the shade. Choose to shade at noon on a sunny day and spray clear water every 1 to 2 days to lower the temperature in the greenhouse. As the temperature decreases, the flowers will gradually sit on the flowers.

(2) Plant adjustment. For non-self-capped tomatoes, single-stem pruning or double-stem pruning can be used. Take a single stem pruning, leaving about 6 ears per plant. The first ear fruit can leave 3 fruits; the second to the fifth ear fruit, each 3-4 fruit is left, and the excess is removed. timely erases the side buds and thins the flowers and fruits in time to keep the fruits large and even. Generally, 5-6 fruits are reserved for each ear of fruit. When the fruits grow to about 2 cm in diameter, the deformed fruits, diseased fruits and insects are removed, and 3-4 fruits are retained. However, the first two ears of tomatoes must not retain too much fruit, to prevent the swelling of the concentrated nutrient supply, leading to serious flower and fruit drop in the upper tribe.

(3) Supplement boron calcium foliar fertilizer. When the plant grows too fast or the temperature is too high, the water evaporates too fast and causes the lack of boron and calcium, which will lead to the insufficient absorption of boron and calcium by the crop. It is recommended to spray 1000 times of Jiamei Cerebellin, which can promote strength, preserve flowers, and expａnd fruits. It can significantly improve the stress resistance of crops. After spraying for 5-7 days, the leaves of the crops will be thick and oily, the flowers will be fresh and sturdy, and the flower stalk (or fruit stalk) will be thick; No fruit setting, slow swelling of young fruit, etc.

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