Since the beginning of the 2000s, the ecological and climatic situation in southern regions of Russia has deteriorated sig­nificantly due to the increased anthropogenic impact. In particular, the Republic of Crimea, especially its steppe zone, has been experiencing a real ecological disaster since 2016 because of water deficiency due to the drying up of the North-Crimean Canal after it has been blocked by Ukraine. All this makes it urgent to search for and collect wild and run-wild plant species in their natural habitats, and con­serve them in controlled conditions at VIR’s branches.  Krymsk Experiment Breeding Station has developed a long-term plan for conducting expeditions to collect stone fruit and berry genetic resources for augmenting VIR’s collec­tions. This plan is being implemented on a regular basis. The goal of this work is to explore natural habitats, collect fruit and berry plant diversity, further maintain it in field collections at Krymsk Experiment Breeding Station, and comprehensively study it with the aim of identifying sources of economically important traits for creating new highly adaptive and technologically advanced varieties and root­stocks.  Expeditions were conducted in 2016–2018 in southern areas of the steppe zone and northern steppe regions of Krasno­dar Territory, Volgograd Province, in southeastern regions of Rostov Province, and in the Republic of Crimea. It was es­tablished by field surveys that wild stone fruit plants are found everywhere much less frequently than it was ob­served in previous years, when similar expeditions were launched to these areas. All in all, this work resulted in col­lecting 222 samples of typical representatives of the studied fruit and berry species from the areas of their natural oc­currence. All of them were placed in the nursery of Krymsk Experiment Breeding Station, got established well, and thus augmented the VIR collection of fruit and berry crops.  In view of the observed tendency of the natural distribution areas being reduced for a number of wild stone fruit species due to global climatic changes and recent increase of the an­thropogenic impact, it is necessary to continue conducting expeditions to collect genotypes, especially of such species as ground cherry and Russian almond. In the near future, it is planned to explore the mountainous and Caspian regions in the Republic of Dagestan.  

Pyrus zangezura Maleev (Rosaceae) is a rare species representing the native vegetation of Armenia (Southern Transcaucasus). It was first described in 1936. P. zangezura has been cultivated at the Peter the Great Botanical Garden of the Komarov Botanical Institute (St. Petersburg, Russia) since 1949, where it has reached the height of 8,0 m. For many years, it was in its vegetative state. The first flowering was observed in 2016 (the plant entered the reproductive state). The first progeny from seed was obtained in April 2019. Fruit size was assessed for P. zangezura plants in the dynamics of their development. The studied plants of P. zangezura in the environments of St. Petersburg have demonstrated a high fruiting potential – on average, 109 flowers per 1 m of a shoot. Observations have shown that not all ovules in the opened flowers of P. zangezura are fertilized and produce fruits and seeds. A significant part of the opened flowers, a few days after the onset of flowering, dry up and fall off. On average, 7 fruits are set on 1 m of the shoot in P. zangezura. The reasons for the low flower setting may be variable: impaired pollination processes and insufficient fertility of pollen, underdevelopment of the flower morphological structures, or lack of pollinating insects due to adverse weather conditions. An X-ray analysis of the seeds from the harvests of 2016, 2017 and 2018 showed that the number of plump and fully developed seeds (grades IV and V) in fruits has been growing year by year. As an ornamental plant, P. zangezura may adorn any botanical garden, but it is also promising for urban landscaping, for example, in St. Petersburg. Even in the vegetative state, its elongated lanceolate glossy leaves make it appreciably different from the common P. communis L., and it is especially ornamental during flowering and fruiting. It is as winter-hardy as the common pear-tree, demonstrates resistance to diseases and pests, and may be of importance for breeding programs aimed at the development of resistant cultivars for the Northwest of Russia.  

Background. Modern production imposes increased requirements to the range of used cultivars, so the development of new cultivars and hybrids most adapted to certain soil and climatic conditions is an important task of breeding.

Materials and methods. Table beet accessions from the VIR collection originating from 17 countries were chosen as the material for the present research. The accessions were studied at Pushkin and Pavlovsk Laboratories of VIR, at the Genetic Diversity and Plant Bioresources Center of the All-Russian Breeding and Technological Institute of Horticulture and Nursery (VSTISP) and at Maikop Experiment Station, a branch of VIR, according to VIR’s guidelines.

esults. The relationships between earliness, bolting resistance, cold tolerance and resistance to black root have been established. The majority of the studied accessions had medium resistance to black root. The cultivars ‘Asmer Detroit 72’ (k-3113, Great Britain), ‘Bravo’ (k-3047, Russia) and ‘Podzimnyaya A-474’ (k-1678, Russia) distinguished by resistance to black root, were also characterized by cold tolerance and stable productivity. The differences in bolting resistance among the accessions were found to depend on their origin. The cultivars from Sweden, Finland and from the Russian Northwest were most resistant to bolting. The early accessions ‘Perfected Detroit Dark Red’ (k-1815, Canada), ‘Bikor’ (k-2873, the Netherlands), ‘Severnyshar’ (k-1586, Russia) and ‘Polyarnaya ploskaya’ (k-1585, Russia) were characterized by high rates of the vegetative mass growth and bolting resistance. It was noted that the absolutely monogermic varieties have lower ripening rates, productivity, and resistance to bolting, compared to the multigerm ones, but have similar chemical composition indicators and root quality. Accessions with a wide distribution area that maintain high root productivity at 115–120% to the reference in different climatic conditions have been identified.

Conclusions. The research has resulted in the identification of table beet accessions characterized by a complex of biological and economically important traits. The relationships between earliness, resistance to bolting and cold tolerance have been revealed. Genetic sources of monogermicity, bolting resistance, cold tolerance, black root resistance and high root quality are recommended for the use in breeding.  

Background. To obtain sustainable and high rice yields, it is crucial to select the best cultivars adapted to the cultivation in the main rice-growing areas. Combining high yields and technological quality indicators of wholegrain and milled rice is of vital importance. The practical solution of such an important task largely depends on successful breeding work.

Materials and methods. Eight rice cultivars were evaluated in competitive trials in 2016–2018. Experimental plots were arranged within the rice irrigation system of the All-Russian Rice Research Institute in Belozerny Settlement, Krasnodar Territory. During the growing season, the following traits were visually evaluated: plant density, resistance to lodging, disease and pest infestation, and uniformity of crops. Screening and discarding operations on the plots planned for harvesting were followed by making model sheaves of 10–15 plants each for biometric analysis. Technological characteristics of wholegrain and milled rice were measured according to GOST 10843-76 and GOST 10987-76 standards. The results were mathematically processed and proved reliable.

Results. Four promising cultivars ‘VNIIR 10244’, ‘VNIIR 10275’, ‘VNIIR 10279’ and ‘VNIIR 10282’ with a set of economically useful traits significantly exceeding the standard reference (st) ‘Flagman’ were selected. Their yield was 9.0 t/ha; 1000 grain weight: 29.3; 28.1; 30.4 and 26.3 g; hull percentage: 17.7; 19.7; 19.5 and 21.4%; and wholegrain content: 88.5; 93.5; 89.4 and 97.8%, respectively. Significantly high yields of these cultivars are due to the optimal number of fertile spikelets (150–160 pcs), panicle density (9.8–12.6 pcs/cm), and significant weight of grain from the main panicle (3.7–4.4 g), with an average sterility of 14.2–20.3%. A close positive correlation of yield traits with wholegrain content was observed in cvs. ‘VNIIR 10282’, ‘VNIIR 10279’, ‘VNIIR 10276’ and ‘VNIIR 10275’ (r = 0.92– 0.98). An inverse relationship between yield and kernel fissuring was observed in most genotypes, which testifies to the potential possibility of increasing their yield without the risk of reducing milled rice yield or wholegrain content.

Conclusion. The evaluation resulted in identifying four promising rice cultivars: ‘VNIIR 10244’ and ‘VNIIR 10279’ (large-grain), ‘VNIIR 10275’ and ‘VNIIR 10282’ (medium-sized grain). They significantly exceeded the standard reference ‘Flagman’ in a set of economically useful traits: yield and its structural elements as well as technological characters of wholegrain and milled rice quality. The best of the selected genotypes according to the optimal ratio of the studied traits will be submitted to the State Variety Trials in 2019–2020.  

Background. Studying new potato cultivars in extreme environments of the North as well as identification and development of source materials for breeding are vital challenges faced by for potato breeders. The article presents the results of a study that involved potato cultivars from the VIR global collection grown under the extreme climate conditions of Murmansk Province.

Materials and methods. The study was conducted at the Polar Experiment Station of VIR in 2016‒2018, when 40 potato accessions, which had originated from 9 different countries and had been supplied by VIR, were analyzed. The research was based on the guidelines developed at VIR. The obtained data were compared with the standard reference (st) cv. ‘Khibinsky ranny’ (k-6928).

Results. In the process of long-term research, cv. ‘Muromets’ (k-25268) was identified for early yield formation (128% vs st). Cvs. ‘Mestny’ (k-25286) from Ukraine and ‘Madeleine’ (k-25322) were outstanding for their earliness combined with productivity (115–140%). Cv. ‘Express’ (k-25262) was selected for its earliness (113%), productivity (128%), and high marketability (92%). Cvs. Aktyubinsky-2’ (k-25300), ‘Ushkonyr’ (k-25309), ‘Berkut’ (k-25250), ‘Gala’ (k-25270) and ‘Colleen’ (k-25224) demonstrated high productivity (106–131%). Cv. ‘Pamyati Kanaeva’ (k-25305) had the highest yield of 1154.0 g/bush (155%). The highest starch content of 14.4% was shown respectively by cvs. ‘Aytmurat’ (k-25448) and ‘Mestny No. 2’ from India. Twelve cultivars out of 40 appeared to be the most adaptable to the local growing conditions: ‘Muromets’, ‘Express’, ‘Pamyati Kanaeva’, ‘Volynskaya mestnaya’ (k25274), ‘Dovgenka’ (k-25275), ‘Sorokadenka’ (k-25293), ‘Gala’ (k-25270), ‘Reggi’ (k-25313), ‘Izmir’, form 2 (k-25272, Turkey), ‘Daphne’ (k-25296), and two local cultivars from Ukraine (k-25286 and k-25282).

Conclusions. This study proved useful as it helped to analyze adaptive properties of potato cultivars and describe the studied material in the context of their basic biological and economic traits.  

Background. The article presents the data obtained after the screening of potato cultivars for resistance to Phytophthora infestans (Mont.) de Bary. The selected genotypes combine late blight resistance with other valuable commercial traits, such as high yield, high starch content, resistance to virus dis­eases and potato nematode (Globodera rostochiensis Woll.).

Materials and methods. Potato accessions representing do­mestic and foreign cultivars from the VIR collection served as the material for this research. The screening was performed according to the techniques developed at the Potato Genetic Resources Department of VIR.

Results and conclusion. The following true-breeding cultivars were identified for their re­sistance to Phytophthora infestans: ‘Ania’ (k-24063), ‘Baszta’ (k-24067), ‘Bobr’ (k-21103), ‘Dunajec’ (k-24074), ‘Klepa’ (k-24080), ‘Koga’ (k-24174), ‘Meduza’ (k-24082) and ’Mors’ (k-24083) from Poland; ‘Caprice’ (k-25193), ‘Certo’ (k-19440) and ‘Valetta’ (k-21769) from Germany; ‘Avrora’ (k-12188), ‘Bastion’ (k-25198), ‘Bryansky nadezhny’ (k-12160), ‘Vdokh­noveniye’ (k-12192), ‘Vektor’ (k-25200), ‘Velikan’ (k-25201), ‘Zvezdochka’ (к-25209), ‘Kalinka’ (k-25148), ‘Lukyanovsky’ (k-11750), ‘Musinsky’ (k-25312), ‘Nakra’ (k-11916), ‘Nikulin­sky’ (k-12171), ‘Prizer’ (k-25217), ‘Rapsodiya’ (k-25258), ‘Rossiyanka’ (k-12057), ‘Rucheyek’ (k-12213) and ‘Udacha’ (k-11900) from Russia; ‘Aktsent’ (k-12237), ‘Vetraz’ (k-11989), ‘Vytok’ (k-11897), ‘Zhuravinka’ (k-12106), ‘Kupalinka’ (k-12155), ‘Sintez’ (k-11666), ‘Suzorye’ (k-11992) from Be­larus; ‘Vikhola’ (k-11270), ‘Zarevo’ (k-10773), ‘Svitanok ki­evsky’ (k-11665), ‘Olviya’ (k-25094), ‘Rakurs’ (k-25098) from Ukraine; ‘Aytmurat’ (k-25248), ‘Berkut’ (k-25250), ‘Zholbarys’ (k-25155), ‘Nur-Alem’ (k-25253), ‘Senim’ (k-25306), ‘Sey­anets Lapteva’ (k-25161), ‘Sunkar’ (k-25258), ‘Tamyz’ (k-25307) and ‘Udovitsky’ (k-25260) from Kazakhstan; etc. High percentage of plantlets resistant to late blight was ob­served among self-pollination progenies of cvs. ‘Avrora’ (k-12188), ‘Astra’ (k-10697), ‘Vikhola’ (k-11270), ‘Zhuravinka’ (k-12106), ‘Nayada’ (k-12157), ‘Rosinka’ (k-11993), ‘Skarb’ (k-11904), ‘Bobr‘ (k-21103) and ‘Clarissa’ (k-21770). There were cultivars combining late blight resistance with such traits as resistance to potato nematode (Globodera rosto­chiensis Woll.) and viruses, high productivity, and increased starch content: ‘Zhuravinka’, ‘Ania’, ‘Baszta’, ‘Bobr’, ‘Certo’ and ‘Mors’. The selected genotypes are recommended as promis­ing to be included in potato breeding programs.  

Background. Winter wheat resistance to adverse winter­ing conditions is one of the most important adaptive charac­teristics. To obtain high yields, modern wheat cultivars should have various protective reactions. For their success­ful combination in one genotype, the availability of appro­priate initial material is of great importance. In Russia, the accessions from the VIR collection are traditionally used as initial material for wheat breeding. The aims of the present study were (1) to evaluate winter hardiness in accessions from the VIR collection in a field test, and (2) to use the ob­tained data and those on the geographical origin of acces­sions for making up the target sub-collection and perform­ing its eco-geographical studies.

Materials and methods. The initial sample for field screening contained 431 acces­sions of common winter wheat from different regions of Russia and the former USSR, and 484 accessions from 18 foreign countries. Winter hardiness of these accessions was tested in the environmental conditions of the North­western region (Pushkin, 59°41′N 30°20′E, 2006/2007, 2007/2008 and 2013/2014) and of the Central Black Soil re­gion (Yekaterinino, 52°59′N 40°50′E, Tambov Province, 2007/2008 and 2008/2009). The degree of winter hardi­ness was determined in accordance with the technique de­veloped at VIR.

Results and conclusions. In 2006/2007, in Pushkin, a high and a very high degree of winter hardiness was displayed by 114 accessions with the origin from Rus­sia and the former USSR as well as by 12 accessions from foreign countries. Based on the obtained data and taking into account the diversity of the geographical origin of ac­cessions, the target sub-collection was formed, whose ac­cessions were subjected to eco-geographical two-year field studies (Pushkin, 59°41′N 30°20′E, 2007/2008, 2013/2014, and Yekaterinino, 52°59′N 40°50′N, Tambov Province, 2007/2008, 2008/2009). The Friedman’s variance analysis has shown that variation on winter hardiness in 158 acces­sions from the target sub-collection was determined by the environmental conditions of wheat cultivation (χ2э = 256.7; df = 4; χ2W=0.05 = 9.5) and by genetic differences between ac­cessions (χ2э = 239.3; df = 157; χ2W=0.05 = 187.2) at that effect of the prior was stronger than that of the latter. By using the cluster analysis (k-means algorithm), the target sub-collec­tion structure has been revealed. Twelve accessions that overwintered well at both geographical locations during all the years of testing were identified.  

Background. Black currant occupies one of the leading po­sitions among berry plants in terms of the content of nutri­ents and bioactive substances that are necessary for a bal­anced human diet. The modern standards for black currant varieties include mandatory requirements to the quality of fruits, including their biochemical composition. The high content of nutrients and biologically active substances in the berries is one of the priorities in breeding of this crop. The fruit biochemical composition is a genetically deter­mined trait that can vary in different soil and climatic zones. In this regard, the analysis of the degree of bioactive sub­stances accumulation in berries in a particular region of cultivation is relevant.

 Materials and methods. The con­tent of bioactive substances in black currant berries was analyzed in 2010–2012 in the Laboratory of Biochemistry and Molecular Biology of the N.I. Vavilov Institute (VIR). The content of P-active substances (flavonols, phenol car­boxylic acids, flavanes, anthocyanins) was determined in accordance with the methodological guidelines accepted at VIR.

Results and discussion. Black currant varieties culti­vated in Leningrad Province contain from 518.1 to 813.6 mg/100 g of bioflavonoids, including 20.6 mg/100 g of flavonols, 75.4 mg/100 g of phenol carboxylic acids, 233.8 mg/100 g of catechins and 335.1 mg/100 g of antho­cyanins. As a result of the study, the sources of high total content of bioflavonoids and separate groups of phenolic compounds have been identified and can be used in breed­ing programs. The sources of high phenol carboxylic acids content are cvs. ‘Orloviya’(k-35789) and ‘Sensei’ (k-42646); high catechin content is characteristic of cvs. ‘Vospomi­nanie’ (k-40471), ‘Orloviya’ (k-35789), ‘Nadiya’k-42478) and ‘Оcharovanie’ (k-41980); while the sources of Р-active substances (˃ 700 mg/100 g) are cvs. ‘Vospominanie’ (к40471), ‘Orloviya’ (k-35789) and ‘Nadiya’ (k-42478). All the studied varieties are characterized by a high level of antho­cyanins accumulation (˃ 200 mg/100 g) and can be used in breeding for the indicated trait. The highest variability of indicators of phenolic compounds was observed for hydroxycinnamic acids. The existence of negative relation­ships between the berry mass and the content of individual bioactive compounds was established.  

Expedition activities of VIR and its experiment stations greatly broadened the collected diversity of stone fruits with valuable plant material that can be used in breeding. Wild sour cherries from the Caucasus, Central Asia and the Far East introduced in the 1970–80s had a range of such important traits as immunity to fungal diseases, winter hardiness, drought resistance, restrained growth, vegetative reproduction ability, and were later used by Russian breeders for the development of new varieties and clonal rootstocks for growing cherries in various ecological and geographical areas of the country. The study of sour cherry samples collected in vivo helped in some cases to clarify some questions related to the range of polymorphism, taxonomic discrepancies, and the number of sour cherry varieties (Cerasus spp.) of Microcerasus prostrata (Labill.) Roem., Microcerasus incana (Pall.) Roem. and others. In general, this work contributed to the revision of the genus Cerasus Mill. by reducing the number of species in it, eliminating the extensive synonymy and the misidentified taxa. The breeding work aimed at creating new varieties and rootstocks for stone fruit crops is carried out in Russia at 4–5 institutions and employs wild species with important traits as source material. The future of effective breeding of resistant sour cherry varieties is impossible without the involvement of wild species with important breeding characteristics.  

Background. Leaf mold, a disease caused by the fungus Cladosporium fulvum Cooke in tomato, is one of the reasons for a significant decrease in the fruit yield. The most reli­able and environmentally friendly way to protect tomato from diseases is the development of resistant cultivars and hybrids. The study of genetic aspects of disease resistance in plants is the basis of successful breeding work. Marker-assisted selection of the source forms of tomato is a rela­tively new approach in breeding, based on direct selection of plants for genes that determine the economically impor­tant traits. It allows for the time-saving analysis of breed­ing material.

Materials and methods. The present work offers the results of screening more than 30 accessions from the genetic collection of tomato cultivars and hybrids of the Michurinsk State Agrarian University using the P7 molecular marker.

Results and discussion. Polymor­phism of the Cf-19 gene of resistance to leaf mold was evalu­ated, and clear reproducible results were obtained. To test the marker, seven hybrid forms of greenhouse tomato were used. The reliable identification of the Cf-19 gene by using the P7 marker was confirmed through artificial infection with C. fulvum. Six out of seven hybrids demonstrated a high level of resistance to the pathogen, which is con­firmed by the originators’ data. A strong lesion was noted on the leaves of only one hybrid. The molecular genetic analysis has shown that among all control samples, only this genotype was a recessive homozygote. Besides, ac­cording to the originator, this genotype is not resistant to leaf mold. The performed test proves the high efficiency of the P7 marker. By using it, 35 genotypes were analyzed. The data obtained during the work show that the majority of the studied samples turned out to be heterozygous. At the same time, homozygous forms were also noted. For in­stance, the ‘Golden Rain’ tomato cultivar has only one 250 bp fragment, which corresponds to a recessive homo­zygote. Four genotypes were found to contain 300 bp frag­ments, which correspond to dominant homozygotes. The molecular genetic analysis revealed a number of genotypes that can be used as sources of resistance to leaf mold.  

Background. Chaenomeles Lindl. is a popular ornamental and relatively young fruit crop. Genetic diversity of the genus favors breeding not only in these two areas, but also aiming at the development of cultivars of a universal type. To improve the efficiency of the breeding process, a cultivar model with the maximum combination of useful qualities in one genotype is vitally needed. The goal of this work was to identify the criteria for the model of a universal Chaenomeles cultivar, select cultivars that come closest to the model in their main economic traits, and find relationships among such characteristics.

Materials and methods. The study engaged 21 Chaenomeles cultivars and forms selected for their valuable qualities from the Nikita Botanical Gardens collection. They were compared with the cultivar model using cluster analysis, while correlation analysis was employed to assess interrelations between traits.

Results and conclusion. Criteria were identified for the universal cultivar model of Chaenomeles (ornamental and fruit purposes) according to 27 characteristics. Seven genotypes turned out to be closest to the universal model in a set of traits (4.44 units of the Euclidean distance): PХ4/9 (4.25 units), ‘Samurai’ (4.15 units), ‘Araks’ (4.01 units), ‘Afrikanych’, ‘Shatenka’ (3.9 units), ‘Krasavitsa Madlen’ and ‘Rosemary’ (3.7 units). Different degrees of correlation between the main 17 characteristics were observed. The strongest relationships was found between the beginning of flowering and its duration (r = –0.9), between the beginning of flowering and the duration of the dormancy period (r = 0.91), between the durations of flowering and dormancy periods (r = –0.82), between the corolla diameter, the flower’s originality (r = 0.83) and the overall ornamentality of the bush (r = 0.86). A tendency to dependence was observed in 12 pairs of traits (r = 0.46 to 0.61).  

Background. The ultimate goal of studies of any flora is the clarification of the history of vegetation cover and individual taxa formation in the studied region, determination of the degree of its individuality, of floristic links with other territories, and of regularities in flora formation.

Materials and methods. The flora of vascular plants in the island forest steppes of Middle Siberia, i. e. of the Krasnoyarsk, Kansk and Achinsk forest steppes, identified by the specific floras method of A. I. Tolmachev, was chosen as the object of research. The purpose of the paper was to study the structure of the Siberian geographical element in the steppe flora, characteristics of the types of constituent distribution areas selected on the basis of the phytochorion concept. The basis for determining the types of habitats was the planetary regionalization scheme by A. L. Takhtajan, complemented by statistical convergent zonation for Siberia by L. I. Malyshev, and for the Russian Far East by R. V. Kamelin.

Results. The territory of the Middle Siberian forest steppes is a part of the Altai-Yenisei Province. The Krasnoyarsk, Kansk and Achinsk forest steppes (Krasnoyarsk Territory) are the most northern parts of the region (55°28’–57°28’N, 89°– 96°40’E). Twenty-six local floras were examined. Ten distribution area types were identified within the Siberian geographical element of the boreal group according to the names of sub-regions and provinces (154 species, 11.12%), limiting their distribution from West to East or from East to West, including all intermediate Siberian provinces between them. All types of distribution areas were combined into four large subgroups, namely Siberian, West Siberian, Middle Siberian, and East Siberian. Names of geographical elements were composed from the names of several phytochoria, in which they had been registered, according to the rules by M. G. Popov.

Conclusions. The Siberian geographical element rates third in all three forest steppes after the Euro-Siberian and Circumboreal geographical elements. In the flora of the Middle Siberian forest steppes Siberian elements amount to 11%, among which the Middle Siberian ones prevail (4.4%, 61 species) due to the geographical position of the flora. The fraction of species distributed throughout Siberia is 3.25% (45 species), followed by East Siberian species (2.24%, 31 species) and West Siberian ones (1.23%, 17 species).  

Background. The studied population of Prunus pumila L. has been introduced into Chelyabinsk Province, as its natural area of distribution is in North America. Of interest for researchers is the introduced population’s variability, induced by the effect of soil and climate factors natural for its new habitat.

Materials and methods. A collection of 197 plants was employed to study the variability of P. pumila. Morphological characters were described in compliance with atlases dedicated to seed and fruit descriptive morphology, with some adjustments concerning specific features of the subfamily Prunoideae Focke. The confidence interval for means was calculated using the reliability criterion of t2 = 2.576. The degree of variation was assessed for the studied characters according to S. A. Mamaev’s scale.

Results and conclusion. The average fruit weight was 2.49±0.11 g and varied from 1.25 to 5.15 g. The average stone weight was 0.25±0.01 g. Out of the number of morphometric traits, almost all linear characters of fruit and stone size had low variability (coefficient of variation [V]: 8–12%). Of those linear characters, only the peduncle length showed medium variability (V = 13–20%). The stone weight also had medium variability, while the fruit weight demonstrated high variability (V = 21–30%). The fruit shape was subglobose (40.3%), less frequently ovate (20.9%), ovoid (20.9%), broadly ovoid (9.7%), cordate (6.1%) or elliptic (2.0%). The ventral suture was usually barely noticeable, less frequently moderately (3.1%) or strongly expressed (1.0%). Polymorphism was observed in the pulp color, which was usually green-pink (72.8%). The P. pumila stone shape was elliptic (38.1%) or subglobose (34.0%), less frequently prolate (10.7%), ovoid (13.2%) or obovate (4.1%). The stone was symmetrically shaped from the ventral suture and sides, usually looking subglobose from the sides. The shape of the stone’s apex was rounded (85.3%) or, less frequently, obtusely mucronate (15.7%); its base was rounded (80.7%), often attenuate (15.7%), less frequently slightly slanted (3.6%). The stone surface texture was smooth (57.4%), often slightly costate (36.5%). There were several cases of a more costate surface of the stone (6.1%). Thus, the introduced population was found to have broad polymorphism of morphological characters in the fruit and the stone. A considerable increase was observed in morphometric indicators, including the size of fruit and stone, compared with those typical for the species in natural environments, which may be of special significance for breeders. The fusiform shape of the stone, characteristic of var. depressa Pursh. in its natural habitat, was absent in the introduced population.

Background. The efficiency of heterotic breeding is determined by reasonable selection of the lines with the best combining abilities and important breeding traits. It is possible to use the variability potential of the majority of traits when the level of resistance to the main diseases and pests is quite high. The most harmful disease of maize is common or boil smut (caused by Ustilago zeae (Beckm.) Unger). The breeding of resistant lines and hybrids of maize is the most rational, cheap and ecologically safe way to fight the disease. The initial stage of breeding work is the identification of pathogen-resistant forms.

Materials and methods. In 2017, 594 accessions of six main Zea mays L. subspecies were studied using a score scale against the natural infectious background at the Kuban Experiment Station of VIR. The weather conditions (downpours and abrupt daily temperature fluctuations) were favorable for severe infection of maize plants with the pathogen.

Results and conclusion. No disease symptoms were found in 173 accessions; 162 genotypes were affected only slightly. The greatest number of accessions with resistance to boil smut belonged to subsp. indentata (Sturt.) Zhuk. (69.4% of the total studied accessions), subsp. everta (69.2%) and subsp. semidentata (Sturt.) Zhuk. (66.7%). Accessions of subsp. amylacea (Sturt.) Zhuk. were more susceptible to the pathogen than other maize subspecies. The Russian, European and North American local maize varieties and self-pollinated lines had a low infection rate, while the accessions that came to the VIR collection from Asia and South America showed higher rates. After two years of comprehensive studies, the selected forms can be recommended for the use in breeding for immunity.

Background. Fungal diseases are the main cause of the deterioration of grain quality and lower yield of cereals crops. Reduction of acreage, and, as a consequence, violation of crop rotation rules, oversaturation of fields with cereals, spring and summer droughts contribute to the mass emergence and widespreading of new obligate and facultative diseases in all regions of the country. Therefore, the search for a variety of donors and sources of sustainability is a vital task.

Materials and methods. Materials engaged in the research were kernels of 41 oat accessions from the VIR collection of plant genetic resources, obtained in 2016–2018 in field crop rotations by the Genetic Diversity Research Department of ARHIBAN (Mikhnevo, Stupino District, Moscow Province). The specific diversity of micromycetes in grain was identified using Litvinov’s “wet chambers” technique and light microscopy.

Results. The dominant pathocomplex of micromycetes in oat grain in Moscow Province was found to belong to the genera Alternaria (A. infectoria, A. tennuissima), Cladosporium (Cl. cladosporioides, Cl. herbarum) and Fusarium (F. avenaceum, F. culmorum, F. heterosporum, F. nivale var. nivale, F. oxysporum, F. poae, F. proliferatum, F. solani, F. sporotrichioides var. minus, and F. tricintum).

Conclusion. The hulled cultivars ‘Bulanyi’ (VIR-15277, Russia, Moscow Prov.) and ‘Zakat’ (VIR-15384, Ukraine), and the naked cultivar Mestnyi (VIR-15290, UK) demonstrated the least contamination with pathogens: Fusarium fungi in these accessions were represented by one species – F. avenaceum.

Background. The breeding of resistant varieties is an effective way to control greenbug Schizaphis graminum Rondani, an economically important pest of oat and other cereals in southern Russia. The insect-host differential interaction necessitates a constant search for new resistance donors.

Materials and methods. One hundred and ninety one accessions (mostly landraces) from the Caucasian countries (Armenia, Azerbaijan and Georgia) as well as from the North Caucasus of the Russian Federation (Dagestan) were assessed for greenbug resistance. The Krasnodar (Gulkevichi District) insect population was used in the experiments. The intact plants were uniformly infested with differentaged aphids in the phase of two leaves by shaking insects onto them. When the susceptible control (cv. Borrus) died, the plant damage score was determined using the scale from 0 (no damage) to 10 (91–100% of the leaf surface damaged, plant’s death). The plants with the score of 1–4 points were classified as resistant, 5–8 moderately resistant, and 9–10 susceptible.

Results and conclusions. A local oat accession from Georgia (k-4308) was noted for its high insect resistance. Also, heterogeneity of the studied trait was demonstrated by 38 oats forms, most of which were differentiated into two phenotypic classes, and a wide range of plant damage variation was characteristic of 16 accessions. The specific occurrence of resistant forms was the highest among oat landraces from Azerbaijan: two out of five studied accessions (40%) carry resistance genes with a distinct phenotypic manifestation. They are followed by accessions from Georgia (25%), Armenia (17.3%) and Dagestan (13.8%). After selection for resistance, the identified forms can be used in plant breeding.

Background. Knowledge of the reproductive potential in plants is of vital importance for potato cultivation in the Arctic environments.

Materials and methods. From 2008 through 2017, 1594 potato cultivars with diverse maturation schedules from VIR’s collection were studied at the Polar Experiment Station of VIR. The material was evaluated according to the timing of their phenological phases (germination, budding, and flowering) and the possibility of their reproductive organs’ development.

Results: With the same agricultural practice applied, cultivars of different maturation groups began to germinate and produce shoots at about the same time within the growing season, with a slight difference from 0.2 days (2010) to 3.3 days (2015). Further passing of phenological phases under the conditions of the Arctic depended on the mean daily air temperature and precipitation. The duration of the period from germination to flowering was largely affected by the temperature regime. The emergence of mass shoots was observed on average 18.5 ± 2.9 days after planting. The budding phase started 31.9 ± 4.7 to 43.0 ± 6.9 days after planting. The beginning of flowering occurred at the beginning of the third decade of July or 46.8 ± 4.9 to 57.5 ± 7.5 days after planting. The duration of the mass flowering of potato plants on average covered the time frame from the end of July to the middle of the third ten-day period of August. To move a potato plant from the budding phase to the flowering/mass flowering phase, a sum of effective July temperatures of 300°C is required. During the growing season, for all the years of the study, 97% of the varieties, as related to the total number of accessions, were able to set up buds; 85.7% entered the flowering stage; 63.3% moved to the stage of mass flowering; and 22.2% were able to set berries from self-pollination. According to the data of the long-term analysis of perennial agrometeorological data, the most favorable conditions for setting berries after potato self-pollination recurred every five years in the north. These conditions were formed under the sum of active air temperatures from 1170 to 1300°С (for June, July, and August), combined with insufficient provision of precipitation. Under the natural conditions in the north, the lack of moisture stimulates plants to enter the stages of flowering and fruit setting quicker and more intensively.

Conclusion: The study made it possible to identify the optimal conditions for the fruit to be set by a potato plant in the north and also to acquire more data on the reproduction characteristics of potato cultivars.