Heterosis Effects Research Articles

Efficiency of using the new domestic meat-egg hybrid for the production of food eggs in household farms

Aim. A detailed analysis of the egg production and economic effi ciency of using a new dual-purpose hybrid in a comparative aspect with the original forms. Methods. Standard zootechnical methods of estimating body weight, egg production and its intensity, egg weight, feed costs and livability of adult hybrid and purebred hens were used. The effects of heterosis on the main utility indicators and the European profi t ratio IOFC (Income Over Feed Cost), which displays the difference between the revenue from one layer and the cost of consumed food, was estimated. Results. Almost all studied indicators demonstrated the advantage of the hybrid over the original forms. The phenomenon of heterosis was observed in most studied indices – 5.7 % by precocity, 3– 7 % by mass of eggs, 12–14 % by egg production. Early puberty (on 2–16 days), more intensive build-up of egg production (by 3.3–4.2 %), improvement of its medium intensity by 4.6–9.8 % provided by hybrid laying hens per year of life which were 9–20 eggs superior than the origin forms. Due to the high productivity and low feed consumption per 10 eggs (2.1 kg versus 2.8 kg for the paternal form), the profi t ratio IOFC was also 28.7– 29.1 % higher for a hybrid. This indicates the expediency of using layers of a new hybrid combination for the production of food eggs in farming and household farms. Conclusions. The obtained zootechnical and eco- nomic indicators demonstrate the expediency of using layers of a new hybrid combination for the production of food eggs in farming and household farms.

Genetic divergence among interspecific Paspalum hybrids based on seed production traits

ABSTRACT The use of genetic divergence as a basis for identifying superior individuals, with greater heterozygosity, is important in view of the difficulty when selecting of dissimilar genotypes exhibiting high average for interest traits. The aim of this study was to evaluate the genetic divergence and the expression of seed production traits in seventeen apomictic Paspalum plicatulum × Paspalum guenoarum hybrids and two male parents (P. guenoarum). A randomized block design was used, with genotypes individually arranged into ten blocks. The following traits were assessed: total number of tillers/plant (TT), reproductive tiller/plant (RT), number of racemes per inflorescence (NRI), reproductive tiller height (RTH), inflorescence rachis length (IRL), number of seeds/inflorescence (NSI), weight of a thousand seeds (WTS) and seed production (SP). Genetic divergence among the genotypes was estimated using the Tocher method and UPGMA clustering, based on the generalized Mahalanobis distance (D2 ii’). The Tocher and UPGMA optimization methods showed high concordance. The traits that most contributed to genetic divergence were RTH (23.59%), IRL (21.63%), WTS (16.67%) and SP (14.23%). The presence of genetic diversity made it possible to identify divergent genotypes and those with high means for the traits studied, allowing the selection of genotypes with significant breeding potential. Repeated cross-breeding of female superior plants with the genotypes Azulão and H20 can result in a high heterosis effect on seed production characteristics.

토종 종계 이면교배조합 시험에 따른 생산능력 및 잡종강세효과

본 연구는 국산 신품종 토종닭을 개발하기 위하여 국내 토종닭 GPS 계통들을 대상으로 <TEX>$5{\times}5$</TEX>이면 교배조합 시험을 실시하여 교배조합별 성적을 토대로 최적의 종계 조합을 선발하고자 하였다. 총 25개 교배조합의 암컷 1,157수를 대상으로 주요 생산능력인 생존율, 체중, 시산일령, 난중, 일계산란율 및 산란지수를 조사하고 분석하였으며, 각 조합별 형질들의 잡종강세효과도 추정하였다. 분석 결과, 성계의 평균 생존율은 순계구가 67.7%, 교잡구가 77.1%로 나타났다. 체중 측정 결과, 이들 25개 조합은 뚜렷한 3개의 그룹 즉, 9개의 고체중구, 12개의 중체중구 및 4개의 저체중구로 구분되었다. 12주령 평균 체중은 고체중구는 <TEX>$1,873.8{\pm}43.0g$</TEX>, 중 체중구는 <TEX>$1,595.4{\pm}56.6g$</TEX>, 저 체중구는 <TEX>$1,152.7{\pm}24.7g$</TEX>이었으며, 순계구는 <TEX>$1,560.2{\pm}339.3g$</TEX>, 교잡구는 <TEX>$1,640.9{\pm}213.7g$</TEX>이었다. 산란능력에 있어 시산일령은 순계구는 <TEX>$139.7{\pm}4.9$</TEX>일, 교잡구는 <TEX>$135.8{\pm}5.1$</TEX>일이었고, 평균 난중은 순계구에서 <TEX>$52.3{\pm}1.6g$</TEX>, 교잡구는 <TEX>$53.0{\pm}1.6g$</TEX>이었다. 20주령부터 40주령까지의 산란지수는 순계구가 <TEX>$58.3{\pm}12.9$</TEX>개, 교잡구는 <TEX>$69.2{\pm}10.4$</TEX>개였다. 잡종강세 효과 추정에 있어 전체 조합에 대한 평균 생존율은 16.9%, 12주 체중은 5.4%, 시산일령은 -2.7%, 난중은 1.3% 및 일계 산란율은 14.3%의 잡종강세율을 나타내었다. 전반적으로 생존율 및 산란형질들의 잡종강세 효과가 성장형질에 비해 높게 나타났다. 이상을 종합할 때 최적의 실용계 생산을 위하여 부계통으로는 우수한 성장능력을 가진 HF 조합구의 선정이 바람직하고, 모계통으로는 우수한 산란능력을 가진 GW 및 FW 조합구의 선정이 바람직하리라 예측된다. This study was conducted to establish new synthetic lines of Korean Native Chicken. We performed <TEX>$5{\times}5$</TEX> diallel crossings with GPS lines of Korean Native Chicken for the selection of parent stock. The production traits including viability, body weight, age at first egg laying, egg weight, hen-day egg production, and hen-housed egg production were measured and analyzed for 25 crosses with 1,157 hens. The heterosis effects of these traits were also estimated. The results showed that the average survival rate during laying periods was 67.7% in the pure lines and 77.1% in the crosses. The 25 cross combinations were shown to be distinctly divided into three groups according to body weight; nine crosses in the high-weight group, 12 crosses in the medium-weight group and four crosses in the light-weight group. The average body weight at 12 weeks of age was <TEX>$1,873.8{\pm}43.0g$</TEX> in the high group, <TEX>$1,595.4{\pm}56.6g$</TEX> in the medium group and <TEX>$1,152.7{\pm}24.7g$</TEX> in the light group, and <TEX>$1,560.2{\pm}339.3g$</TEX> in the pure lines and <TEX>$1,640.9{\pm}213.7g$</TEX> in the crosses. In terms of egg production performance, the age at first egg laying was <TEX>$139.7{\pm}4.9$</TEX> days in the pure lines and <TEX>$135.8{\pm}5.1$</TEX> days in the crosses. The average egg weight was <TEX>$52.3{\pm}1.6g$</TEX> in the pure line and <TEX>$53.0{\pm}1.6g$</TEX> in the crosses. The average hen-housed egg production from 20 to 40 weeks was <TEX>$58.3{\pm}12.9$</TEX> eggs in the pure line and <TEX>$69.2{\pm}10.4$</TEX> eggs in the crosses. The average heterosis effect was 16.9% for survival rate, 5.4% for body weight at 12 weeks, -2.7% for age at first egg laying, 1.3% for egg weight, and 14.3% for hen-day egg production. Generally, the heterosis effect for viability and egg production traits was higher than that for growth trait. On the basis of these results, it is expected that the selection of the HF combination, which had excellent growth performance, is the most desirable as the paternal strain, and the selection of GW and FW combinations, which had excellent laying performance, are preferable as the maternal strain.

Genomic-polygenic and polygenic predictions for nine ultrasound and carcass traits in Angus-Brahman multibreed cattle using three sets of genotypes

The objectives of this study were to estimate variance components, genetic parameters, EBV, accuracies, and rankings for nine ultrasound and carcass traits in a multibreed Angus-Brahman population using three genomic-polygenic models and one polygenic model (PM). The genomic-polygenic models used the complete GeneSeek GPF250k SNP set (GPM), top 5% SNP (GPMR1), and 5% SNP evenly spread across the genome (GPMR2). Yearling ultrasound traits were weight (UW), ribeye area (UREA), backfat (UFAT), and percent intramuscular fat (UPIMF). Carcass traits were slaughter age (SLA), hot carcass weight (HCW), ribeye area (REA), backfat thickness (FAT), and marbling score (MAR). The 9-trait GPM, GPMR1, GPMR2, and PM contained fixed contemporary group, age of calf (ultrasound traits only), sex of calf, and direct heterosis effects, and random animal and residual effects. Variance components and genetic parameters were computed using AIREMLF90. Comparable heritabilities were obtained with GPM and PM for UW (GPM: 0.54 ± 0.05; PM: 0.51 ± 0.05), UREA (GPM: 0.36 ± 0.03; PM: 0.34 ± 0.03), UFAT (GPM: 0.12 ± 0.02; PM: 0.11 ± 0.02), UMPIMF (GPM: 0.34 ± 0.03; PM: 0.30 ± 0.03), SLA (GPM: 0.59 ± 0.07, PM: 0.61 ± 0.06), HCW (GPM: 0.58 ± 0.06, PM: 0.52 ± 0.07), REA (GPM: 0.48 ± 0.04, PM: 0.45 ± 0.05), FAT (GPM: 0.41 ± 0.05, PM: 0.30 ± 0.05), and MAR (GPM: 0.56 ± 0.07, PM: 0.51 ± 0.08). Additive genetic correlations between pairs of ultrasound and carcass traits were all between −0.31 and 0.81. The highest positive additive genetic correlations were between UW and UREA, UW and HCW, UW and REA, UREA and HCW, UREA and REA, UFAT and FAT, and between HCW and REA. The largest negative additive genetic correlations were between UREA and UPIMF, UFAT and SLA, UFAT and HCW, UPIMF and REA, and between REA and MAR. High similarity existed among predicted EBV and accuracies from GPM, GPMR1, and GPMR2 as well as high-rank correlations for sires, dams, and progenies. This indicated that the two reduced genotype sets were appropriate alternatives to the complete GPF250k set for genomic-polygenic evaluation and selection in this multibreed Angus-Brahman population. High EBV variability existed among animals of all Angus and Brahman percentages and no specific breed composition was overwhelmingly better or worse for any of the nine traits. This indicated that optimization of genetic progress through selection in multibreed Angus-Brahman populations should be based solely on genetic merit regardless of breed composition.

Estimation of genetic parameters and heterosis for longevity in crossbred Danish dairy cattle.

Crossbreeding has been shown to improve the longevity of dairy cattle in countries across the world. The aim of this study was to estimate heterosis, breed effects, and genetic parameters for longevity in crossbred dairy cattle among Danish Holstein (DH), Danish Red (DR), and Danish Jersey (DJ) breeds. Data were provided from 119 Danish commercial herds that use systematic crossbreeding (i.e., rotational crossbreeding). Additional data from 11 mixed-breed herds with DH and DJ were included to estimate reliable breed effects for DJ. Survival information on 73,741 cows was analyzed with a linear animal model using the artificial insemination-REML algorithm in the DMU package. Five longevity (L) traits were defined: days from first calving until the end of first lactation or culling (L1), days from first calving until the end of second lactation or culling (L2), days from first calving until the end of third lactation or culling (L3), days from first calving until the end of fourth lactation or culling (L4), and days from first calving until the end of fifth lactation or culling (L5). Heritabilities ranged between 0.022 and 0.090. Additive breed effects in units of days were estimated relative to DH for DR as -0.5 (L1), +10.5 (L2), +18.5 (L3), +11.9 (L4), and +28.6 (L5), and corresponding figures for DJ were +2.0, +0.5, +14.2, +27.7, and +44.0. Heterosis effects in L1 were low (1.2%) but favorable in crosses between DH and DR, whereas negative heterosis effects were estimated for crosses between DH and DJ (-2.5%) and DR and DJ (-1.2%). The largest heterosis effects for L2, L3, L4, and L5 were found in DH × DR and were favorable (+3.3, +5.7, +7.7, and +8.5%, respectively). Corresponding figures for heterosis effects in DH × DJ and DR × DJ were favorable as well: +2.3, +4.1, +5.6, and +6.2% in DH × DJ and +3.1, +7.3, +6.9, and +7.2% in DR × DJ. The favorable heterosis effects show that crossbreeding is an efficient tool for improving longevity in Danish dairy cattle.

GENETICS CHARACTERS INTRAPEDIGRYS TYPES OF CARPATHIAN BREED BEES

GENETICS CHARACTERS INTRAPEDIGRYS TYPES OF CARPATHIAN BREED BEES

Relationship between hybrid performance and genetic variation in self-fertile and self-sterile sugar beet pollinators as estimated by SSR markers

Sugar beet hybrid varieties are produced through the crosses between male sterile lines and the multigerm pollinators. The uniformity of pollinators used for hybrid crosses depends on the presence of self-sterility (S s ) and self-fertility (S f ) genes. The aim of the study was to analyze correlation between hybrid performance and genetic distance or heterozygosity of the sugar beet pollinators. Twelve diploid pollinators classified as self-sterile (S s ) or self-fertile (S f ) and two cytoplasmic male sterile (CMS) lines were crossed in line × tester scheme, producing 24 F1 hybrids. The parents and the hybrids were evaluated for root yield and quality traits, from which F1 performance, combining abilities, mid-parent and high-parent heterosis were calculated. Parental genetic distance and diversity of the pollinators were estimated by SSR markers and, together with GCA and F1 performance, correlated with the heterosis effects. The S f hybrids had better GCA and higher values of root yield, root weight, and root circumference than the S s hybrids. Heterosis was recorded in more combinations with the S f than with the S s pollinators. Parameters of genetic diversity were higher in the S s (Na = 3.125; Ne = 2.341; He = 0.555) than in the S f pollinators (Na = 3.000; Ne = 2.188; He = 0.510). Genetic distance between the tested pollinators and the CMS lines was low (0.072–0.224) indicating that the genetic base of the investigated germplasm was narrow. Correlation of the heterosis effects with GD and heterozygosity was detected only for the root yield traits.

Genetic analysis of meat quality traits in maternal lines of rabbit and their diallel cross

Young rabbits, the dams of which came from a full diallel cross among four maternal lines (A, V, H and LP) and the sires from a single paternal line (R), that produce sixteen genetic groups, was carried out to evaluate the genetic groups and to estimate the crossbreeding genetic parameters of meat quality. The meat quality traits were recorded by NIRS from a sample of 285 longissimus lumborum muscles. Crossbreeding parameters were estimated according to Dickerson model. No differences in protein were found. The line A had significant differences with V line for intramuscular fat, and fatty acids groups. Significant differences for these traits appeared between the crossbred AH and VV (in favor of AH). As conclusion, the significant contrasts between genetic types for chemical composition of the meat are mainly consequence of direct-maternal genetic effects, having grandmaternal and maternal heterosis effects a less relevant role.

Preliminary analysis on hybrid vigor in Indonesian indigenous and crossbred cattle population using data from published studies

Hybrid vigor or heterosis is the phenomenon where a crossbreed progeny has better performance compared to its parents. Heterosis can be quantified relative to the mid-parents value or relative to one of its parent’s population average by crossing two breeds. Crossbreeding is aimed to increase the production performance of local breeds. According to the Indonesian government policy, crossbreeding program is one of main strategies to achieve meat self-sufficiency. We explore the possibilities observing of heterosis exhibited by crossing Bali and Peranakan Onggole (PO) cattle as local breed with the exotic breed based on the published data. In this paper, growth and reproductive traits from Bali and PO from year 2000-2010 were used for analysis. Moreover, Limousine and Simmental exotic breed data were collected from official information of artificial insemination (AI) centre. Data in growth trait (chest girth, mature weight, weaning weight and yearling weight) in all breeds and their crosses were then analysed using standard heterosis estimation method. Result, shows that crossbred offspring perform better in the growth trait in relative to Bali and PO as local breed. Specifically in Bali crossed with PO, the offspring shown better estimated heterosis effect in yearling weight compared to both parents. Despite heterosis were observed in some traits, careful planning of crossbreeding program is a must in order to avoid the loss of genetic variance.

104 Genetic, heterosis, and maternal effects on voluntary water consumption in mice

104 Genetic, heterosis, and maternal effects on voluntary water consumption in mice

Heterosis and Specific Combining Ability in Sweet Corn and Its Correlation with Genetic Similarity of Inbred Lines

The heterosis phenomena has been exploited in hybrid maize field production. Theoretically, heterosis was depending on genetic distance of inbred lines. Meanwhile, different from field corn breeding, sweet corn does not have well defined heterotic group. The objective of this study was to determine genetic similarity (GS) of eight selected inbred lines of sweet corn based on morphological traits and its correlation with specific combining ability (SCA) and heterosis. The eight inbred lines were characterized and crossed in full diallel design. Then, the lines, F1 and its reciprocal, were evaluated by using the Randomized Complete Block Design in three replications. The result showed positive heterosis and SCA effect in most of the hybrids which indicated the heterosis effect in the hybrids performance. Based on the morphological traits, the genetic similarity between the inbred lines was 62.2-82.4%. The inbred lines with 70% similarity coefficient were grouped into three. There was significant correlation between the genetic similarity and heterosis in all traits, except in the plant height. Meanwhile, only SCA of days to maturity and TSS showed significant correlation to genetic similarity. This indicated the usefullness of genetic similarity to identify the potential inbred lines for parental hybrid.

Genetic Causes of Phenotypic Adaptation to the Second Fermentation of Sparkling Wines in Saccharomyces cerevisiae.

Hybridization is known to improve complex traits due to heterosis and phenotypic robustness. However, these phenomena have been rarely explained at the molecular level. Here, the genetic determinism of Saccharomyces cerevisiae fermentation performance was investigated using a QTL mapping approach on an F1-progeny population. Three main QTL were detected, with positive alleles coming from both parental strains. The heterosis effect found in the hybrid was partially explained by three loci showing pseudooverdominance and dominance effects. The molecular dissection of those QTL revealed that the adaptation to second fermentation is related to pH, lipid, or osmotic regulation. Our results suggest that the stressful conditions of second fermentation have driven the selection of rare genetic variants adapted to maintain yeast cell homeostasis and, in particular, to low pH conditions.

Heterosis and combining ability of seven maize germplasm populations

Understanding the combining ability and heterosis of available germplasm is a prerequisite for successful maize improvement and breeding. The objectives of this study were to analyze the combining ability and heterosis of seven representative maize germplasm populations, and further, to evaluate their potential utility in germplasm improvement. A total of 21 crosses were made among these seven populations in a complete diallel without reciprocals. The parental populations and 21 crosses were evaluated for days to silking (DS), ear height (EH), and grain yield (GY) in the Northeast and Yellow and Huai River maize growing areas in China in 2012. Csyn5, Csyn7, Cpop.11, and Cpop.12 had desirable general combining ability (GCA) effects for DS and EH in both the Northeast China mega-environment (NCM) and the Yellow and Huai River Regions of China mega-environment (YHCM). Cpop.11 possessed a favorable GCA effect for GY in the NCM, as did Csyn5, Cpop.17, and Cpop.18 in the YHCM. Csyn6 and Csyn7 exhibited tremendous yield-enhancing potential in both mega-environments. Additionally, six combinations including Csyn7 × Csyn6, Csyn5 × Csyn6, Cpop.11 × Cpop.18, Cpop.12 × Cpop.17, Csyn7 × Cpop.17, and Csyn5 × Csyn7 exhibited better specific combining ability effects for GY, yield performance, and mid-parent heterosis in the appropriate mega-environment. These results indicated that the seven populations would be very useful for the improvement of related agronomic traits, and the six candidate combinations possessed great potential for further improvement and utilization.

Genomic prediction of breed composition and heterosis effects in Angus, Charolais and Hereford crosses using 50K genotypes

This study examined the feasibility and accuracy of using Illumina BovineSNP50 genotypes to estimate individual cattle breed composition and heterosis relative to estimate from pedigree. First, ped...

Diallel and prediction (REML/BLUP) for yield components in intervarietal maize hybrids.

Genetic improvement is essential to achieve increments in maize (Zea mays L.) grain yield components. It may be obtained through crosses, which enable to exploit the effects of intervarietal heterosis, allelic complementarity, as well as gene actions and effects. This study estimated the components of variance and genetic parameters (REML/BLUP) of an intervarietal diallel to select and predict the best genotypes for maize yield components. The experimental design was randomized blocks containing 60 intervarietal maize hybrids arranged in three repetitions. They were obtained through intervarietal crosses and evaluated in a diallel scheme, where 14 open-pollinated varieties were designated as parentals. Thus, 10 crosses were performed for each hybrid combination to obtain the number of seeds necessary for the competition test. The measured traits were: grain volume relative index, the mass of one hundred grains, and grain yield. The male parents and the additive genetic fraction were determinants for grain volume relative index. Mass of one hundred grains and grain yield were defined by the specific combining ability, and female parents revealed low narrow sense heritability. The female parent Taquarão and male parent Argentino Amarelo presented the best general combining abilities for the measured traits. The specific combining abilities were expressed for crosses AL 25 x Dente de Ouro Roxo, AL 25 x BRS Pampeano, and Taquarão x Argentino Branco. Genetic estimates and predictions were consistent and applicable to breeding programs and could be applied in future quantitative genetic studies of maize.

Evaluation of Rambouillet, Polypay, and Romanov-White Dorper × Rambouillet ewes mated to terminal sires in an extensive rangeland production system: Lamb production.

Ewe productivity (i.e., total number or weight of lambs weaned per breeding ewe) is a key indicator of lamb production efficiency. This study compared various measures of ewe productivity and ewe and lamb performance among ewes of 3 breed types mated to rams of 4 terminal-sire breed types in an extensive rangeland production system. Purebred Rambouillet ( = 212), purebred Polypay ( = 236), and crossbred Romanov-White Dorper × Rambouillet (RW-RA; = 231) ewes were produced from locally adapted Polypay and Rambouillet ewes and then annually mated to Columbia, Suffolk, Columbia × Suffolk, or Suffolk × Columbia sires for up to 4 yr, beginning at 1 yr of age. The cumulative number and weight of lambs weaned through 4 yr were greater for RW-RA (5.9 lambs and 153 kg, respectively) and Polypay ewes (4.9 lambs and 123 kg, respectively) than for Rambouillet ewes (2.9 lambs and 99 kg, respectively) and also were greater for RW-RA ewes than for Polypay ewes (all < 0.001). Greater productivity of RW-RA and Polypay ewes, compared with Rambouillet ewes, was driven by greater lambing rates (ewes lambing per ewe exposed) as ewe lambs (87 and 77 vs. 31%, respectively; < 0.001) and greater ( < 0.001) litter sizes as ewe lambs (1.3, 1.3, and 1.0, respectively) and adult ewes (2.1, 2.0, and 1.6, respectively). The RW-RA ewes also had greater longevity ( < 0.01) and cumulative lambing rates ( < 0.001) than Polypay and Rambouillet ewes. Lamb BW at birth and weaning in adult ewes favored less-prolific Rambouillet ewes ( < 0.001), but after adjustment for type of birth and rearing and weaning age, differences in weaning BW among ewe breed types were small and not significant ( = 0.08). Effects of sire breed type on measures of cumulative ewe productivity were not significant ( > 0.74), but Suffolk-sired lambs had the heaviest adjusted birth weights ( = 0.01) and Columbia-sired lambs tended to have the lightest adjusted weaning weights ( = 0.12). Combined effects of heterosis and additive breed effects were associated with greater lambing rates in ewe lambs, larger litters at all ages, and substantially greater number and weight of lambs weaned for Polypay and RW-RA ewes than for Rambouillet ewes.

Variability of morphometrical characteristics of needles at a clonal plantation of plus trees of scots pine (Pinus sylvestris L.)

The formation of plus trees assortment for seed orchards is one of the most difficult problems of contemporary forest breeding. This problem is related to the risk of inbreeding depression of the seed progeny of plus trees, which do not have any defense mechanism against self-pollination. Economically, the Scots pine is one of the most important wood species. Diverse characteristics of its needles make a subject for multidisciplinary research. Needle size is accepted as an indirect indicator of growth pine energy. Our research was focused on selection valuation of Scots pine plus trees by morphometric features of needles. Plus trees are represented by their clones in first-order seed orchards in the Nizhny Novgorod region. When collecting the source material, the elimination of differentiating effects of environmental factors and time factors was ensured. The dissimilarity of plus trees at a wide range of signs was manifested to different degrees. Because the heterogeneity of the assortment composition of the seed orchard in question was formed against the background of the aligned environmental conditions, there was every reason to consider it as being caused largely by hereditary factors. It was confirmed by the results of ANOVA. The predominant influence of distinctions between ortets was established. The influence of distinctions between the ramets was revealed – that was comparable to the residual variance. Pronounced heterogeneity of the composition and its genetic determinism set up conditions for effective multivariate comparisons of plus trees. Factor analysis formed its integrated independent variables from a common set of morphological parameters of needles. They are used in cluster analysis along with the original signs. Cluster analysis revealed in the seed orchards plus trees that are to the greatest extent different from the others. They can be combined with all the other plus trees in cross-breeding schemes to achieve the heterosis effect and to eliminate the risk of inbreeding depression.

Inheritance of economically valuable features in F1 hybrids of vegetable haricot bean

The aim and tasks of the study were to investigate peculiarities of inheritance of economically valuable features in intervarietal hybrids of F1 vegetable haricot bean.Material and methods. The study was conducted in 2014. The test material was 9 simple F1 hybrids. Hybrids were grown by the conventional technology for the Forest-Steppe zone. To calculate heterosis and dominance degree, formulae suggested by Chr. DaskalevandB. Griffing were used.Results and discussion. The article presents results of studying the peculiarities of inheritance of economically valuable features in intervarietal hybrids of F1 vegetable haricot bean. We identified varieties that are valuable as components for hybridization investigated some features of inheritance of economically valuable features in F1 hybrids. The study also elucidated that the growing season and its interphase period lengthsby F1 hybrids were inhe3rited via all types ofdominance, however, cross combinations with intermediate inheritance, positive dominance and overdominance prevailed. Inheritance of the lowest pod attachment height above the soil surface included all transitions from positive overdominance to intermediate inheritance. Overdominance prevailed in inheritance of productivity traits, such as "pod number per plant", "seed number per pod", "1000-seed weight", "seed number per plant", "seed weight per plant," in F1 plants.Conclusions. The study showed that the heterosis effect was the highest in F1 intervarietal haricot bean hybrids for the following productivity components: "seed number per pod", “seed and pod numbers per plant” and “seed weight per plant”

Identification of heterotic loci associated with grain yield and its components using two CSSL test populations in maize.

Heterosis has widely been used to increase grain yield and quality. In this study, the genetic basis of heterosis on grain yield and its main components in maize were examined over 2 years in two locations in two test populations constructed from a set of 184 chromosome segment substitution lines (CSSLs) and two inbred lines (Zheng58 and Xun9058). Of the 169 heterotic loci (HL) associated with grain yield and its five components identified in CSSL × Zheng58 and CSSL × Xun9058 test populations, only 25 HL were detected in both populations. The comparison of quantitative trait loci (QTLs) detected in the CSSL population with HL detected in the two test populations revealed that only 15.46% and 17.35% of the HL in the given populations respectively, shared the same chromosomal regions as that of the corresponding QTLs and showed dominant effects as well as pleiotropism with additive and dominant effects. In addition, most of the HL (74.23% and 74.49%) had overdominant effects. These results suggest that overdominance is the main contributor to the effects of heterosis on grain yield and its components in maize, and different HL are associated with heterosis for different traits in different hybrids.

Retrotransposon-related genetic distance among inbred lines of sweet corn (Zea mays var. saccharata) and hybrid performance

AbstractHeterosis is a main force underlying the hybrid seed industry in maize. Our experimental approach consists of a correlation study between retrotransposon-related genetic distances between parental inbred lines and hybrid performance. The assumption is that, at least for certain traits, heterosis results from genome rearrangements, largely related to retrotransposon insertions and/or removals. Fifteen maize inbred lines and one F1 hybrid, representative of the genetic diversity among sweet corn and field corn lines were screened for polymorphism by retrotransposon microsatellite amplified polymorphism markers. DNA fingerprints served as row data for estimating genetic diversity of maize inbred lines and its correlation with the heterotic effect in their hybrids. A correlation between phenotypic and molecular distances was evident only at the level of individual inbred lines. Weak correlation between genetic distances and heterosis effect was observed for the average of all inbred lines. Phenotypic distances negatively correlated with heterosis for insertion height, diameter of the ear and number of kernel rows per ear. The relative contribution of each inbred line to heterosis in its derived hybrids was also estimated. Accordingly, we identified inbred lines with increased genetic distances that mostly add to the heterosis effect in their hybrids and that we recommend as prospective to be used in maize breeding programmes.