Fruit growing
and viticulture of South Russia
The analysis of the state of the viticultural and wine-making subcomplex of the agro-industrial complex of the Republic of Dagestan in dynamics for 2014-2021 was carried out, the main problematic issues in the development of viticulture and winemaking hindering the development of this industry were specified, and the key directions and prospects for the development of the agro-industrial complex of the Republic of Dagestan were identified. The problems and strategic directions of creating the most favorable conditions for viticulture and winemaking in the region to lift the economy, increase production and improve the efficiency of management are identified, based on the analysis of the state and development of the subcomplex, contributing to the socio-economic development of the region. Scientifically-based proposals have been put forward to improve the efficiency of viticultural farms in the region by strengthening state regulation, aimed at improving the material and technical base, eliminating the target disparity, job gaining, increasing yields, reducing costs. The produced strategy for the development of viticulture and winemaking i n the Republic of Dagestan for the period up to 2035 provides for the introduction of certain organizational and legal measures, including the implementation of constant monitoring and comprehensive price regulation of the market of grapes and wine products; the establishment of parity economic relations between the subjects of the viticultural and wine marketing vertical system, the improvement of insurance, tax and financial and credit policy in the field of viticultural and wine production. The approaches to the choice of the directions of the strategy for the development of production, marketing and increasing the efficiency of wine-making products of the processing enterprises of the agro-industrial complex of the region are proposed. The necessity of modernization of the branches of viticulture and winemaking in Dagestan from the placement and technology of sustainable cultivation to processing and marketing in relation to modern conditions of the market economy, based on deepening specialization, vertical and horizontal integration, which provides for cooperation of all forms of ownership, ensures maximum added value, effective marketing, is established. It is shown that the strategy provides for amendments to the regulatory and legal acts of the Republic of Dagestan in order to disseminate measures of state support for measures aimed at increasing the volume of sales of grapes in fresh form to the population, providing processing enterprises with conditioned raw materials, creating additional jobs, increasing the average wage of workers in the industry and additional contributions to budgets of all levels.
The results of studies of biometric indicators and features of the development of the root system of various graft-rootstock combinations of the Stenley plum variety in the foothill zone of the Krasnodar region on overwetting floodplain soils are presented. It was revealed that the main parameters of alluvial-meadow heavy loamy soils leading to a decrease in productivity and inhibition of plum plants are the presence of layers with heavy granulometric composition in the soil profile, which are characterized by very low filtration capacity. These conditions contribute to the prolonged stagnation of excess moisture in the root layer of the soil, which leads to a decrease in productivity, inhibition and premature death of plants. Also, the established low level of soil fertility of the experimental site leads to a decrease in the productivity of plum plants. Under these conditions, the inhibition of plum trees manifests itself to varying degrees, depending on the rootstock. Plum plants on the rootstock of PK SK-2 were found to be the most resistant to periodic prolonged overwetting of soil root layer. The greatest increases of the vegetative part were noted on these trees, in leveled areas and a lower percentage of plant death in areas with less satisfactory water-air regime of soils (depressions, swales). The stability of trees on this rootstock is due to the peculiarity of the placement of potentially active roots in the soil. Studies have shown that the plum on the PK SK-2 rootstock has the main part (more than 60 %) of potentially active roots concentrated in a layer of 0-40 cm. On the AP-1 rootstock, potentially active roots are evenly distributed between the soil layers of 0-40 cm and 40-80 cm, and after heavy precipitation, when the soil is saturated with moisture below the level of 40 cm, more than half of the potentially active roots are in unfavorable conditions.
The problem of grapes adaptive stability in unstable climatic conditions in the important region of grape cultivation - the Anapo-Taman zone of the Krasnodar region, is relevant. The purpose of this work is to conduct comparative studies of grape varieties of various ecological and geographical origin on the dynamics of the content of starch and water-soluble sugars in the conditions of the autumn-winter period, to identify winterhard varieties according to this indicator. The objects of research are grape varieties of various ecological and geographical origin: Kristall (control Euro-Amur-American origin; Krasnostop AZOS, Dostoynyi Euro-American origin; Vostorg Amur-American origin; Zarif Eastern European origin; Aligote Western European origin. Adaptive rearrangements of carbohydrate metabolism arising in response to unstable climatic conditions of the autumn-winter period of 2020-2021 are revealed. It was found that in the varieties Dostoynyi, Krasnostop AZOS, Zarif, the accumulation of starch played an important role in the adaptation processes during overwintering, its content decreased by 10, 38, 9.63 and 8.75 times, respectively. It is shown that in the varieties Dostoynyi, Vostorg, Aligote, water-soluble sugars played an important role in resistance to winter stress conditions, the content of which in the buds increased by 1.2-1.5 times after low-temperature exposure. An important role of the osmoprotector of sucrose in the formation of a protective response in varieties Dostoynyi and Vostorg was revealed, the content of which in the buds and shoots increased by 4.8-6.3 times after the action of low temperatures. According to the results of studies of the content of starch and soluble sugars, it was revealed that Dostoynyi variety has the greatest potential for resistance to winter stresses; Vostorg variety stood out as the most adaptive in terms of the content of water-soluble sugars, including sucrose.
The problem of establishing optimal load criteria remains unresolved to date for successful practical application, since all proposed load calculation formulas have a narrow empirical value. Cases of unjustified mechanical copying of individual formations with the norm of load from some viticultural areas to others are not uncommon in practice, which often ends in failure. The applied methods of calculating the optimal load of bushes to a certain extent take into account the varietal characteristics of plantings (although very tentatively) and the strength of the vegetative development of bushes due to the conditions of culture. At the same time, it is impossible to take into account the interaction between the load of the bush and the specific conditions of vineyard vegetation, and, consequently, the possible change in the potential fruitfulness of shoots. Recently, high-yielding varieties of the new generation that are resistant to adverse environmental conditions have become widely used in the vineyards of our country. Varieties with a large percentage of fruiting shoots tend to be overloaded with yield, and therefore it is necessary to limit the growth of bush yield capacity in order to achieve the yield of the required quality. Viticulture specialist recommend doing this mainly by applying a load norm optimized taking into account the varietal specifics, which allows to obtain conditioned yields suitable for their directed use. Successful planning of the bush load with shoots, stimulates the development of a powerful annual growth with which the necessary yield may be achieved and the skeletal part of the bush may be maintained. In any area, the yield of a particular grape variety is successfully grown and ripens on bushes, the load of which provides optimal conditions for growth and photosynthetic activity of the leaf apparatus. Based on all of the above, it should be noted that the surest way to establish the optimal load of grape bushes, taking into account the potential capabilities of the variety in order to obtain stable high yields of the required quality, is experimental.
The results of studies on the intensity of downy mildew development in the conditions of the vineyards of the Don ampelographic collection in 2019-2021 are presented. The preservation of wintering forms of mildew was facilitated by the weather conditions of the dormant periods i n 2019-2021: the absence of low freezing temperatures and sufficient humidity (61-85 %). The air temperature in the autumn-winter periods during the years of research was significantly higher than the average long-term values (the sum of negative temperatures ranged from 119.4 to 274.3 ). Under such conditions, the oospores of the pathogen, germinating at the beginning of the growing season, produce an inoculum for primary infection of plants. Phytomonitoring of the infestation of various varieties with downy mildew under epiphytotic conditions in 2021 made it possible to identify the most resistant varieties for their further use as donors of downy mildew resistance. During the growing seasons in 2019, 2020, the increased temperature, compared with the average annual values, and low humidity contributed to the depressive development of downy mildew. When the hydrothermal coefficient was from 0 to 0.5, the plants of 70-80 % of varieties had no signs of downy mildew. The intensity of disease development in other varieties did not exceed 2.5 points. In 2021, in all growing months, with the exception of July, there was a shortage of precipitation. Despite this, the increased air humidity in May-July with a hydrothermal coefficient of 0.8-1.2 contributed to the intensive development of downy mildew. As a result, 12 % of the varieties of the Don ampelographic collection showed the highest resistance to downy mildew (up to 2 points): Tavrosi; Pochatochnyy; Ol'khovskiy; Nakutvneuli; Kosorotovskiy; Grdzelmtevana. The intensity of the infestation from 2 to 3.5 points was found in 78 % of the varieties. The least resistance to downy mildew (more than 3.5 points) was manifested in 10 % of varieties: Sypunchernyy; Pukhlyakovskiy chernyy; Megrabuyr; Bessergenevskiy 1; Belobulanyy.