Control of the concentration of the macroelement phosphorus in the substrate when growing tomatoes in protected soil conditions

Abstract

Although most tomatoes are grown in open ground, their cultivation in glass greenhouses or tunnel-type
greenhouses covered with plastic film is becoming more common to supply local markets with fresh fruit. In closed soil, mainly tall varieties of tomatoes are grown. They make it possible to use the area of greenhouses as efficiently as possible and get rich harvests. Tomatoes grown in greenhouses can be stored for 11 months, unlike those grown in open ground. Tomatoes are usually harvested unripe and ripen during transportation or on store shelves. Different types of tomatoes grown in greenhouses tend to have a longer shelf life, better taste and higher market value than those grown in the open field. Usually, plants are attached to the supports with a single wire, while the extra side shoots (stepchildren) are removed so that only one stem remains. The height of the tomato bushes can be gradually reduced for convenience immediately after the ripening of the first bunches of tomatoes. Shoots and inflorescences are removed to increase the length of the tomato bush, the number of fruits on it and their weight in order to meet the needs of the market. Taste, color, shape and texture are extremely important criteria for evaluating the quality of fresh tomatoes. Also, the fruits must be clean and contain no signs of decay or disease. Fresh tomatoes should be uniform in shape, symmetry and size. They should have a bright and uniform color, not contain green shoulders, spots and characteristic signs of immaturity. High concentrations of carbon dioxide (600–1000 ppm) are maintained in greenhouses to improve the process of photosynthesis, growth rate and yield. This practice is very common in low yield regions and intensive agricultural production systems. Although planting tomatoes in soil in tunnel-type greenhouses is still quite common, most intensive-type green-house tomato varieties are grown on substrates such as mineral wool. Fertigation provides adequate nutrient supply and eliminates most of the factors associated with heavy soil characteristics that are difficult to control. Growing tomatoes in greenhouses requires the use of a significant amount of water. To feed tomatoes, their producers also need to take into account the mass and degree of solubility of mineral fertilizers in water. Some elements or compounds present in irrigation water can affect the growth of plants, which is why there is a need to control their level. The paper investigates the influence of the concentration of the macroelement phosphorus in the mineral wool substrate on the growth and development of the Rosaletta (pink) tomato crop during the period of mass fruiting in protected soil conditions. It was established that the photoelectrocolorimetric method for determining the phosphorus content in mineral wool hoods is quite sensitive, simple and recommended for use in serial analyses. The determined average value of the phosphorus macroelement content (50.0 mg/l) turned out to be higher than that required for growing tomatoes in the period of mass fruiting. Controlling the phosphorus content allows you to significantly prevent tomato diseases and obtain high-quality crops.