Search

Relevance. The research is devoted to studying the peculiarities of the high-parent heterosis manifestation which connected with yield traits and the biochemical composition of tomato fruits.Materials and Methods. The work was carried out in 2021–2023 in open field conditions on the experimental plot of the Belarusian State Agricultural Academy (Mogilev region, Belarus). The objects of research were 30 F1 hybrids and 11 parental forms with different levels of economically valuable traits and with the specific set of genes for pathogen resistance and lycopene accumulation. The aim of the research was to create high-yield heterotic F1 tomato hybrids, adapted to open field conditions in Belarus, with a valuable biochemical composition of fruits.Results. The best hybrid combinations showed an early yield of 0.90–2.49 kg/m2, a marketable yield of 7.50–11.40 kg/m2, and a total yield of 8.22–13.12 kg/m2. High heterosis effect was established for early (88.9–291.0%), marketable (36.0–111.2%), and total (28.6–97.8%) yield in some hybrids. Significant differences in the accumulation of dry matter, carotene, and soluble carbohydrates were ascertained between the hybrids. Hybrid combinations with the highest value of true heterosis on accumulation of dry matter (18.3–21.6%), carotene (20.2–22.9%), and soluble carbohydrates (15.7–38.9%) were identified. Inheritance of early, marketable and total yield, dry matter content, carotene and soluble carbohydrates predominantly took place according to the positive overdominance, fruit weight – according to the intermediate inheritance, vitamin C content – according to the negative overdominance. Hybrids Brusnichny F1, Mansiata F1, Rada F1 were transferred to the State Inspection for Testing and Protection of Plant Varieties of the Republic of Belarus and successfully passed the testing stage in 2023.

The work is devoted to the study of statistical parameters of the linear dimensions of the seed, endosperm and embryo, variability, correlations, and the manifestation of these traits in hybrid combinations. Morphometric parameters largely determine the quality of seeds. The presence of an underdeveloped embryo determines the duration of the period of heterotrophic development of the seedling, affects germination, energy, longevity, seed response to changes in germination conditions, and, ultimately, increases the interphase period from sowing to germination. The article shows the high variability of these parameters in numerous representatives of vegetable crops - representatives of the Umbelliferae (Apiaceae) family, analyzes the causes that cause them, and predicts the potential use of this variability in breeding programs. The object of research was the seeds of various varieties of carrots, parsley, parsnips, celery, dill. Measurement of the length of the seed and endosperm was carried out using a caliper. The length of the embryo was determined using a microscope and a video eyepiece at ×40 magnification using the Scope Photo program. The experiment was repeated four times, in each repetition at least 20 seeds. The values of the coefficient of variation in the length of the endosperm and seed varied from 9 to 19%, depending on the species and cultivar characteristics. The variability of the embryo reached 18-28%. between the size of the embryo on the one hand and the length of the endosperm (0.208-0.369) and seed (0.213-0.376) on the other, weak correlations were noted, indicating the independent inheritance of these parameters. The hereditary conditionality of the variability of the embryo, endosperm and seed of carrots (50.8-86.5%) and parsnips (49.6-58.9%) is shown, which characterizes the real possibility of their breeding improvement. In the process of studying distant hybrids of carrots (the parental forms of which differed sharply in morphometric parameters of seeds), it was found that F1 hybrids for these traits predominantly showed positive overdominance (38.1%) and dominance (16.7%). According to the complex of relative parameters (indices), negative overdominance (23.8%) and dominance (4.8%) were more often noted. The results of many years of research indicate that the morphometric parameters (length of the seed, endosperm, embryo) and their ratios (indices) of seeds, like any other biological traits, are genetically determined and depend on species and cultivar characteristics. A comparison of wild-growing and varietal samples of carrots indicates that in the process of cultivation, the size of the embryo underwent significant upward changes, even in the absence of targeted selection. Therefore, when applying artificial selection in this direction, one can expect more significant results.

. Heterotic selection is now widely used in crop production. The superiority of heterotic hybrids over varieties in many respects has long been known. However, the widespread use of heterosis in melon growing is hampered by the high cost of seed material, due to the lack of lines with male sterility. The aim of this work was to evaluate heterotic hybrids of watermelon obtained on the basis of a line with male sterility isolated at the Bykovskaya Experimental Station.Materials and methods. The studies were carried out in 2020 and 2021. at the Bykovskaya melon breeding experimental station - a branch of the FGBNU FNTSO. The object of research is heterosis hybrids of watermelon. The heterosis hybrid of watermelon Barkhan was used as a standard. Classical breeding methods were used in the work: incubation and hybridization.Research results. The assessment of watermelon hybrids according to the main economic characteristics revealed the best combinations in comparison with the standard. According to the content of dry matter, four hybrids of watermelon stood out, the excess over the standard ranged from 0.6 to 1.9%. The indicator of the average weight of the fetus in one LIR hybrid was at the level of the standard and amounted to 6.5 kg. The remaining hybrids exceeded the Barkhan standard by 1.2-4.0 kg. The average yield of the studied hybrids ranged from 19.0 to 22.5 t/ha. The calculation of such indicators as the degree of dominance, the effects of true and hypothetical heterosis made it possible to identify three combinations with high rates.Conclusion. Thus, it was found that the yield in heterotic hybrids of watermelon is inherited according to the principle of overdominance. Inheritance of traits dry matter content and average fruit weight ranges from minus overdominance to overdominance in various combinations. According to the complex of economically valuable traits, three combinations of table watermelon were distinguished: LKn, LMr and LFT.

Relevance. During the formation of cabbage heads, under certain conditions, white cabbage is damaged by a burn of the top of the inner leaves of the head, which abroad received the stable name “tip burn”. This disorder is interpreted as a physiological or non-infectious disease, the cause of which is a violation of calcium intake. The disease manifests itself inside the cabbage head, resulting from the interaction of environmental stress factors and the predisposed genotype. The most effective way to combat this disorder is to develop highly tolerant hybrids. This is especially true for the south of Russia, where the stress load on plants is maximum.Purpose of the study – to develop a principle for selecting parental pairs for developing hybrids that are resistant to the tip burn of the inner leaves of a cabbage head, and to identify promising hybrids. Materials and methods. In 2021-2022 in FSBSI "Federal Scientific Rice Centre", in the department of vegetable growing, 45 hybrid combinations obtained on the basis of 10 inbred lines were assessed under field conditions for the trait "burn damage to the inner leaves of the cabbage head." An analysis of the combining ability of lines according to Griffin, and an analysis of the inheritance of the trait according to Heiman were carried out. In 2023, a competitive test of promising hybrids was carried out.Results. In both years of research, 5 lines had negatively stable TCA for burn damage: Ten4270, Yas25p, Bs1f, Agr 82, 270Hn111. SCA of lines is more subject to changes from year to year. The effects of SCA in hybrids due to dominance, epistasis and overdominance in individual combinations significantly influence the manifestation of the trait in the direction of decrease or increase. The principle of selecting parental pairs to develop stable hybrids is based on a combination of lines with a negative SCA value; in some cases, it is permissible to include one line with an average SCA and low SCA. Analysis of genetic parameters according to Heiman confirms the prevalence of non-additive inheritance of the lesion; in unstable forms, the disorder is controlled by dominant polygenes and is highly heritable.

Rice can form not only white-color kernels, but also of red, brown and black colors. In black-color rice kernels, the pericarp contains anthocyanin, which has antioxidant activity and therefore has a positive effect on human health. The purpose of the current study was to develop rice samples with black pericarp. The paper has presented the study results of the hybrid population ‘Mavr × Kontakt’ of the second generation. The variety ‘Mavr’ has a black pericarp, the variety ‘Kontakt’ has a white one. In the process of hybridological analysis there have been identified the patterns of inheritance of the main quantitative traits affecting productivity; there have been identified the best samples, in which formed compact erect panicles and black kernels; there has been selected the initial material for breeding work. The study was carried out in 2020 on the plots of the ES “Proletarskoye” in the Rostov region. There was established that the color of pericarp was inherited according to the type of complementary interaction of two genes. There was found an overdominance and interaction of two pairs of genes of different strengths according to ‘plant height’. There was also seen partial positive dominance, transgressions, and digenic differences of the initial varieties according to ‘panicle length’. According to the traits ‘number of spikelets per panicle’, there was identified overdominance of large values and positive transgression. There were found the forms with well-kerneled panicles. The trait ‘1000 kernel weight’ was characterized by negative dominance and dihybrid cleavage of 9:6:1. There have been selected the best morphotype F2 forms with black pericarp, which possessed optimal plant height, long panicles, larger kernel size, and an average 1000 kernel weight.

Grain sorghum is basically a forage crop, so a content of nutrients should be controlled during hybridization. Fat is a reserved substance which is considered to be a concentrated energetic and constructional force of a seed. Cellulose is the second significant grain polysaccharide after starch and it’s incorporated into cell walls. Increased content of cellulose in grain reduces nutritious value of forage. Having analyzed domination degree, calculated by B. Griffing, we determined that cultivars of the first generation of grain sorghum which were hybridized on diallel scheme 4x4 with parent forms ‘Belozernoe 100’, ‘ZSK-4’, ‘34045’ and ‘Otbor 100’, inherited types of crude fat and raw cellulose differently. In the most hybrids we saw average content of crude fat relevant to parent forms. As for content of raw cellulose hybrids of the first generation showed dominance of the larger value of the trait and overdominance. Despite the overdominance of the trait all the analyzed hybrids had a low content of cellulose (1,52-1,89%).

In the work with all crops including sorghum, it’s necessary to know the character of the inheritance of basic economic traits so that to decrease the time for breeding of new varieties and hybrids. While studying the hybrids of the first generation the specialist can precisely reveal a recessive or a dominant effect of the gene, which controls this or that trait. The article gives the results of study of the inheritance of plant height, length of peduncle and mass of 1000 seeds characteristic to the hybrids of grain sorghum of the first generation. ‘Plant height’ is an important trait in grain sorghum breeding which largely determines resistance of a variety or a hybrid to lodging and suitability to machine harvesting. Analyzing 21 hybrids of the first generation on the trait ‘plant height’ 80,9% of them revealed presumptive heterosis and 66,7% showed authentic heterosis. The hybrids with authentic heterosis possessed overdominance (hp>1,0) of the trait. ‘Length of peduncle’ is of great importance for grain sorghum breeding and determines its suitability for machine harvesting. The most hybrids (14) revealed their overdominance according to the trait ‘extension of a panicle’. ‘Mass of 1000 seeds’ is one of the basic elements of grain sorghum productivity, which determines grain size and maturity. The studied hybrids of the first generation showed different types of the trait inheritance, such as a depression, a partial and a full dominance of both a little and a large value of the trait, and an overdominance as well.

Background. This work aimed at using Hayman’s methodology to study the inheritance of some quantitative traits, such as the number of pods per plant, pod length, mean pod weight, and yield per plant in 15 diallel hybrids of six green bean cultivars.Materials and methods. The research was carried out at the Experimental Center of Universidad Nacional de Colombia – Sede Palmira (CEUNP). A randomized complete block experimental design with four replications was used.Results. For most of the traits, except yield per plant, the additive-dominant model was adequate. Non-additive effects with overdominance controlled the number of pods per plant, pod length, and mean pod weight. Most of the characters presented an unequal proportion of positive and negative genes in the loci (H1 < H2). The asymmetric distribution of genes in the parents (H2/4H1) was below the maximum value (0.25), except for the character “number of pods per plant”. The KD/KR ratio confirmed for most of the traits that there was an excess of recessive alleles over dominant alleles. Dominance effects (h2) for most characters suggested that the substantial contribution of dominance was not due to heterogeneity of loci in these characters. The narrow-sense heritability was moderate to low. The correlation coefficient r (Yr; Wr + Vr) indicated that dominant genes were responsible for the increased number of pods per plant and recessive genes for increased pod length and mean pod weight.Conclusions. Conventional breeding methods like pedigree selection could be employed to improve the characters “pod length” and “mean pod weight”, and for the number of pods per plant, management of segregating populations should employ the single-seeded descent method.

The main reserve for improving of pea grain production is the development of new highly productive varieties. In this case, intraspecific hybridization is the main tool, but the patterns of inheritance by hybrids of several economically valuable traits are still insufficiently studied. The purpose of the current work was to establish the inheritance nature of productivity traits in pea hybrids. The trials were carried out in 2020–2022. The objects of the study were 8 pea hybrid combinations F1 and F2. The estimation of the collection and hybrid material was carried out in accordance with the Methodology of the State Variety Testing (2019). Segregation analysis in F1 pea hybrids has revealed different types of inheritance of the studied quantitative traits, from hybrid depression to overdominance. According to ‘plant height’, the dominance degree (hp) varied from 0 to 3.00. According to ‘number of pods per plant’ it varied from –0.50 to 3.00. According to ‘number of beans per pod’ it varied from 1.67 to 4.00. According to ‘1000-seed weight’ it varied from 0.20 to 0.44. Hybridological analysis of F2 pea plants based on ‘plant height’ in 4 hybrid combinations has revealed incomplete negative dominance (hp from –0.20 to –0.43), in 4 hybrid combinations it was incomplete dominance (hp from 0.60 to 0.69). According to ‘number of pods per plant’, two hybrid combinations have shown complete dominance (hp = 1.00), one hybrid combination has shown incomplete dominance (hp = 0.35), five hybrid combinations have shown incomplete negative dominance (hp from –0.50 to –0, 71). The trait ‘1000-seed weight’ in all hybrid combinations was inherited according to the type of incomplete dominance (hp from 0.10 to 0.16). According to ‘number of beans per pod’, four hybrid combinations have shown incomplete dominance (hp from 0.67 to 0.83); one hybrid combination has shown incomplete negative dominance (hp = –0.50); three hybrid combinations have shown complete negative dominance (hp = –1.00).

Background. Heterosis is one of the most important and promising plant breeding trends. Its development will make it possible to obtain hybrids with high adaptability and a high heterosis effect in their quantitative and qualitative characteristics.Materials and methods. The studies were carried out under dry conditions of the Volgograd Trans-Volga region in 2019–2020. Heterotic hybrids of table watermelon served as the research material, and hybridization and inbreeding as research methods. The heterotic F1 hybrid of watermelon Barkhan was used as the reference.Results. The characteristics of heterotic watermelon hybrids were compared with the parental forms and the Barkhan F1 reference. The length of the growing season in heterotic hybrids was inherited intermediately. In the average fruit weight, the reference was exceeded by the hybrids ChmsMt and ChmsFt by 1.1 kg. The highest average yield for the two years of research was observed in the F1 hybrids ChmsNts (24.3 t/ha), ChmsFt (24.1) and ChmsMt (23.1) (reference: 20.8 t/ha). The inheritance of fruit weight according to the principle of overdominance occurred in the F1 hybrids ChmsMk, ChmsRn, ChmsNts and ChmsMt. In their fruit weight, the same hybrids showed positive indices of hypothetical and true heterosis. The F1 hybrids ChmsFt, ChmsNts and ChmsIR demonstrated high degrees of dominance in yield (1.8 to 5.0%). The index of hypothetical heterosis had positive results in all studied heterotic watermelon hybrids. Negative true heterosis (–0.49%) was observed in two F1 hybrids, ChmsRn and ChmsPH. The remaining watermelon hybrids had positive true heterosis indices that ranged from 2.4% in ChmsIR to 11.06% in ChmsFt.Conclusion. As a result of the studies, heterotic hybrids of watermelon, developed on the basis of the sterile mother line Chms, were identified for high indices of true and hypothetical heterosis in fruit weight and yield parameters.

The article presents the results of studying the combination ability of new dihaploid maize lines created by diploidization of haploid plants obtained using a haploinducer line. The experiment involved simple hybrids (30 combinations) obtained according to the complete diallel scheme of 6 homozygous lines. The eff ects of GCA and variance of SCA lines, as well as the components of genetic variance in terms of the main morphometric parameters of the plant (stem length, ear height, panicle length, stem diameter, plant leaf surface area) were revealed. Lines with a high GCA score and a dispersion of SCA have been identifi ed, which are advisable to use in the breeding process for tall stature, resistance to lodging, and manufacturability. The infl uence of overdominance in the manifestation of the length of the panicle and the diameter of the stem and the predominance of additive eff ects in the formation of the height of the cob were noted. Analysis of the components made it possible to identify the number of genes or groups of genes that infl uenced the manifestation of traits in 2021 (stem length – 1–2, ear height – 2–3, panicle length – 1–2, stem diameter – 2–3, area of leaf surface – 1–2). Dominance according to the studied parameters is directed towards parental forms with a greater severity of the trait. A signifi cant infl uence of cultivation conditions on the manifestation of the length of the stem, the height of the cob, the length of the panicle, and the diameter of the stem was noted.

The purpose of the study. The aim of the study was to determine the effect of heterosis in short-fruited parthenocarpic F1 cucumber hybrids by the main economically valuable characteristics, when grown using low-volume technology in industrial greenhouses of the Moscow region.Materials and methods. The object of the study is short-fruited parthenocarpic reciprocal hybrids of cucumber Druzhny (F1 I73514 x I74011), F1 I74011 x I73514 and their parent inbred lines I73514 and I74011 of selection by N.N. Timofeev Breeding Station LLC. F1 SV4097CV of foreign selection of Semenis company (Netherlands) was used as a control. The study was conducted in 2020-2021 in industrial greenhouses of the "V. I. Edelstein Vegetable Experimental Station" of the K.A. Timiryazev Russian State Agrarian University-Moscow Agricultural Academy in Moscow on low-volume hydroponics in peat bags. Parental lines and hybrid combinations were evaluated by earliness, early yield, yield, number of fruits per plant, average fruit weight and marketability.Results. According to the results of the study, F1 Druzhny (F1 I73514 x I74011) and the reverse hybrid I73514 x I74011 demonstrated high positive effects of heterosis in yield (MPH=19.4...22%; HPH=13.4...15.9%; CH=9.6...12%) and the number of fruits per plant (MPH=22.5...26.4%; HPH=12.5...15.8%; CH=11.7...15%). Negative indicators of the heterosis effect were noted for earliness from germination to flowering (MPH=-3.4...-1.1%; HPH=-6.5...-4.4%; CH=-4.4...-2.2%) and average fruit weight (MPH=-2.2...-1.3%; HPH=-5.3...-4.3%; CH=-3.4...-2.4%). The value of the degree of dominance indicates the presence of positive overdominance in the inheritance of such traits as yield (hp=2.7...3.2), the number of fruits from the plant (hp=1.5...1.9) and marketability (hp=1.6...2.3). Negative overdomination was observed in earliness from germination to flowering (hp= -2...-1.3) and average fruit weight (hp=-1.7...-1.2). According to the signs of earliness from germination to fruiting (hp =0) and early yield (hp=-0.1...0.5), intermediate inheritance was revealed. The Druzhny hybrid significantly exceeded the control hybrid SV4097CV in early yield, yield and number of fruits from the plant, and the reverse hybrid F1 I74011 x I73514 was at the control level, which indicates the prospects of growing these hybrids in the conditions of spring-summer turnover on low-volume hydroponics.

Relevance. The action of viral phytopathogens changes the quality of the male gametophyte, which ultimately leads to a decrease in plant productivity. So, information on the features of the variability of morphofunctional characteristics of the microgametophyte becomes topical. Taking into account the expression of a part of the plant genome in pollen, the male gametophyte can be used as a reliable system for assessing the response of genotypes to the action of viral pathogens. Presuming that the problems of variability of characteristics of the male gametophyte in conditions of viral pathogenesis have not been enough studied, as well as the main factors determining the variability have not been identified, the aim of the research was to study the effect of viral phytopathogens on the male gametophyte characters in tomato.Material and methods. Hybrids F1 and varieties of tomato were used in the experiments. Plants were grown in a greenhouse. They were inoculated with tobacco mosaic virus (TMV) or tomato aspermia virus (TAV) in the 4-5 leaf phase. To determine the quality of pollen, flowers of control and infected plants were collected; pollen was isolated and sown on a nutrient medium. The preparations were analyzed under microscope. The viability of the pollen and the length of the pollen tubes were assessed, and the ratio of these indicators was calculated.Results. Infection of plants with viruses changes some functional characteristics of the male gametophyte. The responses manifested as stimulation, inhibition, or neutral effect. The main sources of variability in characters of pollen were the genotype and viral agents. In viral pathogenesis, unequal indicators of pollen grains were found in terms of the rate of germination and growth of pollen tubes (PT). Analysis of the heritability coefficients of the ratio of pollen viability and PT length (experiment / control) revealed positive dominance and overdominance in 70% of cases. Genotypes have been identified that combine a high level of viability when infected with different viruses. The prospect of their use in further research is proposed.

Rice is a valuable agricultural crop that is used as food for more than half of the world's population. The development of highly productive varieties and hybrids with high product quality assumes the utilization of new initial material from different countries in the breeding process. The purpose of the current research was to conduct an ecological testing of the rice varieties from Uganda in the Proletarsky district of the Rostov region in Russia and use them in the breeding process. There were studied the Ugandan rice samples ‘Nerica 1’, ‘Nerica 4’, ‘Komboka’, ‘Wita 9’, ‘Namche 1’, ‘Namche 2’, ‘Namche 3’, ‘Namche 4’, ‘Namche 5’, ‘Namche 6’ (NaCRRI) in comparison with the Russian variety ‘Komandor’ (FSBSI “ARC “Donskoy”). The study of the Ugandan rice varieties according to a number of economically valuable traits and biological properties showed that the vegetation period from soil flooding to rice maturing took 100–113 days, the standard variety ‘Komandor’ needed 83 days. The varieties ‘Komboka’ and ‘Wita 9’ did not bear blossom. All samples had a short habit, with 63-95 cm of plant height. The long drooping panicles of 18.5–22.3 cm carried from 122 to 213 seeds. The caryopses were elongated, the length of the caryopses varied from 9.0 to 9.5 mm, and the width ranged from 2.7 to 3.1 mm. 1000 seed weight varied from 26 to 34 g, number of seeds per panicle ranged from 122 to 213 pieces. Genetic analysis of the second generation hybrids ‘Kontakt × Nerica 1’ and ‘Boyarin × Nerica 4’ showed different types of traits’ inheritance, from negative dominance (vegetation period) through the absence of dominance (caryopses size) to overdominance (plant height, seed weight per panicle and number of seeds per panicle).

The current paper has presented the analysis results of the value of heterosis and the degree of phenotypic dominance of hybrids F1 obtained by saturating crossings of two-row and multi-row spring barley forms. The purpose of the study was to determine the value of heterosis and the degree of phenotypic dominance of the main quantitative traits of the multi-row hybrids of spring barley. The study was carried out in the laboratory for grain crops and groats breeding of the FSBSI FRC of Agrobiotechnologies of the Far East named after A. K. Chayka. There were studied 68 varieties of multi-row spring barley forms selected from the world collection of IPI of various ecological and geographical origin. The two-row varieties ‘Primorsky 98’, ‘Primorsky 44’, ‘Primorsky 89’, ‘Tikhookeansky’ and ‘Vostochny’ developed by FSBSI FRC of Agrobiotechnologies of the Far East named after A. K. Chayka were taken as maternal forms. Four multi-row barley varieties ‘Kazminsky’ (Khabarovsk Territory), ‘Peguis’ (Canada), ‘Kolchan’ (Altai Territory), ‘07N1’ (China) with valuable economic traits were taken as a paternal form. There was conducted a five-fold backcrossing of hybrids with paternal forms and there were selected the populations of multi-row genotypes. The most of the hybrids F1 manifested their heterosis simultaneously according to four traits, productive tillering, number of grains per main head, grain weight per main head, and grain weight per a plant. Only two hybrids ‘Primorsky 98 x Kolchan’ and ‘Primorsky 89 x Peguis’ showed a depression. There was identified heterosis by the traits ‘number of grains per main head’, ‘grain weight per main head’ in all hybrids. When analyzing the inheritance of the trait ‘grain weight per a plant’, there was established overdominance of this trait at the highest values of the hybrids ‘Tikhookeansky x Peguis’ (9.7) and ‘Primorsky 44 x 07N1’ (5.2), the heterosis degree was 50.4% and 82.2%, respectively. There has been established that three hybrids ‘Primorsky 98 x 07N1’, ‘Primorsky 44 x 07N1’, ‘Tikhookeansky x Peguis’ can belong to the most promising ones.

Genetic potential of productivity is a primary and essential factor in the period of formation of high productivity of winter wheat. Such quantitative traits as 1000-grain weight, a number of seeds per ear, length and width of a flag leaf are of primary importance while forming productivity of the crop. It’s possible to create a highly productive wheat variety knowing inheritance of these traits, their genetic basis and their genes combining ability. Our study has been carried out in two directions. The first one was an assessment of hybrid combinations. The article gives the results of study of soft winter wheat hybrids of the first generation. We have presented various types of trait heritage, from negative dominance to overdominance and we have found heterosis. The second direction was an assessment of parent forms of winter wheat on total combining ability. The assessment of total (TCA) combining ability and specific combining ability (SCA) of the varieties and lines gives an opportunity to use received hybrids in breeding work planning transgressive forms in the second generation. Thus it will result in more possibility to choose forms with new valuable traits. In the result of the conducted biometrical analysis of hybrids and their parents we received a number of average indexes of the traits of 10 combinations, which was used for calculation of total and specific combining ability of initial forms. The work presents the best parent forms of soft winter wheat according to their combining ability and hybrid combinations with high specific combining ability on some quantitative traits.

Purpose. To reveal breeding and genetic peculiarities of modern spring barley varieties for the “number of grains per main ear” trait and identify genetic sources of increased combining ability for involving in hybridization. Methods. Investigations were carried out at the V. M. Remeslo Myronivka Institute of Wheat of NAAS of Ukraine. Modern varieties of domestic (‘Virazh’, ‘Talisman Myronivskyi’, ‘Komandor’) and foreign (‘KWS Aliciana’, ‘KWS Bambina’, ‘Zhana’, ‘Explorer’) breeding were involved in crossing for a full (7´7) diallel scheme. Parents and F1 were studied in field conditions during 2014–2016. Results. The analysis of variance of combining ability has shown a significant advantage in varying of general combining ability (GCA) effects. The mean square of specific combining ability (SCA) was significantly less than the GCA, but reliable throughout the years. The reciprocal effect was reliable only in 2014. Stably high effects of GCA during all years of investigations were noted in the varieties ‘KWS Aliciana’ (1.18–1.62) and ‘Virazh’ (1.33–1.48). The variety ‘KWS Bambina’ was characterized by lower but reliable positive effects of GCA (0.43–0.99) as compared to mentioned above. Non-allelic gene interaction was not found, that allowed to calculate the basic parameters of genetic variation. During all years of investigations, dominant effects of genes (H1 and H2) prevailed over the additive (D) ones in phenotypic expression of grain number per main ear. Mean degree of dominance in the experiment (H1/D) has shown overdominance. The same pattern was also distinctive for the index of mean degree of dominance in the loci . The dominance was reliably directed. Dominant effects of genes increased grain content, and recessive ones reduced it. At least 3–4 genes (groups of genes) have been revealed which determined the effects of dominance. At the same time, recessive genes (F

Рurpose. To investigate inheritance of “plant height” trait in populations of the first (F1) and second (F2) generations of the soybean (Glucine max (L.) Merrill) and evaluate hybrid combinations in order to identify phenotypes with the highest level of heterosis for plant height. Methods. Laboratory test, mathematical and statistical analysis. Results. The inheritance of plant height in soybean was investigated. Hybrid combinations were assessed for the ability to select phenotypes with an optimal height. Different types of inheritance of this trait were found in populations of the second generation. The highest degree of heterosis for plant height was expressed by such soybean hybrids of the second generation as ‘АЕЕМ ’/‘Cherniatka’ (102.6%), next were ‘№ 427/‘Коrado’ (36,1%) and ‘Yelena’/‘Vizhion’ (32,0%). For the above trait, the ‘Legend’ variety in combinations with such varieties as ‘Staroukrainka’, ‘Korado’ and ‘Medeia’ expressed a heterosis amounting to 28.1%, 8.3%, 6.1% accordingly. Plant height was inherited mainly in terms of negative overdominance (34.2% combinations). There were 21.1% of combinations that had a negative semidominance. Conclusions. Among large majority of crossing combinations, forms were revealed that differed greatly for the plant height. The highest variability was observed in combinations such as ‘Legenda’/‘Korado’, ‘Ustia’/‘Vizjion’, ‘№894’/‘Vizjion’, ‘Ug-30’/‘Vizjion’, ‘Legenda’/‘Annushka’, ‘№441’/‘Gentleman’, ‘№441’/‘Vizjion’, ‘Yug-30’/‘Gentleman’, ‘Angelica’/‘Annushka’ and ‘Angelica’/‘Gentleman.

Heterosis as the increased performance of hybrid progeny compared to their inbred parents is one of the most intriguing phenomena in genetics. The first attempts to find out about underlying mechanisms were based on theoretical models, which were useful, but could not characterize this unique phenomenon as a whole. With the advent of molecular markers great efforts were made to identify genomic regions causing heterotic response and clarify prospects of using information about molecular divergence of parental forms as a criterion for the prediction of F1 performance. Despite some achievements, the effec-tiveness of both molecular divergence and prospective heterotic QTL for practical goals was limited, confirming that genetic heterogeneity is necessary, but not sufficient to produce perfect phenotype. Current methodological tools of functional genomics and related disciplines have provided new opportunities for searching for mechanisms of heterosis at different levels in the context of relative importance of dominance, overdominance and epistasis. To date, differences in genome organization, gene expression and epigenetic status have been found between hybrids and their parents. At the genomic level, some QTLs associated with heterosis were identified and the impact of DNA divergence on F1 performance was evaluated. At the level of transcriptome, it was shown that heterosis in hybrids occurs along with changes in gene expression regulation under the influence of circadian clock genes. Several studies have been conducted to clarify the role of epigenetic DNA modification and genomic imprinting in the manifestation of heterosis. Taken together, data indicates that heterosis cannot been explained by a single common mechanism, because this complex phenomenon involves many components, a cumulative effect of which leads to the formation of an outstanding phenotype.

This study was carried out in spring and summer crop rotation in film unheatedgreenhouse in condition of Transnistria. The parameters of phenotypic variability weredetermined during the continuous periods including: from shoots to plantlet maturing;from plantlets to flowering; from flowering to ripening F1 hybrids and their parental lines. Early and middle early functionally sterile (gene ps-2) and fertile lines were taken for the experiment. It was shown that duration of vegetative period varied insignificantly in lines and hybrids. Phenotypic variation in interphase periods was also insignificant;however, the second period was characterized by stronger variation. The lines phenotypicvariation in lines during the continuation of vegetative period and its compounded phases depended on the genotype, year of study and their interactions. On the phenotypic variability of continuation of the period from shoots to flowering sterile lines significantly was caused by the genotype, the variation of the period from flowering toripening was equally caused by genotype and year of the study, the variability of theperiod from shoots to ripening was affected by genotype. On the phenotypic variation ofthe continuation of the vegetation in fertile lines is influenced by the genotype and itsinteraction with year of study, on the variability of the period from shoots to floweringequally genotype and year of study and their interaction on the variability of the periodfrom to ripening the interaction of genotype and year of study. Inheritance of continuation of vegetative period and its components, interphase periods, mainly had the character of a negative overdominance (heterosis for earliness). The nature of inheritance of the continuation of vegetation and interphase periods may vary depending on the year of the study; however, there remained its direction. A strong correlation between the continuation of the period from shoots to maturation and its components of the interphase periods. Between the continuations of individual interphase periods from shoots to flowering and from flowering to ripening correlation was insignificant, which indicated the independent nature of inheritance of these periods.

New types of CMS-inducing cytoplasms cannot be applied to hybrid sorghum breeding without knowledge of their effects on major biological and commercial plant traits. In our studies of F1 hybrids obtained by crossing of two sets of isonuclear CMS lines (with nuclear genomes of cv. Pishchevoye 614 (P614) and Zhelyozyornoye 10 (Zh10)) to two pollen parents (cv. Pishchevoye 35 (P35) and Mercury), we focused our attention on the effects of A3, A4, 9E, and M35-1A cytoplasms on chlorophyll content at different developmental stages of sorghum plants. It was found that hybrids with different types of male-sterile cytoplasm differed in chlorophyll content, and the genotypes of the CMS line and the pollen parent influenced the manifestation of cytoplasmic differences. In the F1 hybrids obtained with CMS lines possessing the P614 genome, sterile M35-1A cytoplasm increased chlorophyll a content, in comparison to 9E cytoplasm. In the F1 hybrids obtained with CMS lines with the Zh10 genome and the P35 pollen parent, sterile A4 cytoplasm increased the sum of chlorophyll a and b, in comparison to A3 and 9E cytoplasms, whereas no differences were recorded in the F1 hybrids obtained with Mercury. The F1 hybrids obtained with CMS lines with the P614 genome showed heterosis for total chlorophyll content at the tillering stage. Overdominance of this trait was observed in hybrids with M35-1A cytoplasm; true heterosis exceeded analogous indices in 9E cytoplasm by 19.0 %, and the hypothetical heterosis, by 20.6 %. These data demonstrate that the application of new types of CMS-inducing cytoplasms allows raise of F1 hybrids with heterosis for chlorophyll content. Thus, such types can be used to increase hybrid productivity.

The problem of accounting for a genetic estimation of expected linkage in the disposition of random loci was solved for the additive-dominant model. The Comstock-Robinson estimations for the sum of squares of dominant effects, the sum of squares of additive effects, and the average degree of dominance were modified. Also, the Wright's estimation for the number of loci controlling the variation of a quantitative trait was modified and its application sphere was extended. Formulas that should eliminate linkage, on average, were derived for these estimations. Nonbiased estimations were applied to the analysis of maize data. Our result showed that the most likely cause of heterosis is dominance rather than overdominance and that the main part of the heterotic effect is provided by dozens of genes.

The dependence of the expression of genotypic values (Y) on gene dosage (X) have been analyzed for four types of intralocus interactions (additivity, dominance, overdominance, and neutrality) using a linear model. Artificial numerical examples have been used to demonstrate that X and Y are positively associated with each other in the cases of additivity, dominance, and overdominance and are not associated in the case of neutrality. The averaging of single-locus genotypic values to obtain multiple-locus genotypes yields different results for different types of intralocus interactions. Genotypic values and individual heterozygosity are positively correlated with each other in the cases of dominance and overdominance and are negatively correlated in the case of additivity. In the case of neutrality, there is still no correlation after averaging. The results obtained and their interpretation suggest a new view on the experimental studies and generalizations on the relationship between heterozygosity and quantitative traits.

A relationship between heterozygosity of 6 biochemical loci and variability of 4 anthropometric traits at birth has been studied in 304 boys and girls from Moscow population. All 4 traits in boys are positively correlated with the number of loci for which they are heterozygous. The values of all the traits in girls are highest in homozygous individuals. In order to reduce the number of variables the principal component analysis is applied. Boys and girls with average level of heterozygosity turned out to be closest to the corresponding population averages of morphological traits. The results are discussed in terms of 3 models: Lerner's concept of genetical homeostasis, additive and overdominance polygenic models. It is concluded that an average level of heterozygosity is optimal for a population.

Unequal inheritance of characters, i.e. flower glume colour, degree of lateral spikelets development, hairy rechis of the ear, were observed in diallel crosses among the varieties Nutans 244, Trumpf, DZ-02389, Hiproly and Brachitic. Recessive inheritance was marked for short rachilla hairs. The dominant effect of genes for the leaf length and overdominance for the plant height were ascertained. The partial dominance for the number of internodes and leaf width was found. The character of the upper internode length did not correspond to additive-dominant model.

The relationships of heterozygosity with the mean and variance of quantitative character were considered under neutrality, additivity and overdominance of polymorphic loci. Attention was drawn to dependence of the patterns of relationships on the number of polymorphic loci (which varied from 1 to 10) and on the type of polymorphic loci, both homogeneous (polymorphic loci are of the same type) and heterogeneous (polymorphic loci are of the two types) samples of 10 polymorphic loci and their combination. It is shown that increase in the number of polymorphic loci is accompanied with extension of the limits of corresponding relations, whereas the patterns of these relations depend on the type of connection of separate polymorphic locus with the quantitative character and on the ratio of different loci in the set of polymorphic loci. It is assumed that the relationship of heterozygosity with quantitative characters, displayed in the number of experimental works, may contain a component mediated by similar statistical effects. It is inferred that the discrepancy between different authors' experimental data on existence or lack of some relationships between multiplicative heterozygosity and morphological variability of quantitative characters can be explained by different types of relations of polymorphic loci to quantitative characters encountered in their works.