Influence of LED lighting power on Indau (Eruca sativa (Mill.))

The article investigates the reaction of four varieties of Indau sowing to the power of illumination by LED lamps. Indau sowing cultivars responded positively to the increase in lighting power at different stages of development, with the exception of Sicilia, which showed a neutral reaction. The Hooday variety has tasty formed a high rosette with wide leaves and the largest average weight of one plant of 25.72 g at an illumination power of 140 μmol / m2 / s. The Sicily cultivar formed standard rosettes of wide leaves weighing 16.33 g at an illumination power of 170 μmol / m2 / s. The Chudesnitsa cultivar formed standard rosettes of narrow leaves weighing 19.28 g at an illumination power of 140 μmol / m2 / s. Variety Dikovina formed a high rosette with wide leaves and the largest average weight of one plant 20.11 g at an illumination power of 170 μmol / m2 / s.


Introduction
Vegetable crops are plastic that is, external and morphometric parameters, and yield change under the influence of external environmental factors. The influence of growing conditions in open and protected ground is well studied, while the influence of growing conditions in closed systems, or in factories of plants with artificial lighting, has not been studied enough [1][2][3][4][5][6][7][8][9][10]. The closed cultivation system is a facility designed for the year-round production of vegetables, vegetable seedlings and ornamental crops on vertical farms under controlled artificial conditions. To regulate and control the parameters of microclimate and nutrition, technical systems of heating, ventilation and air conditioning, hydro-and international methods of nutrition and photo culture of plants are used. Growing conditions in closed systems are characterized by negative biotic factors (microalgae, introduced beneficial or pathogenic microflora) and stable and optimal nutrition of abiotic factors (temperature and humidity conditions, CO 2 content, macro-and microelements, photoperiods), but, in comparison with the conditions of an open type or protected ground, the illumination power is lower and the spectrum is different from natural, which leads to varietal responses to growing conditions. 70% of the costs are spent on growing electricity used to illuminate the grown crop; therefore, determining the optimal power is relevant.
Indau sowing (Eruca sativa (Mill.)) Is an annual, cold-resistant, light-loving plant of the Cabbage family (Brassicaceae). Indau has a spicy, mustard taste. The plant contains alkaloids, flavonoids, vitamin C, B vitamins, mineral salts, iodine up to 700 μg / kg, iron, malic and citric acids, steroids, fatty and mustard oil are found in the seeds. Several studies have shown the potential role of phytochemicals in plants of the Brassicaceae family in the prevention of certain diseases and types of cancer; inhibition of carcinogenesis and hepatoprotective effect [4; 7]. Currently, there are no Indau cultivars bred specifically for full photo culture conditions, so the purpose of our study is to study the response of four Indau cultivars to the power of LED lighting during the growing season.

Materials and methods
The research took place in the phytotron of the Laboratory of Photoculture and City-Farming of the SPbGAU in 2020. All varieties are included in the State Register for growing in open and protected ground [9].
The plants were fed by the aeroponic method. The composition of the nutrient solution, mg / l: N -190, P -26, K -166, Mg -9 and trace elements; The pH was maintained at 5.5-6.0, the conductivity of the solution was 1.5-2.0 mSm / cm. Planting density was 180 plants / m 2 . The growing season from mass shoots was 39 days.
When carrying out biometric measurements (plant height, leaf width), the following guidelines were followed: "Guidelines for studying the collection of cabbage and leafy green crops (lettuce, spinach, dill)" [2] and "Methodology of field experiment in vegetable growing" [3].
The illumination power was measured with a TKA-Spektr spectrophotometer (LLC "Scientific and Technical Enterprise TKA", St. Petersburg) at a suspension height of the lamps of 40 cm. The average illumination power was calculated according to PNST 211-2017 "Irradiation of plants with LED light sources. Measurement methods ".
The placement of variants is systematic; the studies were carried out in 3 analytical replicates and 10 biological replicates. Statistical processing of the experimental data on the average weight of one plant was carried out by the method of analysis of variance according to the Student's t-test (the significance of the difference between the means was estimated at a 5% significance level) using Microsoft Excel software. To determine the degree of influence of illumination power on the morphometric parameters and the average weight of one plant, the coefficient of determination was calculated. Average values of indicators are indicated with standard error of the mean. Table 1 shows the results of biometric measurements of four cultivars of Indau sowing under different illumination power at 25, 32 and 39 days from mass shoots. Table 2 presents data on the average weight of one plant of four varieties of Indau sowing under different illumination power on days 25, 32 and 39 from mass shoots.

Discussion
An increase in the illumination power had a strong effect on the morphometric parameters (table 1)     The Sicily cultivar is tolerant of increased lighting power. The lighting conditions did not have a significant effect on the increase in plant height (r 2 = 0.01-0.16) and leaf width (r 2 = 0.04-0.29) during the growing season. However, the average weight of one plant was largely determined by light conditions (r 2 = 0.32-0.51) during the growing season. The Sicily variety on the 25th day formed plants with a height of 99-164 mm, a leaf width of 34-47 mm and an average weight of one plant of 1.13-3.29 g. By the end of the growing season, on the 39th day, the plant height was 220-308 mm, leaf width -47-57 mm, average weight -8.67-16.33 g. Tall plants with narrow leaves and the smallest average weight cultivar Sicily formed at an illumination power of 140 μmol / m 2 / s, and at 170 μmol / m 2 / s the largest mass of one plant with a standard rosette of wide leaves was formed.
The Chudesnitsa cultivar reacted positively to an increase in the illumination power, especially by the 25th day from mass seedlings: with an increase in the illumination power, the plant height (r 2 = 0.88), leaf width (r 2

Conclusion
Based on the research results, the following conclusions can be drawn:  Indau sowing cultivars reacted positively to an increase in lighting power at different stages of development, with the exception of Sicilia, which is tolerant to lighting conditions.  The Hooday variety has tasty formed a high rosette with wide leaves and the largest average weight of one plant of 25.72 g at an illumination power of 140 μmol / m 2 / s.  Variety Sicily formed standard rosettes of wide leaves weighing 16.33 g at an illumination power of 170 μmol / m 2 / s.  Cultivar Chudesnitsa formed standard rosettes of narrow leaves weighing 19.28 g at an illumination power of 140 μmol / m 2 / s.  Variety Dikovina formed a high rosette with wide leaves and the largest average weight of one plant 20.11 g at an illumination power of 170 μmol / m 2 / s.