F1 Heterosis Research Articles

Genetic divergence study in greengram [Vigna radiata (L.) Wilczek

The present investigation was undertaken to obtain information on the nature and extent of genetic diversity among 60 greengram genotypes for yield related traits and quality traits by using Mahalanobis’s D2 statistics.  The genotypes were grouped into eleven clusters. Cluster I was found to be the largest  with 38 genotypes followed by cluster V with 13 genotypes and all the other clusters were found to be solitary, each containing a single genotype. Clusters VIII and XI had the maximum inter-cluster distance, followed by clusters IV and XI. Cluster XI had the highest mean values for yield and other yield attributing traits. Iron content contributed high towards total genetic diversity followed by protein content and test weight. Based on the mean performance and diversity studies, the genotypes COGG 18-17, LGG 460, Daftri vikas and IPM 1603-3 were found to be the best for further yield improvement in greengram. Utilizing the genotypes from the more divergent clusters as parents in breeding programmes will yield relatively good amount of heterosis in F1 and high frequency of transgressive segregants and genetic variability in subsequent generations can be acquired. Keywords: D2 statistic, Cluster analysis, Genetic Divergence, Greengram, Tocher’s method.

RESEARCH ON THE BEHAVIOR OF SOME SUNFLOWER CULTIVATIONS IN THE SPECIFIC CONDITIONS OF THE NORTH AREA OF OLT COUNTY

The sunflower, unlike other phytotechnical plants, tolerates drought much better, this is primarily due to the better developed root system with a high capacity to absorb and solubilize water and nutrients from the soil, for a longer period of time, its ability to reduce evapotranspiration and, respectively, the possibility of a rapid return of the leaves to the state of turgor, but the production decreases proportionally to the intensity and duration of these processes. To achieve high performance, sunflower cultivars must have stable F1 heterosis, high seed oil content, high production capacity, short growing season, uniformity in average plant height, high resistance to agents pathogens. In the ecopedological conditions of the Bărăşti - Olt area, on a preluvosol type soil, research was carried out on a number of 6 hybrids: Favorit, Performer, Venus, Saturn, Alex, Vera, the production results highlighting their different adaptation to specific culture conditions. The highest yields were recorded for the Performer hybrid -3935 kg/ha and the Venus hybrid -3786 kg/ha. All hybrids achieved productions above 3000 kg/ha.

Assessment of cold resistance in <i>Momordica charantia</i> l. accessions according to pollen germination at low temperatures <i>in vitro</i>

Background. Bitter melon (Momordica charantia L.) is a vegetable and medicinal crop new for Russia. Its high heat demand is the main factor limiting the possibilities of its cultivation in a temperate continental climate. Evaluation and selection of more cold-resistant accessions is required for breeding new cultivars and expanding production. Previously obtained data attest to a possibility of assessing cold hardiness in the mature male gametophyte phase in vitro.Materials and methods. Eight bitter melon accessions, including parent forms, F hybrids and cv. ‘Gosha’, were grown in the unheated film greenhouse of the Central Siberian Botanical Garden, Novosibirsk (54°49’ N, 83°06’ E) for evaluation and selection for cold resistance. The ratio of pollen germination in vitro on a 15% polyethylene glycol solution with a molecular weight of 6000 (PEG 6000) with the addition of boric acid (0.006%) at a temperature of 10°C for 24 h to the same indicator at 25°C / 3 h (in %) was used as a criterion of cold resistance.Results. The cultivar ‘Gosha’, the accession Okinawa green from Japan, and the F1 hybrid (Feng Guang × Okinawa green) had the highest cold resistance, with the values of 59.7; 53.8 and 48.2%, respectively. The inheritance of cold resistance in F , assessed by the pollen germination index, depending on the crossing combination, changed from intermediate in two hybrids [F1 Feng Guang × Gosha) and F1 Feng Guang × Okinawa green)] to overdominant (positive heterosis) in the hybrid F1 (Feng Guang × Okinawa white).

Comparative performance of hybrid generations reveals the potential application of F2 hybrids in upland cotton

BackgroundThe utilization of heterosis has greatly improved the productivity of cotton worldwide. However, a major constraint for the large-scale promotion of F1 hybrid cotton is artificial emasculation and pollination. This study proposed the potential utilization of F2 hybrids to improve upland cotton production through a comparative evaluation of hybrid generations.ResultsEight upland cotton varieties were analyzed and crosses were made according to NCII incomplete diallel cross-breeding design in two cotton belts of China. Variance analysis revealed significant differences in agronomic, yield, and fiber quality in both generations and environments. The broad-sense heritability of agronomic and yield traits was relatively higher than quality traits. Furthermore, the narrow-sense heritability of some traits was higher in F2 than in the F1 generation in both cotton belts. Overall, parental lines Zhong901, ZB, L28, and Z98 were observed with maximum combining ability while combinations with strong special combining ability were ZB × DT, L28 × Z98, and ZB × 851. The yield traits heterosis was predominant in both generations. However, the level of heterosis was altered with trait, hybrid combination, generation, and environment. Interestingly, L28 × Z98 performed outstandingly in Anyang. Its lint yield (LY) was 24.2% higher in F1 and 11.6% in F2 than that of the control Ruiza 816. The performance of SJ48 × Z98 was excellent in Aral which showed 36.5% higher LY in F1 and 10.9% in F2 than control CCRI 49. Further results revealed most hybrid combinations had shown a low level of heterosis for agronomic and fiber quality traits in both generations. Comparatively, ZB × DT and L28 × Z98 showed hybrid vigor for multiple traits in both generations and cotton belts. It is feasible to screen strong heterosis hybrid combinations with fine fiber in early generations. In the two environments, the correlation of some traits showed the same trend, and the correlation degree of Anyang site was higher than that of Aral site, and the correlation of some traits showed the opposite trend. According to the performance of strong heterosis hybrid combinations in different environments, the plant type, yield and fiber traits associated with them can be improved according to the correlation.ConclusionsThrough comparative analysis of variance, combining ability, and heterosis in F1 and F2 hybrids in different cotton belts, this study proposed the potential utilization of F2 hybrids to improve upland cotton productivity in China.

Comparison of soft spring wheat breeding lines and F1 hybrid according to economically valuable traits

Creation of doubled haploid lines in wheat is a promising direction of research in Russia. However, the criteria for identifying good cross combinations, for which it is advisable to carry out androgenesis in vitro, have not been defined. One of these criteria could be the rate of heterosis in F1 or F2. The aim of this work was to establish the possibility of achieving the yield level of the F1 hybrid by the lines of later generations. The studies were carried out at the experimental fields of the FSBSI “Federal Altai Scientific Center for Agrobiotechnology” in 2017-2019. Varieties ‘Golubkovskaya’, ‘Omskaya 28’, ‘Saratovskaya 70’, F1 ‘Omskaya 28’ × ‘Saratovskaya 70’, F1 ‘Golubkovskaya’ × ‘Saratovskaya 70’, four breeding lines from cross ‘Golubkovskaya’ × ‘Saratovskaya 70’ and seven breeding lines from cross ‘Omskaya 28’ × ‘Saratovskaya 70’ were material for this research. Germination, survival rate, plant height, number of spikes per m2, plant biomass, number of spikelets per spike and grain per spike, 1000-seed weight, grain weight per spike and plant, harvest index, yield, duration of the “germination – ear formation” period, lodging resistance and leaf and stem rust resistance were examined. In three cases out of six, high-parent heterosis in the studied F1 hybrids was observed (yield increase – 3–19 %). Five cases of significant yield improvement in breeding lines compared to F1 hybrids were detected in 2017–2019 (additional yield 2–44 %). Lines exceeding hybrid F1 in the context of yield were taller (+5–30 cm), with more extended period “germination – ear formation” (+7–8 days), higher plant biomass (+1.24–5.16 g), a larger number of spikelets per spike (0.5–2.8 units) and larger number of kernels (+3.5–8.0 units). Pure lines of soft spring wheat can be compared in yield to F1 hybrid, from which they were obtained. This fact was possible due to the selection of lines for desired traits determined by recessive genes.

Inheritance of resistance of spring barley to Erysiphe graminis f. sp. hordei in F1 and variability in F2 in the conditions of the Right-Bank Forest-Steppe of Ukraine

The nature of the inheritance of resistance to Erysiphe graminis f. sp. hordei in the crosses of genotypes of spring barley in F1 and transgressive variability in F2 populations are investigated. Inheritance of the trait of resistance to Erysiphe graminis f. sp. hordei in F1, by hybridization of genotypes of spring barley with known genes of resistance to Erysiphe graminis f. sp. hordei in European varieties Eunova (mlo11) and Barke (mlo9), which are located on chromosome 1H, was positively dominated. Inheritance of the F1 trait in Aspen (mlo11) and Adonis (mlo9) cultivars was partially positive. The influence of parental pairs for hybridization on the indicators of the degree of phenotypic dominance, hypothetical and true heterosis was established. Resistance to Erysiphe graminis f. sp. hordei in F1 hybrids was observed heterosis (positive dominance) in fve hybrid combinations (hp = 1.1–1.9 %): Barke/Badoryi, Barke/Sanktrum, Parnas/Rostentsii, Badoryi/ Barke, Eunova/Zvershennia. Hypothetical heterosis (Ht) in F1 was observed in 13 of 16 hybrids (from +2.8 % to +97.6 %). A positive value of true heterosis (Htb) in F1 was observed in 15 hybrids out of 16 (from +1.9 % to +98.8 %). Inheritance of the trait of resistance to Erysiphe graminis f. sp. hordei in all studied hybrids was influenced by the cytoplasm of the mother plant, except for the hybrid Eunova / Triangel, where the influence of the nuclear apparatus was detected. Hybrids were found in the F 2 population with high resistance to Erysiphe graminis f. sp. hordei, which exceeded the parental components, which indicates a signifcant shaping process and the possibility of selection on the basis of the studied trait. The degree of positive transgression ranged from 16.0 % to 73.0 % in hybrids Aspen / Skarlet, Adonis / Vanja, Barke / Badoryi, Barke / Sanktrum, Eunova / Triangel and Eunova / Zvershennia, where highly resistant varieties were used for the mother form. The combinations in which the frequency of transgression was observed in more than 50.0 % of plants are hybrids: Eunova / Triangel, Barke / Sanktrum, Eunova / Zvershennia, Parnas / Rostentsii and Barke / Badoryi. Key words: spring barley, resistance, Erysiphe graminis f. sp. hordei, combinations of crossing, inheritance, F1, true and hypothetical heterosis, degree of phenotypic dominance, F 2, degree and frequency of transgressions.

Estimation of Gene Action and Heterosis in F1 And F2 Diallel Crosses among Seven Genotypes of Field Bean

Heterosis, gene action, combining ability (GCA and SCA) effects and variances were studied in 21 F1 and F2 crosses derived from 7x7 half diallel scheme of field bean. To detect prospective and efficient material for immediate use in breeding programs to enhance field bean productivity. F1 and F2 with parents were arranged in RCBD with 3 replicates to evaluate seed yield and its components traits in 2018/2019 season. Mean squares (MS) for genotype and its partitioning (parent, crosses and parent vs crosses) were significant for all studied traits in both generations. P1xP5 and P3xP6 exhibited significant heterotic effect for seed yield plant-1 in F1 and F2 generations. Significant GCA and SCA MS were found for all studied traits, where proportion of additive was great for most traits in both generations, reveling predominance of additive gene effects. P2 (Sakha 2), P5 (M-13), P7 (M-1017) in F1 and P6 (M-148) in F2 were good combiners for seed yield and at least one of its components. More than 25 % of studied crosses showed positive and significant SCA effects for seed yield in F1 and F2 generations. The cross P1xP5 showed desirable SCA effects in both generation for seed yield and resistance to chocolate spot disease%. Significant and larger values of dominance component (H1) than additive were obtained for all studied traits resulting in more values of (H1/D)0.5 which were exceeded unity in both generations. Low narrow-sense heritability was exhibited in both generations for all traits, indicating that presence of non-additive genetic effects.

Supplementing selection decisions in a hybrid wheat breeding program by using F2 yield as a proxy of F1 performance

Hybrid wheat breeding programs need to use chemical hybridizing agents for seed production due to its simplicity. Alternative methods such as cytoplasmic systems or hand pollinations restrict genetic combinations or seed production which limits testing experimental hybrids in large-scale multi-environment trials (METs). Using F2 seed instead of F1 can allow programs to test hybrid cross combinations in METs and the data can be used to supplement selection decisions at early stages of breeding cycle. To test this hypothesis, two METs consisting of 40 entries were conducted in 2017 and 2018 in six locations across Texas and Nebraska. The entries included hybrids at the F2 stage and their respective parents, selected from a previous preliminary F1 evaluation experiment. In six out of 10 test environments, a F2 hybrid had statistically significant higher yield than highest yielding parent. The F2 mid-parent heterosis ranged from − 20.97 to 27.52% in 2017 and − 9.90 to 9.17% in 2018. The F2 high-parent heterosis ranged from − 21.07 to 17.85% in 2017 and − 16.57 to 6.68% in 2018. The heterosis estimates of these cross combinations at F1 stage were extracted from previous large scale METs conducted on nine environments across Nebraska and Texas in 2016–2017. A comparison of F2 heterosis from this study and F1 heterosis from the previous study revealed that F2 heterosis was highly indicative of superior F1 performance. The results provide strong evidence for utility of F2 yield data in selecting superior F1 hybrids. In addition, a practical framework for using F2 performance to aid selecting F1’s in a hybrid wheat-breeding pipeline is provided.

Genetic diversity studies in safflower germplasm (Carthamus tinctorius L.)

The investigation on Genetic diversity studies in safflower germplasm (Carthamus tinctorius L.)” was undertaken to estimate the extent of diversity and to estimate the contribution of each character towards genetic diversity. The set of 63 genotypes along with three checks 'A-1, PBNS-12, PKV Pink' were evaluated at the field of Oilseeds Research Unit, Dr. PDKV, Akola during rabi 2018-2019. Based on measurements of genetic diversity by Mahalanobis D2 distance and grouping by Tocher’s method, these genotypes were grouped into ten clusters. Clusters VI and VIII (3896.92) had maximum average inter cluster distance followed by clusters X and VIII (3096.12), clusters III and VI (2772.88), clusters II and VIII (2383.65), clusters V and IV (2296.31). Seed yield per plant (25.69%) contributed maximum towards genetic divergence followed by days to maturity (18.41%), days to 50% flowering (16.08%), number of seeds per capitulum (12.82%) and plant height (10.58). The present investigation projected the importance of GMU-7363, GMU-5135, GMU-5134 as parents for higher heterosis in F1 and potential transgrassive segragants in subsequent generations for earliness as they have least mean for days to maturity whereas high mean of GMU-7448, GMU-5136, GMU-2648, GMU-2928, GMU-667, GMU-1798 GMU-2830 and GMU-7355 for characters viz plant height, number of branches per plant, number of capitula per plant, number of seeds per capitulum, 100 seed weight, volume weight, oil content and seed yield per plant respectively.

Fodder qualities of heterotic hybrids from intergeneric crosses between maize and eastern gamagrass

Green biomass yield and fodder qualities are the starting point in the choice of forage crops. Maize, as a plant with the C4 pathway of photosynthesis, is highly efficient in transforming the energy of light into chemical bond energies, which ultimately leads to the highest yield per unit area of cultivated land. Its grain and green biomass possess good fodder qualities and are actively used in feed rations for cattle, smaller ruminants, and poultry. Eastern gamagrass (Tripsacum dactyloides L.), a wild relative of maize, is widespread over the plains of North and South Americas. To date, it has received universal recognition among breeders as a forage and fodder crop. More than 10 commercial cultivars have already been developed and cultivated in the United States. Eastern gamagrass is a C4 plant as well, characterized by high yield and high feed value of hay. We decided to combine in our research economically valuable qualities of this plant by developing apomictic intergeneric hybrids. This paper presents the results obtained in the process of assessing fodder qualities of apomictic maize × Tripsacum hybrids, where two maize genomes from the lines participating in hybrid selection for F1 seeds were added to the 36 chromosomes of eastern gamagrass. The maize × Tripsacum hybrid forms, produced during a number of years, persistently demonstrated an apomictic reproduction pattern and heterosis in green biomass productivity. Zootechnical analysis of plant samples showed that the hybrids, in which chromosomes of the lines used in commercial seed production to obtain heterosis in F1 had been added to the 36 chromosomes of eastern gamagrass, exceeded in their biochemical indicators the plants, in which 20 chromosomes from one of the maize lines earlier used in hybridization at our laboratory had been added. A theoretical estimate of green biomass yield calculated per hectare for the maize × Tripsacum hybrids is about 65 tons.

Genome Sequence and QTL Analyses Using Backcross Recombinant Inbred Lines (BILs) and BILF1 Lines Uncover Multiple Heterosis-related Loci.

Heterosis is an interesting topic for both breeders and biologists due to its practical importance and scientific significance. Cultivated rice (Oryza sativa L.) consists of two subspecies, indica and japonica, and hybrid rice is the predominant form of indica rice in China. However, the molecular mechanism underlying heterosis in japonica remains unclear. The present study determined the genome sequence and conducted quantitative trait locus (QTL) analysis using backcross recombinant inbred lines (BILs) and BILF1 lines to uncover the heterosis-related loci for rice yield increase under a japonica genetic background. The BIL population was derived from an admixture variety Habataki and japonica variety Sasanishiki cross to improve the genetic diversity but maintain the genetic background close to japonica. The results showed that heterosis in F1 mainly involved grain number per panicle. The BILF1s showed an increase in grain number per panicle but a decrease in plant height compared with the BILs. Genetic analysis then identified eight QTLs for heterosis in the BILF1s; four QTLs were detected exclusively in the BILF1 population only, presenting a mode of dominance or super-dominance in the heterozygotes. An additional four loci overlapped with QTLs detected in the BIL population, and we found that Grains Height Date 7 (Ghd7) was correlated in days to heading in both BILs and BILF1s. The admixture genetic background of Habataki was also determined by subspecies-specific single nucleotide polymorphisms (SNPs). This investigation highlights the importance of high-throughput sequencing to elucidate the molecular mechanism of heterosis and provides useful germplasms for the application of heterosis in japonica rice production.

HETEROSIS AND COMBINING ABILITY IN MELON (CUCUMIS MELO L.)

The purpose of this study was to estimate heterosis, general and specific combining ability in melon hybrids to identify the best combinations during the period from 2017 to 2019 at the Vegetable Research Farm, Horticultural Research Institute, Agricultural Research Center (ARC), Kaha and Dokki, Egypt. Six parents and their respective hybrids were evaluated in a randomized complete block design (RCBD) with three replications. The following traits were assessed of: main stem length, number of leaves, average fruit weight, fruit length, fruit diameter, flesh thickness, fruit cavity, fruit shape index, TSS and total yield/fed. The heterotic expression for total yield was the most important trait in this investigation. Potence ratio that measured the average of dominance confirmed the partial dominance for plant length and total yield but over-dominance appeared in the other characters. The range of both types of F1 heterosis for studied characters indicated that the expression of heterosis varied according to different crosses and characters investigated. The results showed significant and highly significant mean squares for both GCA and SCA in all studied traits except fruit shape index, indicating the important role of both additive and non-additive gene effects in the expression of these traits. However, a greater ratio of GCA/SCA than unity as detected for number of leaves, fruit diameter, fruit weight, TSS and total yield revealing that the inheritance of these traits mainly was controlled by additive gene action. The estimates of GCA effects in individual parental genotypes of the F'1s generation were significant and highly significant for the most studied traits. However, the crosses (P1×P3) and (P2×P4) achieved highly SCA effects for the most traits in this study, which means that GCA effects of the parents were reflected in the SCA effects in the crosses for the most studied traits.

Genetic dissection of yield-related traits and mid-parent heterosis for those traits in maize (Zea mays L.)

BackgroundUtilization of heterosis in maize could be critical in maize breeding for boosting grain yield. However, the genetic architecture of heterosis is not fully understood. To dissect the genetic basis of yield-related traits and heterosis in maize, 301 recombinant inbred lines derived from 08 to 641 × YE478 and 298 hybrids from the immortalized F2 (IF2) population were used to map quantitative trait loci (QTLs) for nine yield-related traits and mid-parent heterosis.ResultsWe observed 156 QTLs, 28 pairs of loci with epistatic interaction, and 10 significant QTL × environment interactions in the inbred and hybrid mapping populations. The high heterosis in F1 and IF2 populations for kernel weight per ear (KWPE), ear weight per ear (EWPE), and kernel number per row (KNPR) matched the high percentages of QTLs (over 50%) for those traits exhibiting overdominance, whereas a notable predominance of loci with dominance effects (more than 70%) was observed for traits that show low heterosis such as cob weight per ear (CWPE), rate of kernel production (RKP), ear length (EL), ear diameter (ED), cob diameter, and row number (RN). The environmentally stable QTL qRKP3–2 was identified across two mapping populations, while qKWPE9, affecting the trait mean and the mid-parent heterosis (MPH) level, explained over 18% of phenotypic variations. Nine QTLs, qEWPE9–1, qEWPE10–1, qCWPE6, qEL8, qED2–2, qRN10–1, qKWPE9, qKWPE10–1, and qRKP4–3, accounted for over 10% of phenotypic variation. In addition, QTL mapping identified 95 QTLs that were gathered together and integrated into 33 QTL clusters on 10 chromosomes.ConclusionsThe results revealed that (1) the inheritance of yield-related traits and MPH in the heterotic pattern improved Reid (PA) × Tem-tropic I (PB) is trait-dependent; (2) a large proportion of loci showed dominance effects, whereas overdominance also contributed to MPH for KNPR, EWPE, and KWPE; (3) marker-assisted selection for markers at genomic regions 1.09–1.11, 2.04, 3.08–3.09, and 10.04–10.05 contributed to hybrid performance per se and heterosis and were repeatedly reported in previous studies using different heterotic patterns is recommended.

Heterosis in Flue‐Cured Tobacco and Its Utility in Predicting Transgressive Segregation within Derived Populations of Inbred Lines

Heterosis might be used in a strategic way to increase yields of flue‐cured tobacco (Nicotiana tabacum L.), but previous reports have suggested levels of heterosis to be low for F1 hybrids of this market class. Based on analysis of a 14‐parent diallel, we found average levels of F1 midparent heterosis to be 10.3%, a level that is substantially higher than previous estimates from the 1960s. Thirteen of ninety‐one tested hybrids significantly outyielded the highest yielding parental lines. Heterosis might also be an indicator of superior allelic complementation by parental lines that, in principle, could be fixed in derived inbred lines. We compared F3:4 families derived from three high heterotic crosses and three low heterotic crosses and observed positive correlations between F1 heterosis and desirable transgressive segregation. Hence, the data support the use of F1 heterosis as a predictor of breeding crosses with increased potential for desired outcomes. Several derived F3:4 families exhibited yields that were comparable with, or significantly better than, corresponding heterotic F1 hybrids, indicating that heterotic effects could be fixed within inbred lines. Results suggest a reconsideration of heterosis for increasing yields of flue‐cured tobacco.

Estimation of Gene Effect for yield, yield Components and Foliar Diseases of Two Faba Bean Hybrids at Nubaria Region

Two crosses of faba bean (Giza716xGiza40) and (Giza716xNubaria2), each represented by six population (P1, P2,F1, F2, BC1 and BC2) were tested for yield, yield components, growth attributes and two diseases (chocolate spot andrust). Heterosis in F1, which exhibited highly significant positive effects were detected for number of branches /plant,number of pod /plant, number of seed /plant, seed yield /plant and plant height in the two crosses over mid and betterparents. Significant negative Heterosis effects were obtained for chocolate spot and rust diseases in the two crosses overmid parents. Highly significant positive values of inbreeding depression were detected for number of branches/ plant,number of pods/plant, number of seed /plant, seed yield /plant, 100-seed weight and plant height in both crosses.However, highly significant negative values of inbreeding depression were found for chocolate spot and rust diseases inthe two crosses. Over dominance towards the higher parent were detected for number of branches/plant, number ofpods/plant, number of seeds/plant, seed yield /plant and plant height in both crosses. It was also found that overdominance controls spot and rust diseases in the second cross. Additive gene effects were significant for all characters,excepted number of seed/plant and seed yield/plant in both crosses. Dominance effects were highly significant for alltraits, excepted, seed yield/plant and plant height in both crosses and rust disease in second cross. Additive x additive,additive x dominance and dominance x dominance types of gene action were significant for most traits in both crosses,except, chocolate spot and rust disease. In both crosses, high heritability values in broad sense were detected for all traitswhich, ranged between 63.20 for rust disease and 85.32 % for reaction to chocolate spot and for cross (Giza 716 X Giza40). However, cross (Giza 716 X Nubaria2) had values ranged from 60.7% for reaction to rust to 70.93% for seedyield/plant in (Giza 716 x Nubaria2). The values of heritability in narrow sense were detected for all traits which, rangedbetween 60.19 to 80.36% for resistance to rust and chocolate spot disease in first cross, respectively and between 59.36and 68.42% for number of pods/plant and seed yield / plant in the cross (G.716 x Nubaria.2).The estimates of expectedgenetic advance from selection in F2 generation reflected low or moderate values for all studied traits in both crosses thatranged between 7.78 cm for plant height to 1.8 for rust disease in cross (Giza 716 X Giza 40) and between 8.13 cm forplant height to 1.84 for number of branches/plant in (Giza 716 X Nubaria2) cross.

Genetic divergence studies in blackgram (Vigna mungo (L.) Hepper

Divergence among 112 genotypes for yield and yield contributing traits was carried out by using mahalanobis D2 statistics. The maximum inter cluster distance was observed between cluster XII and IV (18.80) followed by cluster VI and IV (18.79). The maximum intra cluster distance was reported in cluster XII (14.74). The crosses which involve parents from these more divergent clusters will yield relatively good amount of heterosis in F1 and high frequency of transgressive segregants and genetic variability in subsequent generationsBased on the mean performance and diversity studies the genotypes KU 11–667, ABG 11–036, IC 436729 and IC 335331 were found to be the best for further yield improvement.

Identification and application of markers closely linked to the restorer gene (Rfm) in rapeseed (Brassica napus L.).

The Mutsu-Isuzu cytoplasmic male sterility (MI CMS) system is one of the three-line hybrid systems used in China. As we know, the hybrid system is tightly associated with the yield variation in F1 heterosis, while the restorer gene for the MI CMS (Rfm) has not been finely mapped for further application in marker-assisted selection (MAS). In this study, the sets of near-isogenic lines (NILs) of Rfm in two different genetic backgrounds were hybridized with the genome-wide 60 K single-nucleotide polymorphism (SNP) chip of Brassica for screening the possible associated genomic region of Rfm. Through screening genotypes with SNP loci and sequencing the candidate loci, one 2.5 Mb physical region (covering three scaffolds) on chrA09 was identified as the candidate for the Rfm region. Then, the SSR markers for the target scaffolds were used to detect the recombination in an F2 population and narrowed the Rfm gene within the genetic distance of 0.52 cM, equivalent to a 350 kb physical segment. Moreover, the markers were tested to improve new elite restoration lines and to assess the percentage of hybrid seeds. Our results could potentially accelerate the map-based cloning of the Rfm gene to benefit rapeseed breeding.

Genetic studies of fibre yield-related traits and days to anthesis in some kenaf (Hibiscus cannabinus L.) accessions

Kenaf (Hibiscus cannabinus L.) is an economically important and multi-purpose natural fibre crop with several industrial applications. However, its potentials have not been fully maximised due to poor yield and its narrow genetic base which limited the available hybrids. The low yield is attributed to high photoperiod sensitivity of most kenaf accessions because it reduces the vegetative growth. This study attempts to understand the genetic architecture of days to anthesis of kenaf towards the development of a photo-insensitive kenaf hybrid. Two early maturing Nigerian kenaf accessions: NHC (12)1 and NHC (3)2, and two late maturing accessions (NHC [9]2 and NHC 15) were crossed to generate F1 population. The F1 hybrid together with its parents and its reciprocals were planted in a randomised complete block experiment design with three replicates. Data were collected on days to anthesis (DTA), plant height (HAH), basal stem girth (GAH), base diameter (BDAH) and weight at harvest (WAH) for analysis. The mean squares were significant for DTA, HAH, DBAH, GAH and WAH. DTA exhibited the highest broad-sense heritability value (0.98) among other traits. The GCA: SCA ratio for DTA and BDAH signifies that the effect of non-additive genes was prevalent because it was lower than a unity while the additive gene action was predominant in HAH. The negative GCA estimates for NHC (12)1 and NHC (9)2 indicated a poor combining ability. Only NHC (3)2 x NHC (9)2 showed good specific combining ability (-5.75, 0.33, 0.85, 91.46) for DTA, GAH, BDAH and WAH respectively. NHC (12)1 x NHC (9)2, NHC (3)2 x NHC (9)2, NHC (3)2 x NHC 15, NHC (9)2 x 3NHC (3)2, NHC (9)2 x NHC 15, NHC 15 x NHC (3)2, NHC 15 x NHC (9)2 showed negative significant percent of F1 heterosis above the mid-parent in days to anthesis and could be employed to breed photo-insensitive early maturing kenaf.

Genetic Variability and Heterosis in F1 and F2 Generations of Diallel Crosses among Seven Wheat Genotypes

In order to study the effect of heterosis and nature of genetic on plant height and yield traits were studied in a 7x7 diallel cross without reciprocals and their F2 generation in wheat to define and select an efficient and prospective material for immediate use in hybridization programs to improve grain yield of wheat in Egypt. Parents, F1 and F2 were evaluated for quantitative traits in 2016/2017 season. Significant genotype mean squares and its components (parents and crosses) were obtained for all traits in both generations. Significant heterosis in F1 generation was obtained for all studied traits. Heterosis of grain yield/plant relative to mid parent varied from 4.64 to 75.50% in F1 crosses. The P2xP3, P1xP4 and P2xP5 were the best crosses for grain yield heterosis. General (GCA) and specific (SCA) combining ability mean squares were significant for all traits. MS (GCA)/ MS (SCA) ratios indicated the relative importance of additive and non-additive gene action in their inheritance for all the traits. The nine crosses i.e. P1xP2, P1xP6, P2xP5, P2xP6, P4xP5, P4xP6, P5xP6 and P5xP7 had significant and positive effects in F1 and F2 generations and contained Inter-and intera-allelic interactions. Generally, no wide differences in the genetic parameters in F1 and F2 generations were detected. Highly significant and larger (in magnitude) values of dominance component (H2) than additive were obtained for all studied traits resulting in more values of (H1/D)0.5 which were more than unity in both generations. High heritability values (in a broad-sense) along with medium or low ones in narrow-sense were exhibited in both generations, indicating that most genetic variances were due to non-additive genetic effects. The regression line passed through the origin in spike length and No. of spikes/plant in F1 generation and 1000-grain weight in F2 generation, revealed a presence of complete dominance. Meanwhile, it intersects the Wr axis above the origin in plant height in both generations,1000-grain weight in F1, No of spike/plant and Spike length in F2, reflecting partial dominance.

Allelic and epigenetic DNA variation in relation to F1 heterosis manifestation in F1 hybrids of Capsicum annuum L.

Managing F1heterosis is one of the major objectives in hybrid crop breeding programs. The classical theory considers the heterozygosity in F1hybrids to be the main factor contributing to heterosis and therefore presumes a linear relationship between the value of genetic polymorphisms in parental lines and the heterotic response of their F1offspring. Therefore, the genetic diversity information is viewed as a tool for selection of promising cross-combinations, but results published by different researchers are inconsistent. In this work, we studied the contributions of structural and nonstructural DNA polymorphisms to F1heterosis manifestation. We used SSR and methyl-sensitive AFLP (MSAP with HpaII and MspI izoshisomers) protocols for obtaining specific patterns for heterotic and nonheterotic F1hybrids of sweet pepper (Capsicum annuum L.) from a Belarusian breeding program. We found out that a certain portion of heterosis for yield-related traits might be explained by the polymorphism revealed by SSR analysis. According to our data, the total number of polymorphic SSR loci and the ratio of polymorphic and nonpolymorphic loci demonstrate a significant predictive value and can serve as additional prognostic criteria for the selection of promising cross-combinations. From the MSAP assay, we found a relationship between heterosis and the numbers of methylated and nonmethylated DNA loci for yield traits. Our results indicate that cross-hybridization may favor epiallelic modifications in F1hybrids, presumably responsible for heterosis. Thus, epigenetic DNA variation may explain the absence of a linear relationship between the level of structural DNA divergence and F1heterosis, as well as the manifestation of heterosis in crosses of related (genetically similar) accessions.