Showing papers on "Diallel cross published in 1994"
TL;DR: Evolution via selection of maternal effects would be possible in the study population because these effects are in part due to genetic differences among parents, suggesting strong interaction of the observed effects with the environment.
Abstract: To predict the possible evolutionary response of a plant species to a new environment, it is necessary to separate genetic from environmental sources of phenotypic variation. In a case study of the invader Solidago altissima, the influences of several kinds of parental effects and of direct inheritance and environment on offspring phenotype were separated. Fifteen genotypes were crossed in three 5 × 5 diallels excluding selfs. Clonal replicates of the parental genotypes were grown in two environments such that each diallel could be made with maternal/paternal plants from sand/sand, sand/soil, soil/sand, and soil/soil. In a first experiment (1989) offspring were raised in the experimental garden and in a second experiment (1990) in the glasshouse. Parent plants growing in sand invested less biomass in inflorescences but produced larger seeds than parent plants growing in soil. In the garden experiment, phenotypic variation among offspring was greatly influenced by environmental heterogeneity. Direct genetic variation (within diallels) was found only for leaf characters and total leaf mass. Germination probability and early seedling mass were significantly affected by phenotypic differences among maternal plants because of genotype (genetic maternal effects) and soil environment (general environmental maternal effects). Seeds from maternal plants in sand germinated better and produced bigger seedlings than seeds from maternal plants in soil. They also grew taller with time, probably because competition accentuated the initial differences. Height growth and stem mass at harvest (an integrated account of individual growth history) of offspring varied significantly among crosses within parental combinations (specific environmental maternal effects). In the glasshouse experiment, the influence of environmental heterogeneity and competition could be kept low. Except for early characters, the influence of direct genetic variation was large but again leaf characters (= basic module morphology) seemed to be under stricter genetic control than did size characters. Genetic maternal effects, general environmental maternal effects, and specific environmental maternal effects dominated in early characters. The maternal effects were exerted both via seed mass and directly on characters of young offspring. Persistent effects of the general paternal environment (general environmental paternal effects) were found for leaf length and stem and leaf mass at harvest. They were opposite in direction to the general environmental maternal effects, that is the same genotypes produced "better mothers" in sand but "better fathers" in soil. The general environmental paternal effects must have been due to differences in pollen quality, resulting from pollen selection within the male parent or leading to pre- or postzygotic selection within the female parent. The ranking of crosses according to mean offspring phenotypes was different in the two experiments, suggesting strong interaction of the observed effects with the environment. The correlation structure among characters changed less between experiments than did the pattern of variation of single characters, but under the competitive conditions in the garden plant height seemed to be more directly related to fitness than in the glasshouse. Reduced competition could also explain why maternal effects were less persistent in the glasshouse than in the garden experiment. Evolution via selection of maternal effects would be possible in the study population because these effects are in part due to genetic differences among parents.
174 citations
TL;DR: A diallel analysis of heterosis using two classes of molecular markers: restriction fragment length polymorphisms, (RFLPs) and microsatellites indicated that high level heterosis is common among these crosses: more than 100% midparent and 40% better-parent heterosis were observed in many F1s, including some crosses between maintainer lines.
Abstract: Hybrid rice has contributed significantly to the dramatic increase of rice production in the world. Despite this, little attention has been given to studying the genetic basis of heterosis in rice. In this paper, we report a diallel analysis of heterosis using two classes of molecular markers: restriction fragment length polymorphisms, (RFLPs) and microsatellites. Eight lines, which represent a significant portion of hybrid rice germ plasm, were crossed in all possible pairs, and the F1s were evaluated for yield and yield component traits in a replicated field trial. The parental lines were surveyed for polymorphisms with 117 RFLP probes and ten microsatellites, resulting in a total of 76 polymorphic markers well-spaced in the rice RFLP map. The results indicated that high level heterosis is common among these crosses: more than 100% midparent and 40% better-parent heterosis were observed in many F1s, including some crosses between maintainer lines. Heterosis was found to be much higher for yield than for yield component traits, which fits a multiplicative model almost perfectly. Between 16 and 30 marker loci (positive markers) detected highly significant effects on yield or its component traits. Heterozygosity was significantly correlated with several attributes of performance and heterosis. Correlations based on positive markers (specific heterozygosity) were large for midparent heterosis of yield and seeds/panicle and also for F1 kernel weight. These large correlations may have practical utility for predicting heterosis.
166 citations
TL;DR: The parents from the Mexican highlands tended to have a positive GCA effect for yield in Mexico but negative values in Colombia, whereas parents adapted to mid-elevation tropical environments showed the opposite tendency.
Abstract: To develop an effective breeding programme for rainfed production of the common bean (Phaseolus vulgaris L.), the inheritance of seed yield under such conditions should be understood, preferably considering the effects of environment to account for site or season specificity. Thus, heritability, expected and realized gain from selection, and combining ability were evaluated for a nine-parent diallel of common bean without reciprocals but including parents, at two locations each in Mexico and Colombia, using the F2 and F3 population bulks. Heritability estimated from regressions of F3 on F2 ranged from 0·09 ± 0·18 (S.E.) to 0·75±0·25 for seed yield, from 0·26±009 to 0·34±009 for days to maturity and from0·57±004 to 0·80±004 for 100-seed weight. Expected gain from selection in the F2 was estimated as a percentage of the population mean, selecting the upper 20% of the populations. Expected gain in seed yield ranged from 1·8 to 8·4% in Mexico and from 6·5 to 28·1% in Colombia. Realized gains in seed yield in the F3 were 0·4–7·4% in Mexico and 2·9–15·7% in Colombia. Realized gain values for days to maturity were 13·4%. General combining ability (GCA) mean squares (estimated using Griffing's Method 2, Model 1) were significant (P <0·01) and larger than those for specific combining ability (SCA) for all traits at all locations. The parents from the Mexican highlands tended to have a positive GCA effect for yield in Mexico but negative values in Colombia, whereas parents adapted to mid-elevation tropical environments showed the opposite tendency. However, all significant GCA values of breeding line V8025 were positive in both countries.
82 citations
TL;DR: A microcomputer program has been developed to be used as a teaching tool in quantitative genetics classes and as a means of analyzing real data from diallel crosses.
Abstract: A microcomputer program has been developed to be used as a teaching tool in quantitative genetics classes and as a means of analyzing real data from diallel crosses. The first part of the program, the simulation module, is of use as a teaching tool, offering students the opportunity to examine the ramifications of the underlying genetic and statistical assumptions of diallel mating designs. In particular, the program illustrates the difficulty in obtaining reliable estimates of genetic components of variance when employing a restricted number of parents. Using user-entered values for the population mean, the number of parents, and genetic, environmental, and error variances, the program generates and analyzes multiple sets of data. The user can experiment by altering the parameters to test different strategies to cope with the difficulties inherent in the diallel mating design. The second module allows the analysis of real-world experiments made in any of four diallel mating designs. The user may enter and correct data in the program itself, or import data as ASCII files from other programs. The program prints an analysis of variance table, and tables of means by variety and cross, heterosis, general and specific combining abilities, and genetic components of variance and their standard errors.
62 citations
TL;DR: In this paper, the optimality of complete diallel cross in incomplete blocks is investigated, and a table of optimal complete cross plans for up to 15 lines is provided, where the optimal complete crossing plan is derived using nested balanced incomplete block designs.
Abstract: SUMMARY Optimality of complete diallel crosses in incomplete blocks is investigated. Optimal complete diallel crosses are characterized, and such binary plans are derived using nested balanced incomplete block designs. A table of optimal complete diallel crosses for up to 15 lines is also provided.
58 citations
TL;DR: Major genetic progress for resistance can be expected among progeny from crosses with resistant parents, however, selection would be most effective if delayed to later generations because of dominance, and choice of the specific female parent may produce a higher level of resistance.
Abstract: Septoria tritici blotch constitutes a major disease problem of wheat world-wide. To efficiently breed wheat for resistance to this disease, an understanding is required of the inheritance of resistance. Our objective was to study the quantitative inheritance of resistance under field conditions. A nine-parent diallel and a generation mean experiments were conducted at Toluca, Mexico in 1986 and 1987, respectively, to investigate gene effects. General combining ability effects accounted for most of the variation although specific combining ability effects were detected in some crosses. Ias20*5/H567.71, Thornbird, and RPB709.71/Coc contributed the most to reduced disease severity. Reciprocal effects were detected in two of 36 crosses, where RPB709.71/Coc contributed additional reduced disease severity when used as female. The analysis of generation means confirmed results obtained from the diallel. Additive effects were also most important. Dominance effects and epistasis, mostly of the additive × additive type, were found in some crosses. Hence, substantial genetic progress for resistance can be expected among progeny from crosses with resistant parents. However, selection would be most effective if delayed to later generations because of dominance, and choice of the specific female parent may produce a higher level of resistance.
57 citations
TL;DR: Major dominant effects for resistance were associated with KO54W, which makes it particularly suitable for use in backcross recovery programs for gray leaf spot resistance.
Abstract: Diallel cross analysis of resistance to gray leaf spot (caused by Cercospora zeae-maydis) in an inbred set of diverse heterotic types revealed marked differences in general and specific combining abilities. The former component was of greater relative importance in maize breeding material largely unselected for resistance to this disease, although nonadditive effects were recognized as playing a significant part in the resistance mechanism. Inbreds KO54W and SO507W, representing the F arid M heterotic groups, respectively, exhibited the highest resistance and inbred SP713W (P heterotic group) the lowest resistance. Major dominant effects for resistance were associated with KO54W, which makes it particularly suitable for use in backcross recovery programs for gray leaf spot resistance
55 citations
TL;DR: It was concluded that the first generation of hybrids, likely to appear on the market in the next few years, will be characterized by a yield potential only slightly superior to that of the best standard cvs but associated with other desirable traits, such as bread-making quality.
Abstract: Combining ability for grain yield, yield components, and several agronomic and qualitative traits, was studied in a seven-parent diallel cross. The 21 F1 hybrids and the seven parental cultivars were grown in replicated plot trials sown at normal seed density in three locations in the years 1992 and 1993. The effects of general combining ability (gca) were highly significant for all the traits measured with the exception of seeds per spikelet, while the specific combining ability (sca) effects were statistically significant for grain yield, plant height, heading time, for all the yield components, and for the Chopin alveographic parameters P and P/L ratio. For the majority of the traits measured gca was greater than sca. Standard heterosis (sh) for grain yield, i.e., the superiority of the hybrids over the best pure line cultivar(cv Eridano), was only 3.3%, confirming previous finding which indicate sh effects in the range of 10%. The most interesting hybrid derived from the cross Maestra x Golia revealed a yield level approaching that of the highest yielding cv Eridano but appeared more interesting because of its reduced plant height and superior bread-making quality, signifying a selling price 30% higher. It was concluded, therefore, that the first generation of hybrids, likely to appear on the market in the next few years, will be characterized by a yield potential only slightly superior to that of the best standard cvs but associated with other desirable traits, such as bread-making quality.
49 citations
TL;DR: This study determined the relative magnitude of genetic components and combining ability estimates for the GF parameters by growing parents and F 1 generations resulting from a 4 × 4 diallel mating scheme in 1987 and 1988.
Abstract: Grain yield of wheat (Triticum aestivum L.) is determined in part by kernel weight, which is a function of the rate and duration of grain fill (GF). The lack of information regarding the inheritance of GF rate and duration prompted this study to determine the relative magnitude of genetic components and combining ability estimates for the GF parameters. Parents and F 1 generations resulting from a 4 × 4 diallel mating scheme were grown in space-planted experiments in 1987 and 1988. The plots were sampled at 2- to 3-d intervals after anthesis to obtain GF data [...]
48 citations
TL;DR: The inheritance of phosphorous (P) — deficiency tolerance in rice was investigated by a sevenparent diallel and graph analysis revealed that tolerant parents have an excess of recessive genes, while moderate and susceptible parents possess more dominant genes.
Abstract: The inheritance of phosphorous (P) — deficiency tolerance in rice was investigated by a sevenparent diallel The parent materials involved were four P-efficient (IR20, IR54, IR28, and Mahsuri), one moderately P-efficient (TN1), and two P-inefficient (IR31406333-1 and IR34686-179-1-2-1), genotypes Relative tilering ability (RTA) under P-deficient and P-supplemented soil conditions was the parameter used in determining the tolerance level of the different genotypes Diallel graph analysis revealed that tolerant parents have an excess of recessive genes, while moderate and susceptible parents possess more dominant genes Genetic-component analysis suggested that both additive and dominance gene effects are involved in the inheritance of P-deficiency tolerance in rice The trait exhibited over doiminance as confirmed by the graphical analysis Narrow-sense heritability of the trait was moderate (050) and environmental effects were low Both the general combining ability (GCA) and the specific combining ability (SCA) were significant, but GCA was more prevalent than SCA Tolerant parents exhibited a high GCA whereas susceptibles have a very poor GCA, suggesting that tolerant parents were mostly enriched in additive genes and susceptible parents in non-additive genes Crosses involving two high general combiners showed low SCA effects whereas crosses between poor general combiners manifested highly-significant SCA values
47 citations
TL;DR: Low heritability and evidence that maternal effects on seed mass are largely environmental suggest that in this population there is little evolutionary potential for change in seed mass under conditions experienced during the study.
Abstract: We determined the genetic basis of several traits related to overall fitness of Aquilegia caerulea, a perennial herb of the Rocky Mountains in western North America. To obtain measures of heritability relevant to the evolutionary potential of wild populations, we performed full and partial diallel crosses and studied progeny performance in the field. Based on a joint analysis of two designs with a total of 18 parents and 102 crosses, we detected significant maternal variance for seed mass and emergence time, but this component was negligible for later-expressed traits. Low heritability and evidence that maternal effects on seed mass are largely environmental suggest that in this population there is little evolutionary potential for change in seed mass under conditions experienced during the study. Seed mass varied depending on particular combinations of parents and cross direction. Such an interaction can have several different biological interpretations, including that particular maternal parents selectively provision embryos sired by particular pollen genotypes. Width of the first true leaf after 4 wk of growth and leaf size of juvenile plants at years one and two were significantly heritable and positively genetically correlated. Juvenile survival exhibited significant dominance variance, as expected from evidence of inbreeding depression in this trait. In contrast, for other traits that exhibit inbreeding depression in this population (seed mass and third-year leaf size), dominance variance was negligible.
TL;DR: A four-parent complete dialleld mating-set of three Triticum aestivum L. cultivars, and an alloplasmic line of ‘Selkirk’ in Aegilops variabilis Eig was used, and significant reciprocal effects for callus induction and green plant yield were observed.
Abstract: A four-parent complete dialleld mating-set of three Triticum aestivum L. cultivars ‘Edwall’, ‘Chris’ and ‘Spillman’, and an alloplasmic line of ‘Selkirk’ in Aegilops variabilis Eig. cytoplasm was used. Genetic components among total variation for callus induction, green plant percentage and green plant yield werr 92%, 80% and 77%, respectively, but lower (36%) for plant regeneration. General combining ability (GCA) variance components and narrow-sense heritabilities estimated for callus induction, green plant pereentnge and green plant yield were 74%, 66%, and 53%, and 0.68, 0.54 and 0.43. respectively. Specific combining ability (SCA) variancw was calculated as 85%) of total genctie variation for plant regeneration. Significant reciprocal effects for callus induction. green plant percentage and green plant yield were observed.
TL;DR: A significant association of early anthesis, long GF duration, low GF rate, and high protein concentration was found in a set of F 1 hybrids and their parents from a 4 × 4 diallel cross involving Chinese and U.S. cultivars.
Abstract: Understanding the relationship between grain filling (GF) characteristics, earliness, and N accumulation would aid in improving grain size and grain protein content in wheat (Triticum aestivum L.). A significant association of early anthesis, long GF duration, low GF rate, and high protein concentration was found in a set of F 1 hybrids and their parents from a 4 × 4 diallel cross involving Chinese and U.S. cultivars. This association was also found in an F 2 population of a cross between an early hard red winter Chinese wheat and a late soft white winter U.S. cultivar [...]
TL;DR: This work presents four models for postpollination traits and discusses them in the context of diallel and equivalent reciprocal crossing designs, which can be used to examine hypotheses of evolutionary interest.
Abstract: Plant reproduction includes a series of critial "postpollination" stages that begin with deposition of pollen and culminate in formation of mature seeds. Interest in sexual selection, along with advances in empirical methods, has fostered efforts to characterize genetic variation of reproductive traits expressed during these stages, for example, traits of ovules, of pollen growing through pistillar tissue, and of mature seeds. However, because such phenotypes are attributable in many cases to triploid endosperms or haploid gametophytes alone or in combination with diploid tissue of the maternal plant, the standard quantitative genetic theory does not apply. The complex and nonstandard determination of postpoilination reproductive traits makes it necessary to develop models that are appropriate to the genetic participants in question. We present four models for postpollination traits and discuss them in the context of diallel and equivalent reciprocal crossing designs. These models can be used to examine h...
TL;DR: Adult-plant resistance (APR) to powdery mildew in wheat has been documented as being more durable than hypersensitive resistance, but little is known about the inheritance and diversity of this resistance.
Abstract: Adult-plant resistance (APR) to powdery mildew [Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal] in wheat (Triticum aestivum L.) has been documented as being more durable than hypersensitive resistance. However, little is known about the inheritance and diversity of this resistance. Combining abilities and gene effects for APR to powdery mildew were studied in a diallel cross involving one susceptible and six APR cultivars. Parents, F 1 , and F 2 populations were evaluated in replicated field trials under natural epidemics of powdery mildew [...]
TL;DR: It is postulated that head rice percentage SCA effects were due predominantly to additive X additive epistatic effects rather than dominance effects, indicating the importance of additive genetic effects in the inheritance of head rice Percentage.
Abstract: The value of rough rice (Oryza sativa L.) is often determined by the percentage of head rice and total milled rice produced after milling. The objective of this study was to obtain information on general combining ability (GCA), specific combining ability (SCA), and high-parent heterosis for head rice percentage, total milled rice percentage, and rough rice yield. An eight-parent diallel (F1 crosses plus parents) was evaluated in 1991 at two Arkansas locations: Stuttgart and Marianna. Genetic variation among the hybrids for total milled rice percentage was nonsignificant. The GCA effects were more important than SCA effects for head rice percentage, indicating the importance of additive genetic effects in the inheritance of head rice percentage. it is postulated that head rice percentage SCA effects were due predominantly to additive X additive epistatic effects rather than dominance effects. Additive and additive X additive epistatic types of gene action are most easily exploited by producing homozygous genotypes. Single cross performance for head rice percentage could largely be predicted by GCA effects or mid-parent means. Average heterosis, as indicated by the Parent vs. Hybrid mean squares, was nonsignificant for head rice percentage, but significant for rough rice yield. High-parent heterosis for rough rice yield, head rice percentage, and head rice per plot averaged 21, -5, and 22%, respectively. High-parent heterosis, obtained from the hybrids of this eight-parent diallel, for head rice per plot was due primarily to rough rice yield heterosis rather than head rice percentage heterosis. Based on the yield of bead rice per plot, hybrid rice production would be feasible.
TL;DR: A complete diallel cross among three populations of red swamp crawfish, Procambarus clarkii, was used to estimate genetic effects for body size traits and dressout percentage.
TL;DR: The differences in patterns of GCA and SCA among the parents strong evidence that genetic variation for osmotic adjustment among the ten parents was controlled by more than one gene.
01 Jan 1994
Journal Article•
TL;DR: A 10 × 10 diallel combining ability analysis showed the predominant role of the additive gene action for the expression of all the characters under study except for the leaf area, biological yield and harvest index.
Abstract: A 10 × 10 diallel combining ability analysis showed the predominant role of the additive gene action for the expression of all the characters under study except for the leaf area, biological yield and harvest index. The variance owing to specific combining ability was also significant for the days to flowering, plant height, days to maturity and yield/plant, indicating the operation of a non-additive gene action as well. The variety CPAN 1992 was identified as a good general combiner for the yield and the major yield components and HD 2329 for the seed yield and the harvest index. UP 2121 may be used for the improvement of the seed size and the duration of the crop
TL;DR: In this article, a large number of incomplete block designs for Griffing's complete diallel cross-systems I, II and III, involving from five to 12 lines, are suggested, using two-associate triangular partially balanced incomplete blocks.
Abstract: A large number of incomplete block designs for Griffing's complete diallel cross-systems I, II and III, involving from five to 12 lines, are suggested, using two-associate triangular partially balanced incomplete block designs. Analysis of incomplete block designs for complete diallel cross-systems has been carried out assuming the most appropriate model for genetic yield, as advocated by Hinklemnann. This includes estimation of the general combining ability, specific combining ability and reciprocal cross- effects. An illustration of the design for each system is presented.
TL;DR: Diallel analysis showed that «Morex» and Iran-3a were the best combiners for partial resistance to bacterial leaf streak in barley and could be successfully used for breeding purposes.
Abstract: Seven barley genotypes with high genetic variability for resistance to bacterial leaf streak (Xanthomonas campestris pv. hordei) were crossed in diallel fashion to determine the inheritance of resistance to this disease. Two experiments were undertaken in a controlled growth chamber using a complete-block design with four replicates. Each replicate consisted of a row of 20 seedlings per parent or F 1 hybrid. An Iranian strain of bacterial leaf streak was used for inoculation of 12-day-old seedlings. Results showed that the cultivars «Express» and «Morex» and the Iranian pure line Iran-3a had a high partial resistance in both experiments. Diallel analysis showed highly significant general and specific combining abilities. «Morex» and Iran-3a were the best combiners for partial resistance to bacterial leaf streak in barley and could be successfully used for breeding purposes
Journal Article•
TL;DR: Both GCA and specific combining ability (SCA) effects were significant for plant size traits, but SCA was more important than GCA in predicting progeny plant size.
Abstract: Fifty-two alfalfa (Medicago sativa L.) clones, randomly selected from the cultivar Baker and the experimental line MNGRN-4, were evaluated for resistance (based on nematode reproduction) to Pratylenchus penetrans in growth chamber tests (25 C). Twenty-five clones, representing the range of nematodes and eggs per plant, were selected and retested. Four moderately resistant and two susceptible alfalfa clones were identified. Inheritance of resistance to P. penetrans was studied in these six clones using a diallel mating design. The S[sub1], F[subl], and reciprocal progenies differed for numbers of nematodes and eggs per g dry root and for shoot and root weights (P 0.05). Resistance, measured as numbers of nematodes in roots, was correlated between parental clones and their S[sub1] families (r = 0.94), parental clones and their half-sib families (r = 0.81), and S[sub1] and half-sib families (r = 0.88). General combining ability (GCA) effects were significant for nematode resistance traits. Both GCA and specific combining ability (SCA) effects were significant for plant size traits, but SCA was more important than GCA in predicting progeny plant size. Reciprocal effects were significant for both nematode resistance and plant size traits, which may slow selection progress in long-term selection programs. However, the GCA effects are large enough that breeding procedures that capitalize on additive effects should be effective in developing alfalfa cultivars with resistance to P. penetrans. Key words: alfalfa, inheritance of resistance, Medicago sativa, Pratylenchus penetrans, nematode, nematode resistance, root-lesion nematode.
TL;DR: Genetic correlations between shoot formation and other in vitro traits, except callus weight and root formation, were higher in magnitude than the corresponding phenotypic correlations estimates, indicating the importance of genetic effects.
Abstract: Combining ability for six in vitro culture traits in wheat were studied in a 8×8 diallel cross (excluding reciprocals). Specific combining ability effects (sca) were significant for all six traits derived from immature embryos on two media protocols, whereas general combining ability (gca) variances were significant only for five of them. Furthermore, based on ratios obtained by comparing the ratio of K2 gca to K2 sca, sca was more important than gca for all six traits. Genetic correlations between shoot formation and other in vitro traits, except callus weight and root formation, were higher in magnitude than the corresponding phenotypic correlations estimates, indicating the importance of genetic effects.
TL;DR: A characterization of spontaneous nitrate tolerance of nitrogen fixation in soybean was carried out by means of 2 reciprocal grafting experiments, with a top cross and a diallel type design, indicating that interaction effects with root control could not be excluded for this trait.
Abstract: Summary — A characterization of spontaneous nitrate tolerance of nitrogen fixation in soybean was carried out by means of 2 reciprocal grafting experiments, with a top cross and a diallel type design. Shoot-root control of nitrate tolerance was studied in a spontaneous tolerant line (Tielingbaime), a non-tolerant cv (Kingsoy), and 5 progeny lines derived from their cross. Both experiments demonstrated a shoot control for nitrate tolerance of nodulation. Nitrate tolerance was expressed as the maintenance of a higher number and a greater specific mass of nodules in the presence of nitrate. Regulation of nitrogen fixation in the presence of nitrate also seemed to be related to shoot factors. However, diallel analysis of reciprocal grafts indicated that interaction effects with root control could not be excluded for this trait.
TL;DR: Hybrids between indica varieties which have biomass controlled by dominant genes and japonica varieties which show over-dominance in crosses with indica are promising for breeding hybrid varieties with high biomass coupled with high yielding.
Abstract: This experiment was carried out to study the relationship between heterosis and the polymorphism of genetic markers in rice. We employed 14 varieties, 4 japonica, 4 javanica and 6 indica. Of all the 91 possible combination, one indica × indica cross was missing, so 90 F1 cross combinations were used for half diallel analysis. They were transplanted in a field at 40 × 60 cm spacing and the top part of the plants was sampled and dried 43 days after transplanting to examine the degree of heterosis of biomass. The diallel analysis of the heterosis of biomass showed that dominant effect was larger than additive effect, suggesting that heterosis was contributed by the accumulation of dominant genes. More than 10 genes were considered to be involved in the heterosis. The general combining abiliy of biomass was highly significant and the heterosis of hybrids from crosses between indica and japonica varieties were generally large. Significant relationships were observed between the heterosis of biomass and the polymorphism of the 10 isozymes as well as 29 RFLP markers. However, the correlation coefficients were not so high. It seemed to be difficult to use the polymorphism of markers as an index of heterosis. The analysis of each marker and heterosis showed that several markers which were located dispersedly over the chromosomes showed significant correlations with the heterosis of biomass. According to the diallel analysis, more than 10 genes were related to the heterosis of biomass. Hybrids between indica varieties which have biomass controlled by dominant genes and japonica varieties which show over-dominance in crosses with indica are promising for breeding hybrid varieties with high biomass coupled with high yielding.
TL;DR: Variation and heritability of traits associated with hay quality in intermediate wheatgrass are assessed, the relative magnitude of general and specific combining ability (SCA and GCA) for these traits are ascertained, and relationships among important agronomic and quality traits are examined.
Abstract: Knowledge of heritability and inheritance of nutritive quality traits in intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Deweys would be helpful in choosing effective selection techniques. This study assess variation and heritability of traits associated with hay quality in intermediate wheatgrass, ascertains the relative magnitude of general and specific combining ability (SCA and GCA) for these traits, and examines relationships among important agronomic and quality traits. Six parent clones and the 15 progenies from a diallel cross (reciprocal crosses not included) were evaluated in a replicated field test for in vitro digestible organic matter (IVDOM), neutral detergent fiber (NDF), and N concentration of whole plants, leaf blades, and stems (stem plus leaf sheath)
TL;DR: The results revealed that both additive and dominance components, with the preponderance of later, were important in the inheritance of TH%, indicating that selection for high TH% might be effective.
Abstract: The threshing percentage (TH%) has been suggested as a selection criterion to identify the pearl millet (Pennisetum glaucum (L.) R.Br.) lines with improved ability to fill and set grains under water limiting conditions. In this study, eight genetically diverse pearl millet inbreds and their 28 crosses produced by half diallel crossing design were used to examine range in TH%, to evaluate general combining ability (GCA) of parents and specific combining ability (SCA) effects of crosses. The results showed significant variation among parental lines for TH%. The inbreds differed for their GCA effects and crosses for their SCA effects. Parents with high TH% and positive GCA effects were identified. The results of the study revealed that both additive and dominance components, with the preponderance of later, were important in the inheritance of TH%. Heritability in narrow sense was moderate (55%) indicating that selection for high TH% might be effective.
Journal Article•
TL;DR: Variation due to gca was more pronounced than due to sca indicating the importance of additive gene effects, and specific combining ability was very important for kernel depth and ear diameter.
Abstract: General and specific combining abilities were estimated for ear and grain characters in maize using 6-parent diallel cross excluding reciprocals. Variation due to general combining ability (gca) was highly significant for ear length, ear diameter, ear and cob weight/plant, kernel depth, and 100-kernel weight. Specific combining ability (sca) was very important for kernel depth and ear diameter. Variation due to gca was more pronounced than due to sca indicating the importance of additive gene effects.