Showing papers on "Diallel cross published in 1995"
TL;DR: Neither diversity measure showed promise for predicting F1 performance, but both measures similar information for grouping and differentiating genotypes grouped the genotypes similarly.
Abstract: The probability of recovering a superior individual from the cross of 2 inbred parents is greater if both parents are similar in performance as opposed to one parent being inferior. Heterosis, coefficients of parentage, and molecular markers have been advocated to assess genetic diversity directly between parents. This study was done to determine the extent of DNA polymorphisms among a set of 7 hard red spring wheats and the relationship between genetic diversity based on these molecular markers and coefficients of parentage, and to examine the relationship between diversity and hybrid performance in a diallel cross of these parents. Parents plus the F1 hybrids were grown in 3 field environments (one irrigated and 2 dry-land) near Bozeman. Grain yield, grain weight and protein concentration were measured. Coefficients of parentage, r, were computed for all pairwise combinations of parents. Parents were assayed with 63 sequence tagged site-polymerase chain reaction (STS PCR) primer sets. Genetic similarities, GS, were computed using 27 STS PCR primers sets that showed polymorphism. Rank correlations were computed between the 1 - r and 1 - GS measures of genetic diversity and F1 performance, mid-parent heterosis and SCA effects. The only significant associations between diversity and hybrid performance were those between 1 - r and grain weight SCA effects and heterosis, and protein concentration heterosis. Genetic diversity was inversely related to heterosis and SCA effects for protein concentration. Correlations between the 1 - r and 1 - GS measures of diversity and hybrid performance traits were of the same sign and about equal in magnitude. Coefficient of parentage and GS were significantly correlated, and cluster analysis based on the 1 - r and 1 - GS measures of diversity grouped the genotypes similarly. Neither diversity measure showed promise for predicting F1 performance, but both measures similar information for grouping and differentiating genotypes
124 citations
TL;DR: Very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis.
Abstract: This study was undertaken to determine the relationship between genetic distance of the parents based on molecular markers and F1 performance in a set of diallel crosses involving eight commonly used parental lines in hybrid rice production. The F1s and their parents were measured for five traits including heading date, plant height, straw weight, grain yield and biomass. The parental lines were assayed for DNA polymorphisms using two classes of markers: 140 probes for restriction fragment length polymorphisms (RFLPs) and 12 simple sequence repeats (SSRs), resulting in a total of 105 polymorphic markers well spaced along the 12 rice chromosomes. SSRs detected more polymorphism than RFLPs among the eight lines. A cluster analysis based on marker genotypes separated these eight lines into three groups which agree essentially with the available pedigree information. Correlations were mostly low between general heterozygosity based on all the markers and F1 performance and heterosis. In contrast, very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis. The analyses also suggest the existence of two likely heterotic groups in the rice germplasm represented by these eight lines.
92 citations
TL;DR: Prospects were good for simultaneously improving all four traits by multitrait genotypic recurrent selection for tetraploid potato breeding programme at the Scottish Crop Research Institute.
Abstract: A diallel set of crosses, including selfs and some reciprocal crosses, was made between 15 parents chosen for their male fertility from those included in a tetraploid potato (Solanum tuberosum subsp. tuberosum) breeding programme at the Scottish Crop Research Institute. Seedling progeny tests were used to evaluate the progenies for non-race-specific resistance to late blight (Phytophthora infestans) in both foliage and tubers, quantitative resistance to the white potato cystnematode (PCN) (Globodera pallida) and the commercial worth of their tubers as judged by breeders' visual preference. No reciprocal differences were found. Comparisons of the selfs and crosses revealed inbreeding depression for breeders' preference, which varied among the parents from negligible to severe, whilst there were also statistically significant differences for foliage and tuber blight, but not for PCN. When the selfs were omitted from the combining ability analyses, large differences in general combining ability (GCA) were found for all four traits, and smaller differences in specific combining ability for tuber blight and breeders' preference. The only statistically significant correlation between GCAs for different traits was a favourable one of r = 0.56 between foliage and tuber resistance to late blight. It was concluded that prospects were good for simultaneously improving all four traits by multitrait genotypic recurrent selection.
66 citations
TL;DR: Combined across years, analyses of two eight-parent diallel subsets of the original 10-parent Diallel indicated GCA was more important than SCA in inheritance of preference/nonpreference.
Abstract: Maize weevil (Sitophilus zeamais Motschulsky) can cause severe grain damage in maize (Zea mays L.). Knowledge of inheritance of weevils' preference would be helpful in designing breeding strategies to develop more tolerant/resistant cultivars. This study was conducted to estimate general (GCA) and specific combining ability (SCA) for weevil preference/nonpreference. We used a 10-parent diallel cross in 1992 (Griffing's Method 3, Model 1). In 1993, due to insufficient seeds for some crosses, two eight-parent diallels (Griffing's Method 4, Model 1) were evaluated for GCA and SCA for maize weevil preference of maize grain. The two eight-parent diallels were subsets of the original 10-parent diallel. Second generation grain samples (100 g per plot) from F 1 crosses grown in the field were evaluated for maize weevil preference during 96-d (1992 experiment) and 108-d (1993 experiments) periods in the laboratory. The GCA, SCA, and reciprocal mean squares from the 10-parent diallel results from 1992 were significant. Both GCA and SCA were important in the analysis of the Subset 1 eight-parent diallel combined across years, whereas only GCA was significant in the Subset 2 eight-parent diallel combined across 1992 and 1993 data. Positive effects indicated non-preference and negative effects, preference of grain. Common parent means and GCA effects showed that L108 transmitted the most nonpreference and Mo17, the least nonpreference to its hybrids. In the 1992 data, significant positive GCA effects were detected in L108, L605, and L654 ; and significant negative GCA effects in B73, Mo17, L329, L729, and L266. Mo17 had a significant positive maternal effect (11.6), whereas B73 had a significant negative maternal effect (-11.93). The single cross Mo17 ? x B73 ? would possess more nonpreference than its reciprocal cross. Combined across years, analyses of two eight-parent diallel subsets of the original 10-parent diallel indicated GCA was more important than SCA in inheritance of preference/nonpreference.
37 citations
TL;DR: Breeding methods which explore the additive portion of genetic variance should be employed for obtaining higher-yielding cacao and high seed weight, where the segregant populations should involve cultivars CEPEC 1, SIAL 169 and ICS 1.
Abstract: The objective of this study was to assess five cacao cultivars (selfs) and 20 hybrids with regard to their general-and specific-combining ability for yield components using method 1, model I, of the diallel analysis system. The selfings and the hybrids were obtained through controlled crossings, tested in the field in a random block design with four replications and plots containing 16 plants. The experiment was set up in the Centro de Pesquisas do Cacau, in Itabuna, Bahia, Brasil, in 1975. The characteristics studied were: the number of healthy and collected fruits per plant (NHFP and NCFP), the weight of humid seeds per plant and per fruit (WHSP and WHSF), and the percentage of diseased fruits per plant (PDFP), for 5 years (1986–1990). The F-test values, highly significant for general combining ability (GCA) and specific combining ability (SCA), demonstrated the existence of variability for both effects. However, the effects of SCA were greater than those of GCA, when compared in terms of the average squared effects. This condition held for the characteristics NHFP, NCFP and WHSP, which shows the relative importance of the non-additive genetic effects over the additive effects. The reciprocal effects did not show significance. Breeding methods which explore the additive portion of genetic variance should be employed for obtaining higher-yielding cacao and high seed weight. For this, the segregant populations should involve cultivars CEPEC 1, SIAL 169 and ICS 1. Combinations involving the cultivar ICS 1 presented the most favorable results for the characteristics WHSP and WHSF, where the hybrid SIAL 169 x ICS 1 and its reciprocal were outstanding.
36 citations
TL;DR: Results generally agreed with the reported relationships among the parents and pointed to Yucatan as a potentially useful genetic resource for tropical maize breeding programs.
Abstract: Few of the world's maize (Zea mays L.) germplasm collections have been systematically evaluated in spite of the recognized necessity of broadening the germplasm base of this crop. Knowledge of new heterotic patterns and the breeding potential of maize collections stored in gene blanks can contribute to a widening of the genetic base. The objectives of this study were to (i) evaluate the breeding potential of eight tropical maize germplasms, and (ii) provide further information to clarify the relationships among them. Five Colombian landraces («Andaqui», «Comun», «Costeno», «Puya», and «Yucatan») and three improved maize populations («Tuxpeno-1», «Suwan-1», and «ETO») were crossed in a dialled mating system. The parents and the 28 hybrids were evaluated in six environments for grain yield, days to 50% silking, prolificacy, and ear height. Cultivar (additive) and heterotic effects were highly significant (P ≤ 0.01) for all traits except ear height. Significant (P ≤ 0.05) cultivar heterosis and specific heterotic effects were found for grain yield, with an average 10% high-parent heterosis. Cultivar effects were positive for Suwan-1 (0.86**) and Tuxpeno-1 (0.62**) and negative for Andaqui (−0.42*) and Puya (−0.78**). The same materials showed significant cultivar heterotic effects (0.29**, 0.12*, −0.23**, and −0.22**, respectively). Specific heterosis was found in crosses between Tuxpeno-1 and Comun (0.44**), Yucatan (0.35*), and Suwan-1 (−0.67**). The best materials were improved populations, Suwan-1, and Tuxpeno-1. The ETO population did not perform well per se or in hybrid combinations. Yucatan outyielded ETO and was a parent in two of the three highest yielding crosses. The hybrid Tuxpeno-1 × Ycatan showed the highest high-parent heterosis value (25%**). Results generally agreed with the reported relationships among the parents and pointed to Yucatan as a potentially useful genetic resource for tropical maize breeding programs
35 citations
TL;DR: The results suggest that enhancing the level of high temperature tolerance in wheat germplasm is feasible utilizing existing levels of genetic variability and exploiting additive genetic effects associated with high temperatureolerance.
Abstract: The development of high temperature-tolerant wheat (Triticum aestivum L.) germplasm is necessary to improve plant productivity under high-temperature stress environments. The quantification of high temperature tolerance and the characterization of its genetic control are necessary for germplasm enhancement efforts. This study was conducted to determine the genetic control of acquired high temperature tolerance in common bread wheat cultivars. Reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by heat-stressed seedling leaves was used as a quantitative measure to characterize acquired high temperature tolerance. Eleven-day-old seedlings of 20 F1 progeny produced through a complete 5×5 (‘Payne’, ‘Siouxland’, ‘Sturdy’, ‘TAM W-101’, and ‘TAM 108’) diallel mating design were acclimated at 37° C for 24 hours, followed by a 2-hour incubation at 50° C. Under these test conditions, acquired high temperature tolerance ranged from a high of 75.7% for the genotype TAM W-101 × TAM 108, to a low of 37.3% for the genotype Payne × Siouxland. Partitioning of genotypic variance revealed that only the general combining ability component effect was statistically highly significant, accounting for 67% of the total genotypic variation. These results suggest that enhancing the level of high temperature tolerance in wheat germplasm is feasible utilizing existing levels of genetic variability and exploiting additive genetic effects associated with high temperature tolerance.
33 citations
TL;DR: The finding of little or no paternal variance in particular suggests little scope for postpollination sexual selection through the male function of cosexual plants such as I. aggregata.
Abstract: Events that follow pollination, such as pollen-tube growth and seed maturation, comprise an important phase of angiosperm reproduction. Differential success during this "postpollination" phase may represent phenotypic selection, including sexual selection, or interaction between parents caused, for example, by their genetic similarity. By providing a detailed partitioning of variance in success, diallel crossing designs offer great potential to determine which processes are occurring and their relative magnitudes. We performed three partial diallels with the montane herb Ipomopsis aggregata, using a large sample of parental plants (69 total). Embedded in the designs were crossing-distance treatments of 1 m, 10 m, and 100 m, reflecting a range of parental genetic similarity. We partitioned phenotypic variance in seed set per fruit into six components using restricted maximum-likelihood (REML) analysis. For one diallel, we also partitioned variance in seed mass into five components, and estimated two components of covariance between seed set and mass. Variance caused by maternal effects (Vmat ) comprised 12%-35% of total variance in seed set and 62% of variance in seed mass, and there was a significant negative environmental covariance between seed set and seed mass. Parental interaction made no detectable contribution to phenotypic variance in either of our measures of postpollination success, although crossing distance did contribute slightly but significantly to fit of the model in some cases. Finally, there was no detectable paternal variance (Vpat ) in seed set or seed mass. These results are in keeping with reports from other studies of natural plant populations. The finding of little or no paternal variance in particular suggests little scope for postpollination sexual selection through the male function of cosexual plants such as I. aggregata.
29 citations
TL;DR: Broad-sense heritabilityvalues were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively, an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
Abstract: The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (Wr) on variance (Vr) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
25 citations
TL;DR: Average, line or specific heterosis effects were not significant suggesting that crossbreeding these strains would not increase disease resistance due to heterosis, and significant line effects in Norris and M X K strains demonstrated differences for disease resistance in these strains.
23 citations
TL;DR: Comparisons of the predictive power of different genetic distances derived from molecular markers and from protein quantitative variations in a diallel of 210 hybrids among 21 maize inbred lines of various origin found that protein quantities were better for revealing specific genotypes.
Abstract: As it is related to the variability in genome expression, variability in protein quantities revealed by two-dimensional electrophoresis was proposed for describing phenotypic diversity. The objective of this study was to compare the predictive power of different genetic distances derived from molecular markers and from protein quantitative variations in a diallel of 210 hybrids among 21 maize inbred lines (Zea mays L.) of various origin. The lines were characterized for : 1. 142 markers resulting from the analysis of enzyme, RFLP, and protein-structure polymorphism ; and 2. The variation in relative quantities of 190 proteins. The hybrids were evaluated for six forage traits in four environments. Correlations between the genetic distances computed for 142 marker loci and hybrid performances were moderate to high in diallels using crosses between related lines. Genetic distances based on protein quantities showed, in most cases, similar or lower correlations. Distance measures were not useful as predictors of hybrid performance for crosses between unrelated lines. Protein quantities were better for revealing specific genotypes.
TL;DR: In this article, the use of partial diallel crosses in incomplete block designs as environment designs is discussed in detail and a particular method of constructing such combined mating-environment designs by relating both component designs to certain types of partially balanced incomplete blocks is discussed.
Abstract: Various forms of diallel crosses play an important role in evaluating the breeding potential of genetic material in plant and animal breeding (e.g., Hinkelmann, 1975, inA Survey of Statistical Design and Linear Models, 243-269. Amsterdam: North Holland). In this paper we consider the use of partial diallel crosses in incomplete block designs as environment designs. We discuss in detail a particular method of constructing such combined mating-environment designs by relating both component designs to certain types of partially balanced incomplete block designs. This method is compared with a generally applicable method of embedding partial diallel crosses in existing incomplete block designs as environment designs.
TL;DR: Analysis of a 6×6 diallel experiment led to the selection of these hybrids based on their high heterosis and revealed the nature of gene action of the characters under evaluation.
Abstract: Sixty one double haploid (DH) lines were evaluated for yield components and yield and compared with the three corresponding hybrids from which they were derived through anther culture. Analysis of a 6×6 diallel experiment led to the selection of these hybrids based on their high heterosis and revealed the nature of gene action of the characters under evaluation. The DH lines along with the hybrids and parents were planted following a simple lattice design with two replications. The results show that in DH lines the values of the characters expressing predominantly additive genetic effects could reach the heterotic level of the hybrids. For characters including yield showing predominantly dominance effects, values in the DH lines were significantly lower than those of the corresponding hybrids. The promising DH lines, however, possess a higher yield potential than the better parents.
TL;DR: Gene action for adult-plant resistance to powdery mildew was studied using generation mean analyses of parents and of F1, F2, and backcross populations derived from a diallel cross of one susceptible and three adult- plant resistant wheat cultivars and showed an additive-dominance model was sufficient to explain the variability in the expression of adult- Plant resistance.
Abstract: Gene action for adult-plant resistance to powdery mildew was studied using generation mean analyses of parents and of F1, F2, and backcross populations derived from a diallel cross of one susceptible and three adult-plant resistant wheat cultivars. Joint scaling tests showed that an additive–dominance model was sufficient to explain the variability in the expression of adult-plant resistance in one cross, while digenic epistasis was involved in the other five crosses. Additive gene effects were predominant; however, dominance was significant in four crosses, additive × additive interaction was significant in three crosses, additive × dominance interaction was significant in three crosses, and dominance × dominance interaction was significant in one cross. Therefore, selection for adult-plant resistance would likely be most effective in advanced generations derived from crosses among the adult-plant resistant cultivars Redcoat, Houser, and Massey.Key words: gene action, adult-plant resistance, Blumeria, Er...
TL;DR: In this paper, a method for constructing single replicate incomplete block designs for circulant partial diallel crosses is provided, which are orthogonal and retain full efficiency for estimation of the contrasts of interest.
Abstract: Some incomplete block designs for partial diallel crosses have been given in the literature. These designs are obtained by regarding the number of crosses as treatments, and consequently require several replications of each cross. The need for resorting to a partial diallel cross itself implies that it is desired to have fewer crosses. A method for constructing single replicate incomplete block designs for circulant partial diallel crosses is provided in this paper. The designs are orthogonal, and thus they retain full efficiency for estimation of the contrasts of interest.
TL;DR: A half diallel was made amongst five wheat genotypes of which one was susceptible, while the others had adult-plant resistance, to stripe rust, showing that the average effects of alleles were of much greater importance than was dominance in conditioning resistance in response to two of the pathotypes, while for the third pathotype dominance was important.
Abstract: A half diallel was made amongst five wheat (Triticum aestivum L.) genotypes of which one was susceptible, while the others had adult-plant resistance, to stripe rust (Puccinia striiformis West.). The five parent and ten F1 progeny were grown in the glasshouse and were inoculated with three rust pathotypes at the seedling stage. The latent period was measured on the first leaf. Two procedures were used to analyze the half diallel. Both methods showed that the average effects of alleles were of much greater importance than was dominance in conditioning resistance in response to two of the pathotypes, while for the third pathotype dominance was important. Resistance was conditioned by partial dominance for two pathotypes whereas for the third it was determined by full dominance. Broad-sense heritabilities range from 60–73% and the number of genes involved was different (from 1 to 4), depending on the pathotype.
TL;DR: Genetic analysis of plant regeneration ability in rice was studied in 14 x 14 diallel crosses using 4 japonica, 4 javanica and 6 indica varieties, and among the 14 varities, Kele showed the highest regeneration ability.
Abstract: Genetic analysis of plant regeneration ability in rice was studied in 14 x 14 diallel crosses using 4 japonica, 4 javanica and 6 indica varieties. Calli were obtained from mature seeds and regenerated plantlets were induced in suspension cultures. Among the 14 varities, Kele showed the highest regeneration ability. The largest number of regenerated plantlets was obtained in the F1 hybrid of Kele × Banten. No regenerated plantlet was observed in 4 parents and 8 Fls. The relationship between Vr and Wr in the lO X 10 subdiallel table suggested that there was no non-allelic interaction and that the low regeneration ability was dominant. Analysis of variance of lo ×10 diallel table showed that both additive and dominant effects were significant, and reciprocal effect was also significant. There was no significant relationship between ecospecies and above genetic properties. Among the 14 varieties, indica variety, Qing Er Ai and Kele would be useful to improve the re-generation ability, because of their significant high GCA and favorable maternal effects. Heterosis of regeneration ability in the crosses of japouica x indica, javauica x indica and their respective reciprocal crosses was higher than the crosses in japonica × japonica, japonica x javanica and javanica x japonica . There was no significant correlation (r = 0.199) between regeneration ability and shoot dry weight of each F1 hybrid, indicating that it was difficult to obtain the F1 hybrids showing high heter-osis in both characters.
01 Jan 1995
TL;DR: In this paper, six maize inbred were crossed in complete diallel fashion to evaluate their general and specific combining ability for yield and its components, and the magnitude of GCA variance for yield was higher than SCA variance showing the predominance of additive gene action.
Abstract: Six maize inbred were crossed in complete diallel fashion to evaluate their general and specific combining ability for yield and its components. Variance components due to specific combining ability (SCA) were higher than general combining ability (GCA) variances for ears per plant, kernel rows per ear, kernels per row and 100 grain weight which manifested non-additive gene action. The magnitude of GCA variance for yield was higher than SCA variance showing the predominance of additive gene action.
Journal Article•
TL;DR: Combining ability analysis was undertaken in 10 x 10 half diallel progenies of barley for grain yield and its component characters in both F1 and F2 generations, with additive gene action predominant.
Abstract: Combining ability analysis was undertaken in 10 x 10 half diallel progenies of barley for grain yield and its component characters in both F1 and F2 generations. Both additive and nonac!ditive gene actions were important in controlling the inheritance of all the traits. However, additive gene action was predominant. The parents BG 105, DL 88, and DL 165 were the best general combiners for grain yield and average to high combiners for other important traits. The best specific crosses for grain yield were BG 105 X RO 728, BL2 X BG 105, DL 100 X DL 88 and DL 165 X DL 88, involving parents with medium X high and high X high general combiners. Exploitation of additive and nonadditive gene actions through biparental mating and/or diallel selective mating systems is suggested.
15 Aug 1995
Journal Article•
TL;DR: Genotypic correlations between grey leaf spot ratings, yield and kernel quality traits suggested that certain of the tested genotypes displayed sink-induced susceptibility to the disease.
Abstract: The inheritance of resistance to grey leaf spot of maize (Zea mays L.), caused by Cercospora zeae-maydis, was studied using a 12 × 12 diallel cross. Information on the heterotic performance of the inbred lines enabled identification of patterns of transmission of resistance to susceptible genotypes. The study confirmed that an accurate evaluation of heterotic patterns for grey leaf spot requires an assessment of both the inbred lines and all the single crosses among them. Resistance of the tested maize genotypes to grey leaf spot can be expressed in terms of an additive-dominance model, with dominance almost complete. As the incidence of this fungus reached epidemic proportions only after physiological maturity, yield was not adversely affected by grey leaf spot. Genotypic correlations between grey leaf spot ratings, yield and kernel quality traits suggested that certain of the tested genotypes displayed sink-induced susceptibility to the disease. Hayman's (1954) variance-covariance graphical technique co...
TL;DR: Selection of diploid potato genotypes that produce high frequencies of 2n-pollen grains in different environments is an important requirement for analytic breeding as well as for true potato seed production.
Abstract: Selection of diploid potato genotypes that produce high frequencies of 2n-pollen grains in different environments is an important requirement for analytic breeding as well as for true potato seed production. In this context, quantitative estimates of 2n-pollen formation were made in two type of diploid potato populations. One population set consisted of the progeny from diallel crosses of five well-known diploid potato clones (A=US-W 5293.3, B=US-W 5295.7, C=US-W 5337.3, D=US-W 7589.2 and E=772102-37). Another population set was obtained by pollinating three genotypes of Solanum phureja, IvP35, IvP48 and IvP101 with clones A, C and E. It was observed that the behaviour of the parental clones with respect to 2n-pollen grains formation in different environments, such as in Europe and China, was stable. The correlation coefficient between means of 2n-pollen grains frequency of combinations and percentage of genotypes with more than 5% 2n-pollen grains in a given combination were estimated and that between mean and maximum frequency of 2n-pollen grains formation in each combination. The results showed that the former coefficients were significant wheareas the latter were not. The combining ability analysis revealed variation in 2n-pollen grains formation between families. Specific combining ability (SCA) effects contributed much more than general combining ability (GCA) to the variation in 2n-pollen grains formation. The broad-sense heritability of 2n-pollen grains formation was estimated to vary between 0.45 and 0.53 and the narrow-sense heritability was calculated to be 0.15 and 0.20 in the two types of populations. This means that additive variance was relatively low. Two to four genes were estimated to control the inheritance of 2n-pollen grains formation.
TL;DR: Arawaca and Piritu should be chosen as parents for any sesame-breeding programme in view of their large GCA effects, suggesting that hybrids should be produced for specific locations.
Abstract: Heterosis and combining-ability effects were studied in the parents and 66 F 1 hybrids from a diallel cross of 12 elite sesame varieties in five different environments in Venezuela. The mean yield of the hybrids was clearly superior to the parental mean in all five locations. There were three heterotic hybrids that showed a higher yield than controls in all environments. The best hybrid in each place yielded significantly better than the best cultivar, the differences ranging from 28 to 109%. Specific combining-ability (SCA) effects were more important than general combining-ability (GCA) in four of the environments. A large genotype x location interaction was found for all traits, suggesting that hybrids should be produced for specific locations. Arawaca and Piritu should be chosen as parents for any sesame-breeding programme in view of their large GCA effects.
01 Jan 1995
TL;DR: In this article, the authors evaluated the genetic potential of 15 early maturity maize populations in a diallel crossing system and found that the results suggest that either the population themselves or the synthetic composition of selected populations can be used for breeding purposes.
Abstract: Early maturity maize (Zea mays L.) populations are used in short growing seasons areas, and their use is gradually increasing in tropical areas. The objective of this study was to determine the genetic potential of 15 early maturity maize populations in a diallel crossing system. The 15 parents, 105 diallel crosses among parents, and selfed generation of parental were evaluated in a triple lattice design at 13 locations in Brazil. The combined analysis of variance for grain yield, time to tassel, and plant height indicated highly significant (P < 0.01) differences for entries, parents, heterosis, parent heterosis, specific heterosis and for the first-order interactions with environments. Average heterosis was highly significant for grain yield, significant(P < 0,05) for time to tassel, and not significant for plant height. Mean yield ranged from 3187 to 5213 kg/ha for populations, and ranged from 3041 to 6017 kg/ha for the population crosses. Population Pool 17 had the largest inbreeding depression effects, whereas population ACMS 52 had the smallest inbreeding depression effects. The highest specific cross for grain yield was for Across 8528 x Pool 18. None of the population crosses was superior to the hybrid checks for the three traits. No association was found between endosperm type and heterosis. The results suggest that either the population themselves or the synthetic composition of selected populations can be used for breeding purposes.
TL;DR: The finding that the resistance is inherited as a quantitative trait is consistent with results on the epidemiology of anthracnose in tetraploid S. hamata.
Abstract: Eight tetraploid accessions of the tropical pasture legume Stylosanthes hamata with varying levels of response to the anthracnose pathogen (Colletotrichum gloeosporioides) were crossed in a half diallel scheme. Based on mean disease severity ratings (MDR), two parents, 55830 and 75164, were grouped as resistant (R), 55828 and 65365 were susceptible (S), and the remaining four, cvv. Verano and Amiga and 65371 and 75162 were moderately resistant (MR). Of these, the two resistant parents appear to carry different genes for resistance. The MDR of 20 of the 28 F2 populations was significantly different from their mid-parent MDR and the expression of resistance, in most cases, was recessive. Only a limited number of the F2 distributions for crosses between RxS, RxMR and MRxS parents conformed to a single gene model. The inheritance patterns observed were considered to be predominantly quantitative. Variation for general combining ability, was as large as or larger than that for specific combining ability suggesting that a large proportion of the genetic differences among the parents was additive. The finding that the resistance is inherited as a quantitative trait is consistent with results on the epidemiology of anthracnose in tetraploid S. hamata.
01 Jan 1995
TL;DR: This paper presents a meta-analyses of the immune systems of eight types of coronavirus and concludes that the immune system of Crimean Tournaisians is particularly vulnerable to these viruses.
Abstract: 14 Introduction 15 Material and Methods 18 Results 24 Discussion 28 References 34 GENERAL CONCLUSION 48
Journal Article•
TL;DR: The study of phenotypic and genotypic variation, coefficient of variation, heritability and genetic advance for 10 quantitative traits indicated additive and nonadditive effects of genes which facilitates selection for the amelioration of breeds.
Abstract: A study on genetic variability was made with 5 X 5 diallel of genetically divergent multivoltine lines to determine the importance of quantitative traits of mulberry silkworm, Bombyx mon L. Data were collected from rearings made during four commercial seasons of West Bengal. The study of phenotypic and genotypic variation, coefficient of variation, heritability and genetic advance for 10 quantitative traits indicated additive and nonadditive effects of genes which facilitates selection for the amelioration of breeds.
Journal Article•
TL;DR: An experiment was conducted during winter season (rabi) of 1987-88 and 1988-89 to study combining ability through diallel analysis in opium poppy, indicating the importance of both additive and non-additive gene actions with prevalence of dominant gene effect.
Abstract: An experiment was conducted during winter season (rabi) of 1987-88 and 1988-89 to study combining ability through diallel analysis in opium poppy (Papaver somniferum L.). Six pure genotypes ('BR 79', 'BR 88', 'IC 30', 'BR 87', 'BR 85' and 'BR 76') were analysed in a 6 X 6 diallel cross for seed yield/plant (g), opium yield/plant (mg). morphine (%), oil content (%) and other 7 contributing characters in F 1 and F 2 generations. Variances due to general combining ability (gca) and specific combining ability (sca) were significant for all the traits, indicating the importance of both additive and non-additive gene actions with prevalence of dominant gene effect except for plant height in F 1 . 'IC 30' (0.20) in F 1 and 'BR 76' (0.46) in F 2 were the best general combiners for seed yield/plant. Only a few good combiners for seed yield might be due to long selection pressure for opium yield rather than seed yield, which is very recent. 'BR 79' X 'BR 76', 'IC 30' x 'BR 87' and 'BR 85' X 'BR 76' were the best specific cross-combination in F 1 and F 2 for seed yield. The crosses having significant sea effect involved high X high, high X low and low X low combiners.