The work analyzes the development of the state testing of potato varieties Solanum tuberosum L. for distinctness, homogeneity and stability (hereinafter – DHS) in the Republic of Belarus. In order to optimize the organization of state testing of potato varieties for DHS, two patent examination stations were created at SAO «Molodechno Variety Testing Station» and SAO «Gorki Variety Testing Station»; two national testing methods for DHS, developed on the basis of UPOV guidelines, were systematically introduced into practice; national reference varieties were introduced; to ensure the correct definition of DHS criteria, a photo catalogue of the main identification features of potatoes and a national reference collection of well-known varieties have been created.

Potato varieties and hybrids were studied by the biochemical indicators of tubers: dry matter, reducing sugars, total protein, Vitamin C, nitrates. An assessment is given by the indicators of starch quality, namely, the amylose content and the proportion of the coarse fraction. A number of samples with high biological value, as well as with indicators of high-quality starch, has been identified.

Consumer properties were studied: the type of surface, the shape of tubers, the number and depth of buds, the amount of waste during mechanical cleaning and manual post-cleaning, the resistance to darkening of the pulp before and after cooking the tubers of varieties of Yuliya, Desyatka, Mastak, Vodar, Garantiya, Bayarsky, Sapfir. During the research, the dependence of these indicators on the variety, weather conditions, and the granulometric composition of the soil was identified.

At the Research Institute of Potato-breeding of Sumy National Agrarian University, using own potato varieties as basic forms, 23 promising hybrids were obtained according to the main economically valuable traits (yield – up to 50 t/ha, starch content – 22 %, starch yield – up to 8–10 t/ha). Based on the results of the technological assessment, 35 % of hybrids of the early and medium early ripening groups with a high (28–30 %) dry matter content and low (0.2–0.4 %) reducing sugars content turned out to be the most suitable for industrial processing into potato products. The potential maximum yield of dried potato production was up to 27.7 kg from 100 kg of raw materials, crispy – up to 44.4 kg, which is almost 20 and 10 % higher than the established quality standard. Providing the processing industry with high-quality raw materials in the early stages is one of the factors in increasing the efficiency of enterprises and unloading them in the most stressful autumn period.

As a result of the analysis, it was found that in the changed climatic conditions, a decrease in potato yield occurs due to an increase in the harmfulness of diseases and frequent droughts and uneven precipitation during the growing season. In the current situation, through the introduction of varieties which are resistant to these stresses, it is possible to not only significantly reduce potato crop losses, but also to improve the quality of tubers. Data on the resistance of the most common and new potato varieties to these factors are presented. Based on the obtained findings, priority areas of potato selective breeding were proposed.

The article presents the study results on a comprehensive assessment of varieties from the Velikiye Luki State Agricultural Academy collection in the conditions of the Nonblack Earth Region of Russia. The data were obtained for the Pskov and Tver regions. The varieties of the collection belong to different ripeness groups and were obtained by different selective breeding organizations. The adaptive potential of potato varieties of different ripeness groups under annually changing weather conditions has been estimated. In the course of research, varieties with high plasticity and productivity were identified. All varieties are characterized by high yield and resistance to diseases.

The samples from the in vitro collection of wild Solanum species were evaluated for resistance to PVX, PVY, PVS, PVM, Synchytrium endobioticum, Globodera rostochiensis, Globodera pallida, Phytophthora infestans. The screening of lines using DNA markers was carried out. The genotypes of potatoes with a single marker and with a complex of markers of resistance genes were identified.

The article presents the research results on the assessment of potato samples that were created in the laboratory of potato genetics and varieties that are cultivated in the collection nursery of RUE «Scientific and Practical Center of the NAS of Belarus for Potato, Vegetable and Fruit Growing», for resistance to PVM and PVS, and detection of resistance sources to these pathogens with the use of DNA markers. Based on the research results, a number of stable forms was found with the following markers: SC878₈₈₅ to the Gm gene, GP250₅₁₀, UBS822₁₀₇₉ to the Rm gene and markers SCG17₃₂₁ and UBC811₆₆₀ to the N_S gene, which can be used in potato selection for virus resistance.

The results of work (2017–2019) on creation of new initial material of potato resistant to late blight are present in the article. Created six hybrids derived from species S. demissum, S. bulbocastanum, S. stoloniferum, S. polytrichon, S. vernei, S. andigenum, S. rybinii, S. phureja. These hybrids have complex resistance to late blight, in combination with other economically valuable traits.

The article presents the results of studying the biological and economic efficiency of the herbicide Soil Fluid, CS (600 g/l of metribuzin) in potato crops in 2018–2019.

The article presents the research results on the selection of clones free from phytoinfection in original potato seed production. It is necessary to use a number of diagnostic tests that complement each other and allow the detection of a wide range of viral infections such as PVX, PVY, PVS, PVM, PLRV, PVA, TRV, PMTV, AMV, PSTV and bacterioses: Ralstonia solanacearum, Pectobacterium carotovorum subsp. Atrosepticum, Clavibacter michiganensis. Moreover, studies have shown the necessity for TRV detection testing when selecting the initial ancestral material for introduction into the in vitro culture.

The two-year data on resistance of competitive variety trials of potatoes hybrids to Rhizoctonia solani Kuhn. are presented in the article. The evaluation of potatoes breeding material for sprouts and tubers for resistance to Rhizoctonia solani Kuhn. is given and some hybrids have been recommended for selective breeding.

The article presents the assessment of the effectiveness of macro- and micro-fertilizers, growth regulators in the production of the early potato variety of Palats and mid-ripening variety Volat on yield, yield structure and quality of tubers on sod-podzolic light loamy soil in the north-eastern part of Belarus.

The effect of separation of the mother potato tuber from the plant on the productive properties of the offspring is analyzed. It has been established that the disruption of the connection between the plant and the mother tuber causes an increase in productivity of the next generation. The intensity of this effect depends on the period of the connection disruption between the parent plant with the mother tuber and the weather conditions during the growing season.

The article presents the results of assessing the storability of ware potato tubers planted with a planting width of 75 and 90 cm and stored under the conditions of forced blowing using radial and axial fans. It was found that increasing the planting width from 75 to 90 cm can decrease natural loss by 0.18 %, losses due to sprouts – 0.05 % and total losses by 0.22 %. The use of forced blowing systems of the fifth technological order reduces natural loss by 0.89 %, losses due to sprouts – 0.38, absolute rot is reduced by 0.21, total losses by 1.48 %. The storability of ware potatoes directly depends on varietal features, with an influence rate of 70.04 %.

The article presents the research results on the influence of the variety, planting width (75 and 90 cm), conditions during the year and their interaction on the formation of biochemical parameters in ware potato tubers. It was found that reducing sugars, total protein and nitrate contents in tubers mostly depend on a potato variety. Starch, dry matter and Vitamin C contents depend on the conditions during the year.

The article presents the results of studies on the effect of eco-friendly cultivation technology on the quality of potato tubers on sod-podzolic sandy-loam soil in the Minsk region conditions in 2013–2014. It was found that the cultivation of potatoes using green technologies in comparison with the traditional ones increases the content of dry matter, starch, Vitamin C, amino acids and reduces the nitrates and radionuclides content in tubers.

The effect of organic fertilizers based on starch production waste on potato productivity has been studied. It has been found that mezga-based fertilizers have a similar effect to traditional fertilizers on the formation of potato yield. When using mezga as fertilizer, the content of nitrates in tubers did not exceed the maximum permissible standards for ware potato, the starch content was at 16.3–17.9 %.

The research results on the use of biopreparations of Bitoxybacillin, P 3.0 kg/ha and Xantrel, L 5.0 l/ha against the Colorado beetle on potato crops are presented: the biological effect on the 3^rd day was 55.2–64.0 % and 42.9–55.1 %, on the 7^th day it was 82.5–88.6 % and 75.5–80.3 %, on the 10^th day 79.1–82.8 % and 70.7–75.4 %, on the 14^th day it was 75.3–77.3 % and 69.5–74.6 % respectively. When growing potatoes on sodpodzolic medium-loamy soil using ecologically friendly technologies (biofertilizers – zeolite, slurry from the milk processing, cattle manure; biopreparations – Xantrel, L and Bitoxybacillin, P), the yield by varieties was: Pershatsvet 32.4–38.8 t/ha, Nara 28.9–32.8, Rubin 30.4–35.8, commercial yield, respectively, was 31.5–37.6 t/ha, 27.4–31.9 and 28.6–35.1 t/ha.

The article presents the research results on the effectiveness of the AgroNan microfertilizers on potatoes. Double foliage spraying of micro-fertilizers AgroNan Active, L and AgroNan Bio, L contributed to the growth of both total (13.7–18.9 %) and commercial yields (16.8–26.0 %). In addition, the use of these fertilizers contributed to the accumulation of dry matter and starch in tubers and a decrease in the nitrate content.

The article presents the study results on the effect of micro-fertilizers foliage spraying on the yield in protected ground structures using various potato planting methods. The agronomic efficiency of micro-fertilizers in the yield of the first generation of potato tubers of different ripeness groups has been presented.

The research results on the influence of the size of seed tubers in the original potato seed production on the preservation of yielding properties of early potato varieties are presented in the article. It has been established that an increase in the fraction of the first tuber generation from 5 to 30 mm provides increase in the productivity of a potato plant by 1.2–1.4 times, depending on its variety.

Maximum productivity of potato plants and tubers multiplication factor in a first tuber generation nursery in protected ground were obtained when growing in a mixture of turf + sod soil + vermicompost. The most optimal planting density is 25 plants/м².

The article studied the passage of interstage periods and the yield formation of tubers of 93 potato varieties with different ripening periods. The selection of base clones was carried out in northern and southern conditions of Primorsky District in Arkhangelsk Oblast and the highlands of the North Caucasus at an altitude of 2 300–2 500 m above sea level. The growth, development and formation of tubers was significantly influenced by the length of day in the northern region and long sunshine hours in the highlands. The multiplication coefficient of plants in the highlands increased by 1.2–2.3 times compared to the northern region, while the highest increase was observed in late-ripening varieties. The weight of tubers of the early and mid-early ripening varieties was exceeded by 1.9–2.7 times compared with the northern region; the weight of the later period varieties was exceeded by 2.9–3.1 times.

The article presents the 2017–2020 research results on the effect of the mineral oilbased preparations on the accumulation of viral infection in the reproduction process of seed potatoes, taking into account different spatial isolation from personal subsidiary plots (PSP). The data obtained showed that the mineral oil SunSpray 11E, Preparation 30 Plus, based on mineral oil, subject to the spatial isolation appropriate for the potato reproduction category, regardless of the variety, can increase the yield of seed potatoes that meet the requirements of regulatory documents by containing the spread of viral infection on potato plants.

The article presents the research results on determining the optimal concentration of macro- and micro-fertilizers NanoSilicon, Kristalon (universal, yellow, brown), FERTIKA Lux, Batr max in the growing medium for accelerated in vitro reproduction of potato micro-cuttings due to the effectiveness of their action on the growth of the root system, the height of the stem and the number of internodes. It was found that the maximum number of roots and their greatest length in the studied varieties Pershatsvet (11.1–11.2 pcs and 6.0–6.1 cm) and Rubin (10.8–10.9 pcs – 6.2–6.5 cm) was recorded when using the fertilizers Kristalon yellow and brown in a concentration of 0.4 g/l. The largest number of internodes in the Pershatsvet variety was obtained when using the Nanosilicon in a dose of 0.05 ml/l, macro- and micro-elements Kristalon yellow and FERTIKA Lux in a dose of 0.4 ml/l (8.1 pcs). In the Rubin variety, the largest number of internodes was obtained when using Kristalon universal in the growing medium in a dose of 0.4 ml/l (7.2 pcs).