Showing papers on "Diallel cross published in 2004"
TL;DR: The objectives were to estimate the general and specific combining abilities (SCA) for grain yield and secondary traits among high-lysine inbreds from different sources and to identify potential heterotic relationships among them.
Abstract: Development and adoption of quality protein maize (Zea mays L.) (QPM) would increase the nutritional value of food and feed maize products. Breeding programs at the International Center for Maize and Wheat Improvement, Mexico (CIMMYT); Texas AM and University of Natal, South Africa (SA) have developed high-lysine inbreds. Information about how elite QPM inbreds of different origins combine and perform in hybrids will facilitate the selection of parents and breeding strategies for hybrid development. Our objectives were to estimate the general (GCA) and specific combining abilities (SCA) for grain yield and secondary traits among high-lysine inbreds from different sources and to identify potential heterotic relationships among them. Seven white (CML176, CML181, CML184, Bo59W, Tx807, Tx811, and TxX124) and nine yellow QPM inbreds (CML190, CML193, Tx802, Tx814, Tx818, Tx820, Do940y, TxX808, and TxX806) were evaluated in two separate diallel experiments in five southern U.S. environments. The QPM hybrids yielded less than commercial checks. Across environments, GCA effects were nonsignificant for grain yield but highly significant for agronomic and kernel-quality traits. On the basis of GCA effects, TAMU inbreds had earlier maturities, shorter plants, and less grain moisture content than more subtropical CIMMYT and SA inbreds. The best-yielding hybrids and highest SCA effects resulted from crosses among inbreds from different programs: TxX124 x CML176, Tx811 x CML181, and Bo59w × CML184 among the white hybrids, and Tx802 × Do940y among the yellow hybrids. The QPM inbreds developed in different programs could represent potential heterotic groups for use in hybrid development and introgression of germplasm.
113 citations
TL;DR: Inclusion of F(1) hybrids showing high sca and having parents with good gca, into multiple crosses and/or bi-parental mating, or diallel selective mating could prove a worthwhile approach for further improvement of grain yield in bread wheat.
Abstract: The F(1) and F(2) progenies of a ten-parent diallel cross (excluding reciprocals) of hexaploid wheat (Triticum aestivum L. em. Thell) were analyzed for combining ability for quantitative and quality traits. The results indicated significant differences among the parents for general combining ability (gca) and crosses for specific combining ability (sca) for all the characters studied. The gca and sca components of variance were significant for all the traits. However, the gca component of variance was predominant indicating the predominance of additive gene effects for the traits studied. Among the parents Durgapura 65, HD 2285, Lok-1, Raj 1972 and HD 2329 were the best general combiners for grain yield and average to high combiners for tillers per plant, grain yield per spike, grains per spike and 1000-grain weight. The best specific crosses for grain yield were Sonalika x WH 157, HD 2428 x Durgapura 65, Durgapura 65 x Sonalika, HD 2428 x Lok-1 and CPAN 3004 x Raj 1972. The parent Raj 1972, Lok-1 and HD 2285 were the best general combiners for grain yield and protein content, however, Raj 3077 was the best general combiner for protein content. The most suitable specific crosses for protein content were HD 2329 x HD 2285, HD 2428 x Raj 1972 and CPAN 3004 x WH 157. Most of the specific crosses for grain yield as well as protein content involved high x average, average x average and average x poor general combiners. To ensure further increase in grain yield along with high protein, combinations of desirable yield components is advocated. Inclusion of F(1) hybrids showing high sca and having parents with good gca, into multiple crosses and/or bi-parental mating, or diallel selective mating could prove a worthwhile approach for further improvement of grain yield in bread wheat.
99 citations
TL;DR: Good scope for commercial exploitation of heterosis as well as isolation of pure lines among the progenies of heterotic F(1) for improvement of yield levels in bread wheat is revealed.
Abstract: A set of diallel crosses involving 10 parents was made to have information on the extent of heterosis over mid-parent and better parent and inbreeding depression for yield and yield contributing characters under three different environments. Marked heterobeltiosis for grain yield and its important components were observed. For grain yield, 83 crosses showed significant positive heterobeltiosis in all the three sowing dates, however, twenty crosses showed significant consistent heterobeltiosis for grain yield per plant over all the three environments. The maximum heterobeltiosis for grain yield per plant observed was 50.94% (Raj 3765×HD 2285), 121.08% (PBW 373×HD 2329) and 93.96% (PBW 373×HD 2329) under early, normal and late sowing conditions, respectively. Cross PBW 373×HD 2329 in both early and normal plantings and cross Raj 3765×HD 2285 under late planting were observed most heterotic for grain yield. The crosses showing heterosis for grain yield were not heterotic for all the characters. Heterosis for grain yield per spike followed by tillers per plant and 1000-grain weight was independently associated with heterosis for grain yield in early and normal plantings. However, heterosis for grain yield per spike, dwarf plant height and tillers per plant contributed maximum towards yield heterosis. Significant inbreeding depression was recorded frequently for yield and yield contributing traits, however, in a few traits it was observed significant negative indicated that F2 was superior to F1 considered desirable combination for trait(s). The study reveals good scope for commercial exploitation of heterosis as well as isolation of pure lines among the progenies of heterotic F1 for improvement of yield levels in bread wheat.
81 citations
TL;DR: Improved differential display was used in this study to analyze alterations in gene expression between hybrid and parents in leaves at jointing stage and heading stage in a wheat diallel cross, concluding that these differentially expressed genes play an important role for hybrids to demonstrate heterosis.
75 citations
TL;DR: Results validate the gene action, intra -locus interaction, and map position of two loci controlling resistance to Clavibacter michigansensis subsp.
Abstract: Two quantitative trait loci (QTL) from Lycopersicon hirsutum, Rcm 2.0 and Rcm 5.1, control resistance to Clavibacter michiganensis subsp. michiganensis (Cmm). To precisely map both loci, we applied interval mapping techniques to 1,056 individuals in three populations exhibiting F2 segregation. Based on a 1-LOD confidence interval, Rcm 2.0 mapped to a 14.9-cM interval on chromosome 2 and accounted for 25.7–34.0% of the phenotypic variation in disease severity. Rcm 5.1 mapped to a 4.3-cM interval on chromosome 5 and accounted for 25.8–27.9% of the phenotypic variation. Progeny testing of recombinant plants narrowed the QTL location for Rcm 2.0 to a 4.4-cM interval between TG537-TG091 and to a 2.2-cM interval between CT202-TG358 for Rcm 5.1. A population of 750 individuals exhibiting F2 segregation was used to detect epistasis between both loci using ANOVA and orthogonal contrasts (P=0.027), suggesting that resistance was determined by additive gene action and an additive-by-additive epistatic interaction. A partial diallel mating design was used to confirm epistasis, advance superior genotypes, randomize genetic backgrounds, and create recombination opportunities. This crossing scheme created a more balanced population (n=112) containing the nine F2 genotypic classes. Parents in the diallel were selected from the previous population based on resistance, genotype at the Rcm 2.0 and Rcm 5.1 loci, and horticultural traits. A replicated trial using the diallel population confirmed additive-by-additive epistasis (P<0.0001). These results validate the gene action, intra -locus interaction, and map position of two loci controlling resistance to Cmm.
64 citations
TL;DR: Combining ability analyses indicated that additive gene effects were more important than nonadditive gene effects in the inheritance of adult plant resistance to stripe rust in the evaluated material.
Abstract: Inheritance of adult-plant resistance to stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici) in five spring wheats (Triticum aestivum L. em. Thell) following inoculation with the Mexican race Mex96-11 was studied. All possible crosses among these resistant genotypes and a susceptible genotype, 'Avocet-YrA', were made in a one-way diallel mating design. F 1 crosses, F 2 populations, and F 2 :F 3 and F 5 single seed-descent lines were evaluated under artificial field epidemics initiated with race Mex96-11. The adult-plant resistance in crosses of resistant parent with Avocet-YrA tended to be incompletely dominant and was based on the interaction of gene Yr18 and at least three additional additive genes in each parent. Transgressive segregation was detected in all F 2 populations and F 5 single seed-descent lines of the resistant parent inter-crosses, indicating that some additive genes were nonallelic. Combining ability analyses indicated that additive gene effects were more important than nonadditive gene effects in the inheritance of adult plant resistance to stripe rust in the evaluated material. Estimates of narrow-sense heritability ranged from 0.88 to 0.96. Stripe rust resistance in these wheats is expected to be durable.
48 citations
TL;DR: Heterotic responses were determined by evaluating forage yield of the germplasms and their 36 half-diallel hybrids in seeded plots that were harvested five times in each of 2 years, and results suggest that alfalfa breeders may have capitalized on the heterotic response between Flemish and M. varia during past development of al falfa synthetics adapted to the central and northern latitudes of the United States.
Abstract: Identification of heterotic groups and patterns among breeding populations provides fundamental information to help plant breeders more knowledgeably manipulate heterosis. A diallel analysis was conducted among nine alfalfa (Medicago sativa L.) germplasms, commonly referred to as African, Chilean, Flemish, Indian, Ladak, M. falcata, M. varia, Peruvian, and Turkistan, which represent a significant proportion of the genetic diversity present in US cultivars. Heterotic responses were determined by evaluating forage yield of the germplasms and their 36 half-diallel hybrids in seeded plots that were harvested five times in each of 2 years. Commercially acceptable yields were obtained from some hybrids of unimproved parents, where at least one parent was adapted to the study environment. Variation among crosses was attributed primarily to general combining ability (GCA) effects; however, specific combining ability effects were also significant. GCA estimates for African, Chilean and Peruvian were positive, while those for Ladak, M. falcata, and M. varia were negative. Estimates for variety heterosis effects were positive for Peruvian and M. falcata and negative for Indian and M. varia. Significant mid-parent heterosis [(MPH) range of −21% to 55%] and high-parent heterosis [(HPH) range of −33% to 23%] was detected. M. falcata hybrids exhibited the highest MPH values. However, this likely reflects the poor yield of M. falcata per se in the study environment and consequently, low MPH values. Peruvian hybrids demonstrated the highest cross mean performance, significant positive MPH in all crosses, and positive HPH in five out of eight crosses. The results indicate that Peruvian should be recognized as a heterotic group. Alfalfa breeders may wish to explore opportunities for heterotic yield gains that are likely to exist in hybrids between the Peruvian germplasm and elite breeding populations, in particular, those adapted to the southwestern United States. MPH results suggest that alfalfa breeders may have capitalized on the heterotic response between Flemish and M. varia during past development of alfalfa synthetics adapted to the central and northern latitudes of the United States.
47 citations
TL;DR: In floating rice, stem elongation begins much earlier than in non-floating rice, which is the major survival mechanism for flooding, and Inheritance of this early elongation ability was studied using diallel and quantitative trait locus (QTL) analyses.
Abstract: In floating rice, stem elongation begins much earlier than in non-floating rice, which is the major survival mechanism for flooding. Inheritance of this early elongation ability was studied using diallel and quantitative trait locus (QTL) analyses. The diallel analysis was undertaken using a set of 6x6 half-diallel crosses involving four floating ("Goai", "Habiganj Aman VIII", "Badal 106", and Oryza rufipogon strain W120) and two non-floating ("Latisail" and "Patnai 23") parents. The additive gene effects were higher than the dominant effects. The dominant alleles were concentrated in the cultivated floating parents (("Goai", "Habiganj Aman VIII", "Badal 106"), whereas the recessive alleles were in the wild floating parent (W120). A QTL analysis using a "Patnai 23" x "Goai" F(2) population detected two putative QTLs. Of these QTLs, the one on chromosome 12 behaved as a partially dominant major gene that explained more than half of the total genetic variation.
44 citations
TL;DR: Thirteen characters were evaluated over four years in progenies from a diallel cross among the olive (Olea europaea L.) cultivars 'Arbequina, 'Frantoio, and 'Picual to determine if phenotypic correlations existed between these characters.
Abstract: Thirteen characters were evaluated over four years in progenies from a diallel cross among the olive (Olea europaea L.) cultivars 'Arbequinaʼ, 'Frantoioʼ, and 'Picualʼ to determine if phenotypic correlations existed between these characters. Yield per tree, ripening date, oil yield components and fatty acid composition were recorded annu- ally once seedlings began to fl ower and produce fruit. Signifi cant correlations were found between several characters including oil yield components and fatty acids composition. Lower correlation coeffi cients were obtained between ripening date and oil and oleic acid content. Generally, yield was not correlated with the other characters evaluated. Principal components analysis confi rmed the main correlations among characters and showed them to be independent of the parents used. Fruit breeding programs require a good knowledge of the agronomic traits to improve, including the relationships among them, since selection for one character will result in progress for positively correlated traits but regress for negatively correlated traits (Scossirolly et al., 1963). Understanding the correlations among characters might also allow indirect selection for mature crop traits during the juvenile period (Visser, 1976; Zimmerman, 1977). A long juvenile period is a major hindrance in olive breed- ing since fruit characters can only be evaluated once fl owering and fruiting have been established (Lavee et al., 1996; Santos- Antunes et al., 1999). The knowledge of high correlations among characters could also allow the improvement of several traits by selecting only one, thus reducing the number of traits to be measured (Hansche et al., 1972). Studies of correlation between different characters in olive (Olea europaea L.) have usually been carried out in cultivars collections and rarely in progenies from crosses. The objective of these studies was to determine the correlations among several fruit characters (Fanizza, 1982; Fontanazza et al., 1999), among oil yield components (Sanchez-Gomez and Fernandez-Diez, 1991) or fatty acids composition (Tous and Romero, 1993). However, none of these works have provided an overall view by either evaluating a large number of individuals or analyzing a large number of characteristics. The objective of this work was to determine if phenotypic cor- relations existed among some agronomic traits in olive progenies,
43 citations
TL;DR: Six S5 lines of maize, previously identified as having contrasting responses to nitrogen (N) supply, were used to carry out a complete series of diallel crosses to achieve acceptable hybrids for environments with both high and low N.
Abstract: Six S5 lines of maize, previously identified as having contrasting responses to nitrogen (N) supply, were used to carry out a complete series of diallel crosses. The resulting 15 hybrids were grown in a field at two N levels. The general combining ability (GCA) and specific combining ability (SCA) were estimated using the method 4, model I analysis of Griffing for grain yield kernel weight, grain number, harvest index, green leaf number, ear leaf area, N utilization efficiency, total plant N, grain N content, anthesis-silking interval, chlorophyll content and prolificacy. For the majority of the traits, GCA was more important than SCA and there was an increase of non-additive effects under low N. Significant interactions were observed between GCA and N levels for grain yield, grain number and chlorophyll content, indicating the selection of different lines for each N level. The lines with the largest effects of N supply per se on grain yield, were those with the largest effects of GCA for this trait. This association indicates that the response of the lines to N supply, should be considered in breeding programmes in order to achieve acceptable hybrids for environments with both high and low N.
41 citations
Journal Article•
TL;DR: The results from the yields of Fl crosses suggest that lines with high GCA and specific combining ability (SCA), should be selected as parents of QPM lines, and these lines are divided into three heterolic groups.
Abstract: Information on combining ability and heterotic grouping is important to maize (Zea mays L.) breeders. Ten yellow, quality-protein maize (QPM) inbreds were included in this study, among which five were subtropical, tropical QPM lines introduced from CIMMYT and another five were Chinese elite temperate QPM lines. The combining ability for grain yield of the ten PQM lines was analyzed through evaluating 45 crosses from a diallel in three typical environments. Inbreds CML161, CML166, CML171, and Qi205 had high general combining ability (GCA), and it is possible to get high-yielding crosses by using them as parents. The results from the yields of Fl crosses suggest that lines with high GCA and specific combining ability (SCA), should be selected as parents. Genetic similarities of the ten QPM lines were estimated by using simple sequence repeal (SSR) markers. 57 polymorphic SSR primers were selected, which detected 105 alleles among the ten lines. The 105 alleles were used to estimate the genetic similarities. On the basis of the SCA effects and the genetic similarity of the 45 crosses, the ten QPM lines were divided into three heterolic groups. It is reasonable to classify the subtropical, tropical and temperate germplasm into different groups. This study has provided useful informalion for QPM breeding.
TL;DR: This work shows that susceptibility to A. tumefaciens is a heritable trait, and the transfer of susceptibility into resistant lines is demonstrated, and these findings may help to overcome genotype restrictions to genetic transformation.
Abstract: The genetic control and heritability of Agrobacterium tumefaciens susceptibility was investigated using a doubled haploid (DH) mapping population of Brassica oleracea and the associated RFLP map. Preliminary studies were carried out by analysis of an 8 x 8 diallel, for which the parental lines were selected to include a range of susceptibilities to A. tumefaciens. The variation observed within the diallel was attributed to both additive and dominant gene effects, with additive gene effects being more important. A broad sense heritability value of 0.95 suggested that 95% of the observed variation was due to genetic effects, with just 5% attributed to non-genetic or environmental effects. A high narrow-sense heritability value of 0.79 suggested that 79% of this trait was controlled by additive gene effects and, therefore, the potential to introduce this trait into breeding material is high. Fifty-nine DH lines from the mapping population were screened for susceptibility towards A. tumefaciens. Variation in susceptibility was observed across the population. The results of the DH screen were entered into the mapping programme MAPQTL and a highly significant quantitative trait loci (QTL) associated with susceptibility to A. tumefaciens was identified on linkage group 09. The use of substitution lines covering this region confirmed the location of this QTL. This work shows that susceptibility to A. tumefaciens is a heritable trait, and the transfer of susceptibility into resistant lines is demonstrated. These findings may help to overcome genotype restrictions to genetic transformation.
TL;DR: Nine winter wheat genotypes with differential reaction to WSMV were crossed in a complete diallel mating design to determine the combining ability of W SMV resistance, indicating that progeny performance cannot be adequately predicted from GCA effects alone.
Abstract: Wheat streak mosaic virus (WSMV) (Family: Potyviridae; Genus: Tritimovirus), disseminated naturally by the wheat curl mite (Aceria tosichella Keifer), is an important disease of wheat (Triticum aestivum L. em Thell.) worldwide. Breeding for resistant cultivars remains the best strategy to control the disease. Nine winter wheat genotypes with differential reaction to WSMV were crossed in a complete diallel mating design to determine the combining ability of WSMV resistance. Parents, F 1 , and reciprocal crosses were inoculated at the seedling (2-3 leaves) stage with a WSMV-SD isolate and evaluated for reaction under greenhouse conditions. Disease reaction was assessed twice (at 1-wk intervals) by a 1-to-5 scale (1 = no visible symptoms to light green streaks, 5 = severe yellow streaks and necrosis). Data were analyzed according to Griffing's Method 3 and Model 1, where one set of F 1 and reciprocal F 1 are included. Highly significant genotype effects (P 0.05). The ratio of combining ability variance components [(2σ 2 GCA)/(2σ 2 GCA + σ 2 SCA)] was small (0.1), indicating that nonadditive (i.e., dominance and epistasis) gene effects were more important than additive gene effects in controlling WSMV resistance in these crosses; therefore, progeny performance cannot be adequately predicted from GCA effects alone.
TL;DR: The ability to introduce and increase shoot regeneration potential into otherwise recalcitrant lines was demonstrated and both shoot regeneration and the production of multiple shoots were controlled by additive and dominant gene effects.
Abstract: Diallel analysis was used to investigate the genetic control of in vitro shoot regeneration in Brassica oleracea. Twelve doubled haploid (DH) lines, selected to include a range of genotypes with differing shoot regeneration potentials, were crossed reciprocally to produce 132 F1 and 12 selfed, DH families. Cotyledonary petioles from 4-day-old seedlings, from all families, were excised and maintained on MS medium supplemented with 2 mg/l BAP. Explants were scored after 44 days for both the presence or absence of shoots and the number of regenerating shoots per explant. Diallel analysis showed both shoot regeneration and the production of multiple shoots to be controlled by additive and dominant gene effects, with additive effects being more important. Additive gene effects accounted for 71% and 77% of the genetic variation observed within the diallel for shoot regeneration and multiple shoot regeneration, respectively. By investigating the shoot regeneration potential of subsequent backcross and F2 populations, the ability to introduce and increase shoot regeneration potential into otherwise recalcitrant lines was demonstrated.
TL;DR: It is demonstrated that extra‐nuclear effects are important contributors to the phenotypic variation in life history traits of G. firmus by demonstrating that reciprocal effects are due, at least in part, to maternal effects.
Abstract: Although largely ignored until recently, parental effects on the phenotypes of their offspring are both ubiquitous in nature and of a potentially great importance to evolution. Our study examines the presence of extra-nuclear (maternal and paternal) effects in growth traits, development time and adult size in the sand cricket Gryllus firmus using a diallel cross of inbred lines. Sex linkage was shown to be nonsignificant for development time but the other traits could not be tested. We assume that they are nonsignificant but use the term ‘reciprocal’ effects to include this effect. We show that reciprocal effects are present in the growth traits and development time, where they account for 10–30% of the phenotypic variance. They are not present in adult size as indexed by head width. We demonstrate that reciprocal effects are due, at least in part, to maternal effects by an analysis of the positive correlation between egg size, a maternal trait, and the growth traits. The growth rate traits show no significant decline with age either with respect to extra-nuclear contributions to variance or difference between phenotypic means of reciprocal pairs. This study demonstrates that extra-nuclear effects are important contributors to the phenotypic variation in life history traits of G. firmus.
TL;DR: Results suggest that fundamental differences in stomatal conductance exist between subspecies sativa and falcata, and their ability to predict hybrid A varied substantially between the first harvest and later harvests.
Abstract: Designing effective breeding strategies to integrate selection for carbon isotope discrimination (A), as a means to improve alfalfa (Medicago saliva L.) water-use efficiency (WUE), will depend upon the association between Δ and forage yield. The current study was conducted to determine responses in Δ affiliated with significant yield responses that were previously observed among 36 diallel hybrids of nine alfalfa germplasms (commonly referred to as African, Chilean, Flemish, Indian, Ladak, M. falcata, M. varia, Peruvian, and Turkistan). The influence of additive and nonadditive gene action on Δ, and the behavior of A across harvests was also determined. Forage yield and A of the germplasms and their half-diallel hybrids were evaluated near Las Cruces, NM, during May, June, and July in each of 2 yr in seeded plots that were flood irrigated every 14 d. Values for A of hybrids did not significantly exceed those of the most extreme parents in any harvest. Variation for A among crosses was attributed primarily to general combining ability (GCA) effects. The magnitude of parental per se and GCA effects, and their ability to predict hybrid A varied substantially between the first harvest and later harvests. Variety effects for Δ in Ladak, M. varia, and M. falcata became increasingly negative as the growing season progressed, while those for African, Chilean, Flemish, Indian, Peruvian, and Turkistan increased. Results suggest that fundamental differences in stomatal conductance exist between subspecies sativa and falcata.
TL;DR: It is proposed that the heterotic pattern of texana-pepo crosses could be potentially used to achieve increased yields in hybrids by introgressing one group into another in a manner that would maintain fruit attributes of the cultivar-group.
Abstract: Heterotic response for total yield among five cultivar-groups of summer squash, Cocozelle, Vegetable Marrow, Zucchini, Crookneck and Straightneck, was studied in two sets of diallel crosses evaluated in two harvest seasons Each diallel cross included two representatives of each the five cultivar-groups Griffing and diallel GGE biplot (genotype main effect and interaction) analyses were carried out The relative importance of the specific combining ability variance on total variance was greater than that reported earlier for intragroup crosses Highly significant heterosis was manifested only in combinations of Crooknecks or Straightnecks crossed to Cocozelles, Vegetable Marrows or Zucchinis GGE biplots showed a consistent arrangement where testers of ssp texana interacted with cultivars of ssp pepo and vice versa We propose that the heterotic pattern of texana-pepo crosses could be potentially used to achieve increased yields in hybrids by introgressing one group into another in a manner that would maintain fruit attributes of the cultivar-group
TL;DR: The results suggest that selection for high ETE and TE in terms of grain yield should be undertaken under both stress and optimal conditions and in early segregating generations may lead to effective identification of desirable recombinants.
Abstract: Inheritance of water use and transpiration efficiency was studied in diallel F1 hybrids from six cultivars of T. durum, selected for their different responses to drought stress. Plants were grown in 10 l pots at optimal (control) and low soil moisture levels in the glasshouse. GCA and SCA effects were significant at both soil moisture levels. Results demonstrated that evapotranspiration (ETE) and transpiration efficiency (TE) were under additive and dominant gene control. Interactions of GCA and SCA with moisture levels were also highly significant. GCA effects were the major components of the genetic variance of the biological and generative measures of ETE and TE. Narrow sense heritabilities for both ETE and TE based on grain yield were higher at the soil stress moisture level. Heritability estimates of ETE and TE based on the total biological yield, however, declined under the lower soil moisture level. Measures of ETE and TE showed significantly high and positive genotypic and phenotypic correlations among them as well as with grain yield and harvest index. In most cases, genotypic correlations were higher than phenotypic correlations. The results suggest that selection for high ETE and TE in terms of grain yield should be undertaken under both stress and optimal conditions. Selection in early segregating generations may lead to effective identification of desirable recombinants.
TL;DR: Plant height and primary branch number per panicle are traits that may be readily improved by selection in saline environments and contributed significantly to the total heritable variation observed.
Abstract: The release of rice cultivars with improved performance in saline environments is reliant on an understanding of the genetic control of plant and panicle characters in plants exposed to salinity. The regulation of agro-physiological characters of rice plants grown in a saline environment was thus investigated. A complete diallel cross was prepared from 8 parental rice accessions with a range of tolerances to salinity. F1 hybrids and parents were grown in saline-sodic soil in artificially constructed salinity blocks. At maturity, the plant height, productive tiller number per plant, panicle length, primary branch number per panicle, panicle fertility, time to maturity, shoot dry weight, shoot Na, Ca, and K concentrations, and paddy yield were recorded. Additive and dominant genetic effects contributed significantly to the total heritable variation observed for plant height, panicle length, and sodium and potassium shoot concentrations. Additive genetic effects were important for the expression of variation of productive tiller number per plant and the number of primary branches per panicle, while dominant genetic effects were important for the expression of variation of the number of days to maturity. Plant height and primary branch number per panicle are traits that may be readily improved by selection in saline environments.
Journal Article•
TL;DR: Evaluated open pollinated populations of quality protein maize and their crosses for total grain protein revealed the superiority of the hybrids over the parents, as well as the presence of heterosis.
Abstract: Corn is employed in animal feed as an energy source, but as a protein source it is deficient in lysine and triptophan. Thus, the present study evaluated open pollinated populations of quality protein maize (QPM) and their crosses for total grain protein. The heterosis and its components were quantified as useful parameters for breeding these populations. The analyses were carried out on 96 hybrids, derived from eight populations of dent grains (group 1) and thirteen of flint grains (group 2), including their parents in a partial diallel intergroup design. Kjeldahl's method was used to analyse total protein content. Variance analysis results were significant for all effects, revealing heterogeneity among and within the groups, as well as the presence of heterosis. The total protein content means of group 1 and group 2 were 9.67 g/100g and 10.51 g/100g, respectively, and the mean of hybrid combinations was 11.86 g/100g. The general mean involving all parents and crosses was 11.61 g/100g. The average heterosis was 17.58%, revealing the superiority of the hybrids over the parents. As far as general combining ability and yield mean are concerned, the best parents were CMS 454, CMS 474 and ZQP 103 (group 1) and CMS 453, BR 473, CMS 463, CMS 458 and ZQP 102 (group 2). These populations are recommended for QPM composites with high protein content. KEY-WORDS: Zea mays ; protein; nutrition quality; QPM; diallel.
TL;DR: The results showed that conditional additive and dominant effects expressed alternatively from 3- to 8-leaf stage of rice seedlings, suggesting that selection for allelopathic activity should be performed during this three leaf phases in order to improve selection response.
Abstract: Five parental rice lines with varied levels of allelopathic potential were employed in a partial diallel crossing program to generate 10 F1 hybrids. The allelopathic effects of the aqueous leaf extracts of the five rice parents and 10 F1s grown under two different conditions were assessed at different growth stages using lettuce (Lactuca sativa L.) as a bioassay species. Conditional genetics of rice seedling allelopathy and its genotype × environment effects were analyzed by using additive–dominant developmental genetic models. The results showed that conditional additive and dominant effects expressed alternatively from 3- to 8-leaf stage of rice seedlings. The additive effects were significant in the 5|4, 6|5, and 8|7-leaf phases, whilst the dominance effects appeared to play an important role in the 4|3 and 7|6 leaf phases. The conditional narrow sense heritability was significant in the 5|4, 6|5, and 8|7 leaf phases, the broad sense heritability was pronounced among all the growth periods investigated, suggesting that selection for allelopathic activity should be performed during this three leaf phases in order to improve selection response.
TL;DR: The results indicated that the differences in the soil types did not influence the selection for the root size or shape in most characteristics, however, the interaction between genetic effects and soil type should be taken into account in the selection of the bluntness of the distal part.
Abstract: We conducted diallel analyses of root shape and size in Japanese radish to determine the interaction between genetic effects and soil type in the selection for these traits in a breeding program. A set of diallel crosses of six inbred lines was grown in an andosol, a clayey soil and a sandy soil. The major shape characteristics accounted for by the principal components of elliptic Fourier descriptors were the ratio of length to width, the bluntness of the distal part, the curvature of the central part, and the curvature of the proximal and distal parts. Analysis of variance of diallel tables showed that the genetic effects were highly significant for all the characteristics. In contrast, the influence of the soil type was markedly different among the characteristics. Soil type effect was significant for size characteristics and the bluntness of the distal part. In the bluntness of the distal part, the interaction between genetic effects and soil type was significant, and the heritability and the degree of dominance varied between the soil types. The results indicated that the differences in the soil types did not influence the selection for the root size or shape in most characteristics. However, the interaction between genetic effects and soil type should be taken into account in the selection for the bluntness of the distal part.
TL;DR: Five divergent snap bean accessions from the vegetables germplasm bank at UENF and their ten diallel hybrids were evaluated to inheritance on five morphoagronomic traits and revealed that dominant alleles increased the number of pods per plant, pod weight per plant and number of seeds per pod.
Abstract: Five divergent snap bean accessions from the vegetables germplasm bank at UENF and their ten diallel hybrids were evaluated to inheritance on five morphoagronomic traits using Hayman's methodology (1954). The results showed that additive effects were predominant for pod weight per plant, number of seeds per pod, height of the insertion of the first pod and number of days to flowering while non-additive effects were more important for number of pods per plant. The best strategy to be adopted was the use of these acessions in an intrapopulation breeding program aiming the obtaintion of superior segregants. For pod numbers the indicated strategy would be an interpopulational breeding procedure, to exploite the heterosis related to the non-additive effects. The analysis also revealed that dominant alleles increased the number of pods per plant, pod weight per plant and number of seeds per pod. Allelic interaction was overdominance to the number of pods per plant, while the partial dominance controled the expression of other traits.
Journal Article•
TL;DR: The analysis revealed that parents and crosses differed significantly for general and specific combining ability effects, and the relative magnitude of gca variances was higher than the sca variance, indicates the role of additive component in the expression of all the traits except green fruit yield which was found to be under the control of non-additive gene action.
Abstract: Six genetically diverse lines/varieties of chilli namely PC-1, Jwala, 339, 7722, 8601 and raj-1 were selected from the germplasm available at Vegetable Research Station, Kalyanpur of C.S. Azad University of Agriculture & Technology, Kanpur for making diallel cross to study the combining ability during 1996-97. During 1997-98, 15 F1s and their 6 parents were studies in RBD with three replications. Results indicated that parents namely Pant C-1, 339 & 7722 were best general combiners for yield, earliness & pod characters. The hybrids 8601 x 7722, PC-1x339 and 8601 X Raj-1 were best specific crosses for several characters on the basis of specific combining ability effect. The results suggested exploitation of hybrid vigour in chilli.
01 Jan 2004
TL;DR: En this trabajo se estimaron los parámetros genéticos de la raza de maíz (Zea mays L.) Tuxpeño así como los efectos de aptitud combinatoria general (gi) y específica (sij) de diez líneas S1 derivadas of tres compuestos varietales pertenecientes a esta raza.
Abstract: En este trabajo se estimaron los parámetros genéticos de la raza de maíz (Zea mays L.) Tuxpeño, así como los efectos de aptitud combinatoria general (gi) y específica (sij) de diez líneas S1 derivadas de tres compuestos varietales pertenecientes a esta raza. Se hicieron las 45 cruzas dialélicas (método 4 de Griffing) entre las diez líneas cuyos progenitores fueron considerados inicialmente como una muestra aleatoria de líneas S1, mediante las cuales se estimaron los parámetros genéticos de población: media genotípica y las varianzas genéticas aditiva y de dominancia. En un segundo enfoque, al considerar las 10 líneas como un grupo selecto, se estimaron los efectos de aptitud combinatoria general (ACG) y los efectos de aptitud combinatoria específica (ACE) de sus cruzas. Las 45 cruzas se evaluaron por rendimiento de mazorca por planta en cinco ambientes del trópico húmedo de México. La varianza genética aditiva resultó cinco veces mayor que la varianza genética de dominancia. Las líneas 9 y 10 presentaron los efectos más altos de ACG (4.26 y 7.32, respectivamente) y las cruzas en que intervinieron fueron las de mayor rendimiento. Las líneas 3 y 5 que tuvieron los efectos más bajos de ACG (-9.60 y 3.19, respectivamente), produjeron las cruzas con los rendimientos más bajos.
01 Jan 2004
TL;DR: The field performance of 45 tomato hybrids produced according to a half diallel genetic design was evaluated together with their parents at the Field Crops Research and Development Institute, MahaIlluppallama, Sri Lanka, during January to May 2004 to select suitable hybrids for cultivation under dry zone conditions.
Abstract: The field performance of 45 tomato hybrids produced according to a half diallel genetic design wes evaluated together with their parents at the Field Crops Research and Development Institute, MahaIlluppallama, Sri Lanka, during January to May 2004 in order to select suitable hybrids for cultivation under dry zone conditions. Molecular investigations were carried out to test for true hybridization. Yield, net photosynthesis rate, instantaneous transpiration efficiency, stomatal conductance and root length were evaluated in the parents and hybrids. Analysis of variance revealed existence of highly significant genetic variability between genotypes for all the traits studied. The general combining ability (GCA) was significant for all characters while the specific combining ability (SCA) was significant for all traits except root length, indicating the importance of both additive as well as dominant gene effects. The dominance variance was much higher than the additive variance indicating the possibility of producing superior hybrids. The variety LC5 showed the highest value for GCA for yield, stomatal conductance and root length while UP8 was the best combiner for photosynthetic rate and transpiration efficiency. Based on heterosis in all traits considered, hybrids (UP5 x UP1), (UP5 X UP3), (UP2 X UP3), and (UP8 X LC5) were recommended as new tomato hybrids with potential for cultivation under dry zone conditions. The micro-satellite molecular technique was effective in testing true hybrids.
TL;DR: Seven soybean cultivars with different levels of resistance to Cercospora sojina, race 04, were crossed according to a diallel design to determine the general and the specific combining abilities for the resistance, although the additive genetic effect was the most important component.
Abstract: Seven soybean cultivars (Bossier, Cristalina, Davis, Kent, Lincoln, Parana and Uberaba), with different levels of resistance to Cercospora sojina, race 04, were crossed according to a diallel design, with no reciprocals, to determine the general and the specific combining abilities for the resistance. The evaluations of the reaction to the disease were performed 20 days after the inoculation of the fungus on the most infected leaflet of the plant, in the parents and in the F1 hybrids. To quantify the resistance, the following characteristics were evaluated: infection degree (ID); number of lesions per leaflet (NLL); lesion mean diameter (LMD); lesioned leaf area (LLA); percentage of lesioned leaf area (PLLA); number of lesions per square centimeter (NLC) and disease index (DI). The relative importance of each characteristic was evaluated by the canonical variables analysis and the LLA and NLL characteristics were eliminated from the multivariate function. With the remaining five characteristics, a multivariate index was created using the first canonical vector, which was submitted to the diallel analysis, according to Griffings fixed model, method 2. The most important characters to discriminate resistant from susceptible soybean plants to C. sojina were: ID, LMD, NLC, DI and PLLA. Cristalina, Davis and Uberaba cultivars are the best ones among those tested that can be recommended as parents in soybean breeding programs seeking resistance to Cercospora sojina. The additive, dominant and epistatic genetic effects were important for the expression of the resistance, although the additive genetic effect was the most important component.
TL;DR: The GCA effects were more important than SCA for this set of inbred lines, suggesting that additive genetic effects are the most important sources of variation for this trait.
Abstract: In breeding programs directed towards genetic resistance against diseases, the estimation of genetic parameters that control resistance allows the introduction of resistance into suscetible germplasm to be clearly focused. The purposes of this study were to estimate heterosis effects, and the general (GCA) and specific (SCA) combining abilities by using two rating methods for resistance to Phaeosphaeria maydis in a diallel analysis of 36 F1 maize hybrids and their nine inbred lines. Trials were conducted in three environments. Disease severity was evaluated in the whole plant (PI) and in the leaf positioned just below the point of insertion of the main ear (AFA). The trials followed a randomized block design with plots represented by a 5 m long rows. Differences among combining ability estimates for different environments and in both evaluation methods showed significant effects (P < 0.01) for environment (E), GCA, and GCA × E. The SCA, and SCA × E effects were not significant for any of the disease severity variables. The GCA effects were more important than SCA for this set of inbred lines, suggesting that additive genetic effects are the most important sources of variation for this trait. Heterosis effects for resistance were estimated, and it was possible to identify specific hybrid combinations between lines which have high potential for genetic control of this pathogen. Results for both disease severity variables were practically identical, even though the PI method was more convenient to use.
TL;DR: Broad-sense heritability estimates showed that >90% of the TDR and SDR were associated with genotypic effects, and Diallel analyses showed that T1 and U2 had the highest general combining ability (GCA) for reducing damage.
Abstract: Banks grass mite [BGM; Oligonychus pratensis (Banks)] and the twospotted spider mite (Tetranychus urticae Koch) cause significant yield reductions in maize (Zea mays L.) grown in the Great Plains states. Understanding the inheritance of mite resistance will be useful in developing mite resistant hybrids. A Griffing's Method 2 diallel mating design was used to evaluate the range of resistance and combining ability of parents in F 1 crosses of seven mite resistant maize lines (T1, U2, A3, A4, A5, A7, and T9). Parent lines, F 1 crosses, and three checks (Mo17, B73 × Mo17, and Pioneer hybrid 34K77) were included in a randomized complete block design with three replications at Halfway, TX, in 2002 and Lubbock, TX, in 2001 and 2002. Following artificial infestations, mite resistance was evaluated for differences in mite infestations and feeding damage. Weekly mite densities and damage samples were used to calculate total mite densities, total damage ratings (TDRs), mite per damage ratio (MID), and a seasonal damage ratio (SDR). Total damage rating was significant for environments, genotype, and environment × genotype interaction. Total mite density (TMD) and M/D were significant for genotype and environment × genotype interaction. The SDR was significant for environment and genotype, but no interaction. Broad-sense heritability estimates showed that >90% of the TDR and SDR were associated with genotypic effects. Crosses with T1, U2, and T9 consistently supported larger mite populations, but had higher MID values than those with A3, A4, A5, and A7, indicating greater tolerance to mite feeding. Crosses between tolerant lines or between tolerant lines and antibiotic lines had overall better resistance than crosses between antibiotic lines. Diallel analyses showed that T1 and U2 had the highest general combining ability (GCA) for reducing damage. Tl × A4, T1 x A7, A3 x AS, and A4 x A7 were the best crosses for specific combining ability (SCA) for resistance to spider mites.