Technologies of cultivation of red onion varieties

. Red onion varieties are among the richest sources of food flavonoids derived from quercinus. This study presents material on agrotechnological evaluation of red onion samples. Field experiments were carried out on typical light chestnut soils of the right-bank part of the Lower Volga in the zone of a sharply continental climate with a drip irrigation method. 9 samples of onion of red color of integumentary scales of selection BEJO ZADEN B.V., NETHERLANDS (4 samples) were studied: Red Bull F1, Red Baron F1, Red Ram F1, Robin F1; NUNHEMS B.V., NETHERLANDS (3 samples): NUN 9003 F1 (Merenge), Countach F1, NUN 9005 F1; HAZERA SEEDS, ISRAEL (1 sample): Retano F1; ENZA ZADEN, NETHERLANDS (1 sample): Monastrell F1. The samples were studied according to: characteristics of bulb coloration, morphometric parameters of the bulb, yield and ripeness.


Introduction
Onions are one of the richest sources of dietary flavonols consumed by humans in the form of anthocyanins and flavonols.
It was found that yellow onions contain 270-1187 mg of flavonols per kilogram of raw weight, red onions contain 415-1917 mg of flavonols.Studies have established 25 different flavonols of quercetin derivatives [7].
A number of authors have established the same content of quercins in yellow and red onions (from 60 mg/kg to > 1000 mg/kg) and its complete absence in varieties of white onions [8].
Quercetin selectively suppresses the growth of transformed tumor cells (ras/3T3 and H35) and prevents neoplastic transformation of NIH/3T3 cells by the H-ras oncogene [8].
The authors established the antioxidant potential of quercetin [3].
In addition to the known antioxidant properties, a powerful membrane-stabilizing, antiinflammatory, antispasmodic, immunomodulatory and anabolic effect of quarticin was noted [2-3;9].Studies have established the effect of quarticin on human immunodeficiency virus, herpes virus type 1, polio virus type 1, parainfluenza virus type 3, respiratory syncytial virus and hepatitis C virus [5].
The content of quercin in onions varies from the outer integuments to the inside.The maximum concentration is in the first juicy integumentary scales.This research is particularly interesting in connection with the process of preparing the bulb for its processing (cooking), as a result of which, as a rule, the outer dry integumentary scales and the first two juicy layers are removed [4].
It should be noted that the quercin content decreased significantly during the first month of storage and remained stable for 12 months of storage at 4 or 22°C [4].
Other studies have not established the effect of storage periods and types, as well as the effect of heat treatment on the content of the total amount of flavonols [6].
An increase in quercetin in the human body is possible due to a high-containing 6-week vegetable -fruit diet, which leads to a doubling of quercetin levels in plasma, and a diet with their low content leads to a 30% decrease in its plasma level [1].
In this connection, the authors of the article have begun research on the content of quercin in onions.Earlier we reported on the development of elements of onion cultivation technology [10][11].In preliminary studies, varieties and hybrids of F1 onion with yellow and white coloration of the integumentary scales were studied.This paper presents the material on agrotechnological evaluation of red onion samples.The experiment was laid by the following method of split plots.The entire area of the sown experimental plots was 400 m 2 .The accounting plots were -50 m 2 .

Materials and methods
The number of plants on all accounting sites was 2,400.In one variant, the number of plants was -100 pcs. the number of repetitions of the experiment is 3-fold.The layout of the experimental variants is randomized.
The main mineral fertilizers were used: ammophos (400 kg/ha) autumn application + sulfoammophos (30 kg/ha) pre-sowing application + ammonium nitrate (300 kg/ha) during the growth period.Our tests were carried out according to generally accepted methods for small field experiments (Dospekhova B. A. 1985).The repetitions on the variants are 3-fold.For reliable information and effective study of this experience, weather conditions were taken into account during the entire growing season of onions (Pavlova M.S., 1974, Losev A.P., 1994), as well as soil and its granulometric composition were studied (according to N.A. Kachinsky).
Mathematical processing was carried out in the form of using nonparametric statistics (Vox & Whiskers Plot technique) regression analysis of variance with a significance level of 0.05 (Statistica 6.0 program).

Results and Discussion
The color pattern of the onion's integumentary scales and the color saturation of the integumentary scales are among the factors determining consumer demand.In the studied samples, the color background of the integumentary scales varied from "red" to "dark purple" (Table 1).According to the "color of juicy scales", the studied samples were divided into three groups with white, red and dark red coloration.
Table 1.Characteristics of the color of the bulbs of the studied onion samples.
The shelf life of onions depends on the "cracking of the bottom".As a rule, infections and fungal spores penetrate through cracks in the field and in the future, various kinds of diseases develop during storage.NUN 9003 F1 (Merenge), Countach F1 and Red Baron F1 were assigned to the group of samples in which we did not detect cracking of the bottom.
"Multitasking" is a factor on which the shelf life also depends.We studied this feature by the presence of one or more rudiments when cutting the bulb.The presence of singletouchedness has been established only in Countach F1.

Conclusion
The yield of red varieties and hybrids of onions is always lower than that of yellow ones [10][11].This largely determines the cost of red bows.In this connection, the appearance of samples of red onions with yields above 100 t / ha is desirable for farmers.Despite the fact that Countach F1 is a relatively "old" hybrid of NUNHEMS B.V., its genetic potential makes it possible to obtain a crop (149 t/ha) at the level of yellow onion hybrids under drip irrigation.
Good results on the "maturation" feature were obtained from Countach F1, Red Baron F1 and Monastrell F1.
Experimental work was carried out in 2008-2016.Field experiments were carried out in the fields of the farm Zvolinsky V.V. (village of Saline Zaymishche, Chernoyarsky district, Astrakhan region).located on typical light chestnut soils of the right-bank part of the Lower Volga in the zone of a sharply continental climate.Duration of the warm period (with air temperature above 0°C) was 235-260 days.Total annual active air temperature (above 10°C) was 3370-3500 °C.The soil on the site is light chestnut with salty soils and the absence of salty spots.The terrain of the site is leveled.9 samples of onion of red color of integumentary scales of foreign selection were studied:  BEJO ZADEN B.V., NETHERLANDS (4 samples): Red Bull F1, Red Baron F1, Red Ram F1, Robin F1.  NUNHEMS B.V., NETHERLANDS (3 samples): NUN 9003 F1 (Merenge), Countach F1, NUN 9005 F1.  HAZERA SEEDS, ISRAEL (1 sample): Retano F1.  ENZA ZADEN, NETHERLANDS (1 sample): Monastrell F1.

Table 3 .
Yield of the studied onion samples.