The influence of the rootstock on the formation of quality indicators of sweet cherry variety Alexandria

The tested 27 samples of sweet cherry Alexandria variety grown on rootstocks with different growth rates (low-growing, medium and vigorous) had different indicators both in marketable conditions and in the content of a complex of biologically active substances – sugars, acids, vitamins. According to the level of accumulation of substances that form the nutritional, therapeutic and prophylactic properties of sweet cherry fruits, variety-rootstock combinations have been identified that provide an improvement in the quality indicators of fruits: ANT x Maaka 9-8, ANTD 12/20, S 33, Gegard, ANT x 2-77-1, ANT self-fertile 17, ANT w / n 5, Chufut Kale.


Introduction
Sweet cherry is one of the most popular stone fruit crops cultivated in the south of Russia, which is especially popular due to its early time of fruits ripening. Cherry plantations are mainly concentrated in the southern zone of our country with favorable growing conditions [1,2].
Sweet cherry opens the fruit season, ripening earlier than other fruit crops. Its fruits are eaten fresh, and only a small part is used for industrial processing [3]. Cherry fruits are distinguished by a high content of sugars, which are mainly represented by fructose and glucose, which enhances its dietary properties. The palatability of the fruit is characterized by a favorable combination of sugars with acids, represented by malic, citric, succinic, and lactic acids.
Sweet cherry is becoming a very popular crop and is gaining more and more markets in Russia and abroad. The productivity of sweet cherry plantations depends on the varietal composition and selection of rootstocks [4,5]. The use of various rootstocks (low, medium, above medium vigor) is very important for the cultivation of sweet cherries. The correct choice of rootstock in combination with the use of the best varieties of sweet cherry allows to reduce the growth rate of trees, to reduce the volume of the crown, to improve the quality of fruits [6,7,8]. To solve this problem, it is necessary to use clonal rootstocks, which make it possible to improve adaptability to stress factors while increasing the yield of plantings [9][10][11][12]. The use of clonal rootstocks in gardens of an intensive type with a growth force above average is interesting in conditions in the south of Russia using modern formations where guaranteed irrigation is impossible. [13][14][15][16].
The purpose of this work is to select clonal rootstocks of different growth rates for the Alexandria variety, ensuring the production of fruits with high marketable indicators.

Materials and Methods
Objects of research: 27 samples of sweet cherry fruits grown on rootstocks of different growth rates, growing at the Crimean Experimental Station. The cherry orchard was planted in 2015 according to the scheme 5.0 × 2.0 m. The tree formation was according to the type of Kim Green Bush, consisting of several vertical conductors -leaders.
The weather conditions during the period of the garden's growth were varied: the amount of precipitation was 657 mm (mainly October-April); during the growing season, there was a moisture deficit in the soil. Observations and counts were carried out according to the "Program and methodology for the study of varieties of fruit, berry and nut crops." Methods of biometric statistics were used for mathematical processing (BA Dospekhov "Methodology of field experience", 1979), Microsoft Excel, Statistika-99.
The rootstock forms above the average vigor of growth (ANT11 / 74, ANT S56, Kamensk 18, ANT w/n 5, S-3) were early-growing and had a yield from 12.1 to 15.4 kg / tree, which was more than in control.
One of the modern and necessary methods of growing fruit trees are various rootstocks, which can affect the biochemical indicators of the quality of the fruit.
The influence of various variety-rootstock combinations on the formation of commercial qualities of sweet cherry fruits (shape, size, color, density) is noted. Fruit weight is a characteristic feature of the variety; however, to a certain extent this indicator is due to the type of rootstock and its strength of growth.
It should be noted that, in terms of commercial quality, the studied sweet cherry fruits grown on different rootstocks belonged to the highest commercial grade (the largest transverse diameter was more than 20 mm) and varied from 26.0 mm (ANT b/n 16) to 30 mm (ANT x Maaka 9-8 and ANT self-fertile 15-38) (table 1).
The results of studies on the vitamin composition of sweet cherry fruits showed that the amount of ascorbic acid, depending on the rootstock in the fruit, ranges from 6.8 mg / 100g to 9.8 mg/100g. The amount of vitamin C in cherries grown on rootstocks ANTD12/20, ANT w/n 5, ANT self-fertile 17 exceeded the average content (8.3 mg/100g) and amounted to 9.7-9.8 mg/100 g. The vitamin P content varied from 38.6 mg/100 g to 66.6 mg / 100. More than 63.4 mg/100 g of P-active catechins contained cherry fruits grown on the rootstocks of Chufut Kale, ANT x Maaka 9-8, S33, ANT w / n 5, S 39-4.