Maintaining the tomato gene pool from the VIR world collection in the open field of the Moscow region
World collection of tomato samples from V.I. NI Vavilova (VIR), represents the richest material for the search for sources and donors of economically valuable traits used in the selection of highly productive varieties and hybrids [1,2,8]. The tomato culture is distinguished by high plasticity, productivity and multipurpose use of fruits, which contain substances valuable for human nutrition, namely: vitamins C, B1, V2, V3, V9, PP, β-carotene, mineral salts and organic acids [1].
Tomato seeds begin to age from the time they are excreted from the fruit of the mother plant. In order to prevent the loss of germination of the samples, during storage, it is necessary to carry out repeated crops after 7-8 years in order to maintain the samples in the form in which they were introduced. And with the set of biological and economically valuable traits that were originally inherent in them [3, 7].
To maintain a collection of tomatoes in open and protected ground, the correct selection of samples is important, since the variability of their biological and economic properties is not the same [6]. The growing conditions are reflected in the sowing and economically valuable traits of the plants grown from these seeds.
From 1974 to 2004, the VIR collection was maintained in the amount of 25-70 samples, along with the study of new acquisitions. Due to the reduction of the VIR experimental stations, the volume of work since 2005 has increased to 100 samples, since 2011 - up to 150 samples.
A number of specimens reproduced at other stations are a mixture of two or three varieties, or even do not correspond to the descriptions at all. Therefore, in addition to restoring germination, it is necessary to check reproductions.
Getting early and high yields of seeds from collection samples depends on the quality of seed preparation and the timing of their sowing, growing seedlings. In southern conditions, tomatoes are grown directly by sowing in the ground and by the seedling method. In the conditions of the Moscow region, the best way is seedling, using cassette technology, which helps to preserve the integrity of the root system and does not require additional time for its rooting. As a result, the processes of fruit formation and ripening are accelerated, the vegetative period is shortened.
Sowing preparation
When maintaining and studying the collection of open ground tomatoes, we use for sowing washed and disinfected seed boxes measuring 35 x 25 x 10 cm. We fill the boxes with a mixture of turf soil, humus, sand in a ratio of 2: 4: 0.5. If possible, it is advisable to add one part of deoxidized peat to this mixture. It is important to prepare the boxes with the mixture in advance before sowing, so that they warm up to the required temperature. Sowing tomato seeds in unheated soil leads to uneven germination, the occurrence of diseases and the death of seedlings, which sometimes took place in our practice. We spill boxes with the mixture with a warm solution of potassium permanganate (KMnO4) pink, with a ruler we make grooves to a depth of 1 cm at a distance of 3-5 cm between the rows.
Sowing tomatoes
Sowing of the collection in the suburbs - in the first ten days of April. We lay out the seeds next to each other, which gives more friendly and faster shoots than those laid out by 0.5 cm.Fill the seeds with the same mixture as in the box, and spill the boxes with a weak solution of potassium permanganate (pink), cover with a film until seedlings.
The boxes with the sown seeds are kept in a glass greenhouse at a temperature of 20 ... 25 ° C until mass shoots appear. In most of the tomato samples from the collection, seeds begin to germinate at a temperature of 16 ... 18 ° C, but they germinate more closely and faster at a temperature of 23 ... 25 ° C, in further phases of life the plants grow and develop better at a temperature of 20 ... 25 ° C. The minimum temperature for plant development and growth depends on the cold hardiness of the variety.Some collection samples sprout at temperatures below + 10оС, and at + 34оС seeds do not germinate [3].
Growing seedlings
An important measure for strengthening seedlings after germination is to lower the temperature to + 12 ... 15 ° C during the day and + 10 ... 12 ° C at night. However, it is practically impossible to do this agricultural practice on the collection, since often some of the samples, with good seed energy, in the same box, germinate after 4-5 days, and others - after 8-12 and up to 15 days. In addition, the greenhouse contains collections of other crops that need warmth. Very carefully you need to monitor the soil moisture in the boxes, to prevent waterlogging. Watering of plants is carried out rarely, as the top layer of the soil dries up, preferably in the first half of the day with heated water not lower than + 20оС. Frequent watering contributes to the spread of fungal diseases. In order to prevent disease damage to seedlings, we use fresh ingredients for preparing the mixture, avoid thickened sowing in boxes, ventilate the premises, loosen between the rows of seedlings, watering with a weak solution of potassium permanganate. In the event of the appearance of a "black leg", sprinkle the soil with wood ash, mix it and poke the mixture above the lesion site, which causes the growth of new roots.
To obtain high-quality tomato seedlings, you need a small, bright, warm room with controlled growing conditions. In the last two years, in connection with the renovation of greenhouses, the boxes were placed in the laboratory building. Germination was influenced not only by the quality of the seeds sent, which were stored for 9-10 years, but also by the placement of the boxes. As a rule, the boxes located on the windowsill and on tables at a distance of 1-1.5 m from the heating battery had friendly shoots in 4-6 days. In more distant places, the seeds germinated uncommonly and with a delay, stretched strongly towards the window, and did not develop well. The seedlings were tender, refined, which later affected its growth and disease. Thus, without additional good uniform lighting and compliance with the temperature regime, growing good tomato seedlings is difficult.
Seedling picking
For the next stage of work, we prepare a mixture of turf, humus, peat, sand (3: 2: 1: 0.5) with the addition of 500 g of superphosphate, 250 g of ammonium nitrate, 200 g of potash fertilizers and 300 g of slaked lime per 1 m3 ... We fill the cassettes with a mixture of earth, humus and sand (2: 4: 0.5) with the addition of azophoska 1 kg / m3. Rigid dense cassettes with removable plates are very convenient for picking. When removed, the tomato root system is located in a cube measuring 7.5x7.5x10 cm or 10x10x10 cm. When planting seedlings in the field, the root system is not disturbed, and the plants do not stop their growth and development. This method allows you to grow seedlings with a large "run" and get production much earlier (10-12 days than non-cassette seedlings), which is very important for the unstable climate of the Non-Black Earth Region.
One to one and a half hours before picking, we water the seedlings in the seed boxes, and also moisten the mixture in cassettes. With a peg, the length of which is 10-15 cm and a thickness of 1 cm, we make depressions in the cells for the length of the seedlings. For picking we select the most developed and healthy seedlings. We lower the seedling into these recesses, making sure that the root is not bent. Then we fill the grooves with the seedlings with a well-sifted mixture, pressing the ground to the plant, avoiding air cavities at the roots, do not fill the top of the seedling. Seedlings take root better when picking is carried out in the phase of two developed true leaves. Early picking, at the beginning of their appearance, does not take root well and requires very much attention to care and precise observance of light and thermal regimes.
If the pick is carried out on a sunny day, cover the cassettes with seedlings with lutrasil or spunbond on arcs to prevent severe overheating and wilting of seedlings. We install pegs with sample numbers in all cassettes.We save the remaining seedlings in the seed boxes in case of death or poor survival of the main plants. After 4-5 days, you can judge how the plants have taken root. We change the bad ones or the fallen ones for the reserve ones.
Seedling care
For the survival of seedlings, we create the best light and thermal conditions. The temperature is maintained at + 18 ... 25оС during the day, + 14 ... 16оС at night. Watering is rare, but abundant, in the first half of the day.
The first feeding is carried out 8-10 days after the pick. For 200 liters, we lay 2 buckets of 10 liters of mullein (you can fresh) and add 2 kg of azophoska. For better dissolution, we soak azophoska in advance (6-10 hours) in warm water. Liquid consumption - 10 liters per 1 m2. Before feeding, we moisten the plants with clean water, and then wash off the remaining fertilizers to prevent burns. We carry out the second and third feeding 8 days after the previous one.
Before planting tomato seedlings in open ground, you need to harden them. To do this, we take out the seedlings from the greenhouse to an open area (May 11-15), when the air temperature in the shade reaches 8 ... 12оС. The first few days, in sunny weather, cover the seedlings in boxes with lutrasil or spunbond, and then leave them open. In the event of a threat of freezing, we cover with a film and covering material.
Planting seedlings in the ground
For a tomato, the best is an area sheltered from the wind, with a slope to the south. In a vegetable crop rotation, we plant the tomato in the same place after 5-6 years, avoiding the placement of potatoes next to it. The predecessors are cabbage, pure steam, root vegetables. The planting pattern is 70 x 70 cm. The best time for planting tomatoes in open ground is the first decade of June, when the threat of frost has passed. However, when there is a strong heat in May, and the seedlings outgrow in an open area, we plant them in the third decade of May.
We cultivate the plowed plot for planting tomatoes in the spring, before planting we apply mineral fertilizers at the rate of 2.5-3 c / ha of azophoska or nitroammofoska, cultivate and cut 70 x 70 cm furrows with a hiller in two directions.In the center of the resulting square, we dig holes with a depth of respectively grown seedling height. We fill the wells with water by 2/3 and arrange the seedlings according to the samples, without mixing anything, 30-60 plants according to the sample. When studying according to the VIR method [4, 8], the standards are placed after 10 samples. We drown the roots, which are in cubes, in the soil soaked at the bottom of the hole and fall asleep. We maintain the planting depth for half of the seedling stem. To count the number of leaves on the stem up to the first brush, we pre-impose paper labels over the third leaf, since usually three leaves are covered with earth. It is better to plant tomatoes in sunny weather in the afternoon, and in cloudy weather - throughout the day.
Plant care
After planting the seedlings, in 2-4 days we carry out the first loosening. Loosening ensures the destruction of the crust, the retention of moisture in the soil and the access of oxygen to the roots, and also facilitates the release of carbon dioxide from the soil. After 15 days, simultaneously with loosening, we carry out hilling of the plants, which contributes to the formation of an additional root system, an improvement in the thermal regime, due to the formation of ridges, and a decrease in morbidity. We loosen the row spacing to a depth of 10-15 cm every 2-3 weeks, as well as after rain and watering, removing weeds near the plants by hand.
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Mineral fertilizers in dry form (NPK-16: 16: 16 azophoska) are applied to wet soil or before rain, with their obligatory incorporation. The first time feeding is carried out 10-12 days after planting the seedlings, the subsequent ones - every 15-20 days until the beginning of August.
If weather conditions add up with a significant lack of sunlight and heat, a large amount of precipitation in June and July, this contributes to the early appearance of a dangerous disease - late blight. Treatment is carried out with systemic preparations Ridomil MC, Ridomil Gold MC, starting from July and no later than 20 days before harvesting.For prevention, contact preparations can be used: 1% Bordeaux liquid, copper-soap emulsion, 0.5% oxychom solution, copper oxychloride - 40 g per 10 liters of water, etc.
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Protection of tomatoes from late blight (gardeners' recommendations)
In 10 liters of water, dissolve one tablespoon (with top) of copper sulfate, one tablespoon of baking soda and 2 tablespoons. granulated sugar. We mix. We carry out the processing of seedlings once before planting in open ground or in a greenhouse, then 10 days after planting the seedlings and repeat after rain or 10-15 days. Ripe fruits are thoroughly washed before use.
Fruit harvesting
Although the tomato is an optional self-pollinator, fruits are harvested to obtain seeds from rows located inside the plot in the phase of full maturity. The extreme butt rows play the role of protection, and the crop harvested from them is not used for seed production. Let the tomatoes in boxes stand until they are completely reddened, slightly wilted and softened.
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Seed isolation
Cut the fruits across, squeeze out the seeds and clean the chambers into plastic containers with a capacity of 1 liter. Then we pour the tomato seeds with juice and pulp into gauze bags, attach labels with the numbers of the corresponding plots. We put the bags in enameled or plastic fermentation tanks. In the process of isolating seeds, do not use metal utensils and add water. Fermentation takes place, depending on the temperature, for 2-5 days. The sign of its end is the appearance of foam and clarification of the juice. After fermentation, the seeds in bags are well washed in clean water and hung up to dry. Stir the seeds in bags every 2-3 hours to prevent the formation of lumps, turn the other side to the sun. After the end of harvesting, we refine the well-dried seeds, cleaning them from the remnants of pulp, peel and other impurities. We weigh the seeds and pack them in clean paper bags.
Thus, the preservation of the uniqueness and viability of tomato collection specimens from the VIR world collection is a multilevel and laborious process that requires thoroughness in all stages of work and knowledge of the genetic characteristics of the specimens, biological and agrotechnical characteristics of the culture.
About varieties of tomatoes for the Moscow region - in the article Bush tomatoes: varieties.
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