Length Of Vegetation Period Research Articles

Fine mapping and grain yield analysis of a major QTL controlling primary branch number in rice (Oryza sativa L.)

Panicle size is one of the most important agronomic traits highly associated with grain yield in rice. For quantitative trait locus (QTL) analysis and breeding utilization of panicle size in rice, a large panicle rice line YR1 was used as a donor to cross and backcross with a commercial cultivar Ningjing 1 (NJ1), and developed backcross populations. In a BC2F2 population, a total of 3 QTL associated with panicle size were found on chromosome 1 and 8. Two of the QTLs, qPBN1 and qGNP1, were mapped to an interval on chromosome 1, where a previously cloned gene GN1a was located. qPBN8, a major QTL for primary branch number on chromosome 8, was finally narrowed to a 51.8 kb region, containing reported gene OsSPL14 regulating branch number and plant architecture. Through sequence and expression comparison, the qPBN8 was considered to be the allele of OsSPL14. The investigation of yield structure in six pairs of near-isogenic lines revealed that the effects of qPBN8 on grain yield were related to the length of vegetative period. The qPBN8 allele of large panicle was suitable for late-maturing varieties to improve yield.

Resource availability drives trait composition of butterfly assemblages.

How species respond to environmental change is a fundamental question in ecology and species traits can help to tackle this question. In this study, we analyze how the functional structure of species assemblages changes with selected environmental variables along an elevational gradient. In particular, we used species traits of local butterfly communities (body size, voltinism, overwintering stages, and host specificity) in a national nature reserve in China to assess the impacts of temperature, net primary productivity, and land use. Our results show that productivity, measured as NDVI, had a stronger influence on the functional community structure of butterflies than temperature. Within the butterfly assemblages, net primary productivity mainly affected body size and supported few but large species. Length of vegetation period demonstrated dominating effects on the functional structure of local butterfly assemblages. However, an observed increase in dietary generalists with longer vegetation periods contradicted expectations based on niche breadth hypothesis, that more stable conditions should favor specialists. Furthermore, the general positive impact of vegetation period on species abundances differed considerably among functional groups. Only the group containing species hibernating as egg decreased with the length of vegetation period. Our results suggest that trait associations are instructive to explain environment-herbivore relationships, that resource availability can predominantly influence the functional composition of herbivore assemblages, and that conservation priority should be given to specialist butterfly species overwintering as egg, especially in the face of global warming.

Изучение сортов клевера лугового различного типа спелости и плоидности

For creating new cultivars of red clover it is necessary to use traditional and modern methods: polyploidy, mutagenesis, heterosis and ecological breeding. These methods have been used in breeding for a long time, but it was necessary to modify them to the cultivation of red clover considering its biological fea-tures (perennity, length of vegetation period, winter hardiness) in conditions of harsh continental climate in Siberia. The complex-hybrid population, late maturing, diploid based – the cultivar SibNIIK 10 has been created based on best polycross offspring by polycross method in West Siberia. The winter hardy, early maturing, tetraploid based cultivar Meteor has been created as the result of combination of mutage-nesis, polyploidy, hybridization and selection methods together with FWRC FPA for the first time ever in Siberia. The research cites a comparative study of two cultivars of red clover (SibNIIK 10 and Meteor) of different types of maturity and ploidy by main economically valuable traits. Early maturing tetraploid based cultivar Meteor in herbage and dry matter yield exceeds late maturing cultivar SibNIIK 10 by 9–39 and 7–41% and in seed yield SibNIIK 10 exceeds Meteor by 30%.

THE SOWING TERM EFFECT ON SEED QUALITY, ECONOMIC AND ENERGETIC EFFICIENCY OF SOYBEAN CULTIVATION

The nutritional value of soybean seeds is in high protein (up to 35%) and fat (up to 25%) percentage. In the Russian Federation, there is a positive trend in increasing the soybean acreage (e. g. from 1.537 million hectares in 2013 to 2.919 million hectares in 2018). The field trials were carried out in the laboratory of cultivation technology of row crops of the FSBSI “Agricultural Research Center “Donskoy” (Zernograd, southern soil-climatic region of the Rostov region) in 2016–2017. The experiments were conducted with the varieties of local breeding “Don 21” and “Diva”, included in the State Register of Breeding Achievements of the Russian Federation in 6 regions, differing in the length of vegetation period. The soil of the experimental plot is favorable for soybean cultivation, the humus content in the topsoil is 3.36%; pH is 7.0; P2O5 is 24.4; K2O is 360 mg/kg of soil. Depending on the sowing period, the soybean yields varied from 0.85 to 1.25 t/ha for the variety “Don 21” and from 0.77 to 1.38 t/ha for the variety “Diva”. The protein content in soybean seeds was the highest in the fourth term of sowing (41.9 and 39.8%), and the fat content in the first term was 19.0 and 20.2% (the varieties “Don 21” and “Diva” respectively). The analysis of economic and energy efficiency identified the most effective variants of the trial. The variety “Don 21” had the second sowing period, the variety “Diva” had the third one, with the highest values of profitability (129.8 and 147.7%) and the energy efficiency ratio (2.03 and 2.18).

THE RESULTS OF VARIETY TRIALS OF NEW VARIETIES OF MELONS IN CONDITIONS OF THE VOLGOGRAD TRANS-VOLGA REGION

Presents comparative characteristics of the 4 new varieties of melon breeding Bykovskaya melon experiment station in comparison with the standard. A brief description and varietal characteristics of the new varieties of melons of different ripening periods. Data on the yield, length of vegetation period, dry matter content, as well as complex resistance to diseases. According to the results of comparative evaluation in station variety testing, new melon varieties exceed the standard in yield from 2.7 t/ha (Harmony) to 4.6 t/ha (Originalnaya x Osen), in dry matter content from 0.2% Cometa variety to 1.1% Harmony variety (standard Osen variety – 13.0%). Testing for complex resistance to Anthracnose and powdery mildew revealed that the lowest degree of damage in a hybrid combination of the Originalnaya x Osen was powdery mildew – 51.3%, with a score of 1.4, anthracnose – 80.6% at a score of 1.5.

Reponses and sensitivities of maize phenology to climate change from 1981 to 2009 in Henan Province, China

With the global warming, crop phenological shifts in responses to climate change have become a hot research topic. Based on the long-term observed agro-meteorological phenological data (1981–2009) and meteorological data, we quantitatively analyzed temporal and spatial shifts in maize phenology and their sensitivities to key climate factors change using climate tendency rate and sensitivity analysis methods. Results indicated that the sowing date was significantly delayed and the delay tendency rate was 9.0 d·10a-1. But the stages from emergence to maturity occurred earlier (0.1 d·10a-1<θ<1.7 d·10a-1, θ is the change slope of maize phenology). The length of vegetative period (VPL) (from emergence to tasseling) was shortened by 0.9 d·10a-1, while the length of generative period (GPL) (from tasseling to maturity) was lengthened by 1.7 d·10a-1. The growing season length (GSL) (from emergence to maturity) was lengthened by 0.4 d·10a-1. Correlation analysis indicated that maize phenology was significantly correlated with average temperature, precipitation, sunshine duration and growing degree days (GDD) (p<0.01). Average temperature had significant negative correlation relationship, while precipitation, sunshine duration and growing degree days had significant positive correlations with maize phenology. Sensitivity analysis indicated that maize phenology showed different responses to variations in key climate factors, especially at different sites. The conclusions of this research could provide scientific supports for agricultural adaptation to climate change to address the global food security issue.

Regional diversification of fruit production in Poland

The aim of the study was to identify the spatial differentiation of cultivated area and fruit harvest in Poland in year 2015. The sources of data for the study were based on studies of subject literature and statistical publications of the Central Statistical Office of Poland. The research shows that the location of orchards is primarily determined by natural conditions, such as temperature, precipitation, sun exposure, length of vegetation period, level of groundwater retention and slope exposure to sun. The largest fruit orchards in Poland are located in Grójec-Warka area in Mazowsze, near Sandomierz and Lublin. According to the administrative system most of the orchards are located in Mazowieckie, Lubelskie, Łódzkie, Świętokrzyskie, Wielkopolskie and Lubuskie Voivodeships. In addition, various socio-economic determinants of the development of fruit production are determined by the different socio-economic conditions. It contains closeness to the absorptive markets, price to costs relation, processing base, specialized equipment and storage facilities.

Safety of Potato Consumption in Slovak Region Contaminated by Heavy Metals due to Previous Mining Activity

Heavy metals are among the most serious environmental contaminants in mining districts. Soil, as one of the main components of the environment, is the place of heavy metal entry into plants and consequently into the food chain, too. Potatoes grown in the region of Middle Spis (Slovakia) may be a source of increased content of heavy metals and pose a health risk to the consumer. The contents of heavy metals (Cd, Pb, and Ni) in potato and soil samples were determined using the AAS method and compared with limit values set by the Slovak Republic and the European Union. The content of heavy metals was determined in 12 potato cultivars with different length of vegetation period (mid-early, very early, and early, resp.), which were grown in three localities with a highly disturbed environment. Total contents and mobile forms of heavy metals as well as physical and chemical properties were determined in soil samples which were collected from the same sampling sites. Only Pb content in potato tubers was higher than the hygienic limit value (0.1 mg kg−1 FM) in 15 sampling sites (interval was n.d. –0.2298 mg kg−1 FM). The contents of exchangeable forms (total content) of heavy metals in soil were ranged between the intervals: Cd 0.004–0.055 (0.94–1 56), Pb 0.023–0.295 (17.00–26.80), and Ni 0.019–0.475 (30.80–71.00) mg kg−1. At current average consumption levels of potatoes, tolerable weekly intake (TWI) or tolerable daily intake (TDI) for observed heavy metals was not exceeded.

Relationships between race-specific and race-non-specific resistance to potato late blight and length of potato vegetation period in various sources of resistance

Late blight is the most destructive potato disease, and there is consequently strong market demand for disease-resistant cultivars. However, potato resistance to P. infestans is strongly associated with late maturity. In this study, the relationships between race-specific and race-non-specific potato late blight resistance and length of the vegetation period were examined in three unselected progenies with various origins of resistance. The vegetation period and late blight resistance of 514 progeny clones were evaluated in laboratory and field tests. The relative area under the disease progress curve (rAUDPC) and auxiliary parameters for the delay of infection onset (ΔT) and disease progression rate (ΔA) were calculated based on field observations. In all examined progenies, late maturity was correlated with foliage resistance to P. infestans in field experiments, but not under laboratory conditions. Regardless of the resistance source, potato late maturity was always correlated with a low disease progression rate, which is typical for race-non-specific resistance. The mechanism underlying this relationship is likely physiological, and both traits are consequences of the same phenomenon, that is, the higher level of race-non-specific resistance resulting from a tendency for late maturation. Race-specific resistance appears to be unrelated to maturity because none of the tested R-genes against P. infestans, with the exception of R1, contributed to a longer vegetation period of the potato plants. However, late maturity of potato plants enhanced the efficacy of the R-genes under field conditions.

Effect of sowing technology on the yield and harvest grain moisture content of maize (Zea mays L.) hybrids with different genotypes

From the aspect of the efficiency of maize production harvest grain moisture content shall be considered beside the amount of harvested grain yield. Hybrids with different genotypes and vegetation period length lose their moisture content different that is affected by row spacing and plant density – among agrotechnical production factors – depending on the given crop year. In the present research work three crop years with different weather conditions were studied (2013, 2014, and 2015). The small-plot field experiment was set up at the Látókép Field Research Centre of the University of Debrecen, Centre for Agricultural Sciences with four replications on a chernozem soil type. The effect of three factors was analysed in the experiment on yield amount and its moisture content. Factors were row spacing (45 and 76 cm), plant density (50, 70 and 90 thousand plants ha-1), while hybrids were of very early (Sarolta: FAO 290), early (DKC 4014: FAO 320, P 9175: FAO 330, P 9494: FAO 390) and medium (SY Afinity: FAO 470) ripening.&#x0D; In the crop year of 2013 the highest yield was produced – regarding the average of the hybrids – by the application of a row spacing of 45 cm (4.5%, 673 kg ha-1), however there was no significant difference between the yield of the populations of different row spacings. Significant difference (14.9%, 1751 kg ha-1; 6.3%, 583 kg ha-1) could be found in case of yield between different row spacing applications in 2014 and 2015. The effect of insufficiently distributed low amount of precipitation and lasting heat days in 2015 could be revealed in yield amounts and harvest grain yield moisture content results that were lower than in the previous years. In 2015 grain yield moisture content varied between 10.3 and 13.9% in case of a row spacing of 45 cm, while by 76 cm between 11.0 and 13.9%.

The diversity of spring hexaploid triticales, differing on the time of the onset of developmental phases under conditions of near Ob region of Western Siberia

The time of the onset of developmental phases of 78 spring hexaploid triticale samples from the world collection of N.I. Vavilov Institute of Plant Industry is studied under natural conditions, in two replicates with a 18-day interval between two dates of sowing. The number of days from the date of sowing up to the date of heading of triticale samples at the I term sowing was from 31 to 49, and at the II term sowing, from 30 to 52. Samples from Argentina, Portugal, Eastern Europe, Poland, Belarus, and Ukraine headed within the interval of mean values (34–40 days). Triticale M2A/Cin from Ethiopia was relatively early ripening. Late ripening were the samples from Zambia, Brazil, North America. Among triticales from Mexico, Dagestan and Russia both early and late ripening forms occurred. Most samples (82 %) at the II term sowing headed 1–9 days earlier than at the I term sowing, which was probably due to a shortening of the period «shoots– the first node» by 1–7 days in 87 % of samples. After lengthening this period, in the triticales studied in the present work, as in wheat, the length of vegetation period increased. The length of the interphase period «heading– ripening» in these samples increased, while in wheat some authors noticed its shortening. Hexaploid triticale samples studied had different times of the onset of developmental phases and response to different terms of sowing, which means their possible use in regions with different daylength.

Characterization of spring barley lines in a competitive cultivar trial

The results of evaluation of spring barley lines belonging to different varieties bred at the Plant Production Institute are presented. Lines of the hulled group (nutans Schűbl., rikotense R. Red, medicum Koern., pallidum Ser.) and hulless variety nudum Koern were distinguished.The aim and tasks of the study. The study purpose was to create and evaluate hulled lines of two-row and multi-row spring barley as well as a hulless spring barley variety with high yield capacity and lodging resistance.Materials and methods. The studies were conducted in a competitive cultivar trial at the Plant Production Institute nd. a V. Ya. Yuriev of NAAS. The staring material was spring barley lines created by hybridization of different cultivars and collection accessions of different origin. The data on yield capacity were statistically processed using analysis of variance according to the BA Dospekhov’ procedure.Results and discussion. High-yielding spring barley lines were created in the Laboratory of Barley Breeding and Genetics of Plant Production Institute nd. a V. Ya. Yuriev of NAAS . The best of them were generated by using cultivars ‘Efekt’, ‘Etiket’, ‘Parnas’, ‘Feniks’, ‘Dzherelo’, ‘Vyklyk’, and ‘Lad’ bred at the Plant Production Institute; ‘Vakula’ bred at the Plant Breeding and Genetics Institute; ‘Omskiy Golozerniy1’ (RF); accessions UA 039699, UA 039701 (USA); IR 6576, IR 6912 (Mexico); Ebson (Czech Republic); and Tokada (Germany) as starting material in crosses. The average yield capacity of lines for two years was in the range from 5.54 t / ha (104% of the standard) to 6.20 t / ha (116% of the standard), with 5.32 t / ha in the standard ‘Vzіrets’. As for the vegetation period length, the test lines were sorted as middle-ripening (82-90 days). An important feature of barley is its lodging resistance; it was different in the test lines: 7.0 - 8.5 points in 2014 and 7.0-8.5 points in2015. In 2015, the grain-unit was moderate (655-695 g / L) in hulled lines and high (705-780 g / L) in hulless ones, which is attributed to the shape of caryopsis.Conclusions. We identified lines with a complex of valuable economic traits; among them were two-row hulled lines 06-652, 12-486, 12-116, 12-333, and 12-1014; multi-row hulled lines- 12-476 and 12-1131; hulless line 13-728. The lines distinguished are valuable starting material for breeding.

Polytolerance to abiotic stresses: how universal is the shade-drought tolerance trade-off in woody species?

According to traditional ecophysiological theories stress tolerance of plants is predominately determined by universal physiochemical constraints. Plant acclimation to environmental stress therefore compromises plant performance under a different stress, hindering successful toleration of several abiotic stress factors simultaneously. Yet, recent studies have shown that these trade-offs are less exclusive than postulated so far, leaving more wiggle room for gaining polytolerance through adaptations We tested whether the polytolerance to shade and drought depends on cold and waterlogging tolerances - hypothesizing that polytolerance patterns in different species groups (angiosperms vs. gymnosperms; deciduous vs. evergreen; species originating from North America, Europe and East Asia) depend on the length of the vegetation period and species's dormancy through limiting the duration of favourable growing season. Northern hemisphere. Our study analyzed four main abiotic stress factors - shade, drought, cold and waterlogging stress - for 806 Northern hemisphere woody species using cross-calibrated tolerance rankings. The importance of trade-offs among species ecological potentials was evaluated using the species-specific estimates of polytolerance to chosen factors. We found that both cold and waterlogging tolerance are negatively related to species' capabilities of simultaneously tolerating low light and water conditions. While this pattern was different in angiosperms and gymnosperms, species region of origin and leaf type had no effect on this relationship. Our results demonstrate that adaptation to different abiotic stress factors in woody plants is highly complex. Vegetation period length and dormancy are the key factors explaining why woody plants are less capable of tolerating both shade and drought in habitats where vegetation period is relatively short and water table high. While dormancy enables angiosperms to more successfully face additional stress factors besides shade and drought, gymnosperms have lower polytolerance, but are better tolerators of shade and drought when other environmental factors are favorable.

Evaluation of selected Polish potato cultivars and breeding lines regarding their resistance against Phytophthora infestans and usefulness for organic farming

The presented studies concern an evaluation of 10 potato cultivars (5 starch and 5 table) and 9 selected potato breeding lines re-garding their resistance against Phytophthora infestans as well as other traits such as length of vegetation period, yield, tuber size, regularity of tuber shape, depth of eyes. The aim of these studies was to evaluate of the potential usefulness of tested potato cultivars/clones for organic farming. The obtained results indicate that none of the tested table cultivars should be recommended for organic farming, due to their low resistance to P. infestans. The examined starch cultivars show high resistance to P. infestans, but their cultivation in organic farming seems to be restricted due to other features’ for example very long vegetation period. On the cont-rary, the group of tested potato breeding lines seems to be very useful for organic farming since they are high yielding and display relatively short vegetation period and high resistance to P. infestans. Moreover, these clones produce tubers with an attractive tuber appearance that is indispensable for table potatoes. Przedstawione badania dotyczą oceny 10 odmian (5 jadalnych i 5 skrobiowych) oraz 9 klonów hodowlanych ziemniaka pod względem poziomu odporności na Phytophthora infestans oraz wybranych cech użytkowych (długość wegetacji, wysokość plonu, wielkość bulwy, regularność zarysu, głębokość oczek). Badania te miały na celu określenie ewentualnej przydatności badanych form do upraw ekologicznych. Wyniki badań wskazują, że żadna z badanych odmian jadalnych nie powinna być rekomendowana do upraw ekologicznych ze względu na bardzo niski poziom odporności na P. infestans. Badane odmiany skrobiowe posiadają wysoki poziom odporności na P. infestans, bardzo pożądany w uprawach ekologicznych. Jednakże ich wykorzystanie w tym celu może być ograniczone przez niedobory innych cech użytkowych (np. bardzo długą wegetację). Natomiast grupa badanych klonów hodowlanych charakteryzowała się bardzo wysokim poziomem odporności na P. infestans, skróconym okresem wegetacji, wysokim plonem oraz atrakcyjnym wyglądem bulw.

Birch stands growth increase in Western Siberia

Birch (Betula pendula Roth) growth within the Western Siberia forest-steppe was analyzed based on long-term (1897–2006) inventory data (height, diameter at breast height [dbh], and stand volume). Analysis of biometry parameters showed increased growth at the beginning of twenty-first century compared to similar stands (stands age = 40–60 years) at the end of nineteenth century. Mean height, dbh, and stem volume increased from 14 to 20 m, from 16 to 22 cm, and from ∼63 to ∼220 m3/ha, respectively. Significant correlations were found between the stands mean height, dbh, and volume on the one hand, and vegetation period length (rs = 0.71 to 0.74), atmospheric CO2 concentration (rs = 0.71 to 0.76), and drought index (Standardized Precipitation-Evapotranspiration Index, rs = −0.33 to −0.51) on the other hand. The results obtained have revealed apparent climate-induced impacts (e.g. increase of vegetation period length and birch habitat drying due to drought increase) on the stands growth. Along with this, a high correlation of birch biometric parameters and [CO2] in ambient air indicated an effect of CO2 fertilization. Meanwhile, further drought increase may switch birch stand growth into decline and greater mortality as has already been observed within the Trans-Baikal forest-steppe ecotone.

Anthocyanins profile and antioxidant capacity of red cabbages are influenced by genotype and vegetation period

The profile and content of anthocyanins in five red cabbage varieties were analyzed using HPLC–DAD–MS/MS method. The antioxidant capacity of red cabbages was evaluated using five in vitro assays. Red cabbages contained twenty different anthocyanins with the main structure of cyanidin-3-diglucoside-5-glucosides. The presence of nonacylated, monoacylated and diacylated form was identified. Nonacylated and diacylated with sinapic acid derivatives of cyanidin-3-diglucoside-5-glucoside were predominant. The content of anthocyanins varied significantly in plants grown in two different years (P<0.05). Moreover, the vegetation period length was demonstrated to affect the anthocyanins profile. The extract of red cabbages scavenged radicals and their antiradical potential differed significantly across the varieties (P<0.05). In addition, red cabbage antioxidant capacity was positively and significantly correlated with anthocyanins content (P<0.05). This study demonstrates that red cabbage varieties possess own anthocyanins fingerprint and specific antioxidant capacity, which are also under the influence of vegetation period.

The studies on vegetation period and plant characters determining seed yield in soybean

12 Soybean strains bred by the author were tested with respect to their adaptation to different environments in the period 1975-1977. Better environmental conditions in Przecław (Rzeszów region) than in Radzików near Warsaw have beneficial effect on seed yield and the lenght of vegetation period in tested soybeans. Generaly, tested strains yielded better than population variety 'Warszawska' used as a check. Highest yield was produced by strain M-17/76 - 22,7 q/ha. This strain is already registered as a variety 'Ajma'. Seed yield, fat and protein content are determined by genotype and environmental factors. The negative correlation was found between seed yield, its components and the length of vegetation period. It suggests that selection of early and, at the some time, high yielding varieties can and should be done.

Digital analyses of cartometric Fruska Gora guidelines

Modern geo morphological topography research have been using quantity statistic and cartographic methods for topographic relief features, mutual relief features, mutual connection analyses on the grounds of good quality numeric parameters etc. Topographic features are important for topographic activities are important for important natural activities. Important morphological characteristics are precisely at the angle of topography, hypsometry, and topography exposition and so on. Small yet unknown relief slants can deeply affect land configuration, hypsometry, topographic exposition etc. Expositions modify the light and heat of interconnected phenomena: soil and air temperature, soil disintegration, the length of vegetation period, the complexity of photosynthesis, the fruitfulness of agricultural crops, the height of snow limit etc.

Predicting soil and forest floor carbon stocks in Western Anatolian Scots pine stands, Turkey

The objective of this study was to determine the models which estimate the soil plus forest floor carbon stocks (TC) using some stand, climate, and topographic parameters in Scots pine (Pinus sylvestris L.) stands. 40 sample plots were taken from sites differing in aspects, elevation, slope degree, slope position, and stand growth condition. TC of the stands, as dependent variables, and stand, climate, and topographic properties, as independent variables, were determined and evaluated with multiple regression analysis (MRA) and classification and regression tree technique (CART). In conclusion, TC were related with elevation, slope degree, slope position, aspect, actual evapotranspiration, mean annual precipitation, length of vegetation period, rainfall in the driest month, rainfall from June to September, stand volume, and site index. 91% of the variance in TC was explained with CART while 60% with MRA in a local scale. The results showed that soil and forest floor might become a carbon source where the rainfall decreased, but a sink, especially in productive sites where rainfall of the driest month increased. Key words: Carbon stocks, forest floor, regression tree, Scots pine, soil.

Length of vegetation period as parameter of common oak (Quercus robur L.) phenological variability

Paper presents results for length of vegetation period as factor in common oak?s (Quercus robur L.) phenological variability. Trees in two common oaks populations on two locations in area of Belgrade were researched. Average length of vegetation period on site Ada Ciganlija is 166 days, while in location Bojcinska suma is 179 days. Regarding that populations are in similar environmental and habitual conditions, differences in results should be treated as consequence of common oaks intra-specific variability and genetic structure of population. Significant differences in three consecutive years of observation are confirmed.