The effect of fertilizer rate on the growth, development and yield of sweet pepper in protected areas

. The article presents information on the development of the root system when the Marjona variety and the Zombello F1 hybrid of sweet pepper are grown in the conditions of greenhouses in the meadow gray soils of Samarkand region, Samarkand district, with different fertilizer rates.


Introduction
In Uzbekistan, sweet pepper is grown in film greenhouses in several cycles.In unheated spring greenhouses, it is grown in a spring-summer rotation, in which seedlings are planted in greenhouses in mid-March and completed in July-August.During this cycle, the fastest growing varieties are grown and seedlings that have produced 4-5 true leaves in 55-60 days are planted.In this case, the harvest starts from the middle of May (V.I.Zuyev and others, 2018).
Sweet pepper fruits contain 7-12% dry matter, including 4.1-7.4% sugar (mainly fructose and sucrose) and 1.3-2.6%protein.That is why sweet pepper is a valuable vegetable crop.Its high nutritional value is significant due to the presence of vitamins (A, B1, B2, B3, C, P) and mineral salts useful for human health (calcium, phosphorus, iron and others).
According to the amount of vitamin C (ascorbic acid) contained in its fruits, sweet pepper surpasses all vegetables.Its fruits contain from 50 to 270 mg of vitamin C per 100 g of dry weight at technical maturity, and from 170 to 450 mg at biological maturity.Sweet pepper fruits contain 12.6 mg% of carotene (provitamin A).They accumulate a significant amount of rutin (vitamin P) and group B vitamins (thiomin, riboflavin, folic acid).Sweet pepper fruits are eaten fresh, processed and cooked as a vegetable crop (F.F.Rasulov, 2021).

Materials and methods
Taking into account the above, in the years 2022-2023, in the meadow gray soils of the farm "Halimova Iroda", Samarkand region, Samarkand district, sweet pepper Marjona variety and Zombello F1 hybrid in different fertilization rates in greenhouse conditions.We conducted a field experiment to study the effect on root mass and volume when grown.
As the research object, meadow gray soils, sweet pepper variety Marjona and Zombello F1 hybrid, and different rates of mineral fertilizers (NPK) were taken.
Field experiments were conducted under the conditions of a film greenhouse based on the following experimental systems.The experiment was carried out in 4 variants, 4 repetitions, the total area of 112 m2, 50-55-day-old seedlings of sweet pepper, which produced 4-5 true leaves, were planted on March 1 in a planting scheme of 60x30 cm (Azimov B.J., Azimov B.B, 2002).

The results and discussion
When the fertilizer is used in the cultivation of sweet pepper, it first affects the root system of the plant and, through the root, the upper part of the earth.The results of the experiment show that the fertilizer rates have a significant effect on the change in root mass and volume of the Marjona variety and the Zombello F1 hybrid of sweet pepper (Table 1-2).
Marjona cultivar and Zombello F1 hybrids of sweet pepper were studied under different fertilizer rates under film greenhouse conditions.root mass in the layer was 19.1-19.6 grams.It was found that the fertilizer rate was 26.3-27.0grams in the variant with an increase of N160 P112 K80 kg/kg.A relatively high root mass of 24.7-25.1 grams, i.e., was observed in the version where the mineral fertilizer norm N140 P98 K70 kg/ha was used.The root volume of one bush of sweet pepper varied in the range of 20.1-28.2cm3 at different rates of fertilizers of Marjona variety and Zombello F1 hybrids studied in the experiment.The highest root volume was determined in both studied cultivars and hybrids (27.4-28.2cm3) in the variant with N160 P112 K80 kg/ha fertilizer.In our experiments, the smallest root size was observed in the studied Marjona variety and Zombello F1 hybrids, in the control variant, in the variant with N100 P70 K50 kg/ha fertilizer.
It was found that the development of root mass and volume of sweet pepper varieties and hybrids was observed in 61-60 and 75-76 days, and it was relatively weakened in the following periods.Sweet pepper Zombello F1 hybrid N160 P112 K80 kg/ha, the root mass of one plant was 7.8 grams on 15-16 days after planting in the 0-20 cm soil layer, 30-31 days -1.6; 45-46 days -4.5; 60-61 days -11.8;It was found that on the 75th-76th day -16.6 and on the 90th-91st day -19.2 grams.The volume of the root is 8.9 cm3, 2.4; 4.6; 12.0; It was found to be higher by 16.7 and 19.3 cm3.
It was found out from the conducted research that 80-85 percent of the sweet pepper root is formed in the 0-20 cm layer of the soil.The remaining 15-20 percent is located below the 20 cm layer of the soil.The tallest (121-124 cm), the number of side branches (2.7-2.8 pieces), the number of leaves (78-81 pieces), the number of fruits per plant (31-34 pieces), one fruit length (11-14 and 12-15 cm), diameter (6-11 and 6-12 cm), and average weight of one fruit (142-156 g) studied in Marjona variety and Zombello F1 hybrid the highest rate was recorded when applying N200P110K100 kg/ha.
2. Mineral nutrition at the rate of N200 P110 K100 kg/ha fertilizers for obtaining a stable, high-quality harvest at optimal fertilization rates from sweet pepper has a positive effect on productivity, increasing it from 31-34 tons per hectare ensured quality harvest.

Table 1 .
Formation of root mass when sweet pepper cultivars and hybrids are grown in film greenhouses at different rates of fertilizer (2022-2023 years) T/

Table 2 .
Changes in root volume when sweet pepper cultivars and hybrids are grown in greenhouses at different rates of fertilizer (2022-2023 years)