Heterosis Effects Research Articles

Genomic retained heterosis effects on fertility and lifetime productivity in beef heifers

This study evaluated the effects of three genomic indicators of heterosis on female fertility and lifetime productivity, and quantified changes over 11 production cycles in a crossbred cow herd. Pedigree-based breed composition (pBC) was determined and used to calculate retained heterozygosity for 412 replacement heifers born from 2004 to 2014 at the Lacombe Research and Development Centre (AB, Canada). Heifers were followed as cows over 1050 mating opportunities, 11 production cycles, and five parities. Heifers and their sires (51) were genotyped and these genotypes were used to predict each animal’s genomic breed composition (gBC) and three genomic indicators of heterosis: (1) retained heterozygosity (RHETg), (2) heterozygous proportion (H), and (3) retained heterosis (RHg). Correlations between pedigree and genomic breed fractions for Angus, Hereford, and Charolais were high (rp = 0.74–0.94; P < 0.001). Genomic indicators of heterosis were highly related (rp = 0.61 for RHETg vs. H; 0.71 for RHg vs. H; 0.96 for RHETg vs. RHg; P < 0.001). Each 10% change in RHETg resulted in 51 ± 20 d longer survival (P = 0.011) in the herd and 35.7 ± 15.2 kg more (P = 0.019) calf wean weight per cow exposed to breeding when summed over five parities. These differences resulted in an extra $161 per heifer in a year. Optimizing heterosis using genomic tools can be very beneficial for the cow herd if applied correctly.

Keragaman Genetik Klon Kakao Lokal Sulawesi Tenggara Berdasarkan Marka SSR dan Karakter Morfologi

<em>Molecular and morphological characterization of cacao clones obtained from exploration in Southeast Sulawesi is very important to know their superiority and genetic relationships. Analysis of genetic diversity using molecular markers is also useful for detecting duplication found among collected clones. The research aimed to determine the genetic diversity of local cacao clones derived from Southeast Sulawesi based on SSR markers and morphological characters. The research was conducted at Cacao Research Sub-Station, Lebojaya Village, Konda Subdistrict, South Konawe Regency, Southeast Sulawesi, and Integrated Laboratory of Indonesian Industrial and Beverage Crops Research Institute Sukabumi, and Molecular Biology Laboratory of Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development Bogor, from April to November 2015. Genetic diversity analysis was performed on 21 cacao clones covering 19 local clones and 2 national varieties using 22 SSR markers. The molecular characterization results showed that 11 markers are polymorphic, and subsequently used to group cacao clones using NTSYS program. The grouping results divided the cacao clones into 4 main groups at 0.46 genetic similarity values. Based on genetic distance values >0.7, 8 combinations of cacao clones can be selected as parental clones with the expectation to increase the effect of heterosis on progeny. On the other hand, result of morphological characterization generally indicated the diversity between the four cacao groups. Based on molecular and morphological characterization, it can be seen that cacao clones derived from Southeast Sulawesi have a high diversity and can be utilized in the development program of new improved varieties.</em>

Акселерация лабораторных крыс: синтетическое Исследование данных за столетие в аспекте возможной связи с радиочувствительностью

Purpose: A synthetic study of published data on the growth and development of laboratory rats (albino random-bred, Wistar and Long–Evans) depending on the period of their breeding since 1906 was carried out. Material and methods: Data for the dynamics of growth and age periods of rats were used for calculations and general analysis. Results: Acceleration in terms of age–weight indices for strain animals was found: in conditions of complete diets ad libitum the contemporary rats grew several times faster than the bred ones of 1906–1932. For random-bred rats only the tendency to acceleration was obtained. For more than a century, the Wistar males showed an inverse linear correlation between the breeding year and the age (in weeks) at the of the onset of puberty period (according to the Spearman test: r = –0.952; p = 0.00026; Pearson’s criterion: r = –0.950, p = 0.0003). There was also a direct correlation between the body mass of rats at the time of puberty onset and the year of their breeding (according to the Spearman test: r = 0.975; p = 0.005; Pearson criterion: r = 0.927; p = 0.023). The possible reasons for the acceleration of laboratory growth of rats, which are unlikely to be analogous to the factors presumably causing the known ‘growth acceleration’ in humans (changes in natural and artificial lighting, the effect of heterosis, improvement of socio-hygienic conditions, the growth of information flow, warming of the climate, change in the geomagnetic or radiation background, etc.) were discussed. Apparently, in addition to the probability of special and/or subconscious selection during century, the stimulation of rat acceleration may be explained by the ‘increase in living space and resources’ due to improved standards for keeping animals in the modern period (fewer animals in the cage or even an individual cage). In random-bred animals such standards can be apply for economic reasons to a lesser extent. Conclusions: It is concluded that the physiological, anatomical, possibly behavioral and other standards and patterns for strain rats, including, possibly, its radiosensitivity, published even 30 years ago, and especially more than 50 years ago, should be cautiously transferred to the animals grown under present-day conditions.

Закріплення гетерозису серед нащадків у Arabidopsis Thaliana (L.) Heynh. та інших самозапильних рослин

An important task of plant breeding is to develop methods of fixing heterosis in the second and subsequent generations. In many cross-pollination crops, in particular sunflower, corn, have to lead complex seed production. For self-pollinating plants of wheat, barley, oats, the use of the effect of heterosis is limited to a low percentage of tying of grains, a weak seed multiplication factor. The solution of the problem of preserving heterosis in plants in a number of generations would make it possible to simplify and reduce the cost of practical use in plant growing. Success in addressing the issue of fixing the effect of heterosis is the use of Arabidopsis thaliana (L.) Heynh. as a model plant. Studies on model objects are always considered to be advanced. They allow us to develop new genetic approaches that can later be used at other sites. The aim of the present study was to study the possibility of the emergence and fixation of heterosis in subsequent generations in self-pollinating plants by crossing the races of Col-O and La-0 Arabidopsis thalian a. The material for research was the plants Arabidopsis thaliana ecotype (race) Columbia (Col-O) and Landsberg (La-0). The plants were grown in a soil culture laboratory in a mixture of soil, sand and peat in a ratio of 4: 2: 1. Castration and forced hybridization were carried out under a microscope. Genetic analysis of plant inheritance was carried out in F1, F2. When crossing plants of different races, Col-0 and La-0, hybrids of the first generation showed somatic heterosis, which manifested itself in a more powerful development of the rosette of leaves compared to the original forms. In the second generation there was a process of splitting hybrids, and their superiority in diameter of the rosette of leaves over the parental forms was reduced. This is due to a decrease in the heterozygosity of plants in the F2 generation. In the cross examined, a stronger development of the diameter of the rosette of leaves is associated with the action of two pairs of polymer genes. To repeat the heterosis in self-pollinating plants in subsequent generations, without resorting to complex seed production and a system of recurrent, stepwise crossings, it is possible with the help of an analyzing crossing when crossing a dominant homozygote with a recessive homozygous of F 2 hybrids (AABB × aab → AB). Through the fact that the maternal form was the dominant homozygote, the phenotype does not split. In this case, in self-pollinating plants, it is possible to fix heterosis in subsequent generations when selecting such genotypes in F 2 with an extreme degree of expression of sign. In order to identify these genotypes in F 2 plants, it is possible, using the halves method, to conduct analyzing crosses with a recessive homozygote on the basis of heterosis. The use of analyzing crosses and the halves method with single individual selection in self-pollinating plants makes it possible to speed up the selection process by shortening the time for multiple inspection by progeny of selected individual plants, related to the phenomenon of splitting in generations of selected elite forms. In the case of a polymer in self-pollinators in the second generation, a transgression phenomenon is often observed. Transgressive variability, which usually appears in hybrids of the second generation, can be considered one of the forms of heterosis in self-pollinating plants. In this case, F2 plants have stable genotypes (dominant or recessive homozygotes), combining polymeric genes of additive action, causing the extreme manifestation of an economically valuable trait, in the selection of which in the future, it is possible to obtain a new variety whose yield exceeds the parent pairs by 20 -40%. Key words: Arabidopsis thaliana (L.) Heynh, heterosis, gene, mutation, race

Assessment of Genetical Parameters of Yield and its Attributes in Bread Wheat (Triticum aestivum, L.)

The experiment was performed at the Experimental Farm of Agronomy Department , Faculty of Agric. Al-Azhar Univ. Naser City, Cairo, Egypt during the two following growing seasons 2016/2017 and 2017/2018. Eight parents of bread wheat (Triticum aestivum , L.) illustrate a wide range of diversity for some agronomic traits were selected for the study namely; Gemmiza 11, Giza 168, Sids 14, Masr 2, Sids 12, Sakha 95, Masr 1 and Sakha 94 were crossed at 2016/2017 growing season in one direction diallel cross . The genetic analysis (variance, combining ability, heterosis, and type of gene actions) of grain yield / plant and some related traits were evaluated at 2017/2018. Results indicated that variances of genotypes, parents and crosses were highly significant for all evaluated traits. The variances connected to general and specific combining abilities were established be highly significant for all evaluated traits, except number of kernels /spike for GCA .The estimates of GCA/SCA were less than unity recommended the greater amount of non- additive gene actions in determining the performance of all traits. The crosses (P1xP2), (P2xP6); (P3xP5), (P3xP6) and (P5xP6) recorded greatest mean values for grain yield/plant.P6 and P8 were considered as the best general combiners for grain yield /plant . The best crosses for SCA and heterosis effect for grain yield / plant recorded for P1xP2, P3xP8 and P5xP6 where be revealed highly significant and positive SCA and high percent heterosis making them hybrid promising in breeding programs for crop improvement . Hayman and Morley –Jones testing showed that the ratio of (H1/D)1/2 is larger than one for all the studied traits, so over dominance is participating in the genetic of these traits .Estimates of percentage of negative and positive genes (H2/4H1) in the parents ranged from 0.18 for plant height to 0.23 for number of kernels /spike and grain yield /plant hence, negative and positive alleles are consistent distributed in this traits. Heritability in broad-sense were high values detected for all the studied traits, indicated that these traits are more genetic, while narrow sense heritability were low for no. of spikes/plant, spike length and grain yield / plant , so the role of additive part is low. Significant differences were observe for additive (a) effect for all the studied traits in Morley Jones method, Also , dominance (b) part was significant for all the studied traits, appropriately these traits are controlled by both dominance and additive type of gene actions. As (b2) and (b3) were highly significant for all the studied traits, thus epistasis is participating in their genetics. As the part(b1) was significant for all the evaluated traits, with the exception of plant height and 1000-kernel weight, so dominance genes were attributable to directional dominance. Significant (b2) part for all traits showing imbalance of gene giving out for these traits. Significant (b3) part for all traits showed residual dominance effect (b3) outcome from additive × additive, additive × dominance and dominance × dominance interactions .

English

For the estimation of genetic parameters (such as heterosis effect, potence ratio, combining ability and reciprocal effects) of five fruit traits, in order to suggest breeding strategies in Citrullus mucosospermus (Fursa), a field trial was carried out at Kononfla city in Western Cote d’Ivoire using 4x4 full diallel. All 12 F1 hybrids and their parents were planted in a randomized complete block design with three replications. A positive heterosis effect relative to mid-parental values was observed to hybrids having one parent Bebu for characters’ fruit weight, fruit diameter and fruit volume. Variances due to general (GCA) and specific (SCA) combining abilities were significant (PE‚0.001) for all studied traits, indicating the involvement of both additive and non-additive gene actions in the inheritance of these traits. Non-additive gene effects were predominant for all studied traits. Bebu was the best general combiner for all traits except fruit number which the best combiners were three morphotypes of Wss. For NF, Wss1×Wss2 and Wss2×Wss3 recorded the highest positive SCA values. Crosses involving Bebu as one parent, presented the best SCA values for other traits. Key words: Bebu, Wlewle small seeds, heterosis, potence ratio, combining ability.

Heterosis in the components of lactation curves of Girolando cows

The objective of this study was to evaluate the effect of heterosis on the lactation curve components of Girolando cattle obtained by fitting different mathematical models. Data consisted of 258,891 test day milk yield records of the first lactation from 37,965 cows of Minas Gerais State (Brazil) between 1998 and 2014. Those cows were from the Holstein breed (H), Gyr breed (G) and six genetic cross-breedings of Holstein × Gyr, (1/4H, 3/4G (1/4H); 3/8H, 5/8G (3/8H); 1/2H, 1/2G (1/2H), 5/8H, 3/8G (5/8H); 3/4H, 1/4G (3/4H); 7/8H, 1/8G (7/8H)), which is officially named as Girolando breed in Brazil. The Wood’s linear model (WDlin), Wood’s non-linear model (WDnlin), Wilmink’s model (WL) and Ali and Schaeffer’s model (ASH) were used for estimating the peak milk yield (PY), time to peak yield (PT), 305-day milk yield (TMY) and four different persistency measures (P, P2:1, P3:1 and P3:2). Regardless of the fitted model, the highest estimates of PY and TMY were for the H group. The heterosis effect was significant (p < .001) for TMY and all components of the lactation curve, except for P2:1. Girolando cattle presented a heterosis effect of 12.30% and 13.03% for PY and TMY, respectively. The magnitude of heterosis effect was larger for PT (24.18%), whereas the different persistency measures presented the smallest magnitude of heterosis values. The producers may use the different genetic groups to benefit from the heterosis mainly for the time to peak, peak yield and 305-day milk yield.HIGHLIGHTS• Girolando cows in production systems in Brazil has shown positive results. • The greater productive efficiency may be because of heterosis on the production.• Thus effect of heterosis on lactation curve can contribute to the improvement of the production system.

Additive genetic and heterosis effects for milk fever in a population of Jersey, Holstein × Jersey, and Holstein cattle under grazing conditions

The aim of this study was to estimate additive genetic and heterosis effects for milk fever (MF) in Costa Rican dairy cattle. A farm-based management information software was used to collect 223,783 parity records between years 1989 and 2016, from 64,008 cows, 2 breeds (Jersey, Holstein × Jersey crosses, and Holstein), and 134 herds. The pedigree file comprised 73,653 animals distributed across 10 generations. A total of 4,355 (1.95%) clinical cases of MF were reported within this population, affecting 3,469 (5.42%) cows. Data were analyzed using 2 animal models, both accounting for repeatability and assuming different distributions for MF event: normal (linear model) or binomial (threshold model). The models included parity as fixed effect, breed and heterosis as fixed regressions, and herd-year-season, additive genetic, and permanent environment as random effects. The models were fit using a generalized linear mixed model approach, as implemented in ASReml 4.0 software. We noted significant regression on the percentage of Holstein breed, depicting a -0.0086% [standard error (SE) = 0.0012] decrease in MF incidence for each 1-unit increase in percentage of Holstein breed. A favorable heterosis of 5.9% for MF was found, although this was not statistically significant. Heritability and repeatability were, respectively, 0.03 (SE = 0.002) and 0.05 (SE = 0.002) for the linear model, and 0.07 (SE = 0.007) and 0.07 (SE = 0.007) for the threshold model. The correlation between BLUP (all animals in pedigree) for linear and threshold models, was 0.89. The average accuracy of the estimated BLUP for all animals were 0.44 (standard deviation = 0.13) for the linear model and 0.29 (standard deviation = 0.14) for the threshold model. Heritability and repeatability for MF within this population was low, though significant.

USE OF HETEROSIS IN THE SELECTION OF TOMATO ON SPEED

The research was carried out at the Surkhandarya Scientific Experimental Station of the Vegetable-Melon Plant and Potato Research Institute in 2013-2015.mThe aim of the research was to evaluate F1 hybrids and their parental forms by early maturity and to identify the most promising combinations in the conditions of southern Uzbekistan. The studies are devoted to the selection of the parental forms of tomato of different maturation period and the creation on their basis of F1 tomato hybrids and their evaluation on a set of economically valuable traits, primarily on early maturity. The total yield was highest for Dar Zavolzhye, Chelnok, Persey, Utro-2, Slava Moldova, Gruntoviy Gribovskiy 1180, Lyana (51.4-64.4 t/ha) and F1 hybrids: Ion-N x Persey, Novichok x Persey, Dar Zavolzhye x Slava Moldovy, VIR-100 x Perseus, Gruntoviy Gribovsky 1180 x Liyana, Lyana x Persey, Novichok x Slava Moldova, (76,2-90,8 t/ha). High early yield properties are distinguished in the samples of Ion-N, Lyana, Gruntovy Gribovsky 1180, Utro -2, VIR-100, Dar Zavolzhye (21.7-30.5 t/ha) and hybrid combinations Ion-N x Persey, Novichok x Persey, VIR-100 x Persey, Dar Zavolzhye x Slava Moldovy, Gruntoviy Gribovsky 1180 x Lyana, Lyana x Ion-N, the productivity of which for the first three harvest is 25.8-34.2 t/ha. The high effect of heterosis on the overall yield was noted in combinations of Novichok x Persey, Ion-N x Persey, VIR-100 x Persey, Argo x Slava Moldovy, Lyana x Persey, Dar Zavolzhye x Slava Moldovy, Novichok x Slava Moldovy. The above hybrids exceeded the most productive parent by 21.6-33.6 t / ha. The effect of heterosis was 39.6-64.0%. A high effect of heterosis (from 107.5 to 161.2%) on early yield was noted in combinations of Novichok x Persey, Ion-N x Persey, Dar Zavolzhye x Slava Moldovy, Dar Zavolzhye x Novichok, Lyana x Ion-N. Ion-N, VIR-100, Argo, Lyana, and the Slava Moldovy are distinguished according to this important indicator of the maturity of ripening. Only three combinations of Ion-H x Persey, Ion-N x VIR-100, Lyana x IonN, with the maturity of fruit ripening 43-54%.

Is Longevity a Heritable Trait? Evidence for Non-genomic Influence from an Extended Longevity Phenotype of Drosophila melanogaster.

Although genetic variations are heritable, some quantitative traits like longevity may have non-genomic influence on heritability. Laboratory-selected inbred strains of extended longevity phenotype of Drosophila offer an opportunity to study the inheritance of longevity. The aim of the study was to examine the heritability of longevity in an extended longevity phenotype of Drosophila melanogaster using reciprocal cross effects in F1 and F2 generations. Lifespan variations of virgin and mated flies in parent, F1 and F2 generations were investigated using reciprocal crosses between normal and long lifespan lines of inbred population of D. melanogaster. Heterosis, narrow-sense heritability, recombination loss, maternal effect and overdominance with respect to survivorship in virgin and mated flies were analyzed. Virgin flies lived longer than mated flies. There was no significant effect of mid-parent heterosis, recombination loss and overdominance on variations in longevity, whereas, significant maternal effect and narrow-sense heritability were observed in mated and virgin flies, respectively. Absence of heterosis in our study population of Drosophila phenotypes could be due to the lack of genetic heterogeneity. The heritability of the longevity trait in an inbred extended longevity phenotype depends on the variations in genetic and environmental factors.

Phenotypic Data from Inbred Parents Can Improve Genomic Prediction in Pearl Millet Hybrids.

Pearl millet is a non-model grain and fodder crop adapted to extremely hot and dry environments globally. In India, a great deal of public and private sectors’ investment has focused on developing pearl millet single cross hybrids based on the cytoplasmic-genetic male sterility (CMS) system, while in Africa most pearl millet production relies on open pollinated varieties. Pearl millet lines were phenotyped for both the inbred parents and hybrids stage. Many breeding efforts focus on phenotypic selection of inbred parents to generate improved parental lines and hybrids. This study evaluated two genotyping techniques and four genomic selection schemes in pearl millet. Despite the fact that 6× more sequencing data were generated per sample for RAD-seq than for tGBS, tGBS yielded more than 2× as many informative SNPs (defined as those having MAF > 0.05) than RAD-seq. A genomic prediction scheme utilizing only data from hybrids generated prediction accuracies (median) ranging from 0.73-0.74 (1000-grain weight), 0.87-0.89 (days to flowering time), 0.48-0.51 (grain yield) and 0.72-0.73 (plant height). For traits with little to no heterosis, hybrid only and hybrid/inbred prediction schemes performed almost equivalently. For traits with significant mid-parent heterosis, the direct inclusion of phenotypic data from inbred lines significantly (P < 0.05) reduced prediction accuracy when all lines were analyzed together. However, when inbreds and hybrid trait values were both scored relative to the mean trait values for the respective populations, the inclusion of inbred phenotypic datasets moderately improved genomic predictions of the hybrid genomic estimated breeding values. Here we show that modern approaches to genotyping by sequencing can enable genomic selection in pearl millet. While historical pearl millet breeding records include a wealth of phenotypic data from inbred lines, we demonstrate that the naive incorporation of this data into a hybrid breeding program can reduce prediction accuracy, while controlling for the effects of heterosis per se allowed inbred genotype and trait data to improve the accuracy of genomic estimated breeding values for pearl millet hybrids.

Modelling non-additive genetic effects using ridge regression for an Angus–Nellore crossbred population

Data from 294045 records from a crossbred Angus × Nellore population were used to estimate fixed genetic effects (both additive and non-additive) and to test different non-additive models using ridge regression. The traits studied included weaning gain (WG), postweaning gain (PG), phenotypic scores for weaning (WC) and postweaning (PC) conformation, weaning (WP) and postweaning (PP) precocity, weaning (WM) and postweaning (PM) muscling and scrotal circumference (SC). All models were compared using the likelihood-ratio test. The model including all fixed genetic effects (breed additive and complementarity, heterosis and epistatic loss non-additive effects, both direct and maternal) was the best option to analyse this crossbred population. For the complete model, all effects were statistically significant (P &amp;lt; 0.01) for weaning traits, except the direct breed additive effects for WP and WM; direct complementarity effect for WP, WM, PP and PM and maternal epistatic loss for PG. Direct breed additive effect was positive for weaning traits and negative for postweaning. Maternal breed additive effect was negative for SC and WP. Direct complementarity and heterosis were positive for all traits and maternal complementarity and heterosis were also positive for all traits, except for PG. Direct and maternal epistatic loss effects were negative for all traits. We conclude that the fixed genetic effects are mostly significant. Thus, it is important to include them in the model when evaluating crossbred animals, and the model that included breed additive effects, complementarity, heterosis and epistatic loss differed significantly from all reduced models, allowing to infer that it was the best model. The model with only breed additive and heterosis was parsimonious and could be used when the structure or amount of data does not allow the use of complete model.

Hybridity has a greater effect than paternal genome dosage on heterosis in sugar beet (Beta vulgaris)

BackgroundThe phenomenon of heterosis is critical to plant breeding and agricultural productivity. Heterosis occurs when F1 hybrid offspring display quantitative improvements in traits to levels that do not occur in the parents. Increasing the genome dosage (i.e. ploidy level) of F1 offspring can contribute to heterosis effects. Sugar beet (Beta vulgaris) provides a model for investigating the relative effects of genetic hybridity and genome dosage on heterosis. Sugar beet lines of different ploidy levels were crossed to generate diploid and triploid F1 offspring to investigate the effect of; (1) paternal genome dosage increase on F1 heterosis, and; (2) homozygous versus heterozygous tetraploid male parents on F1 triploid heterosis. A range of traits of agronomic and commercial importance were analyzed for the extent of heterosis effects observed in the F1 offspring.ResultsComparisons of parental lines to diploid (EA, EB) and triploid (EAA, EBB) F1 hybrids for total yield, root yield, and sugar yield indicated that there was no effect of paternal genome dosage increases on heterosis levels, indicating that hybridity is the main contributor to the heterosis levels observed. For all traits measured (apart from seed viability), F1 triploid hybrids derived from heterozygous tetraploid male parents displayed equivalent levels of heterosis as F1 triploid hybrids generated with homozygous tetraploid male parents, suggesting that heterosis gains in F1 triploids do not arise by simply increasing the extent of multi-locus heterozygosity in sugar beet F1 offspring.ConclusionsOverall, our study indicates that; (1) increasing the paternal genome dosage does not enhance heterosis in F1 hybrids, and; (2) increasing multi-locus heterozygosity using highly heterozygous paternal genomes to generate F1 triploid hybrids does not enhance heterosis. Our findings have implications for the design of future F1 hybrid improvement programs for sugar beet.

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

In standard laboratory conditions, inbred mouse strains with normal kidney function show a 4-fold range of daily water consumption. This study uses two strains of inbred mice identified as high and low consumers, their reciprocal F1 crosses, and inter se bred F2s. Daily consumption data were collected on 607 animals for 4 d during the 4th, 5th, and 6th wk using custom water bottles. Animals were weighed at the beginning of the 4th, 5th, 6th, and 7th wk. Consumption data were corrected for metabolic BW (Bwt0.67) prior to analysis, so units of water consumption are expressed in mL consumed per gram of Bwt0.67 per day. Variables BW and water consumption were fitted to a mixed model including the effects of sex, strain, and their interaction with sire within strain fitted as a random effect. Contrasts were designed to test the direct genetic, maternal genetic, individual heterosis, and maternal heterosis effects. An interaction (P < 0.0001) was observed between sex and strain so all analyses were conducted separately for each sex. C57Brown/CDJ animals (Brown) consumed more water than C57Black/10J animals (Black) (P < 0.0001). A maternal effect (P = 0.036, P = 0.029) was observed in males at the 4th and 5th wk as F1 animals with a Black dam (F1Black) consumed less than F1 animals with a Brown dam (F1Brown) males. No significant heterosis effect was observed for water consumption. For weight analysis, Black animals were significantly larger than Brown animals at 28 d (males P = 0.004, females P = 0.026), but no difference was observed the remainder of the trial. Further, F1Brown females were significantly smaller than F1Black females at 28 d (P < 0.0001) and F1Brown males tended to be smaller than F1Black males (P = 0.078). Animals from the reciprocal F1 crosses showed an increase in birth weight (P < 0.0001) over pure strains. These strains form the foundation stock of an experiment designed to isolate genes influencing water consumption by reciprocal backcrossing and selection.

Heterosis and combining ability studies for economic traits in garden pea (Pisum sativum L.)

A line × tester analysis comprising of 7 promising lines and three testers having wider genetic base was carried out for pod yield and related horticultural traits in garden pea (Pisum sativum L.) Among parents, line 17, line 14 and Palam Triloki were observed as best general combiners for pod yield and majority of component traits. Cross, line 17 x Arkel showed high heterosis and SCA effects for pod yield and related horticultural traits. The cross combination line 17 x Palam Triloki was most promising for early flowering and green pod picking. For most of the traits including pod yield per plant non-additive gene actions were of prime importance.

Live weight and growth of Holstein-Friesian, Jersey and crossbred dairy heifers in New Zealand

ABSTRACTThe objective of this study was to model the growth of dairy heifers to estimate the effects of breed and heterosis on live weight (LWT) and growth from three to 22 months of age. Data comprised of 1,653,214 LWT records obtained from 189,936 dairy heifers in 1547 herds. At all ages Holstein-Friesian (F) heifers were heavier than Holstein-Friesian–Jersey crossbred (F × J) which were heavier than Jersey (J) heifers. Heterosis effects for LWT were greatest at nine months of age (3.6%) and least at 22 months of age (2.0%). The growth pattern differed, as evidenced by the regression coefficients of the Legendre polynomial. Growth was non-linear and heterosis effects were different throughout the growth period. Friesian, J and F × J heifers exhibited different growth patterns. These differences in growth pattern should be considered when formulating target LWTs and growth rates for a pasture-based system.

Assessment of Ratooning Ability and Heterotic Effects for Yield and Yield Contributing Traits in Intraspecific Hybrids of Upland Cotton

The development of high yielding cotton hybrids is essential to meet the current cotton demands. On the other hand, the cotton ratooning allows to obtain maximum seed yields with early maturity of plant. Therefore, the present study was aimed to investigate the per se performance, ratooning ability and heterosis effects for yield and yield contributing traits in 28 novel hybrids through line x tester analysis by considering four varieties as lines and seven varieties as testers. Significant variability was observed for all investigated traits excluding the number of monopodial branches and boll weight traits in parents and their 28 hybrids. Among the parents, TSH 0499 and TSH 04/115 exhibited a fair performance for yield and yield contributing traits and SURABHI, TSH 0250 and VS 9-S11-1 expressed superior ratooning ability. Therefore, these parents have a potential to be exploited for the development of the efficient cotton hybrids. Among the tested F1 hybrids, TSH 0499 x TCH 1777, BGDS 1063 x TCH 1819, TSH 0499 x TCH 1819 and TSH 04/115 x SVPR 4 hybrids recorded superior performance for number of bolls, boll weight, lint index and seed cotton yield in first crop, respectively. The hybrids ARBC 19 x TSH 0250, TSH 0499 x SURABHI , TSH 0499 x TSH 0250 and TSH 0499 x TCH 1705-101 displayed good ratooning performance for number of bolls, boll weight, lint index and seed cotton yield, respectively. All the hybrids expressed a range of significantly positive and negative heterosis for tested traits. However, the observed negative heterosis for seed index is desirable since the hybrids produce more lint. The results of this study would give insights into the understanding of genetic variance present in the intra-hirsutum hybrids.

Study of Gene Action and Heterosis Effects of Different Genotypes for Yield and Yield Attributing Traits in Maize (Zea mays L.)

Study of Gene Action and Heterosis Effects of Different Genotypes for Yield and Yield Attributing Traits in Maize (Zea mays L.)

THE PECULIARITIES OF MILK QUALITATIVE CONTENT OF UKRAINIAN WHITEHEADED COWS

THE PECULIARITIES OF MILK QUALITATIVE CONTENT OF UKRAINIAN WHITEHEADED COWS

Elucidation of diversity among $$\hbox {F}_{1}$$ F 1 hybrids to examine heterosis and genetic inheritance for horticultural traits and ToLCV resistance in tomato

Genetic diversity during prebreeding or postbreeding programme, is the key pillar to characterize the valuable traits and gene of interest. Whereas, superior or inferior heterotic performance of F1 depend on the diverse nature of their pedigree. Therefore, the aim of this study was to see the diversity between the interspecific crosses and effect of heterosis, and inheritance for the morphological traits and ToLCV resistance. All the 24 F1 interspecific crosses were classified into four clusters on the basis of morphological traitsas well as simple sequence repeat (SSR) markers. Among the F1 hybrids, 23 were grouped into clusters II, III and IV with different phylogeny, while PBC×EC 521080 was individual with cluster I. On the basis of visual observation of fruit colour, deep red and green colours in the crosses of S. pimpinellifolium (EC 521080) and S. habrochaites (EC 520061) exhibited dominant effects. In context of heterosis breeding, the crosses which were made using Solanum pimpinellifolium (EC 521080), S. chmielewskii (EC 520049) and S.cerasiforme (EC 528372) were better for yield capacity and the crosses of S. habrochaites (EC 520061) exhibited low and negative heterosis for ToLCV resistance. The F1 progenies were segregated in various Mendelian ratio as follows 3:1, 1:2:1, 1:3, 13:3, 15:1, 12:3:1 and 9:6:1 for ToLCV disease reaction of incidence, plant growth habit and fruit colour appearance, respectively. Therefore, these interspecific crosses can be utilized for developing high yield, impressive fruit colour combiners and resistant hybrids/varieties of tomato.