First, the symptoms of premature aging of tomatoes
The premature senescence of tomato is mainly characterized by short plants, slow growth, slender stems and few side branches; Tomato leaves are small and yellow, and some leaves have raised tumors; The flowering and fruiting time is ahead of schedule, accompanied by serious phenomenon of falling flowers and fruits, small fruits, uneven coloring, prone to deformed fruits, reduced plant stress resistance and other symptoms.
Second, the causes of premature senescence of tomatoes
The premature senescence of tomato is mainly caused by continuous cropping obstacle, improper use of fertilizer and water, excessive length control and unreasonable hormone application.
1, continuous cropping leads to premature aging.
Tomato is a vegetable that is not suitable for continuous cropping. However, due to some factors, continuous cropping is widespread in vegetable growing areas at present. Years of continuous cropping have caused serious problems such as soil hardening, pests and diseases, and the first one is the impact on tomato roots. Root system can't grow normally and absorb water and nutrients, which is one of the main reasons for premature senescence of tomato.
2, premature aging caused by improper management of fertilizer and water.
The premature aging caused by improper fertilizer and water mainly has the following aspects: First, it does not pay attention to the application of organic fertilizer. Many vegetable farmers are willing to invest in chemical fertilizers, but they often ignore the application of organic fertilizers. At present, excessive application of chemical fertilizer is a common phenomenon, which leads to soil hardening and reduced permeability, affects the normal growth and development of roots, and then causes premature aging of tomatoes. The second is premature aging caused by fertilizer removal and dehydration. High temperature and drought without timely watering and fertilization, excessive crouching of seedlings and extensive management of fertilizer and water will all lead to premature senescence of tomatoes. Third, excessive watering and fertilization at one time will increase the concentration of solution in the soil, hinder the respiration and absorption of roots, and cause premature aging.
3. Improper temperature and humidity control will lead to premature aging.
Too high or too low temperature will have an adverse effect on the growth and development of tomato plants, especially when the temperature exceeds 33℃ for too long, the plants are prone to grow point distortion, middle and lower leaves curl and other phenomena, which are important factors leading to premature aging of tomatoes.
4. Excessive growth control at seedling stage leads to premature aging.
Early seedling raising or late harvest of previous crops leads to unreasonable sowing time and long seedling stage. Many vegetable farmers take measures such as water control, fertilizer control and temperature control to control seedlings, which may form small and old seedlings and cause premature aging.
5, premature aging caused by improper use of hormones.
In the process of tomato growth and development, in order to prevent overgrowth or promote flowering and fruiting, vegetable farmers like to use spraying chemicals, such as paclobutrazol, chlormequat chloride, chlormequat chloride and so on. In the process of using these chemicals, if the concentration is too high or the drugs are used repeatedly, it is easy to form aging seedlings and cause premature aging of tomato plants.
Third, measures to prevent premature senescence of tomato and prolong fruiting period
1, reasonable rotation
Tomato is a crop that is not suitable for continuous cropping. For premature senility caused by continuous cropping obstacles, rotation system can be implemented with spinach, leek, onion and other crops.
Step 2 sow at the right time
Protected cultivation, seedling age is generally 60~70 days in spring, 30~35 days in autumn and 40~45 days in autumn and winter. The suitable sowing date should be determined according to the stubble, so as to prevent premature aging caused by the influence of too long seedling age and large seedling size on its normal growth.
3. Control the suitable temperature and humidity environment of tomatoes.
Generally, the temperature of tomato cultivation in greenhouse is controlled at 25~28℃ during the day, with the highest temperature not exceeding 30℃, 15~ 17℃ at night and the lowest temperature not lower than 8℃ in the morning. Generally, the temperature difference of tomato in different growth and development stages is slightly lower than the main control standard 1~2℃, and the fruit development period is slightly higher than the main control standard 1~2℃.
Tomatoes need relatively dry air to grow, blossom and bear fruit. Therefore, on the basis of ensuring the normal growth and development of tomatoes, the humidity in the greenhouse should not be too high, otherwise it will breed and spread various tomato diseases. The relative humidity of air should generally be kept at 50%~60%.
4. Reasonable water and fertilizer management
(1) Increase the application of organic fertilizer and bacterial fertilizer.
Tomato is a kind of crop with high fertilizer demand and consumption. While ensuring the nutrients needed for tomato growth, the application amount of organic fertilizer and biological fertilizer should be appropriately increased, the number of soil organic matter and biological population should be increased, the soil permeability and water and fertilizer retention capacity should be improved at one time, and an environment suitable for tomato root growth should be created.
(2) Fertilizer and water management
Before the fruit expansion period, the growth of tomato plants was mainly vegetative growth, and after entering the fruit development period, it changed from vegetative growth to vegetative growth and reproductive growth. According to this characteristic, irrigation and topdressing should be properly controlled in the early stage, the supply of fertilizer and water should be appropriately increased in the middle and late stage, and the soil should be kept moist frequently. Generally, water every 8~ 10 days 1 time, and control the amount of water each time. It is not advisable to flood irrigation with large water, but to irrigate with small water frequently.
When fertilizing, when the first ear fruit begins to swell, combined with watering the fruit-promoting fertilizer, about 20 kilograms of fully water-soluble compound fertilizer and polypeptide compound fertilizer are applied per mu, and 20 kilograms are applied per mu when the first ear fruit is harvested. In the full fruit stage of tomato, combined with spraying, spraying 0.5~ 1% potassium dihydrogen phosphate+bumper harvest 1 and Dayun 120 on the leaves for 2~3 times has a good effect on delaying senescence and improving fruit quality.
5. Adjust the growth of plants
Attention should be paid to the number of fruits left in the flowering and fruiting period, so as to adjust the balance between vegetative growth and reproductive growth, avoid excessive consumption of nutrients caused by excessive fruits, and make the plants enter the premature aging period in advance. In addition, timely harvesting is also an effective means to prevent premature aging and prolong the harvest period, especially the harvesting of the first ear fruit, which can effectively prevent premature aging of plants and promote more fruits.
6, timely pruning and picking leaves, maintenance of leaves.
According to the growth and development of plants, vines should be hung, cut, forked, tied and cored in time. Most varieties with limited growth adopt the method of single stem pruning when improving, and each plant leaves 4~5 ears of fruit and then picks the core; Infinitely growing varieties adopt the method of single stem pruning, and each plant leaves 2~3 ears of fruit and then picks the core. When picking leaves, it depends. Many vegetable farmers like to promote the habit of fruit discoloration by thinning leaves. If the leaves are removed too much, it will not help the fruit to swell and change color. Therefore, when picking leaves, leave enough leaves according to the number of upper fruits, and spray amino acids and chitin foliar fertilizer regularly to supplement nutrition.
7. Do a good job in pest control.
Prevention should focus on the prevention of pests and diseases, especially early blight, late blight, gray mold, bacterial spot disease and so on. And attention should be paid to early prevention and early treatment to control the spread of the disease as soon as possible. When the disease occurs, targeted chemicals should be selected, such as Kaiser, chlorpheniramine and fludioxonil. Early blight can be controlled by iprodione and polyoxin. Late blight can be controlled by Shannon 1, cyazofamid and dimethomorph. Bacterial maculopapulosis can be prevented and treated with basic copper sulfate, amber, copper thiamethoxam, copper quinoline, zinc thiazole, copper collophosphate and copper chloramine. When spraying medicine, combined with chitin, amino acids and other foliar fertilizers, the leaf resistance can be improved and the effect is obvious.
The premature senescence of tomato is closely related to continuous cropping, unreasonable fertilization, phytotoxicity, pests and diseases. Through comparative analysis, the causes of premature senescence were found out, and then reasonable preventive measures were taken to prevent premature senescence of tomato plants, prolong its fruiting period as much as possible, and improve the economic benefits of vegetable farmers.