One of the main factors in obtaining consistently high tomato yields is to optimize the plant nutrition area. Determination of the optimal plant density, on the one hand, prevents oppression of plants at increased density. On the other hand, to avoid unnecessary expenses from the irrational use of the cultivated area. Vegetables are one of the main suppliers of biologically active substances necessary for a good human nutrition. They give the body a lot of vitamins, fiber, hemicelluloses, pectin substances, organic acids, various carbohydrates, mineral salts and a number of other biochemical compounds. Tomato is one of the main protected ground crops for Ukraine. Compared to other crops, tomatoes give early and stable yields. The issue of planting density of tomatoes is still not fully resolved, these elements of technology are not adapted to the soil and climatic conditions of the eastern part of the Left-Bank Forest-Steppe of Ukraine. The objective of our research was to determine the optimal crop density of hybrid tomato of indeterminate type in order to obtain the highest yield without reducing the quality of the product. The method of research. The research was carried out during 2018-2019. In film greenhouses, spring-summer crop rotation. The experiments were carried out with an indeterminate tomato hybrid: Tobolsk F1. Producers of seeds of indeterminate hybrids recommend different plant densities for growing conditions in film greenhouses 2.5-3.5 pcs/m2. Therefore, our research was planned to determine the optimal plant density of the indeterminate tomato hybrid Tobolsk F1 for film greenhouses. The total number of plants is 312 pcs. Sowing of seeds was carried out in the third decade of February. The seeds were sown into cassettes, and the seedlings were dived into pots (volume - 500 cm3) on time. Seedlings were grown using bottom irrigation and, at the age of 3-5 true leaves, the seedlings were planted on a test plot in a film greenhouse without heating. Research results. An analysis of phenological observations of plants showed that a change in the density of plants had practically no effect on the timing and rate of passage of the stages of organogenesis in plants, that is, in all variants of the experiment, the phases of development in plants began simultaneously. Indicators of plant parameters indicate that the data obtained both in the phase of mass flowering and mass fruiting of tomatoes differ among themselves. The difference in biometric parameters can be traced depending on the density of plants. Comparing the main biometric indicators, it can be noted that in the flowering phase, the height of plants ranged from 111.0 to 134.9 cm, in the fruiting phase - from 257.0 to 275.8 cm, while the plants differed in height by the density of 4.0 pcs/m2. The vegetative mass of a plant in the flowering phase was from 1884 g with a plant density of 2.5 pcs/m2 to 1144 g with a density of 4.0 pcs/m2. In the phase of flowering fruiting, the weight of the plant ranged from 1704 g to 1574 g, also decreasing with increasing density. In the flowering phase, an increase in the value of the leaf area indicator was observed to 5.8% with an increase in plant density, and in the fruiting phase, a slight decrease in the indicator to -1.8% was observed with an increase in plant density. So, according to biometric indicators, plants develop better with a density of 3.5 pcs/m2: tomato plants have the best indicators of vegetative mass and plant height, the leaf surface area varies within insignificant limits. The size of the fruits and the yield of standard tomato production are in direct proportion to the density of plants, that is, the more of them per unit area, the lower these indicators. In general, the increase in the density of tomato plants significantly affected the yield. Conclusions. Two-year researches have established that with an increase in plant density, in terms of leaf area in tomato plants of the Tobolsk F1 hybrid, on average, there was a slight fluctuation in the indicator at the level of 0.9-1.1%. The indicator of the vegetative mass of the plant ranged from -4.1 to +1.8% as compared to the control, also decreasing with increasing density. The indicator of plant height both in the flowering phase and in the fruiting phase, on the contrary, grew with an increase in plant density and ranged from -4.0 to + 7.1% compared to the control, while the plants differed in height by a density of 4.0 pcs/m2. In general, the studies carried out give grounds to conclude that in a spring film greenhouse, according to biometric indicators, on average, plants develop better with a density of 3.5 pcs/m2: tomato plants have the best ratio of vegetative mass, plant height and leaf area. The maximum yield of tomato hybrid Tobolsk F1 at the level of 15.8 kg/m2 in the eastern part of the Left-Bank Forest-Steppe of Ukraine was obtained with a plant density of 3.5 pcs/m2.
Manifestation of heterosis in F1 petunia hybrids