Purpose. To study the protein content and other economically valuable traits in soybean varieties of various origin, to determine the stability and plasticity indicators of these traits, as well as to identify varieties that are promising for use in breeding programs. Methods. Field, laboratory, biochemical and statistical. Results. In total 22 soybean varieties of various origin in terms of yield, protein and oil content in seeds were investigated. High-yield and high-plasticity varieties are distinguished: ‘Muza’, ‘Mentor’, ‘Asuka’, ‘Valas’, ‘Kofu’, ‘Asuka’, ‘Cardif’, ‘Alligator’, ‘Vyshyvanka’, ‘Suziria’ and varieties of domestic breeding with stable yield ‘Siverka’, ‘Vilshanka’, ‘Ustia’, and also the ‘Lisbon’ variety. High protein content was noted in the variety ‘Opus’ – 45.0% in 2017. This variety on average for three years showed 43.63% of the protein in the seeds, and was second after the ‘Ustia’ variety (44.3%). The highest value of the regression coefficient b = 4.289 was observed in the ‘Lisbon’ varie­ty, which shows its high sensitivity to growing conditions with a fairly low average seed protein content of 38.60%, as well as the variety ‘Silesia’ b = 4.289 with an average protein value of 42,73%. Standard variety ‘Muza’ with a low protein content of 38.60% was quite stable in the expression of this characteristic – S2 = 0.222. A number of high-oil varieties were distinguished: ‘Valas’ – 22.77%, ‘Sigalia’ – 22.7%, ‘Alligator’, ‘Siverka’ – 22.53%, ‘Kofu’ – 22.13%, standard variety ‘Muza’ – 21.77%. Conclusions. In breeding programs aimed at increasing the protein content in seeds, the following varieties should be used: ‘Opus’ – as a carrier of the maximum value of the trait, as well as ‘Ustia’, ‘Asuka’, ‘Silesia’ and ‘Kasidi’ as combining high yield and high protein content. The weather conditions of the year in different ways influenced on the manifestation of the studied traits: in a favorable year for obtaining high yields, the protein content in the seeds decreased, the high protein content accumulated in a drier year, and the oil content in seeds changed insignificantly.

Purpose. To define the level of impact of such factors as rate, time and methods of sowing on seed productivity and certified seeds, and the individual response of winter wheat varieties to these factors if used the ecological system of seed farming, that would allow to form and obtain genetically determined potential of variety productivity. Methods. Weight measurement for determining seed yield; statistical, variance and regression analysis for identifying the reliabi­lity of the experiment results. Results. During the research period, weather conditions were greatly differed both by temperature regime and precipitation, but stability of grain and seeds yield on an annual basis was the main requirement to varieties. During the study of «grain productivity» value and quantitative indices of winter wheat yield structure, the results from 684 plots were obtained which were grouped and analyzed for impact factors for complete certainty, and NIR0,05 was calculated. Conclusions. Thus, in case of shifting sowing time from optimum to later period, efficiency of water use by plants was decreasing to a greater extent during years with insufficient precipitation. The shift of sowing time to later period providing optimal seeding rate and row seeding method did not reduce yield. The yield of winter wheat varieties to be studied when sowing in usual manner with seeding rate of 5,5 million seeds/ha in the period from September 15 and October 5 was the highest. Varieties ‘Slavna’ and ‘Chorniava’ provided the highest grain productivity for seeding rate of 5,5 million seeds/ha and using row seeding method, with slight impact of sowing time factor. Grain yield of studied varieties showed negative response during the experiment when seeding rate decreased up to 2,5–3,0 million seeds/ha. ‘Astarta’ varie­ty provided the highest productivity for certified seeds yield as compared to the control (from 1,59 to 3,38 t/ha). The variant of the experiment when sowing on October, 5 in usual manner with seeding rate of 5,5 million seeds/ha showed the highest productivity of 7,02 t/ha (+3,38 t/ha, or +92,9%). Shifting of sowing time for October, 5 resulted in a significant decrease in yields of certified seeds as compared to sowing time on September 15 and 25. Seed yield of studied varieties when sowing on October, 5 was higher than in case of sowing on September, 25. The highest percentage of certified seeds output in the studied varieties was observed for a seeding rate of 2,5–3,0 million seeds/ha. For seeding rate of 5,5 million seeds/ha for varieties with seeding time between September 15 and 25, the difference in grain yield was negligible. The winter wheat variety ‘Astarta’ provided the highest yield of seeds during the research years – 9,36 t/ha, the standard variety ‘Bogdan’ – the lowest one in the best variant of 5,55 t/ha.

The article highlights the results of studying hybrid combinations of common onion to the Botrytis allii Munn pathogen. It is found out that as for the combinations being studied the resistance to pathogen was inherited as dominant, intermediate or recessive trait. Better resistance to neck rot was inherent in the hybrid combinations which parents comprised resistant and immune varieties, insofar as the determination of inheritance coefficient has indicated F1 hybrids have this characteristic expression dependant by 50 to 78% on the parental plant (h2 =0,50–0,78). Studying the determination of the impact of both parental components on inheritance of the resistance to B. allii pathogen showed that the regression coefficient subject to hybrid combination fell within R = 0,12–0,39, while the resistance coefficient within 0,24–0,78, respectively. Efficiency of selection is proved by the trait of resistance to neck rot based on the populations of Grandina х Mavka, Olina х Grandina, Grandina х Skvyrska і Skvyrska х Grandina, as their respective inheritance coefficient reached the level of 0,42 to 0,78.

Purpose. To develop a tobacco variety model with optimal inflorescence traits such as size and shape that will allow to increase seed productivity of the crop. Methods. Statistical and mathematical (correlative, regressive) ones. Results. Basic collection consisting of 282 variety samples registered in the National Genetics Center was evaluated, optimal parameters of inflorescence were defined that can provide a high seed yield. During statistical analysis, correlation matrix was developed with the purpose to highlight traits that correlate with inflorescence productivity. According to the results of correlation analysis, a strong relationship between the width and height of inflorescence (r = 0,773±0,038) was established. Somewhat weaker correlation was observed when modeling regressive relation between inflorescence height and width, where regression showed the medium relationship. Regression equation of these traits is as follows: y = 0,5585x + 8,4649. Inflorescence density (r = 0,646), height (r = 0,556) and width (r = 0,527) also had quite a high positive effect on seed productivity. The results of regression analysis pointed to the fact that there were a linear relationship between inflorescence size and seed productivity. Conclusions. Among 282 samples of basic tobacco collection, 29 varieties with high seed productivity was defined which can be used in the breeding process, and ‘Sobolchskyi 15/21’, ‘Ergo 23’, ‘C-11’, ‘Sygarnyi 99’ varieties were selected for large-scale implementation into the production of raw material of cigar type.

The use of regression analysis for estimation of inbred lines is a breeding - oriented method, as it indicates scientifically grounded stages of the further breeding studying of these lines and a strategy of their use. Admissible levels of inbred depression of agriculturally valuable characters are limited in lines of the Verkhnyachka and Lgov geneplasms by two - three generations of self - pollinations, which testifies to the necessity "to keep" the characters of sufficient basis. Linearity of changes of values of the characters with the advancing of inbreeding shows the absence of epistasis or the weakness of their effects which makes suitable the use of an additive-dominant model for determining breeding-genetical value of inbred lines with the aim of their purposeful hybridization for obtaining genetically determined heterosis in F1.

Purpose. To identify spring durum wheat accessions with high yield level and by yield components for their involvement in breeding programs as a source material. Methods. Field, statistical. Results. The results of the study of 65 collection samples of spring durum wheat of various ecological and geographical origin in terms of productivity in 2016–2018 are presented. The research results indicate that the samples of spring durum wheat had different yield level depending on the conditions of the year of cultivation. According to the calculations of the degree of yield stability parameters, the samples were found that ensure its level under fluctuations in weather conditions with regression coefficient close to one as follows ‘Omskiy izumrud’ (RUS), ‘Korona’, ‘Toma’, ‘Nauryz 6’ (KAZ), ‘Dura king’, ‘Candura’ (CAN), ‘Tera’, ‘Novatsiia’ (UKR), thus indicating their semi-intensive type. Collection samples of spring durum wheat that under optimal weather conditions are capable of producing significant yield increase are distinguished by wide ecological reaction. These are samples with regression coefficient more than one ‘MIP Raiduzhna’, ‘Hordeiforme 13-07’ (UKR), ‘Lan’, ‘Salaut’, ‘Ertol’ (KAZ), ‘Bezenchukskaya 205’, ‘Lilek’ (RUS). These samples can be characterized by their adaptive properties as intense ones, with a pronounced response to the environment. Over the years of the research, grain number per spike varied from 35.9 to 38.8 pcs. Year conditions in 2016 were the most favorable for plant growth and development, while index of conditions was 4.1, and the average grain number per spike was 41.4 pcs. Year conditions in 2017 and 2018 were less favorable for growth and development of durum spring wheat, and therefore there was a negative value of index of year conditions (lj = -5.1 and lj = 0.5, respectively) with less grain number per spike (32.2 and 38.2 pcs., respectively). According to the trait «1000 kernel weight», the samples were identified with regression coefficient close to one under fluctuations of weather conditions, i.e ‘Korona’, ‘Raya’ (KAZ), ‘Lilek’, ‘Bezenchukskaya 205’ (RUS), ‘MIP Raiduzhna’ (UKR). The grain weight per spike in the collection samples varied from 1.27 to 1.77 g. The stable samples ‘Ertol’, ‘Salaut’, ‘Damsinskaya yantarnaya’ (KAZ), ‘Lilek’ (RUS), ‘Novatsiia’ (UKR), ‘Duraking’, ‘Candura’ (CAN) promising in spring wheat breeding were identified and can be involved in hybridization. Conclusions. Stable and plastic samples were identified among collection material of spring durum wheat in terms of productivity for involvement in scientific programs as source material.