Source material for quince varieties selection with high commercial and consumer qualities of fruits in the Krymsk EBS, VIR Branch gene pool

The article presents the evaluation results of varieties, samples, and breeding elites of quince from the gene pool of VIR named after N.I. Vavilov preserved at the Krymsk EBS, VIR Branch. The article presents generalized material based on the study of technical parameters, biochemical composition of quince fruits and products of technological processing (canned food: juice, compote, jam). Differences between varieties by fruit weight and in terms of biochemical indicators content were established: soluble dry substances, sugars, sum of organic acids, ascorbic acid. In the conditions of southern Russia, quince fruits contain relatively higher levels of soluble dry substances (1.2-1.8 times) and ascorbic acid (1.5-2.0 times) compared to apples. According to the research results, selectionally valuable sources of high commercial fruit quality were distinguished, including attractiveness of appearance, taste and density of pulp, organoleptic, biochemical parameters of fresh fruits and evaluation of conversion products: Vernaya, Zvezdnaya, Granitnaya, elite 21-4-51. Varieties sources of high content of soluble dry substances (23.30-24.58%), organic acids (1.45-1.76%), sugars (13.30-14.90%), ascorbic acid (37.01-42.24 mg/100 g) were identified. For amateur gardening, quince species forms Kaunchi 8, Kaunchi 9, Jardem are proposed as they are juicy, soft, with good biochemical indicators.


Introduction
Being valuable in nutritional properties, such seed crop as quince currently occupies a very small proportion in the garden agrocenosis. However, its fruits can increase the variety of fresh products almost all year round, as well as canned. In the south of Russia, the natural and climatic conditions are quite favorable for increasing the specific weight of this crop. Quince is a monotype genus consisting of the single species Cidonia oblonga Mill.quince tree. All cultivated quince varieties are representatives of this species. Quince is an early-maturing, high-yielding fruit crop with a restrained type of growth and a compact crown, which allows to cultivate its varieties with the use of intensive technologies. By economic efficiency, this is one of highly profitable seed crops [1]. Quince fruits are valued for their high taste and dietary qualities. They contain a large amount of mineral (iron, copper, etc.) and biologically active substances: organic acids, pectins, fructose, glucose, complex of vitamins -A, B1, B2, C, P [2,3]. Pectin substances improve organoleptic properties of fruits and conversion products, preserve aromatic substances. Quince is very promising for canned food and confectionery industry. High-quality juices, compotes, jams, marmalade, confiture, candied fruits, and other products are produced from quince fruits, which are highly appreciated for its attractive appearance, excellent taste and bright pronounced specific aroma [4]. Since pectin substances have the ability to complex formation with heavy and radioactive metals, thus forming insoluble complexes with various toxins accumulating in the human body, juice with pulp and other conversion products are functional foods that help to cleanse the body and improve human immunity [5].
However, the quince varieties' lack of universal purpose with a good combination of high taste and canned qualities of the fruit, as well as the food priorities of the population deter the use of this crop in canned food industry. Increasing the production of canned food from quince fruits is possible only based on new varieties creation, their rapid involvement in gardening rotation and processing industry.
Solving the problems of quince assortment improvement requires the use of new donors and sources in breeding, which is possible through a comprehensive potential assessment of both modern varieties and representatives of public breeding varieties. Krymsk EBS, VIR Branch (Krasnodar Region) is studying the quince gene pool represented by more than 160 varieties of various ecological, geographical and genetic origin and elites obtained by the intervariety cross-breeding method [6]. The allocation of new donors and sources, critical selectionally significant traits will allow to improve the effectiveness of targeted breeding programs.

Purpose of research
To assess varieties and samples of quince from the gene pool of N.I. Vavilov All-Russian Institute of Plant Genetic Resources supported at the Krymsk EBS, VIR Branch on a set of technical indicators, determine the organoleptic fruit characteristics, study their biochemical composition and suitability for technological processing. To identify new valuable genotypes for introduction into production, as well as sources of high commercial fruits' characteristics for involvement in targeted breeding programs to improve the fruit quality.

Materials and methods
The research was carried out at the Krymsk EBS structural subdivision of N.I. Vavilov All-Russian Institute of Plant Genetic Resources located in the Western sub-zone of the Foothill Zone of Krasnodar Region. Objects of research -50 varieties of domestic and foreign origin and 8 elite quince forms of the Krymsk EBS, VIR Branch selection. Genotypes grafted on clone rootstock VA 29 grow in the dryland garden, placement scheme -4.0 × 1.5 m, planting year -2010. The soils are gray forest.
Quince variety samples were evaluated by consumer qualities of fresh fruits: weight and appearance of the fruit, pulp density, taste qualities according to generally accepted methods [7][8], as well as biochemical composition according to GOST 28562, GOST 25555.0, GOST R 51240. Conversion products (juice, compote, jam) were made according to GOST 32105-2013, R 54680-2011 [9]. Juice with pulp was evaluated by color and taste; compote and jam -by appearance, color, pulp consistency, taste; the overall assessment for

Results and discussion
In the southern regions of the Russian Federation, quince fruits form the best commercial and full-fledged food qualities. The main parameters characterizing the economic value of the variety are the commercial and consumer qualities of fruits, among which the appearance, weight, pulp density and taste occupy the first place. (Table 1). They depend on variety-specific features, genetic origin. To determine the differences' validity in the fruit weight between the studied varieties and quince elites, a one-factor dispersion analysis was performed, as a result of which significant differences of options were revealed for the level accepted in studies (P = 0.95). Note: pulp density score: 1-very soft, 2-soft, 3-medium dense, 4-dense, 5-very dense For the processing industry, preferred quince fruits are of round shape with an even surface, rich yellow color, sweet and sour taste, unidimensional, medium or large size, with a dense pulp. As a result of many research years, varieties Granitnaya, Zvezdnaya, Vernaya, Novogodnyaya, elite 24-4-51, 8-21-2 were distinguished as sources of a trait complex of high-quality fruits for the canned food industry.
For quince varieties selection for dessert purposes, samples introduced from the natural populations of Central Asia and Southern Transcaucasia were selected from the collection: Kaunchi No.8, No.9, Zhardem. Along with high taste qualities, the size of the fruits from medium to large, they are characterized by a comparatively juicy pulp and soft fruitiness.
The food and nutritional advantages of fruits are determined by their biochemical composition. Studies have shown that the content of dry substances, sugars, organic and ascorbic acids of the studied quince varieties varies significantly depending on the biological characteristics of a variety. On average, quince fruits contain dry substances from 1.2 to 1.8 times more than in apple fruit [11]. This property is especially valuable for The ascorbic acid content in fruits is one of the most important biological features for horticultural crops. Quince fruit has 1.5-2 times higher vitamin C content than apple trees. Out of promising varieties and elites, varieties with the highest content of ascorbic acid in fruits were determined: Zvezdnaya (38.15 mg/100 g), Granitnaya (38.45 mg/100 g), Vernaya (37.01 mg/100 g), Ispolinskaya (39.07 mg) /100 g), Krasnodarskaya Krupnaya (41.36 mg/100 g), Kaunchi 8 (42.24 mg/100 g).
The organic acids content in quince fruits in the conditions of the South-West Caucasus varies from 0.60 to 1.76%. The largest indicators of the sum of organic acids in the quince varieties fruits: Vernaya (1. According to the biochemical indices complex of quince fruits, the following varieties are identified as high content sources of dry substances, vitamin C, sugars, optimal ratio of total sugars and the sum of organic acids of the: Zvezdnaya, Vernaya, Granitnaya, Ispolinskaya, elite 24-4-51; on the basis of the "least amount of dry substances" index at optimal values of other biochemical indices -soft-fruit species forms Zhardem and Kaunchi 8. High content of soluble dry substances in quince fruit pulp, as well as harmonious combination of sugars and organic acids allows to make high-value conversion products from it: juice with pulp, compote, jam. As a result of tasting sessions, the canned products of all researched quince varieties received high scores (Table 2). According to the assessment results of juice products (2017-2019), the best varieties were allocated: Granitnaya (4.83 points), Novogodnyaya (4.72 points). Canned "compote" products had higher ratings in varieties: Granitnaya (4.77 points), Novogodnyaya (4.68 points), Izobil'naya (4.64 points). The taste of jam of all tested quince varieties was very good. Especially high scores for all tasting parameters of jam were obtained in varieties: Izobil'naya, Granitnaya, Novogodnyaya (4.77 points), Blagodatnaya (4.73 points). from South Transcaucasia -Zhardem, juicy, soft-fruit, with high rates of general sugars, amounts of organic acids and vitamin C. Based on the study results of the quince gene pool of the Krymsk EBS, VIR Branch, sources of valuable traits have been identified according to the complex of fresh fruits quality indicators -weight, attractive appearance, taste, density of pulp and conversion products -juice, compote, jam, selected varieties: Granitnaya and Novogodnyaya. Their use in breeding programs will allow to create quince varieties with specified qualitative indicators.
Quince with excellent taste of fresh fruits containing healthy organic substances, from which high value conversion products are made, belonging to functional food products with medicinal, preventive properties should take an appropriate place both in the industrial gardens of the south of Russia and in the processing industry.