Degree Of Heterosis Research Articles

The nature and magnitude of heterosis for the economic traits of vetiver{Chrysopogon zizanioides (L.) Roberty}

A total of 65 F1 vetiver hybrids were developed using the L × T design by mating 13 males with 5 females. The goal of this endeavor is to increase the possibility of developing high-yielding, quality essential oil varieties by utilizing heterosis and genetic variability. The heritability (%) was high for the traits CH4, CH7 to CH11 (81.90–99.69%). A positive and highly significant association exists between the features of CH2 and CH3. The trait CH8 showed the highest direct contributions to CH4, followed by CH-3, CH-5, CH4, and CH1. Heritability, correlations, and heterosis components all have an impact on the nature and degree of heterosis. It recommends that when selecting superior hybrids, breeders should take into account the genetic correlation between key traits. Based on average performance and heterosis for the root yield/plot, the top two crosses were determined to be L13 × T1 and L10 × T3. While hybrids L10 × T5, L2 × T3, and L4 × T5 showed high essential oil yield, four hybrids, L1 × T2, L3 × T3, L9 × T4, and L2 × T5, had the highest essential oil (%). A nor-sesquiterpene aldehyde (khusilal), two cedrene family chemicals (α-cedrenal and α-cedrenol), and one sesquiterpene alcohol, or khusol constitute the oil composition. The inclusion of just alcoholic and aldehydic components makes the oil fingerprint distinct. Further research was conducted on these hybrids to take advantage of heterosis and employ them in further hybridization programs to create superior genotypes.

Morphological and metabolomics profiling of intraspecific Arabidopsis hybrids in relation to biomass heterosis

Heterosis contributes greatly to the worldwide agricultural yield. However, the molecular mechanism underlying heterosis remains unclear. This study took advantage of Arabidopsis intraspecific hybrids to identify heterosis-related metabolites. Forty-six intraspecific hybrids were used to examine parental effects on seed area and germination time. The degree of heterosis was evaluated based on biomass: combinations showing high heterosis of F1 hybrids exhibited a biomass increase from 6.1 to 44% over the better parent value (BPV), whereas that of the low- and no-heterosis hybrids ranged from − 19.8 to 9.8% over the BPV. Metabolomics analyses of F1 hybrids with high heterosis and those with low one suggested that changes in TCA cycle intermediates are key factors that control growth. Notably, higher fumarate/malate ratios were observed in the high heterosis F1 hybrids, suggesting they provide metabolic support associated with the increased biomass. These hybrids may produce more energy-intensive biomass by speeding up the efficiency of TCA fluxes. However, the expression levels of TCA-process-related genes in F1 hybrids were not associated with the intensity of heterosis, suggesting that the post-transcriptional or post-translational regulation of these genes may affect the productivity of the intermediates in the TCA cycle.

Evaluarea diversității genetice a liniilor consangvinizate de porumb din grupa de germoplasmă Lacaune

The purpose of research was to estimate the phenotypic and genetic diversity of 14 inbred lines which were classified into the Lacaune germplasm group, including F2, used as indicator line. Phenotypic diversity was estimated by determining the phenotypic diversity index (idf), calculated based on 28 quantitative and qualitative characters. Genetic diversity was assessed by the mid-parent heterosis (H, %) and SCA constants (ŝij) for grain yield. In the most of cases (98 %), between inbred lines, there was observed a high or medium degree of phenotypic relatedness. The degree of heterosis in related crosses varied from 33,7 to 143,6% has been lower, compared to crosses between unrelated lines (h = 85,2 – 169,0 %), that confirms the belonging of the studied lines to the respective germplasm group. At the non-additive interactions level the most related to the F2 line, are the F2o2, K1, AN615, MKP16 and MV61 inbreds, and the most genetically distant from it are the MV453, MV395 and MV459 lines.

Estimating heterosis and heterobeltiosis in phenological and vegetative traits and correlations in Musa diploid x diploid crosses

This study was conducted to determine the extent of heterosis and heterobeltiosis in phenological and vegetative traits in Musa diploid by diploid crosses. The experimental design was RCB with two replications of 6 plants per genotype. Planting was done in alleys of multispecies hedgerows in an area of 2,880 m2 at a spacing of 3 m x 2 m. The study was conducted at the International Institute of Tropical Agriculture (IITA) High Rainfall Station, Onne, Rivers State, Nigeria for 3 years. Six female diploid banana and plantain clones (maternal/ seed parents) were crossed with a single diploid male plantain accession, TMP2x 2829-62 (paternal/pollen parent). The resulting diploid F1 embryos were cultured in vitro for 6 weeks and their seedlings along with the parental clones, vegetatively propagated from the parents of each genotype, were planted in the field. Data collected included days to flowering, time to fruit filling, plant height, plant girth, and height of next tallest sucker. Data subjected to ANOVA in RCB was tested at 5% level of significance. Heterosis (Ht) and heterobeltiosis (Hbt) were estimated. The degree of heterosis and heterobeltiosis differed for different traits, different crosses and genotype. Overall, 66.7% of the progenies showed heterosis and heterobeltiosis for days to flowering and time to fruit filling; 66.7% exhibited heterosis and 50% heterobeltiosis for plant height; 33% heterosis and heterobeltiosis for plant girth and 16.7% heterosis and heterobeltiosis for height of next tallest sucker. Correlations between the levels of heterosis for different traits between the progeny and the female parents were generally weak except for time to fruit filling (r = 0.816) which showed a significant correlation. Heterosis and heterobeltiosis occur in phenological and vegetative traits in diploid x diploid crosses indicating their importance in further possibilities for breeding.

Изучение гетерозиса роста у гибридов F1 ячменя

The article presents the results of an analysis of the level of heterosis, and the degree of phenotypic dominance observed in F1 hybrids when plants are crossed between barley germplasms obtained from ICARDA and local varieties of barley. Germplasms PENCO/CHEVRON-BAR/3/ ARUPO/K8755 // MORA CBSS04Y00065S-11Y 1M-0Y-0M-0Y- IBYT-HI, Libya/F6NB_7ICB02-0178-OAP-10TR-OAP-INBYT, MSEL/PFC9214 CBS S01 M00318S-0M-0M-1Y-1 M-OY-IBON-HI, SHENMAI N0.3/MSEL // CANELA/CBSS04Y00367T-A-2Y-2M-0Y-0M-0Y-IBON-HI, TOCTE/3/MJA/BRB2 // QUINA/4/PETUNIA 1 CBSS02Y00362S-0M-0M-2Y-1M-OY-IBON-HI, Barjouj/7/ICNBF8-616/6/Cel/WI2269 // Ore/3/AthsNew/4/Mcu59/Mcul // Moch/5/Rta’S ICB 01-1226-7TR-OTR OAP and local varieties such as Karabakh 7, Karabakh 22, Karabakh 23, Kudretli 48, Baharly, Jalilabad-19. The fertility of flowers in reciprocal hybrid combinations obtained with these parental forms, it was 32.3-57.5%. Most of the analyzed F1 hybrids showed heterosis in plant growth. The degree of phenotypic dominance in combinations varied within +0.5-2.5, and the degree of heterosis - within +1.0-8.6%. The highest heterosis is observed in the following combinations: Karabakh 22 × PENCO/CHEVRON-BAR/3/ ARUPO/K8755 // MORA CBSS04Y00065S-11Y 1M-0Y-0M-0Y (IBYT-HI) (+5.9%), Baharly × Kudretli 48 (+6.4%) and SHENMAI N0.3/MSEL // CANELA CBSS 04Y 00367T-A-2Y-2M-0Y-0M-0Y (IBON-HI) × MSEL/PFC9214 CBS S01 M00318S-0M-0M-1Y-1 M-OY (IBON-HI) (+8.6%). True heterosis was positive in 68.7% of combinations and negative in 25%. In 6.25% of the combinations, heterosis was not observed.

Estimation of oil flax intra-species hybrids by breeding-genetic parameters for the creation of material with altered habitus

The creation of a selection material for oil flax with a large number of stems, side shoots and an optimal height for cultivation is an urgent task, since the formation of additional bolls on the side shoots will increase the yield of seeds, and an increase in the vegetative mass of plants will increase its competitiveness against weeds and reduce moisture evaporation. from the soil surface. The use of genetic and statistical parameters allows to efficiently plan and carry out breeding work for oil flax, purposefully select parental pairs in crosses, select valuable genotypes, and reject low-value material at the first stages of breeding. The purpose of this study is to identify promising interspecific hybrid combinations based on breeding and genetic parameters for creating a new breeding material for multi-stem and multi-shoot forms. The studies were carried out at the Institute of Oilseeds NAАS of Ukraine in 2018-2020. The material of the research was F1 and F2 hybrids obtained in a system of dialle crosses with the participation of two wild species (L. angustifolium and L. hispanicum) and three samples of cultivated flax – L 6 (India), M 32/2 (Ukraine), L 5 (Czech Republic). The degree of dominance of traits in hybrids of the first generation was determined by the formula (Beil, Atkins 1965). The degree of heterosis is according to the formula (Rasul et al 2002). The coefficient of heritability in hybrids of the second generation – according to the formula (Ayala 1984). As a result of the research, interspecific hybrid combinations have been identified that are promising for obtaining breeding material with a modified habit: – with the effect of heterosis: by plant height – seven combinations of F1 (Ht = 3,58-13,76%); the number of stems per plant – one (Ht = 35,77%); the number of side shoots is six (Ht = 5,68-43,79%). The most valuable are combinations in which the effect of heterosis manifested itself simultaneously on two grounds – the height of the plants and the number of lateral shoots on the plant – L. angustifolium / L 6, L 5 / L. angustifolium, L. hispanicum / L 6, L 6 / L. hispanicum; plant height and number of stems per plant – M 32/2 / L. hispanicum; – with high coefficients of heritability: by plant height – four combinations of F2 (H = 0,67-0,87); the number of stems per plant – six (H = 0,66-0,81); the number of side shoots is four (H = 0,66-0,72). Interspecific combinations of L. hispanicum / M 32/2 and M 32/2 / L. hispanicum were distinguished by high rates of heritability by two characteristics – the number of stems and the number of lateral shoots on the plant. The potential of the selected combinations will be used in the further breeding process for increased branching.

Genetic Recombination of the Mantle Color Pattern of Two Boring Giant Clam (Tridacna crocea) Strains

According to the RGB law display, the polymorphism of the giant clam mantle color pattern is through four iridocytes. The boring giant clam (Tridacna crocea) exhibits diverse mantle colors, including blue, green, purple, gold, and orange. In order to evaluate the genetic laws driving these mantle color patterns, a complete diallel cross between two color strains [blue strain (only blue iridocyte) and the yellow-green strain (yellow and green iridocytes)] was performed. Using a single-to-single mating system, two intra-strain crosses (BB and YY) and two reciprocal inter-strain crosses (BY and YB) were produced in triplicates. Higher fertilization rate and hatching rate were observed in all experimental groups, suggesting that there was no sperm–egg recognition barrier between the two strains. In the grow-out stage, the size of the reciprocal hybrids was larger than that of the two pure strains with a degree of heterosis. In addition, compared with the two pure strains, the hybrids have higher larval metamorphosis rate and higher survival rate. At 1 year of age, the mantle color pattern of pure strains showed 100% stable inheritance, while the reciprocal hybrids exhibited colorful patterns (a combination of blue, yellow, and green), suggesting that there was a genetic recombination of the mantle colors during the stable expression period. These results provide a theoretical basis for the formation of the mantle color of giant clam and its genetic segregation law, as well as provide guidance for genetic breeding of giant clams.

Standard Heterosis for Seed and Oil Yield in Sunflower (Helianthus annuus L.)

This article is based on a study that was carried out to identify the best hybrid combinations giving high degree of useful heterosis for economic traits such as seed and oil yield in sunflower under high saline soil in coastal saline belts of West Bengal. The present study was carried out at Nimpith (West Bengal) in 2017-18 and 2018-19 with the specific objectives of identifying the standard heterotic cross combinations of sunflower hybrids and identifying the superior sunflower hybrids suitable for growing in rabi season in West Bengal’s agro-climatic conditions. A set of sunflower hybrids along with the three national checks, LSFH-171, KBSH-53 and DRSH-1, were evaluated in a randomized block design. The degree of heterosis varied for important useful characters among the different crosses. Presence of high heterosis in certain crosses and low in others suggested that the nature of gene action varied with genetic architecture of the parents. From the study, it may be concluded that the sunflower hybrids viz. CMS 519A X TSG-255, CMS 148A X EC-201868 and CMS 207A X R-272 may be promoted for AICRP multilocation trial or coordinated trial to evaluate their performance in Indian subcontinent. It is because of their superior traits for oil yield over the best national check sunflower hybrids in given environments.

Performance, Manifestation of Heterosis and Combining Ability for Growth, Productivity and Fruit Quality of Indeterminate Tomato

Six parental lines of indeterminate tomato were used in half diallel model to study performance, degree of heterosis and combining ability.This study was conducted at the Experimental Farm, Faculty of Environmental Agriculture Sciences, Arish University during two successive seasons of 2018/2019 and 2019/2020. Results revealed that the parental lines IRS-43-2, VR-6 and VL-5-4 exhibited the best values for most studied characters,however the cross combinations IRS-43-2 x VR-6, IR-44-2 x VR-6 and VR-6 x VL-5-4 were the best among the crosses.Hybrid vigour was observed in many traits, the significant positive heterosis over the check hybrid was detected in all characters and the highest values were reflected by the crosses VR-6 x VL-5-4 for growth traits and IRS-43-2 x VR-6 for early yield, total yield and Vit. C content. Variances of combining ability and genetic components revealed that additive gene action played the main role in the inheritance of fruit set percentage, total yield plant-1, average fruit weight, fruit shape and Vit. C. Based on GCA effects, the good combiner was Vl-5-4, for growth traits; IRS-43-2 and VR-6 for early yield, total yield, number of locules, and Vit. C. The highly significant positive values of SCA effects observed in crosses VR-6 x VL-5-4 for growth traits and Vit. C; IRS-43-2 x VL-5-4 for early yield; and IR-44-1 x VL-7-4 for total yield and average fruit weight. Three promising crosses (IRS-43-2 x VR-6; IR-44-2 x VR-6; VR-6 x VL-5-4) could be used commercially as local hybrids after testing in multi locations and seasons.

The degree of dominance and heterosic effect in tomato hybrids on the main economic features

In Dagestan, like many southern subjects of the country, the environment of vegetable crops tomato is the most common crop. The basis for getting high tomato yields are heterosic hybrids. The research work was carried out during 2018-2019. on the experimental field of the Federal Agricultural Research Center of the Republic of Dagestan. The object of the study in 2018 were hybrids of tomato of the first generation of recyproccal interbreeding. In 2019, direct and reverse artificial crossings involved 11 pairs of initial forms of early-ripe and medium-ripened groups with higher productivity. Reciprocal hybrids with the participation of the variety Local in pair L 23/12, L 17/03, 23/04 and Spartacus on the grounds of "the number of fruit branches and the number of fruits" was high and, although the parents had the same indicators on these grounds (the number of fruit-bearing branches in the variety Local - 4.2 pieces, L 23/12 - 4.2 pieces, L 23/04 - 4.4 pieces and Spartacus - 4.0). In reverse combinations, heterosis was manifested, but the effect was lower compared to the indicators in direct combinations. The reciprocal hybrids of the pair of Varieties Spartacus and Local had a high heterosic effect in the reverse combination, when The Local acted as a maternal form (the degree of heterosis by the number of fruit-bearing branches 121% instead of 17% and the number of fruits on the first brush 124% instead of 22% in the direct combination of Spartacus x Local).Four reciprocal hybrid combinations with positive overdominance have been revealed. The degree of dominance in the "number of fruits on the first brush" ranged from - 0.4 to 104. The results of the study of the dominance and heterosis effect of the "number of fruits on the plant" indicate the high sectional value of the reciprocal hybrids studied.

Exploitation of heterosis for yield and yield related traits in okra (Abelmoschus esculentus (L.) Moench)

The present study was conducted in okra to estimate the magnitude of heterosis and to identify superior cross combinations for yield and its component traits. Thirty six F1s were developed by crossing 6 lines viz., Pusa Sawani (L1), Parbhani Kranti (L2), Arka Abhay (L3), Arka Anamika (L4), AE 65 (L5) and 14/11 (L6) and 6 testers viz., AE 64 (T1), AE 66 (T2), AE 17 (T3),14/4 (T4), 14/5 (T5) and 14/10 (T6) of okra in line x tester design during summer of 2018. All the 36 F1s along with their 12 parents (6 lines and 6 testers) and one standard check (Bhendi Hybrid CO 4) were evaluated in a randomized complete block design with two replications at Department of Vegetable Crops, Tamil Nadu Agricultural University, Coimbatore. Significance of mean squares due to treatments revealed the presence of considerable amount of genetic variability among the parents and cross combinations for all yield and yield attributing traits. The relative heterosis recorded the highest of 39.71 per cent in L3 x T2 (Arka Abhay x AE 66) in which twenty one cross combinations were positive and significant. Heterobeltiosis (dii) registered the highest of 28.65 per cent in Pusa Sawani x 14/4 (L1 x T4) in which eighteen cross combinations were significant and positive. The standard heterosis (diii) over check hybrid Bhendi Hybrid CO 4 recorded the highest of 37.12 per cent in Arka Anamika x 14/10 (L4 x T6) and twenty hybrids are positive and significant. Based on the results of the heterosis studies, it is clear that none of the 36 F1 hybrids of okra exhibited any consistency in terms of the direction and degree of heterosis over three bases viz., relative heterosis, heterobeltiosis and standard heterosis for all the characters studied. In the present study, the magnitude of standard heterosis was found to be highly variable in direction and magnitude for all the characters under study. Negative heterosis was desirable for the traits viz., days to first flowering, days to 50 per cent flowering, internodal length and per cent disease incidence in respect to yield while positive heterosis was considered to be desirable for the remaining traits viz., plant height, number of branches per plant, fruit length, fruit girth, fruit weight, number of fruits per plant and yield per plant. Arka Anamika x AE 17 (L4 x T3) expressed significant and positive standard heterosis over the standard parent Bhendi Hybrid CO 4 for eleven traits. The same cross combination Arka Anamika x AE 17 (L4 x T3) recorded significant and negative standard heterosis over the standard check for days to first flowering, days to 50 per cent flowering and per cent disease incidence. Similarly, the cross combination Arka Anamika x 14/10 (L4 x T6) recorded significant standard heterosis over the standard parent Bhendi Hybrid CO 4 for eleven characters. The cross combination of 14/11 x 14/4 (L6 x T4) also noted significant standard heterotic effect over the standard parent for ten traits. AE 65 x 14/4 (L5 x T4) is another best hybrid in terms of heterotic effect over the standard check in which it revealed significant values for nine traits. Considering the above facts, the above mentioned hybrids i.e., Arka Anamika x AE 17 (L4 x T3), Arka Anamika x 14/10 (L4 x T6), 14/11 x 14/4 (L6 x T4) and AE 65 x 14/4 (L5 x T4) could be selected for further improvement in yield and yield attributing components.

Impacts of dominance effects on genomic prediction of sorghum hybrid performance.

Non-additive (dominance and epistasis) effects have remarkable influences on hybrid performance, e.g., via heterosis. Nevertheless, only additive effects are often considered in genomic predictions (GP). In this study, we demonstrated the importance of dominance effects in the prediction of hybrid performance in bioenergy sorghum [Sorghum bicolor (L.) Moench]. The dataset contained more than 400 hybrids between 200 inbred lines and two testers. The hybrids exhibited considerable heterosis in culm length and fresh weight, and the degree of heterosis was consistent with the genetic distance from the corresponding tester. The degree of heterosis was further different among subpopulations. Conversely, Brix exhibited limited heterosis. Regarding GP, we examined three statistical models and four training dataset types. In most of the dataset types, genomic best linear unbiased prediction (GBLUP) with additive effects had lower prediction accuracy than GBLUP with additive and dominance effects (GBLUP-AD) and Gaussian kernel regression (GK). The superiority of GBLUP-AD and GK depended on the level of dominance variance, which was high for culm length and fresh weight, and low for Brix. Considering subpopulations, the influence of dominance was more complex. Our findings highlight the importance of considering dominance effects in GP models for sorghum hybrid breeding.

Мінливість елементів продуктивності у рослин сої гібридів F1, F2

The purpose. To study new genofund of soya variants, to create initial material as to attributes of plasticity and stability of main phases of growth, efficiency, to allocate genotypes and hybrid combinations for further use in selection as genetic sources with economic valuable attributes. Methods. Field, laboratory, mathematical-statistical. Results. Studying variability of basic elements of efficiency of F1 plants, has shown that in the first generation is formed both positive and negative heterosis which in a greater degree depends on genetic properties of parental pairs at hybridization. Variation of degree of heterosis was very great — from 1,8% in a combination of crossing Medeya/Omega Vinnitskaya up to 327,8% in a combination Medeya/Kniazhna. The degree of domination by quantity of beans on one plant was positive with variation from 1,5 units (Medeya/Omega Vinnitskaya) up to 21 (Medeya/Kniazhna). By quantity of seeds from a plant in 8 combinations of crossing positive superdomination — from 1,83 units (Lambert/Smuglianka) up to 13,73 (Medeya/Kniazhna) is noted. On weight of seeds from a plant 7 combinations of crossing with positive superdomination — from 2,34 (Lambert/Smuglianka) up to 50,41 (Omega/Vinnitskaya/Medeya). As to total percent of heterosis degree and frequency of manifestation of a complex of attributes, the following combinations of crossing were better: Medeya/Kniazhna — height of plants 50%, height of attachment of the bottom bean — 78,6, quantity of beans — 42,8, quantity of seeds — 50%, weight of seeds — 50%; Omega Vinnitskaya/Medeya — 47,4%; 57,9; 68,4; 73,7; 84,2% accordingly. Conclusions. By the level of heterosis manifestation and frequency of transgression of basic elements of efficiency — quantity of beans and seeds on a plant and weight of seeds — they lead selections in F2 of phenotypes for crop in nursery of hybrids of the third generation.

Marker-Assisted Improvement of the Elite Maintainer Line of Rice, IR 58025B for Wide Compatibility (S5n ) Gene.

The degree of heterosis in different hybrid rice varieties is reported to be at the highest in indica/japonica cross combination, however, there is a problem of sterility and semi-sterility in such inter sub specific hybrids. To overcome this problem, it is essential to develop parental lines having wide compatibility (S5n) gene. In this study, a functional marker S5-InDel was used for marker-assisted backcrossing (MABB) to introgress S5n gene from Dular into the genetic background of a widely grown recurrent parent IR 58025B, a maintainer line of wild-abortive (WA) cytoplasmic male sterile line, IR 58025A. Further, a closely linked marker nksbadh2 was used for the identification of plants devoid of aroma in backcross population to develop hybrids with no aroma. The stringent phenotypic selection followed by background selection of BC3F4 identified plants with 94.51–98.90% of the recurrent parent genome recovery of lines carrying S5n gene. Subsequently, at 10 promising BC3F5 lines possessing S5n gene with high yielding and long-slender grain type were validated for their maintainer behavior through test crosses with IR 58025A. Also the improved lines showed significantly improved spikelet fertility performance while crossed with japonica and javanica testers in comparison to the original recurrent parent. The improved lines developed in the present study, are being converted to CMS lines through marker-assisted backcross breeding to facilitate precise and improved hybrid breeding program in rice.

Evaluation studies of hot pepper hybrids (Capsicum annuum L.) for yield and quality characters

Chilli is the most important worldwide grown and consumed vegetable and spice because of its colour, taste, pungency, flavor and aroma. Hybridization has assumed commercial dimensions in numerous vegetable crops. Hot pepper offers great scope for improvement through this method. Diallel mating design is useful to select a suitable cross combination from large number of germplasm. Hence, present study was carried out to find out degree of heterosis in chilli hybrids. Six homozygous inbreds of hot pepper viz., Arka Lohit, K 1, LCA 334, LCA 625, PKM 1 and Pusa Jwala were crossed in June 2013 by making direct and reciprocal crosses for yield and quality aspects at the Department of Vegetable Crops, HC&RI, TNAU, India. From the present study, the hybrids were selected on the basis of high per se performance and heterosis. Marked heterosis was observed for all the ten characters studied. Thus, the potential hybrids viz., LCA 625 × K 1, PKM 1 × LCA 625, Pusa Jwala × PKM 1, Pusa Jwala × K 1, K 1 × Arka Lohit and Arka Lohit × LCA 334 were identified for number of fruits, dry pod weight, fruit quality and high yield. These F1 hybrids could be tested in different seasons over different locations for assessing their stability for high yield and quality. The hybrids LCA 625 × K 1, K 1 × Arka Lohit and Pusa Jwala × PKM 1 could be particularly exploited for dry pod yield, since they also had improved economic traits besides good fruit quality parameters. The best hybrids might be utilized for further chilli improvement programme.

Gene Action, Combining Ability, Genetic Expression of Heterosis and Characterization of Rice (<i>Oryza sativa</i> L.) Genotypes for Quality Traits

Present investigation was conducted to estimate the per se performance, combining ability and heterosis for grain quality traits in rice using line × tester mating design. Analysis of variance with respect to crosses revealed significant differences for all the traits studied. GCA and SCA results revealed the predominance of SCA variance in relation to GCA variance for all the traits. For aroma, twenty one cross combinations were identified having slight to moderate aroma. Among lines, investigation of highest gca effects illustrated that HPR 2858, HPR 2761, HPR 2754, HPR 2668 and HPR 2748 (P) were good general combiners for different quality traits. Among the testers, HPR 2216 exhibited maximum gca effects for protein content, amylose content and gel consistency while Pusa Basmati 1509 was good combiner for gelatinization temperature. Further, cross combinations HPR 2748 (W) × HPR 2216, HPR 2755 × Kasturi, HPR 2761 × Pusa Basmati 1509 and HPR 2748 (P) × Pusa Basmati 1509 were identified as best specific combination for different grain quality traits. Cross combinations HPR 2748 (W) × HPR 2216, HPR 2761 × HPR 2216, HPR 2748 (P) × Pusa Basmati 1509 showed high degree of heterosis over standard check for different quality parameters.

Performance and carcass traits in the diallel crossing of pacu and tambaqui

With the purpose of evaluating the changes and the degree of heterosis on performance and carcass traits of fish from the diallel crossing between Pacu and Tambaqui, four genetic groups were generated through hormonal induction: pacu, tambaqui, tambacu and paqui. For 196 days, 400 juveniles of each genetic group were stocked in a pond divided into four parts of equal size, one for each group. At the end of this period, when the fish weighed on average 1024 g (±115.52 g), 20 specimens of each genetic group were sampled, weighed, measured: head length; standard length; body height; and width; and also processed resulting in following body yield: viscera; carcass; head; fillet; rib; residue and skin yields. There was positive heterosis for body weight, viscera and skin yield and head measures and negative heterosis for carcass and filet yield and body width, indicating that the hybrids have better performance on weight gain, but are inferior in relation to the carcass conformation.

Accumulation of Three Clubroot Resistance Genes through Marker-assisted Selection in Chinese Cabbage (Brassica rapa ssp. pekinensis).

Many clubroot resistant (CR) cultivars of Chinese cabbage (Brassica rapa ssp. pekinensis) have been bred so far, but their usage is limited because the capacity for resistance breaks down with time. This degradation is caused by a pathogenic variation in the causal fungus Plasmodiophora brassicae. We attempted to accumulate 3 CR genes, CRa, CRk, and CRc, through marker-assisted selection. Five doubled haploid CR lines with an individual CR locus were used as breeding materials. The CR lines were crossed with each other. A subsequent selection for resistance was performed using sequence characterized amplified region markers in segregating generations. As a result, 4 homozygous lines for 3 resistance genes and the F1 hybrids between them were developed. CR pyramiding lines were inoculated with 6 field isolates of P. brassicae. The homozygous lines for 3 CR genes, whether selfed or crossed, exhibited exceedingly high resistance against all of the isolates. Morphological characters of F1 hybrids were comparable to those of a control cultivar, but the degree of heterosis was less than expected, which is probably because of genetic similarity of the parents. The results of this study prove that clubroot resistance can be reinforced through the accumulation of varied resistance genes in B. rapa.

Manifestation of Heterosis for Yield and Component Traits in Rice (Oryza sativaL.) under Temperate Environment

Hybrid rice technology offers a readily available opportunity to increase the productivity of rice in acceptable manner. In present study, 36 cross combinations developed by crossing two CMS lines with 18 testers in line x tester mating design were evaluated to find out best heterotic combinations in terms of yield and yield components. Assessment of heterosis based on standard checks (SR-1 and Jhelum) of effectively restored cross combinations showed that there was significant heterosis for all the traits except number of filled grains per panicle and the degree of heterosis varied from trait to trait. All combinations that showed superiority over standard checks for grain yield per plant (ranged from 25.88% to 55.70%), also showed significant heterosis for majority of other traits. The best cross combination in terms of grain yield was SKAU7A x K-08-61-2 and for early maturity SKAU11A x SR-2 over check SR-1 only. Cross combinations SKAU 7A x K-08-61-2, SKAU 7A x SR-2, SKAU 11A x K-08-60-2, SKAU 11A x K-08-59-3 and SKAU 11A x SKAU-389 were found to be good specific combinations for grain yield per plant and other desirable traits and need to be tested on large scale for their commercialisation under temperate conditions.

Investigation on direct and reciprocal crosses in maize ( Zea mays L.)

Seven traits of twelve hybrids derived from direct and reciprocal crosses of four parental lines were examined during three years in Hungary. No significant differences were found between the direct and reciprocal crosses for stalk diameter or leaf number over the average of three years in any of the hybrids. Significant differences in the number of primary tassel branches were observed between UDH5 and its reciprocal UDH8, and between UDH6 and its reciprocal UDH11. It was evident in both instances that the degree of heterosis in the reciprocal crosses far exceeded that in the direct ones. A high number of tassel branches was dominant over a low number, so this trait was preferentially inherited in the hybrids. A positive correlation was observed between plant height and main ear attachment height (r = 0.67**). A positive correlation (r = 0.89**) was also found between the length of the main tassel axis above the lowest and above the uppermost side-branch. A medium correlation was observed between the number of primary tassel branches and the plant height (r = −0.42**). The number of primary tassel branches exhibited the highest heterosis. These results can be utilized in practical selection and seed production.