Heterosis Effects Research Articles

High Divergence of Cuticular Hydrocarbons and Hybridization Success in Two Allopatric Seven-Spot Ladybugs.

The seven-spotted ladybug is a widespread species in the Palearctic, and also acclimated in the Nearctic. It has been classified into different species on the basis of certain morphological characteristics, the geographical origin, and the genitalia structure of both sexes. The morphotypes of North Africa and the Canary Islands are separated, under the name of Coccinella algerica Kovář, 1977, from the rest of the Palearctic and Nearctic populations of Coccinella septempunctata Linnaeus, 1758. In this study, we investigated, on one hand, whether potential reproductive barriers have been established during evolution between the geographically isolated North African and the European seven-spotted ladybugs by performing reciprocal crosses. On the other hand, we assessed their cuticular hydrocarbon (CHC) divergence by GC-MS. The 33 CHCs indentified are with a skeleton of 23 to 32 carbon atoms. These CHCs are linear alkanes (24.9 ± 3.6%) and methyl-branched alkanes (75.1 ± 3.6%) including monomethylalkanes (48.8 ± 2.4%), dimethylalkanes (24.6 ± 4.0%) and trimethylalkanes (2.0 ± 1.0%). Although all the CHC compounds identified are present in the two seven-spotted ladybugs and their F1 and F2 hybrids, their profiles diverged significantly. However, these chemical divergences have not altered the sexual communication to cause reproductive isolation. The two ladybugs interbreed and leave viable and fertile offspring, with even a heterosis effect on reproductive performances, without phenotypic degradation after the F1 generation. So, these chemical differences are just an intraspecific variability in response to heterogeneous environments. The two types of ladybugs can be considered as two different races of the same species with reduced genetic divergence.

Identification of quantitative trait loci for growth traits in red swamp crayfish (Procambarus clarkii)

Genetic breeding is an important approach to improve the economic traits of aquaculture animals. Unfortunately, the genetic basis for important economic traits of red swamp crayfish, including growth-related traits, has not yet been reported. In the present study, two full-sib families and two natural populations were employed to identify quantitative trait loci (QTLs) for growth-related traits of red swamp crayfish. In total, 28 QTLs for five growth-related traits, including body weight, body length, carapace length, carapace width, and abdomen length, were repeatedly identified in more than two families/populations, by means of association analysis; nine of these displayed a heterosis effect. The phenotypic variations of the five investigated traits explained by the 28 QTLs ranged from 4.2% to 19.0%. Eight additive and three heterosis QTLs were further successfully validated using comparative analysis of favoured alleles between the small and big size crayfish groups in the natural population. In conclusion, this study investigated the genetic basis of growth-related traits in red swamp crayfish, which is of great significance for their application in the future molecular breeding of the species.

Formation and Variability of the “Weight of Raw Cotton 1 Box” In F1 Hybrids Created on the Basis of Hybridization of American Selection Varieties

In the article in the introduction section, the problem being solved, the purpose and objectives of the research are given in detail. Then, in accordance with the requirement, the place and conditions for the experiment are given. The following are the results of hybridological and variational-statistical analyzes of studies aimed at studying the variability and inheritance of the trait “mass of raw cotton in one box” in intervarietal F1 hybrids. The above hybrids were created as a result of crossing the best varieties of American breeding, isolated from 132 previously unstudied collection varieties. As a result, a large-boxed hybrid combination F1: Hopi oraibi BI x Lambright GL-5 with a raw cotton weight of one box of 6.4 g was isolated and two hybrid combinations in which the effect of heterosis was established, which should be used in further breeding work aimed at breeding large-bodied varieties of cotton of the species G. hirsutum L.

ЭНЕРГИЯ РОСТА И ПОКАЗАТЕЛИ ОБМЕНА ВЕЩЕСТВ У ЧИСТОПОРОДНЫХ И ГИБРИДНЫХ ИНДЕЕК

The article presents data on growth energy, indicators of protein and mineral metabolism in the body of purebred and hybrid turkeys. It has been established that with pedigree-linear hybridization of turkeys, the effect of heterosis can be traced, which contributes to the activation of metabolic processes in the body of hybrid turkeys.

Estimation of genetic parameters and individual and maternal breed, heterosis, and recombination loss effects for production and fertility traits of spring-calved cows milked once daily or twice daily in New Zealand.

The objectives of this study were to estimate genetic parameters and individual and maternal breed, heterosis, and recombination loss effects for milk production and fertility traits of Holstein Friesian (F), Jersey (J), and crossbred Holstein Friesian and Jersey (F × J) cows milked once daily (OAD) or twice daily (TAD) in New Zealand. Data on 278,776 lactations from 30,217 OAD and 170,680 TAD milking cows across 644 spring-calving herds were available. Genetic parameters and individual and maternal breed, heterosis, and recombination loss estimates were obtained from univariate animal models. Heritability and repeatability estimates for milk production, milk composition, and fertility traits were consistent across the milking frequencies. Heritability estimates for yields of milk, fat, protein, and lactose varied between 0.21 and 0.29 in OAD and TAD. Heritability estimates for fertility traits ranged from 0.01 to 0.08 in both populations, and estimates were slightly greater in TAD than OAD milking cows. In both milking populations, individual breed effects for yields were in favor of F cows; however, maternal breed effects for yields were in favor of J dams. Jersey cows were more fertile than the F cows in both milking populations, but maternal breed effects for fertility traits were in favor of F dams. Individual heterosis effects were favorable for all traits and were consistent across milking regimens. Crossbred F × J cows had significantly shorter intervals from start of mating to first service and from start of mating to conception, and a higher proportion of 3-wk submission, 3-wk in calf, and 3-wk calving relative to the average of purebred F and J cows. Recombination loss effects were not always unfavorable for production and fertility traits, but most estimates were small with larger standard errors. Favorable maternal heterosis effects were associated with production traits in both milking systems, but maternal heterosis effects were less likely to influence reproductive performance.

Growing juvenile beluga and its hybrids with sterlet in environmentally friendly conditions

Currently, the general trend of the global fishing industry is to increase the production of fish food products not only due to the development of aquaculture, but also the biological characteristics of the body of sturgeon. The aim of the study was the theoretical justification and practical implementation of the assessment of the growth and development of beluga juveniles and their hybrids with sterlet aged 0+ to 2+ (three-year-olds) in industrial of the Krasnodar Territory. The determined: fish mass, live weight gain, linear growth. By the end of the control cultivation, the weight of fish in the control and experimental groups was 1728.3 and 2236.4 g, respectively. In the experimental group, the absolute increase in live weight of fish was 2198.2 g, while in the control group it was 1692.2 g. The difference in average daily gains was 0.71 g in favour of hybrids. The body length of the fish in the control and experimental groups was 32.7 and 37.3 cm. The positive effect of heterosis had a positive effect on the first- generation crossbreeds obtained from beluga and sterlet.

Sorghum-Sudanese hybrid Dobrynya as a result of heterosis selection

Sorghum-Sudanese hybrids, due to the heterosis effect, have not only increased productivity, but also uniformity, increased vitality, as well as resistance to various diseases and stress factors in comparison with parental forms. The purpose of the work: to characterize the new hybrid Dobrynya, created as a result of heterosis selection, according to the main morphological, biological, economically valuable indicators. The studies were carried out at the Federal State Budgetary Scientific Institution, Agrarian Research Center “Donskoy” (ARC “Donskoy”). The soil of the experimental plot is ordinary carbonate chernozem. The advantages of the hybrid include high foliage (13 leaves per plant) - 39-41% of the leaf mass of plants, good protrusion of the legs (30-35 cm), succulence, tillering, cold resistance. The duration of the period “sprouts-heading” on average for 2019-2022. was 55 days (mid-season), which is 5 days less than the standard. Sorghum-Sudanese hybrid Dobrynya is characterized by a high yield of green mass - 63 t/ha (in total for 2 cuttings) and dry matter - 13.0 t/ha, which is higher than the standard by 28.6 and 31.3%, respectively. -essentially. And in terms of the content of crude protein and the collection of digestible protein, it significantly exceeds it by 1.1% and 0.24 t/ha. According to the results of the assessment in natural conditions, Dobrynya is distinguished by high or practical resistance to loose smut and bacteriosis. The sorghum-Sudanese hybrid has been included in the State Register of Breeding Achievements since 2023 and is recommended for use for green fodder and silage in the Central Black Earth, North Caucasus and Lower Volga regions of Russia.

Heterotic patterns in rapeseed (Brassica napus L.): Crosses between spring-type and winter-type genotypes

Genetic improvement in a crop, viz. Brassica species, through plant breeding essentially requires the presence of adequate genetic diversity within the gene pool. Winter rapeseed is known to be genetically different from spring rapeseed and can therefore be used for extending genetic diversity in the progenies produced via crossing methods. Using line?tester analyses of two spring types of testers and six lines of winter-type rapeseed varieties, heterotic patterns of phenological traits, plant height and seed yield were estimated. Significant mean squares between parents and crosses revealed significant heterosis for all the traits. Line?tester mean squares, indicating the non-additive genetic effects, were significant only for plant height and seed yield. High narrow-sense heritability estimates for phenological traits underline the importance of additive genetic effects and thus the efficiency of selection for improving these traits. Based on the significant and positive expression of heterosis effects for phenological traits and plant height in the winter parents, it was concluded that the F1 progenies had earlier and shorter maturity than the winter parents. F1 progenies were also early flowering, early maturing and taller than the spring-type parents. Significant positive heterosis of the crosses for seed yield was observed in 75% and 42% of F1 progenies compared to the spring and winter parents, respectively, indicating a higher yield potential of the F1 hybrids than the spring and winter parents.

INHERITANCE AND FORMATION OF SOME ECONOMICALLY VALUABLE TRAITS IN COTTON HYBRIDS F1, F2 AND F3

In the article presents results of analysis of inheritance and variability of some agronomic valuable traits in hybrids obtained with participation of cotton varieties that differ sharply in origin. Studied plants Ғ1, it was found that complete dominance of unlimited type of branching in Ғ1, effect of heterosis, complete dominance and intermediate inheritance depending on the genotype of the parental forms according to traits of precocity and weight of 1000 seeds. In the inheritance of fiber length in F2 hybrids, a wide range of variability was revealed and a markedly high variability in interspecific hybrids compared to simple hybrids. From F3Sultan x Surkhan-14 combination were selected and recommended families for breeding.

Genomic rotational crossbreeding with advanced optimum contribution selection methods applied to simulated German Angler and German Holstein dairy cattle populations.

Many local dairy cattle breeds are facing genetic extinction due to a large proportion of foreign genes, which have been introgressed in the past. In addition, the performance gap to popular high-yielding breeds is increasing, resulting in a risk of numeric extinction. In the present simulation study, a genomic rotational crossbreeding scheme with the high-yielding German Holstein breed and the numerically small German Angler breed was analysed with the aim to utilize heterosis effects in the crossbred animals. Simultaneously inbreeding was controlled, and the amount of Holstein introgression observed in the Angler breed was reduced. Different scenarios of implementing OCS methods for Angler individuals were evaluated, which differed in their restrictions regarding kinship, native kinship, as well as the amount of genetic contributions from German Holstein. The results showed that rotational crossbreeding can result in superior crossbred offspring compared to the purebred parental lines, whereby OCS methods can simultaneously restrict the increase in inbreeding and keep the Holstein contributions at their current level. However, reducing the amount of migrant contributions while restricting the increase in the native kinship in Angler turned out to be a costly restriction. The reason was that Angler with low genetic contributions from Holsteins tended to have similar Angler ancestors. Consequently, reducing Holstein contributions would considerably increase the native kinship in Angler if it were not constrained. The constraint on the native kinship made a constraint on the conventional kinship superfluous and caused it to increase at a much lower rate than envisaged. This led to both, a high genetic diversity and a low genetic gain. The high genetic diversity in Angler also resulted in lower and oscillating heterosis effects in the crossbred animals. Thus, the reduction of migrant contribution did not increase heterosis effects in the crossbred offspring, and did not result in superior crossbred offspring in general.

PRODUCTIVE AND BIOLOGICAL CHARACTERISTICS OF GROWING SHEEP WITH DIFFERENT GENOTYPES

In order to assess the productive and biological characteristics of growing sheep of different origin we have carried out commercial cross breeding of Kyrgyz hair fat-tailed sheep with dairy Awassi sheep imported from Israel. As a result of basic measurements of body type it was established that crossbred descendants differed with better proportion of majority of body statures with well demonstrated meat and milk shapes. The duration of lactation period with crossbred females of first generation is longer for 50 days, but milk yielding capacity - 88,7 l more than of females of Kyrgyz hair sheep population. Generally having analyzed the effectiveness of crossbreeding, including the received gains in weight, milking capacity, we have become convinced of its advantage. The advantage of crossbred growing sheep has to do with a degree of expression of heterosis effect. The quantity of products derived from crossbred lambs was significantly greater at fewer costs for its production.

Conditions of southern Ukraine pigs productivity under different methods of breeding in modern

The article presents the results of studies concerning pigs’ productivity for purebred breeding and innovative approaches to crossbreeding schemes in the South of Ukraine. In general, sows of all experimental groups had high productivity both in purebred breeding and because of combining different forms with each other however there was no heterosis effect on the sows’ multiplicity in crossbreeding of Large White breed and the complexity of combining the sows of hybrid origin. Young hybrid animals of experimental groups reached a live weight of 100 kg sooner for 2.6-16.4 days or 1.4-8.9 % and feed costs were lower 0.12-0.34 feed units or 3.4-9.7 % per 1 kg gain during the fattening period.
 The obtained results show that the proposed production of final hybrids with a conditional proportion of blood landrace Ч large white in terms of live weight is the most successful and adapted to the technology of moderate intensity. The use of purebred and local animals related to the so-called "White breeds" - Large White and Landrace, is characterized by increased intensity of formation and indices of growth stress. The obtained results additionally confirm the complexity of adaptation of non-ferrous breeds (Duroc and especially Pietrain breeds) to the technological conditions of domestic pork farms. Young pigs were obtained in combinations where the parental form was the breed: Large White, Landrace or Duroc had the best exterior features that characterize the development of animals in length. In combinations where the parent form was the Pietrain breed, the latitudinal measurements and the meat index were improved against the background of a decrease in body length.
 A morphological study of carcasses of young pig stock of different origin has proved that implementation of up-to-date crossbreeding schemes with the use of meat-type breeds as paternal lines results in improved carcass dressing percentage and optimised lean-to-fat ratio. As evident out of the physical and chemical analysis of pork obtained from pigs of different breed-of-origin, all investigated parameters are within the current physiological limits. Most parameters have shown no significant difference, though tended to exhibit some peculiarities associated with the impact of genotype on the manifestation of one or another physical or chemical characteristic. The use of Pietrain breed as a sire line results in decreased intramuscular fat content, and hence the energy value of pork, with the back fat having the highest melting point which is indicative of its enhanced storability, though slightly impaired cooking properties as compared to similar products obtained from the offspring of the Large White and Landrace parents. With respect to its pH level and water-holding capacity, the pork from Pietrain-sired offspring is quite similar to PSE (Pale, Soft, Exudative) meat being slightly less tender and paler in colour and exhibiting greater weight loss during thermal processing. Also, a comprehensive sensory evaluation of boiled pork and pork broth obtained from a group of the Pietrain-sired young stock has got the lowest score, which is consistent with most of the physical and chemical properties of pork from pigs of this genotype; therefore, it is 75% purebred Landrace that should be favoured as a terminal sire line in crossbreeding programmes in order to obtain pork and bacon of improved quality in intensive commercial swine production systems. It is recommended to preliminary combine Pietrain and Duroc lines to produce terminal sires (Pietrain Ч Duroc) which will be further mated with two-breed-cross dams (LW Ч L).

QTL mapping reveals candidate genes for main agronomic traits in Luffa based on a high-resolution genetic map.

Luffa is an important medicinal and edible vegetable crop of Cucurbitaceae. Strong heterosis effects and strikingly complementary characteristics were found between the two domesticated Luffa cultivars, Luffa acutangula and Luffa cylindrica. To explore the genetic basis underlying their important agronomic traits, we constructed the first interspecific high-density genetic linkage map using a BC1 population of 110 lines derived from a cross between S1174 (Luffa acutangula) and P93075 (Luffa cylindrica). The map spanned a total of 2246.74 cM with an average distance of 0.48 cM between adjacent markers. Thereafter, a large-scale field-based quantitative trait loci (QTLs) mapping was conducted for 25 important agronomic traits and 40 significant genetic loci distributed across 11 chromosomes were detected. Notably, a vital QTL (qID2) located on chromosome 9 with a minimum distance of 23 kb was identified to be responsible for the internode diameter and explained 11% of the phenotypic variation. Lac09g006860 (LacCRWN3), encoding a nuclear lamina protein involved in the control of nuclear morphology, was the only gene harbored in qID2. Sequence alignment showed completely different promoter sequences between the two parental alleles of LacCRWN3 except for some nonsynonymous single nucleotide polymorphisms (SNPs) in exons, and the expression level in thick-stem P93075 was distinctively higher than that in thin-stem S1174. According to the natural variation analysis of a population of 183 inbred lines, two main haplotypes were found for LacCRWN3: the P93075-like and S1174-like, with the former haplotype lines exhibiting significantly thicker internode diameters than those of the latter haplotype lines. It showed that LacCRWN3, as the only CRWN3 gene in Cucurbitaceae, was the most likely candidate gene regulating the internode diameter of Luffa. Our findings will be beneficial for deciphering the molecular mechanism of key phenotypic traits and promoting maker-assisted breeding in Luffa.

Features of the marbled veal growing technology at LLC LIVE-STOCK4EXPORT

LLC LIVESTOCK4EXPORT specializes in fattening cattle of specialized meat breeds, i.e., Aberdeen-Angus, Limousin, Simmental and local animals obtained by crossing the Belgian blue breed with the Ukrainian red-spotted and black-spotted breeds. Nowadays the meat sector of the economy needs to find ways to increase the efficiency and profitability of production. The creation of interbreeding herds based on the industrial crossing of dairy and dairy-meat cows with meat breeders is an important reserve for increasing meat resources. LLC LIVESTOCK4EXPORT inseminates cows in the private sector with the purchased sperm of the Belgian blue breed. Then the farm buys and fattens these young calves with a live weight of 55 to 120 kg until they reach a live weight of 300–400 kg with further sale abroad. According to the results of the fattening of meat cattle of various breeds at LLC LIVESTOCK4EXPORT, interbreeding animals had the best growth rate. The adopted technology of growing and fattening animals at LIVESTOCK4EXPORT LLC ensures obtaining average daily gains at the level of 1,706 g reducing feed consumption and livestock fattening times. The advantage in terms of average daily growth of crossbred young is confirmed by the effect of heterosis and the gene of double musculature in crossbreds of the first generation, which significantly increases their meat productivity. They use the same type of year-round feed for animal fattening. In the farm, animals are fed ad libitum according to the developed structure of the diet with 90 % special compound feed and 10 % straw or hay. The composition of special compound feed includes 270 kg/t of corn grain, 190 kg/t of wheat, 150 kg/t of barley, 150 kg/t of malted grain, 110 kg/t of wheat bran, 70 kg/t of sunflower meal, 35 kg/t of soybean cake, 20 kg/t of premix concentrate, and 5 kg/t of sunflower oil. Animals have free access to water and roughage. Keeping animals on the farm is year-round untethered with free access from the premises to the feeding grounds (feedlots).

NON-SPECIFIC HETEROSIS ON A COMPLEX OF FEATURES OF ADAPTABILITY ON THE EXAMPLE OF MINI-PIGS

The authors studied the genetic diversity of the reproductive nucleus of mini-pigs at the Institute of Cytology and Genetics (IC&G) of the Siberian Branch of the Russian Academy of Sciences (SB RAS). To do this, the authors used the indicators of individual homo- and heterozygosity, calculated based on the «blood fractions» of large and small forms of domestic pigs, initial for the breeding group. The study showed that the average value of individual heterozygosity (conditionally actual) is 0.800±0.004, while homozygosity for the contribution of large and small forms of the domestic pig is 0.020±0.002 and 0.180±0.010, respectively. The indicator «blood fraction» can have two interpretations: 1) the probability of transmission of the ancestral allele in several generations; 2) the proportion of the genome of the ancestor that is present in the descendant. The authors determined their frequencies, which turned out to be 0.424 and 0.576 as if assuming the presence of a hypothetical locus with different alleles in the large and small forms of the domestic pig (respectively Ak and Am). The authors calculated heterozygosity for the breeding nucleus based on these frequencies while respecting the Hardy-Weinberg law. As a result, it turned out that the unbiased value is 0.493±0.067, which is significantly (P<0.001) less than the observed conditional-actual value. Selection is carried out according to a set of signs of general fitness (state of health, reproductive qualities, the viability of offspring, etc.) during the formation of the reproductive core of the breeding group of mini-pigs of the IC&G SB RAS. Therefore, the authors concluded that the increased heterozygosity of the breeding stock is due to the preferential selection of heterozygotes. But since selection is carried out according to a set of signs of general fitness, it can be stated that in the reproductive core of the selection group there is an effect of nonspecific heterosis due to heterozygosity. As a result, selection into the reproductive nucleus of individuals with high values of individual heterozygosity calculated by the proposed method can provide heterosis based on general adaptiveness.

19 Heterosis Effects on Pre-Weaning Traits in a Multibreed Beef Cattle Herd in Panama

Abstract The aim of this study was to estimate the influence of heterosis and breed percentage on birth weight (BW) and weaning weight (WW) in beef cows in a tropical environment. Data from 900 calves and 2,843 individuals in the pedigree, from the multibreed herd of the Panama Agricultural Innovation Institute (IDIAP) in Gualaca, Panama were used. The herd was comprised of the following genetic groups and according to their breed percentage: tropical adapted Brahman (BR), Nellore (Ne), Un define Bos indicus (BI), Guaymi Creole (CR), Senepol (SP) Romosinuano (RS); Bos taurus (BT), Simmental (SM), Angus (A), Red Angus (AR), Limousin (LM), Charolais (CH), Wagyu (Wa), and Others (Oth); crossbreeds (cx), Beefmaster (BF), Three cx(F1 x different BT), R1(Backcross BR), R2 (Backcross BT), Composite (combination of at least 4 different breeds with less than 25% of Zebu), Upgrade (87.5% BR 12.5% BT), B1 (62.5% Zebu + 37.5% BT), B2 (62.5% BT + 37.5% Zebu). A bivariate animal model for BW and WW, was utilized to estimate variance components. Contemporary group was defined as year of birth. The effects of sex, birth season, weaning season, and age of dam were included as categorical fixed effects. Weaning age, degree of outcross and breed percentage were included as linear covariates. The estimated regression coefficient for BW on heterosis was not significant (P > 0.05), and for WW was 0.072 ± 0.027 kg (P < 0.05). Lower BW and WW were observed for the Japanese, and B1, while R2 and Upgrade had the highest average (P < 0.05). Heritability for BW was found to be low (0.14 ± 0.06) and moderate for WW (0.26 ± 0.09). The proportion of variation of WW accounted by maternal permanent environment for WW was (0.2 ± 0.09). The estimated genetic correlation between additive genetic BW and WW was 0.63 ± 0.30, while a negative, additive genetic correlation was observed for WW and WW maternal (-0.43 ± 0.37). These results suggested that heterosis had a beneficial influence on WW but limited effect on BW. Additionally, increasing the percentage of Wa, and BR negatively influenced WW measurements in a multibreed beef cattle herd in Panama.

Statistical indicators of seed reproduction of apple <i>(MALUS MİL L.)</i> species introduced on apsheron

We have studied effective methods of seed reproduction of some species of apple trees in the condition of Apsheron. The newly introduced and available in the collection of the Central Botanical Garden of ANAS 23 species of wild apples were taken as research material. Experiments were carried out with both stratified and non-stratified seeds. The germination rate of the studied species was different. As a result, it turned out that in order to obtain good germination of seeds of apple varieties introduced in Absheron, they should be sown either early autumn, or for various reasons (climate, lack of time, etc.), it is better to stratify the seeds and to shorten the germination time it is advisable to sow in spring. Statistical analysis was carried out on the basis of the obtained results. In the course of statistical processing, the statistical programs PAST, SPSS 16. were used. Cluster analysis of samples was carried out using the Ward method based on the Evklid index of genetic distance. According to morphometric and mass parameters, the seeds of the studied species were divided into 3 main groups with 5 values of the genetic distance. The values of statistical indicators were also determined for other studied characteristics of seeds in apple species. The parametrs include minimum and maximum values, mean, standard error, standard deviation, coefficient of variation. And the studied characters are the width, length, and weight of the seeds. This indicates that among the three traits studied between species, the mass trait has greater variability, in other words, higher genetic diversity. That is, the trait of the seed mass of the studied species makes it possible to distinguish more species. It is known that by crossing genetically distant species, a hybrid with new traits can be obtained, i.e. with a high effect of heterosis. From this point of view, high-quality species are selected from the species included in the clusters, and by crossing them with species from other clusters, a hybrid with a high heterosis effect can be obtained. With this method of selection, it is possible to gradually obtain new varieties of high quality.

Estimation of nonadditive and additive genetic effects on growth traits of Horro cattle.

The estimation of nonadditive genetic effects plays a significant role in the accuracy of estimated breeding values for growth traits. Data for estimation of individual and maternal heterosis of crossbreed cattle in Ethiopia are limited to research institutions and universities. This paper aimed to estimate the crossbreeding effects for growth traits of Holstein Friesian × Horro and Jersey × Horro crossbreds in Ethiopia. The data included pedigree and weight data of animals born between 1980 and 2008. Heritability of growth traits was estimated using restricted maximum likelihood (ASREML). However, the additive genetic, maternal, and heterosis effects for growth traits of crossbred animals were estimated using the crossbreeding effects (CBE3) package by fitting Kinghorn's Model one. The direct and maternal heritability estimates for 1-year weight with the model that included the direct maternal covariance were 0.77 ± 0.12 and 0.26 ± 0.09, respectively. Individual heteroses estimated for Holstein Friesian × Horro and Jersey × Horro were significantly high and positive for 1-year weight (21.6 ± 6.7 and 26.0 ± 3.9kg), preweaning average daily gain (27.4 ± 26 and 28.9 ± 15g), and postweaning average daily gain (68.8 ± 16.6 and 61.8 ± 9.9g), respectively. The maternal additive genetic effect for growth traits was mostly positive; therefore, it may be preferable to use crossbred cows from purebred dams instead of crossbred cows from crossbred dams. The significantly higher heterosis and additive genetic parameters in Holstein Friesian × Horro crossbreds indicated that these crossbreds may be preferable to Jersey × Horro crossbreds in areas occupied by Horro cattle.

Characteristics of interline table watermelon F<sub>1</sub> hybrids according to the degrees of dominance and indices of true and hypothetical heterosis

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.

Hybrid Political Regime: The Problem оf Positioning

Introduction. This is not the first time a scientific attempt to position a hybrid political regime in the article has made, again unsuccessful due to the contradictory nature of this regime, pronounced national specifics of combining democratic and authoritarian components, decades of delays in transforming hybrid regimes towards democracies. The methodological basis on which the study is based is a systematic analysis combined with an interdisciplinary approach. The application of this interdisciplinary approach shows that the mixed political regime was called a “hybrid” not by chance - it also has a heterosis effect. Autocratic leaders and parties were well aware that military regimes and personal dictatorships looked too authoritarian and could face sanctions from the international community, so they sought ways to legitimize their autocratic advantages in order to remain in power for a long time. The most effective approach for essentially authoritarian governments has been to fill the hybrid regime with the appearance of democracy, avoiding or distorting, depleting the very essence of democracy. By gaining an externally presentable democratic configuration, an authoritarian regime can pretend to respect rights and freedoms by actually cutting or obstructing their enjoyment. Hybrid regimes can be stable, long-lasting and competitive – while meeting the demands of elites and the needs of society, setting an example of social compromise. The concept of a hybrid regime still has no theoretical basis, which would make it possible to distinguish its identity and clearly distinguish it from other types of political regimes. Conclusions. The study of types of political regimes, the development of the theory of hybrid political regime and the application of interdisciplinary approach gives grounds to define hybrid regime as a separate type of political regime, more stable and durable than pure democratic and undemocratic forms due to its hybrid nature (heterotic effect) and unique national combination of democratic and authoritarian elements. Key words: political regime, democracy, authoritarianism, hybrid political regime