Heterosis Effects Research Articles

Inbreeding is associated with shorter early-life telomere length in a wild passerine

Inbreeding can have negative effects on survival and reproduction, which may be of conservation concern in small and isolated populations. However, the physiological mechanisms underlying inbreeding depression are not well-known. The length of telomeres, the DNA sequences protecting chromosome ends, has been associated with health or fitness in several species. We investigated effects of inbreeding on early-life telomere length in two small island populations of wild house sparrows (Passer domesticus) known to be affected by inbreeding depression. Using genomic measures of inbreeding we found that inbred nestling house sparrows (n = 371) have significantly shorter telomeres. Using pedigree-based estimates of inbreeding we found a tendency for inbred nestling house sparrows to have shorter telomeres (n = 1195). This negative effect of inbreeding on telomere length may have been complemented by a heterosis effect resulting in longer telomeres in individuals that were less inbred than the population average. Furthermore, we found some evidence of stronger effects of inbreeding on telomere length in males than females. Thus, telomere length may reveal subtle costs of inbreeding in the wild and demonstrate a route by which inbreeding negatively impacts the physiological state of an organism already at early life-history stages.

Screening of Grain Development Heterosis Candidate Genes by Integrating QTL Mapping and RNA-Seq in Super Hybrid Rice WFYT025

The application of heterosis during plant breeding increases rice grain yield. However, there have been limited studies on heterosis during rice grain development during the grain-filling stage; therefore, the genetic basis of heterosis for grain development during the grain-filling stage should be highly valued. In this study, a hybrid combination with the super hybrid rice WFYT025 was used to perform a transcriptomic dynamic analysis in grains at the beginning and middle grain-filling stages. A total of 1556 and 1507 transcripts that were differentially expressed between WFYT025 and its parents (DGHP) were identified at 1-day post-anthesis (DPA) and at 10 DPA, respectively. The analysis of the genetic effects of heterosis showed that the over-dominant effect (66.90% and 55.87%) was the main mode of action during grain development. The KEGG pathway and GO analysis of the DGHP indicated that the gibberellin biosynthetic, starch metabolic, and diterpenoid biosynthetic signaling pathways may be associated with heterosis during grain development. To further explore the candidate genes for grain development heterosis, a recombinant inbred line (RILs) population with a high-density genetic map of 2578 bin markers was constructed by crossing the parents of WFYT025, and nine stable QTLs for grain weight-related traits were identified. By comparing the DGHP with 20 QTLs, LOC_Os02g28820, LOC_Os02g32580, LOC_Os04g25440, and LOC_Os12g04980 were identified as grain development heterosis-related candidate genes. These findings provide resources for the study of heterosis during the grain development of super hybrid rice and provide valuable theoretical references for the cloning and functional analysis of heterosis-related genes.

Evaluation of combining abilities and heterosis effect for a better selection of hybrid barley

Heterosis effect and the combining ability are two main indices of hybrids performance. Predicting hybrid performance and heterosis effect is an important approach in the breeding of hybrid barley. In order to i) combine the local and introduced genetic material; ii) study the combining abilities of parents and hybrids; and iii) analyze the relationships between the heterosis effect, the combining ability and the performance of hybrids, the present research has been initiated. In this study, five cultivars of barley (Hordeum vulgare L.) were crossed according to a full diallel plan comprising P² combinations. The twenty hybrids F2 were assessed by the general combining ability analysis (GCA); by the specific combining ability (SCA) as well as by the calculation of the heterosis effect of six agronomic characters, namely, the weight of the spike (WE), the number of grains per spike (NGE), the weight of a thousand grains (WTG), plant earliness at flowering (PRF), plant harvest index (IR) and plant productivity (P P). The results indicate that GCA for all parameters was significant except for the WE trait while SCA was significant for three of the six traits studied: WTG, IR and PRO. The GCA/SCA ratio revealed that non-additive effects were the main effect on traits assessed in the hybrids F2. Heterosis was significantly correlated with SCA for all traits tested, indicating that non-additive effects were the main effect of heterosis. Hybrids from two parents with a high GCA have consistently shown better SCA and better hybrid performance. Indeed, the selection of parents should be mainly based on their GCA.

Parent-of-Origin Effects on Seed Size Modify Heterosis Responses in Arabidopsis thaliana.

Parent-of-origin effects arise when a phenotype depends on whether it is inherited maternally or paternally. Parent-of-origin effects can exert a strong influence on F1 seed size in flowering plants, an important agronomic and life-history trait that can contribute to biomass heterosis. Here we investigate the natural variation in the relative contributions of the maternal and paternal genomes to F1 seed size across 71 reciprocal pairs of F1 hybrid diploids and the parental effect on F1 seed size heterosis. We demonstrate that the paternally derived genome influences F1 seed size more significantly than previously appreciated. We further demonstrate (by disruption of parental genome dosage balance in F1 triploid seeds) that hybridity acts as an enhancer of genome dosage effects on F1 seed size, beyond that observed from hybridity or genome dosage effects on their own. Our findings indicate that interactions between genetic hybridity and parental genome dosage can enhance heterosis effects in plants, opening new avenues for boosting heterosis breeding in crop plants.

Evaluation of heterosis through reciprocal crosses of inbred cucumber lines (Cucumis sativus L.)

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.

Изучение гетерозиса при гибридизации географически удаленных сортов хлопчатника

In the study, hybridization was carried out between the local Gossypium variety and geographically distant Gossypium varieties to obtain a selection starting material. To determine the effect of heterosis, hybrids obtained from the crossing of Ganja-110 Gossypium variety with geographically distant cotton varieties were studied, F1 generation hybrids showed a positive dominance in terms of growing season. The fiber yield of F1 hybrids of Ganja-110 × Selekt hybrid combination was the dominant hereditary character. In F1, the mass of raw cotton obtained from one cocoon was close to the parent form with a larger cocoon in hybrids obtained for all combinations. F1 hybrids were superior in fiber length compared to their parent forms. In the F1 hybrid offspring, all combinations were close to the parent form with high fiber length. The individual samples collected according to the characteristic shown in F3 were higher than the parent form, and sometimes closer to the parent form with higher fiber length. The individual samples collected from the hybrid seeds studied in the experiment were quite effective.

Degree and nature of heterosis effects in corn lines by grain quality parameters

Aim. Widespread use of corn hybrids, which are of key importance for the food security in Ukraine, is one of the most successful examples of the heterosis phenomenon use. In order to recommend new and high-quality corn hybrids for production, it is necessary to assess the inheritance degree and heterosis effects for protein, starch and oil contents as well as for yield. Results and Discussion. To achieve the goal, we used the classic field techniques and methods of qualification examination of plant varieties for suitability for distribution in Ukraine. The protein, starch and oil contents in grain were determined on a InfratecTM 1241 Grain Analyzer (FOSS); the heterosis effects were calculated by D. S. Omarov’s methods. As a result of tester crosses, 65 experimental corn hybrids were obtained. Inbred lines VK13, VK69, AE801 and AE392 (carriers of the wx and ae mutations of endosperm structure, respectively) were the female forms. Inbred lines СО255, АК159, АК157, G255, FV243 and KhLG1203 were used as male components for the first time to obtain hybrids with high grain quality parameters. From the 2020−2021 studies, we found that, in terms of grain quality, the grain starch content-driven selection of parental pairs was the most rational approach, as the influence of parental forms on this trait consistently exceeded 50% across the study years. Conclusion. Hybrids VK13×UKhK678 and VK13×UKhK686 were noticeable for consistently high manifestation the heterosis effects for several parameters. As to the starch content in grain, superdominance of a parental form with stronger expression of the trait was recorded in hybrids VK13×UKhK678, VK13×UKhK686, VK19×FV243, and AE801×VK32; as to the oil content in grain, VК13×UKhК678, VК13×UKhК686, VК13×VК37, АЕ392×СО255, АЕ392×KhLG1203, and АЕ392×АК157 were distinguished. Inbred corn lines that should be used as parents of heterotic corn hybrids (KhLG1203, CO255, AK159 and AK157) were singled out.

Effect of Heterosis on Growth, Earliness and Yield Characters of Brinjal (Solanum melongena L.)

The present study was conducted to estimate the magnitude of heterosis for thirteen characters in brinjal. The analysis of variance revealed that the genotype selected were having sufficient amount of genetic variability amongst them to carry out further genetic analysis. Forty five F1 hybrids (generated by line x tester mating design using diverse fifteen lines and three testers) along with 18 parents and standard check hybrid (Punjab Sadabahar) were evaluated in a randomized block design with three replications at The Research Farm of Department of Vegetable Science, Chaudhary Charan Singh Haryana Agricultural University, Hisar. Highest heterotic value for fruit yield per plant was observed in cross combinations HE-100 x H-8 (42.27%) followed by HE-100 x HLB-12 (40.97%), HE-106 x BR-112 (37.54%) and HE-101 x BR-112 (36.46%). The cross combinations HE-100 x BR-112 followed by HE-100 x H-8 and HE-100 x HLB-12 showed earliness among all the crosses.

THE LEVEL OF HETEROSIS AND THE DEGREE OF PHENOTYPIC DOMINANCE OF THE MAIN ECONOMICALLY VALUABLE CHARACTERISTICS IN F1 HYBRIDS OF THE SILKWORM (BOMBYX MORI L.)

There were presented the results of heterosis level (hypothetical and true) and the degree of phenotypic dominance of the main economically valuable characteristics in hybrids of silkworm Bombyx Mori L. of the first generation. The crossing was conducted by full diallel scheme, including 16 variants (12 hybrids and 4 parental forms), 50 mg in triplicate replications. There were studied the types of heredity and the level of heterosis of the main economically valuable characteristics in F1 hybrids of silkworms. It was revealed that the heredity of caterpillars viability, average cocoon weight and male silkiness was mostly positive as regards to G2, G4, G6 and G7 lines, while the heredity of females was mostly depressed (negative superdominance). Determination of the effect of heterosis and the degree of phenotypic dominance made it possible to identify 7 best combinations in terms of caterpillar viability in comparison with parental forms, among them the best were hybrids G2×G6 and G6×G2 with high degree of phenotypic dominance (positive superdominance) -- 7.8 and 9.0, with hypothetical heterosis of 11.0% and 12.7% and true heterosis of 9.4% and 11.1% accordingly. The effect of heterosis (positive superdominance) was found in 8 hybrids according to cocoon weight out of 12 hybrid combinations, partial positive inheritance in 3 hybrids, and intermediate type of dominance in 1 hybrid. The hybrids G6×G4 (Ht=9.00 %, Hbt=8.30 %) and G6×G7 (Ht=1.68 %, Hbt=1.43 %), whose heredity was of the positive superdominance type, were distinguished by female silkiness with a high level of hypothetic and true heterosis (13, 92 and 6.80, accordingly), while hybrid depression was observed in 5 combinations, intermediate heredity in 3, and partial positive and negative dominance in one combination each. The 9 hybrids had positive overdominance type heredity for silkiness in males. Production of high-quality silkworm biomaterial contributes to extension of possibilities of its use in various spheres of human activity.

Morphometric measurements of calves of beef cattle from different genetic groups up to one year of age

Heterosis plays an important role on yield and profitability of beef production systems. This study evaluates the morphometrics of purebred Nellore (N) and Charolais (C) animals and of the second (G2) and third (G3) generations of their alternating crosses, regarding the effects of genetic group and heterosis from birth to 365 days of age. The experiment comprised 159 calves (C = 29, N = 22, G2 - 3/4C 1/4N = 21, 3/4N 1/4C = 9, G3-5/8C 3/8N = 44 and 5/8N 3/8C = 34). The foreshank girth (FG), thoracic girth (TG), body length (BL), and hip height (HH) were measured after birth, and at 63, 210, and 365 days of age, and the total increases were calculated. The Charolais animals had greater FG, TG, and BL values than Nellore, while the latter had greater HH. For the offspring generations, the predominance of Charolais genes in the genotypes resulted in greater measurements for FG and TG in G2, whereas the predominance of Nellore genes resulted in higher HH values in both generations. The crossbred animals had greater values for all measurements than the purebreds, with more significant differences in FG, TG, and BL compared to Nellore purebreds and in HH compared to Charolais. Charolais animals show higher values for muscularity; while, Nellore animals are taller. Crossbred animals show greater development compared to purebreds, indicating a significant effect of heterosis.

Estimates of breed additive, heterosis and epistasis genetic effects on milk production and reproductive traits from indigenous Borena and crosses with Holstein Friesian dairy cows at Holetta dairy research farm, Ethiopia

Estimates of breed additive, heterosis and epistasis genetic effects on milk production and reproductive traits from indigenous Borena and crosses with Holstein Friesian dairy cows at Holetta dairy research farm, Ethiopia

ВЛИЯНИЕ ИНТЕНСИВНОГО ВЫРАЩИВАНИЯ ТЕЛОК НА ИХ РОСТ И ПРОДУКТИВНОСТЬ

As a result of research aimed at improving the red steppe cattle, using the gene pool of Ayrshire and Holstein Red-and-White cattle, it was found that the resulting crossbreeds were distinguished by higher milk productivity. When studying the livestock, groups of animals with higher productivity rates were identified and formed in comparison with the average for the herd. Crossbred heifers of the first generation were intensively grown and inseminated at the age of 13-15 months when they reached a live weight of 360-380 kg. The effect of heterosis contributed to obtaining such a live weight. The average daily gain in live weight varied from 861 to 900 grams, both for individual age periods and for the entire growing period, the tendency for the superiority of crossbred heifers remained. In terms of milk productivity, crossbred Holstein Red-and-White heifers surpass their peers of purebred red steppe heifers in terms of milk yield by 586,8 kg or 11,3% (P>0,99), in terms of fat content they exceeded by 0,22% (P>0,99) and protein – 0,05% (P>0,99). Crossbred Ayrshire heifers of group II yielded in terms of milk yield to peers of group III by 76 kg, but in terms of fat content they were superior by 0,06, protein 0,15%. The amount of milk fat in the milk of cows II and III was at the same level of 214,8-214,9 kg and exceeded the purebred peers of group I by 34,2-34,3 kg (P>0,99), and the amount of milk protein – 16,2-21,6 kg (P>0,95).

Heterosis for seed and seedling traits in papaya

The current study was aimed to explore the heterosis expressed in the seed and seedlings of 36 papaya hybrids originating from the 6 inbred lines. The results revealed the manifestation of heterosis, occurred in the seed and seedling stage of papaya. The cross combinations, P-9-5 × P-7-2, P-9-12 × PN and PN × P-9-5 exhibited positive average heterosis and heterobeltiosis for physical seed traits. The genotypes, P-9-5, P-9-12, P-9-5 × P-9-12 and P-9-12 × P-9-5 were observed with positive mid-parent heterosis and heterobeltiosis for the seedling traits. The hybrid, P-7-9 × PN and PS3 × P-7-9 showed positive average heterosis (5.89% and 9.91%) and heterobeltiosis (3.41% and 2.09%) for germination percentage, respectively. Whereas in case of seedling length and weight (fresh and dry), the hybrid combination, P-9-5 × P-9-12 exhibited the positive heterosis. The heterosis effect estimated helped us to identify the superior performing hybrids like, PN × P-7-2, PN × P-9-5, P-7-2 × PN, P-7-2 × P-7-9, P-7-9 × P-9-5, P-9-5 × P-7-2, P-9-5 × P-9-12, P-9-12 × PN, P-9-12 × P-7-2, P-9-12 × P-95and PS3 × P-7-9, in the initial stage of seedling development.

Productive features of holstein cows with intra-linear selection and reciprocal cross of lines

In dairy cattle breeding, in order to maintain the level of productivity of cows of a certain line, intralinear selection is used, which allows consolidating valuable genes of the ancestor of the line in the resulting offspring. At the same time, in order to identify the manifestation of the heterosis effect by the leading breeding characteristics, it is necessary to study the compatibility of lines. The purpose of the conducted research was to study and identify the most effective variant of interlinear crossing and intra-linear selection of animals of the Vis Idial 933122 and Reflection Sovering 198998 lines, which increases the productivity of Holstein black-and-white cattle bred in Agro-Soyuz LLC. Four groups of cows were formed for the research, with a total number of 210 heads. Analysis of the data obtained showed that the highest milk yield for lactation, milk fat yield, milk protein yield and milk content index were characterized by cows obtained as a result of in-line selection of animals from the Vis Idial 933122 line, whose superiority over cows of other experimental groups was, respectively, 132-668 kg; 1.5-26.4 kg; 1.7-22.0 kg and 2.8-49.6 kg. Thus, in order to opt for one of the breeding techniques to increase the dairy productivity of cattle, it is recommended that a comparative assessment of the productive qualities of cows obtained on the basis of in-line selection and line crossing be carried out in each dairy herd.

Perspectives of gene editing for cattle farming in tropical and subtropical regions.

Cattle productivity in tropical and subtropical regions can be severely affected by the environment. Reproductive performance, milk and meat production are compromised by the heat stress imposed by the elevated temperature and humidity. The resulting low productivity contributes to reduce the farmer's income and to increase the methane emissions per unit of animal protein produced and the pressure on land usage. The introduction of highly productive European cattle breeds as well as crossbreeding with local breeds have been adopted as strategies to increase productivity but the positive effects have been limited by the low adaptation of European animals to hot climates and by the reduction of the heterosis effect in the following generations. Gene editing tools allow precise modifications in the animal genome and can be an ally to the cattle industry in tropical and subtropical regions. Alleles associated with production or heat tolerance can be shifted between breeds without the need of crossbreeding. Alongside assisted reproductive biotechnologies and genome selection, gene editing can accelerate the genetic gain of indigenous breeds such as zebu cattle. This review focuses on some of the potential applications of gene editing for cattle farming in tropical and subtropical regions, bringing aspects related to heat stress, milk yield, bull reproduction and methane emissions.

Genomic Analysis of Purebred and Crossbred Angus Cows Quantifies Heterozygosity, Breed, and Additive Effects on Components of Reproduction.

Simple SummaryThis study reports a genomic analysis of purebred Angus and Hereford × Angus maternal productivity, which is a key driver of sustainable systems. Heterozygosity effects quantify hybrid vigour or heterosis and were significant for growth and puberty. Breed differences were mostly due to heterosis, but there was an advantage of Hereford genes for reproductive performance. Days to calving was the most important Estimated Breeding Value (EBV) as a predictor of attainment of puberty and subsequent reproductive performance. Genomics offers a cheaper and faster strategy for the development of multi-breed EBVs in commercial herds.Multiple studies have quantified the production differences of Hereford Angus crossbreds compared to purebred Angus for a range of traits including growth, carcass, and reproductive traits. This study aims to quantify breed and heterosis effects on maternal performance using genomics. Thirty Hereford and thirty Angus sires were mated to 1100 Angus heifers and cows in a large commercial herd run on pasture at Musselroe Bay, Tasmania, Australia. Approximately 1650 calves were born. Heifers were weaned, scanned for attainment of puberty prior to joining at approximately 15 months of age, joined, and then recorded for status of pregnancy, calving, lactating, 2nd pregnancy, and weaning of second calf. Heterozygosity effects were significant for heifer pre-joining weight and height as well as proportion pubertal. Breed differences were significant for the same traits plus pregnancy rate at second joining and proportion rearing two calves. Genetic parameters were reported for 13 traits. On average, higher genetic merit (Estimated Breeding Value, EBV percentile) Hereford bulls were used than Angus for growth and puberty, but they were similar for fat and reproduction. Days to calving BREEDPLAN EBVs of the sires were related to puberty and reproduction. Scrotal size BREEDPLAN EBVs of the sires were related to attainment of puberty genomic EBVs calculated. In summary, breed differences in growth and puberty were due to heterosis, but there was an advantage of Hereford genes for reproductive performance. Ongoing emphasis on selection for reduced days to calving and estimation of multi-breed EBVs is important.

ЭФФЕКТИВНОСТЬ СКРЕЩИВАНИЯ БЕСТУЖЕВСКИХ КОРОВ С БЫКАМИ КРАСНОЙ ДАТСКОЙ ПОРОДЫ

The article presents results of studies on milk productivity of crossbred first-calf heifers obtained by crossing Bestuzhev cows with red Danish bulls. Feeding of both groups (control and experimental) was carried out with proper and balanced ration. Total nutritional value of the ration was 14.07 energetic feed units (EFU). One EFU accounted for 85.15 g of digestible protein, dry matter per 100 kg of live weight - 3.6 kg, fiber from dry matter - 23%. Sugar - protein ratio of the diet was at the level of 0.8. As a result, crossbred first-calf heifers had higher parameters of milk yield (by 20.57%), fat content (by 0.23%) and protein (by 0.07%) in milk compared to pure-bred Bestuzhev peers; they had also higher milking capacity index (by 14.14%). In addition, crossbred first-calf heifers show better development, their live weight is 26 kg or 5.64% higher than the level of the breed minimum requirements. Consequently, the effect of heterosis is noted when crossing Bestuzhev cows with red Danish bulls, which has a positive effect on better development of crossbred heifers and on increase of their milk productivity. As a result, crossbred first-calf heifers meet the modern requirements of milk production technology on an industrial basis better than their Bestuzhev peers. Therefore, this method of crossing with the red Danish breed is advisable and should be used in selection and breeding work with the Bestuzhev breed.

Heterosis and reciprocal effects for physiological and morphological traits of popcorn plants under different water conditions

In spite of the benefits of heterosis in maize breeding, little is known about the physiological mechanisms of this phenomenon and its genetic control under different water regimes. This study aimed to understand the heterosis effects on plant growth, the photosynthetic and transpiration traits, and the root traits of four inbred popcorn lines and their hybrids, including their reciprocal combinations. Plants were grown in lysimeters, inside a rain shelter, under two water conditions (water stress – WS; well-watered – WW) until anthesis. Plant growth traits included shoot biomass, plant height, and leaf area. Photosynthetic traits comprised leaf pigment and total nitrogen content, chlorophyll fluorescence, gas exchange, water use efficiency and stomatal index and density, along with the stable carbon (δ13C) and nitrogen (δ15N) isotope compositions of the last developed leaf. Root weight density and specific root length were also recorded. Greater heterosis effects were observed for traits related to plant growth and root weight density, and specifically under WS. Traits related to root weight density in deeper soil layers benefited markedly from heterosis, but there were no advantages in terms of stomatal conductance and water status in general. Apparently, only δ13C supported a better water status under WS, and was observed in the hybrids in particular. Non-additive gene effects were predominant in controlling of most of the growth and root traits studied, supporting the conclusion that the heterosis effect is especially favorable under water-limiting conditions. Moreover, the choice of the female parent is essential for traits related to gas exchange when breeding for better resilience to drought.

Analysis of the reproductive qualities of crossbred sows and determining the effect of a combination at crossing

It is presented the comparative analysis of a manifestation of reproductive qualities of purebred and two-breed sows in combination with boars of different genotypes and the definition of the best forms for further receiving highly productive marketable young pigs. The researches were conducted in the conditions of SE EE "im. Dekabrystiv "of Institute of Pig Breeding and AIP NAAS of Myrhorod district of Poltava region. 5 groups of young animals were formed for the experiment: 1 – (LW×Landrace)×Landrace, 2 – (LW×Landrace) x Duroc, 3 – LW×Duroc, 4 – Landrace×Landrace, 5 – Myrhorod breed x Myrhorod breed. It was determined the fact that by index of the number of piglets born, sows of the combination (LW×L)×D were dominated the purebred Landrace females by 7.41 % (p≤0.05) and pigs of Myrhorod breed by 9.59 % (p≤0.001). The significant variability of the rich fertility index in the sows of the combination of LW×L was revealed: the standard deviation in them was 3.56 heads (compared to 1.22 in other groups), the indicators of the magnitude of variation and the coefficient of variability were also the largest (respectively 10 heads and 10.71 %), which is confirmed by the value of the coefficient of excess – 2.689. The crossbred sows with the LW×L combination had the highest litter weight, they exceeded the sows of Myrhorod breed by 44.2 % (p <0.001) and tended to exceed the sows of Landrace breed by 3.51 %. It should be noted that the weight of the litter at weaning in Landrace sows was 68.3 kg, with a positive asymmetry – 0.743 and an excess coefficient of 0.467; the coefficient of variation was low, which indicates targeted selection for growth intensity in pigs of this breed. According to the results of the researches, the level of combination and the effect of crossing genotypes by multiplicity and the litter weight at weaning were determined. The level of combination of genotypes by crossing exceeded the level of combination by purebred breeding and had positive values in terms of fertility. The highest value of this indexes was obtained from the combination of crossbred sows with boars of Duroc breed – +0.70 units.The next stage of researches was to determine the effect of heterosis. The efficiency of combination (LW×L)×D was determined – 106.93 points for the multiplicity. According to the index of litter weight at weaning, the effect of heterosis was found out at crossing and in pigs of Landrace breed (for purebred breeding). Its highest value was determined in the combination of LW×L – 111.34 %, which indicates the effective use of this combination in the first stage of hybridization. The use of industrial crossbreeding and hybridization in the herd of SE "EE im. Dekabrystiv” helps to increase the multiplicity rate of sows, as well as proves the effectiveness of the use of crossbred sows of the combination LW×L in the first stage of the hybridization to increase the growth rate of young animals. Indexes of the level of combination and the effect of heterosis should be used to assess the effectiveness of crossbreeding in pig breeding. Key words:sows, multiplicity, litter weight, crossbreeding, heterosis, hybridization, genotype.

Проявление гетерозиса у F1 гибридов петунии

The article presents the results of a study of the manifestation of hypothetical and true heterosis in the hybrid petunia according to some decorative features in the conditions of the protected ground of Moscow. The presence of a heterosis effect and overdomination in the time of flowering of the first flower, the diameter of the flower and the number of flowers for the first two weeks of flowering was established. All hybrid combinations showed a small negative hypothetical and true heterosis effect on the early entry of petunia plants into the flowering phase. Keywords: PETUNIA, HETEROSIS, HYBRID, DOMINANCE, OVERDOMINATION