What is a black tomato? Do you have any techniques for growing black tomatoes?

Black tomatoes are native to South America and are treasures of the tomato family. They are named for their red and black fruit color. The fruit is used as medicine and food, has rich fruit fragrance, moderate sour and sweet taste, high nutritional value, especially suitable for fresh food; also contains a large amount of lycopene and rich vitamin C and antioxidants, which have the effects of nourishing yin, protecting kidney, whitening skin and reducing weight for women.

Black tomato, both medicine and food, is a treasure in the tomato family, with rich fruit flavor, high nutritional value, very sweet taste, especially suitable for fresh food, contains 10 times higher than red tomato lycopene and vitamin C and antioxidants, and easy to be absorbed by the body. Black tomatoes Black tomatoes mainly contain a large number of anthocyanins, which can produce strong biological effects in the human body, especially anti-cancer. Moderate consumption can revitalize the sexual function of men and women who have declined. Black tomatoes have the effect of nourishing yin and strengthening yang for men, reducing the risk of prostate cancer and heart disease in men.

(1) Nursery

When the planting period is determined, sow seedlings 60~70 days in advance. Seed disinfection is required before sowing. Black tomato seed coat is thin, thermal disinfection is easy to scald seeds, should be mainly chemical disinfection. Sowing should not be too dense, 25~35g seeds per square meter is appropriate, and 300~450g seeds per hectare are required.

Black tomato is resistant to transplantation, but due to the continuity of flower bud differentiation, it is not suitable to divide seedlings many times in the process of seedling raising. It is recommended to divide seedlings once and early, and divide them before the flower bud differentiation of 2~3 true leaves at the latest. It is better to divide seedlings in plastic nutrition bowl or paper tube. The temperature and ground temperature should be increased 2~3℃ after seedling division of black tomato to promote slow seedling. The seedling grows faster gradually after seedling growth. In order to prevent excessive growth, the seedling bed temperature should be 2~3℃ lower than that of seedling stage, but the night temperature should not be lower than 10℃. The moisture content should be kept dry and wet under the bed soil, and the light green of seedling heart leaves indicates normal moisture content.

Seedling training should be carried out before planting, gradually reducing the seedling bed temperature, especially at night. In the seedling training process, do not over-control water, in order to keep the sunny noon seedlings do not obviously withered Yan is appropriate, otherwise, seedlings easy to age.

(2) Soil preparation and basal fertilizer application

Choose deep, loose, fertile, well-drained soil to grow black tomatoes. In order to promote the deep development of black tomato roots, deep ploughing must be carried out. For winter fallow plots, deep ploughing 25~30cm can be carried out before freezing, and no harrowing can be carried out after ploughing, so as to facilitate soil weathering. Deep ploughing should be combined with increasing base fertilizer, generally 667 square meters of organic fertilizer 5000~7500kg. At the same time of applying basal fertilizer, it is better to mix calcium superphosphate with organic fertilizer, and apply calcium superphosphate 30~40kg per 667m. Black tomatoes can be cultivated in flat or high beds. In the arid areas or highly dense early-maturing cultivation in the north, flat ridges are suitable, generally 1.2~1.5m wide and 8~ 10m long. South and sufficient water irrigated land or low-lying waterlogging land should be used high ridge cultivation.

(3) Colonization and density

The planting period of spring black tomato in open field should be determined according to local climatic conditions. Generally, it should be planted after late frost, when the daily average temperature reaches above 15℃ and the ground temperature is stable above 10℃.

The planting density of spring-black tomato depends on varieties, pruning methods, length of growth period and other factors. The suitable density for close planting of early maturing varieties is 2800~3000 plants per 667 square meters, and that for medium and late maturing varieties is 2000~2500 plants per 667 square meters.

(4) Tillage, topdressing and irrigation

Black tomatoes should be cultivated in time after planting. Early intertillage and deep intertillage are beneficial to the improvement of soil temperature, rapid rooting and slow seedling growth. Intertillage should be carried out 3~4 times continuously, the depth of intertillage is shallower each time, and appropriate cultivation can be carried out to promote adventitious roots at the base of stems and expand root groups.

Black tomatoes need a large amount of fertilizer, in addition to heavy application of base fertilizer, but also according to the needs of quick-acting fertilizer topdressing. When the first fruit cluster begins to expand, combined with watering, one time of seedling-promoting fertilizer should be applied. 15~20kg urea, 20~25kg calcium superphosphate or 20~30kg diammonium phosphate can be applied per 667 square meters. 10kg potassium sulfate should be applied when potassium is deficient. 1000kg decomposed human excrement and 100kg plant ash can also be used instead of chemical fertilizer. When the second panicle and the third panicle began to expand rapidly, topdressing was applied once respectively. In addition to soil topdressing, it can be supplemented with root topdressing in the peak fruiting period, spraying foliar surface with 0.2%~0.5% potassium dihydrogen phosphate, or 0.2%~0.3% urea, or 2% calcium superphosphate aqueous solution, or spraying multiple compound fertilizer. 50~100μl/L boric acid or zinc sulfate can also be used for root spraying.

Black tomato has certain drought tolerance, but in order to obtain high yield, we must pay attention to water supply and regulation. 5~7 days after planting can be watered once, and then intertillage to preserve moisture, control watering, appropriate squatting seedlings. The middle and late maturing varieties blossom and bear late, and the vegetative growth is vigorous, so the water content should be controlled before fruiting. The water absorption of black tomato reached its peak at the peak of fruiting period. During this period, irrigation was carried out once every 4~6 days to keep the soil moist evenly throughout the fruiting period, prevent sudden dryness and humidity, and reduce the occurrence of fruit cracking and top rot. Black tomato on soil ventilation conditions are more strict, after rain should be timely drainage, to prevent rotten roots.

(5) Plant adjustment

Black tomato has the characteristics of luxuriant stems and leaves, strong branching power, rapid growth and easy to drop flowers and fruits. In order to adjust the balanced growth of various organs, improve the light and nutrition conditions, a series of plant adjustment measures should be taken in the cultivation process, such as erecting frames, binding vines, pruning, branching, picking cores, protecting flowers and fruits, thinning flowers and fruits, etc. Black tomato, except for a few erect varieties, all need to be cultivated on shelves. Generally, conical frames (triangular conical frames or quadrangular conical frames) are used, which is relatively simple and firm.

There are many ways of pruning black tomato, each has its own characteristics. The common ways of pruning in open field are single stem pruning, improved single stem pruning and double stem pruning. Single pruning, only retaining the trunk, all lateral branches removed. This method is suitable for dense planting, and can obtain higher yield per unit area under the condition of short growth period. The disadvantage is that the number of seedlings per unit area is too many, the root development is limited to a certain extent, and the plant is easy to premature. In order to overcome the above shortcomings, we can implement the improved single-stem pruning method, that is, on the basis of single-stem pruning, retain a lateral branch under the first inflorescence and leave a panicle fruit to pick the core. Similar to this kind of improved single pruning methods are various and can be flexibly applied according to cultivation needs. Double trunk pruning, in addition to retaining the main branch, and then leave a lateral branch under the first inflorescence, the rest of the lateral branches are removed. This pruning method, early yield is not as good as single pruning, and the fruit is late, suitable for longer growth period, vigorous growth of late maturing varieties. In the process of pruning, remove redundant branches, that is, beat the right. Too late branching will consume too much nutrients. In the early stage of plant growth, premature branching will affect the development of root system, especially for early maturing varieties with weak growth potential, it should be removed by stages and times when the lateral branches grow to 3~ 6 cm long.

For infinite growth type varieties, when growing to a certain ear, the top of the plant needs to be removed, which is called topping or topping, in order to ensure that the fruit can be fully plump and mature during the limited growth period. The topping should be determined according to the cultivation method. In the south, 3~4 layers of ears are reserved; in the north, 4~5 layers of ears are reserved. Black tomato cultivation principle does not pick leaves, keep large assimilation area of plants. Only after the peak fruiting period, the diseased leaves and yellow leaves at the base can be removed one after another to improve ventilation conditions and reduce respiratory consumption.

(6) Flower and fruit preservation

Black tomato flower drop phenomenon is more common, the main reasons for flower drop have the following two aspects: ① malnutrition flower drop. Due to insufficient soil nutrition and moisture, excessive plant damage, poor root development, untimely pruning and branching, excessive nutrient consumption under high night temperature, excessive plant growth, unbalanced nutrient supply and other reasons, flowers and fruits are dropped. (2) reproductive developmental disorders. Too low or too high temperature, rainy or too dry flowering period, will affect the pollen tube elongation and pollen germination, resulting in abnormal flowers (such as long style or short style flowers) and cause flower drop. Low temperature or plant injury was the main reason for early flower drop of open field spring black tomato, and high temperature and humidity was the main reason for flower drop of black tomato in summer.

The use of plant growth regulators can effectively prevent flower drop and stimulate fruit development to form seedless fruits of the same size or even larger than pollinated fruits. Commonly used growth regulators are: 2,4-D(2,4-dichlorophenoxyacetic acid), using a concentration of 10~20μl/L, for dipping or painting flowers;PCPA(p-chlorophenoxyacetic acid, also known as anti-falling element, black tomato), using a concentration of 25~30μl/L, can be used for spray treatment.

(7) Physiological diseases and their control

Physiological diseases of black tomato fruit development are one of the main problems in cultivation. Common physiological diseases include abnormal fruit, hollow fruit, top rot, cracked fruit, muscle rot, sunburn, etc., which have great influence on product quality.

1 abnormal fruit: abnormal fruit mainly produced in flower bud differentiation and development period, that is, in low temperature, more fertilizer (especially excessive nitrogen), water and sufficient light, excessive accumulation of nutrients at the growth point, excessive division of developing flower bud cells, excessive number of carpels, after flowering due to the imbalance of carpels development and the formation of multi-ventricular abnormal fruit. The abnormal fruit with top crack or transverse crack is mainly caused by the bad condition of flower bud development which inhibits the calcium transfer to flower organ. In addition, because the fruit growth is mainly longitudinal growth, and then gradually transverse hypertrophy growth, so the fruit developed under the condition of malnutrition is often pointed abnormal fruit, in order to prevent the occurrence of abnormal fruit, the temperature during seedling should not be controlled too low, water and nutrition must be adjusted appropriately.

② hollow fruit: that is, the flesh of the fruit is not full, the placenta tissue is not full, and the seed cavity becomes hollow, which seriously affects the weight and quality of the fruit. Poor fertilization, the use of growth regulator concentration is too high, etc., are easy to produce hollow fruit. In addition, during the fruit growth period, the temperature is too high, the sun is insufficient, or the application of nitrogen fertilizer is too much, the nutrient growth is too prosperous, and the fruit carbohydrate accumulation is too small, etc., will also form hollow fruit. Management should be strengthened and environmental control techniques improved in cultivation to create suitable conditions for fruit growth and avoid hollow fruit.

Top rot disease: also known as umbilical rot disease, nape rot disease, black brown spots occur at the top of the fruit, rot occurs in rainy weather or when the air humidity is high. It is a physiological disease caused by calcium deficiency in fruit. The causes of calcium deficiency in fruits are as follows: firstly, calcium deficiency in soil; secondly, dry soil, excessive concentration of soil solution, especially excessive potassium, magnesium and ammonium nitrogen, which affect the absorption of calcium by plants; thirdly, calcium is transported slowly in plants under high temperature and dry conditions. In order to prevent top rot, more organic fertilizer can be applied, acid soil should be adjusted by lime, maintain appropriate soil solution concentration, and properly control the amount of ammonia nitrogen. Avoid excessive temperature and drastic changes in temperature. Water supply should be uniform to prevent sudden dryness and humidity. In the fruiting period, 0.5% calcium chloride can be sprayed on new leaves and newly grown inflorescences to supplement calcium content.

Fruit cracking: fruit cracking is easy to occur in the late stage of fruit development. The fruit cracking phenomenon has annular cracking and radial cracking. The main causes of fruit cracking are: soil drought in the early stage of fruit growth, slow fruit growth, rapid expansion of pulp tissue in case of rainfall or irrigation, and unadaptive growth of pericarp, resulting in cracking. In order to prevent fruit cracking, in addition to paying attention to selecting varieties that are not easy to crack fruit, attention should be paid to increasing organic fertilizer, reasonable watering, uniform water supply, and avoiding direct sunlight on fruits.

(5) Rib rot: It is a physiological disease during the fruit expansion period. Symptoms can be divided into two types, brown and albino. The vascular bundle and its surrounding tissues of the former were browned, while the pericarp or fruit wall of the latter were hardened and whitened. The two types of diseases were induced by many kinds of bad conditions. In order to prevent the occurrence of gluten rot, special attention should be paid to the use of fertilizer, appropriate increase in potassium fertilizer, nitrogen fertilizer mainly nitrate nitrogen and so on.

Day burn disease: In the summer high temperature season, due to direct sunlight, the temperature of the fruit shoulder part rises, part of the tissue burns, dies, and produces day burn disease. The harm of sunburn disease varies greatly among varieties. The varieties with smaller leaf area, exposed fruit or thin pericarp were susceptible to disease. In order to prevent sunburn disease, it is better to avoid sunburn of fruits during fruiting period, and it is better to use conical frame or herringbone frame. When binding seedlings, the ears are arranged in the shade of leaves in the frame. Appropriate potassium fertilizer application can enhance its resistance.