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1.
Ten meadow bromegrass genotypes tested as half‐sib (polycross, PX; open‐pollinated, OP) and selfed (S1) progenies were surveyed using random amplified polymorphic DNA. Fourteen primers, which produced 32 markers, were selected to determine the genotypes of 360 individuals from the three progeny tests. Analysis of molecular variance was performed in each progeny test, and genetic distances between genotypes and progeny types were determined. Among genotype genetic variation in half‐sib (PX and OP) progenies was similar. Genetic variation among genotypes for S1 progenies (30.5%) was about twice that found in the half‐sib progenies. Variation between individual S1 progenies ranged from 15.7% to 50.1%, while in the half‐sib progenies, the range was 6.9‐24.1%. Based on average distances between progeny types for a given genotype, OP and PX were closer to each other than to the S1. An analysis of variance of the molecular marker frequency occurrence was performed for 12 plants within each progeny type of each genotype. Marker frequencies, expressed in percentages, ranged from 10.7% to 84.3%. No significant differences were found for genotype and progeny type‐genotype interaction suggesting that all genotypes behave in a similar manner across the different progeny types.  相似文献   

2.
L. Pecetti  E. Piano 《Plant Breeding》2005,124(2):176-179
To estimate heritability and inbreeding in grazing‐type lucerne, 14 parent genotypes and their half‐sib and selfed progeny were grown under spaced‐plant conditions. Dry‐matter weight (four cuts), plant height, basal plant diameter, stem density, and late‐autumn vegetation were recorded on a plant basis. Genetic coefficients of variation for the three germplasm groups, and broad‐sense heritability on a plot basis for parents were computed from variance component estimates; narrow‐sense heritability was estimated from progeny‐parent regression. Genetic variation was generally greater among selfed than half‐sib progeny. Broad‐sense heritability was high, while narrow‐sense heritability was much lower for all traits except plant diameter. Inbreeding effects, assessed with comparison between parents and selfed progeny, were notable for plant weight and late‐autumn vegetation only. The high correlation coefficients computed between parents and either progeny suggested the equivalent value of self‐ and polycross‐progeny tests for selecting superior parents.  相似文献   

3.
Nine polycross (PX) and nine different self (S1) progenies were randomly chosen from 43 selected tall fescue genotypes and evaluated for in vitro digestible organic matter (IVDOM), crude protein, neutral detergent fibre, acid detergent fibre and acid detergent lignin of whole plants, leaf blades and stems (stem plus leaf sheath) at each of four harvest dates in 1991 and 1992. Significant variation for all whole‐plant and leaf quality traits occurred among the PX progenies at the May harvest. Variation among S1 progenies was significant for almost all of the stem traits. Genetic variance components for both progeny groups were significant for almost all of the traits, confirming the presence of additive genetic variation. Heritability estimates on a progeny‐mean basis ranged from medium to high for almost all the traits of the whole‐plant and the leaf and stem fractions. The results suggest that spring would be the time at which direct selection for high IVDOM or low fibre content would be successful and that selection for leaf or stem quality traits improves whole‐plant quality. Selection for quality traits in the summer or in the autumn would be difficult since no significant genetic variability was found.  相似文献   

4.
Higher ruminant intake potential and in vivo digestibility as indicated by lower neutral and acid detergent fibre (NDF and ADF), respectively, and higher crude protein (CP), may be valuable targets in tall fescue breeding. Some 105 full‐sib families from a diallel cross of Mediterranean parent germplasm were grown in a heated greenhouse simulating the temperature pattern of a Mediterranean environment, to estimate genetic parameters for NDF, ADF, CP and dry matter (DM) yield in one autumn and one winter harvest. Family x harvest interaction was large for NDF and ADF, moderate for CP and absent for DM yield. Additive genetic variance was mostly larger than specific genetic variance, and tended to be small for quality traits and large for DM yield. Narrow‐sense heritability was low for CP and ADF in autumn and moderate to fairly high in the remaining cases. Predicted gains per selection cycle never exceeded 5% for quality traits while being greater than 10% for DM yield. An inverse genetic correlation between DM yield and any quality trait emerged in the presence of sizeable genetic variation.  相似文献   

5.
Summary Seventy-two plants regenerated from leaf-derived calli of a single plant of Lotus corniculatus have been evaluated for several morphological and agronomical traits. The analysis of selfed and polycross progenies of the regenerants indicates that the variation among regenerants was, at least in part, of genetic origin. Most of the mutations induced by tissue culture were recessive and were detected only after sexual propagation. Although in vitro culture had a depressive effect for most of the traits, the selfed progenies of 2 regenerants displayed higher values for leaflet width and seed yield than the selfed progeny of the initial plant. However the somaclonal variation did not increase the variation for any trait with respect to the variation of the donor cultivar of the initial plant.  相似文献   

6.
The present study aimed to assess the effect of contrasting levels of molecular and phenotypic diversity among polycross parents of orchardgrass on the performance of synthetic progeny with respect to physiological responses and drought tolerance. Four polycross groups each composed of six parental plants were evaluated under normal irrigation and drought stress conditions. A number of 923 inter simple sequence repeats and sequence related amplified polymorphism markers and several phenotypic traits were used to select contrasting levels of diversity (high and low) in parental genotypes. Highly significant correlation was observed between molecular distance and progeny performances at both normal irrigation and drought stress conditions. High molecular diversity among polycross parents led to a significant yield advantage of first generation progeny with averages of 34.40% for normal irrigation and 48.10% for drought stress conditions. Also crosses between genetically distant parents produced progeny with considerable drought tolerance and yield stability. Positive associations between phenotypic distance of parents and progeny performance were found for most physiological traits at both moisture regimes but phenotypic distances had weak association with forage yield, stress tolerance index and yield stability of progeny. Significant associations between drought tolerance index and some physiological traits confirmed the importance of these traits in conferring drought tolerance of orchardgrass. Our results underscore the effectiveness of marker‐assisted polycross breeding to improve drought tolerance and yield stability through physiological traits in orchardgrass.  相似文献   

7.
The autotetraploid forage Congo signal grass (Brachiaria ruziziensis) is an important component in the Brachiaria breeding programme. As with other tropical forage grass species, the association between flowering and seed yield components, the mode of inheritance and the effects of population structure on phenotypic breeding are lacking. Seventeen characteristics evaluated in 59 half‐sib progeny of seven subpopulations were analysed using a mixed model methodology. According to the commonality analysis, the total seed yield (0.67) and number of days to flowering (0.22) had a greater influence on the filled‐seed yield. The flowering synchrony, total number of panicles, filled‐seed yield, green matter yield and dry matter yield presented statistically significant additive genetic variance between and within the subpopulations. The QST estimates ranged from 0.09 for the flowering synchrony index to 0.31 for the filled‐seed yield. The effects of population structure and its use in breeding programmes are further discussed.  相似文献   

8.
Brassica napus is a most important oilseed grown worldwide with a limited genetic background, due to the short history of speciation, domestication and cultivation. To create novel germplasm for rapeseed breeding, we made interspecific crosses followed with chromosome doubling between B. rapa and B. oleracea to generate novel B. napus with favourable agronomic traits. The resynthesized (S0) hybrids were confirmed by SSR and cytogenetic analysis, and the fertility was increased from 32.7% in S0 generation to ~97.31% in S1 generation. The plant shapes of the progeny were dramatically improved compared to the diploid parents and B. napus cv. ‘Yangyou 6’, especially for the branch initiation height, branch number and pod number. The single‐plant yield was significantly improved in S1 progeny for the variations in branching sites and number. Significant improvement in plant shape and yield was observed on S2 generation compared to the local elite commercial open‐pollinated cultivar, which would be further fixed by intensive selection and pyramiding breeding. Such variation is of great value for breeding rapeseed with improved plant architecture and harvest index.  相似文献   

9.
Summary Three thousand two hundred and sixty-seven kabuli chickpea (Cicer arietinum L.) germplasm accessions were grown during the spring season of 1980 at Tel Hadya, the main research station of ICARDA, Syria to determine the components of seed yield. Observations were recorded on seed yield and 14 other characters. Correlation and path coefficient analyses were done to find out associations among characters and to assess the direct and indirect contribution of each character to seed yield.Large variation was observed for all the characters studied except days to flowering, days to maturity and protein content. Correlation and path coefficient analyses showed that biological yield and harvest index were the major direct contributors to seed yield. The 100-seed weight, plant height, days to flowering and maturity, canopy width, and protein content contributed to seed yield mainly through indirect effect via biological yield and harvest index. The 100-seed weight and seed yield were major contributors to biological yield. Major contributor to protein content was days to maturity. Results indicated that selection for high biological yield and harvest index would lead to high seed yield; and selection for large seed size would lead to high biological yield. Therefore, these characters should receive the highest priority in selecting high yielding plants in chickpea breeding.  相似文献   

10.
Seed yield is a major breeding target in tetraploid red clover. We investigated if marker‐assisted parentage analysis can identify progeny plants with two high seed‐yielding parents in tetraploid red clover and if this technique is more advantageous than traditional half‐sib selection. Parentage analysis was successfully performed on the progeny from the 10% highest seed‐yielding genotypes from a second‐cycle family selection trial: 16.0% of progeny were identified with a high seed‐yielding father. However, progeny plants with two high seed‐yielding parents did not produce more seeds than traditionally selected progeny (27.3 g vs. 30.7 g/plant, respectively). The 10% highest seed‐yielding genotypes displayed on average 2% self‐fertilization. Four genotypes were self‐fertile with individual selfing rates up to 20%. Our results discourage the use of marker‐assisted parentage analysis to improve seed yield in tetraploid red clover when the material has been preselected for seed yield. Breeders should be aware that intensive selection for seed yield in tetraploid red clover may inadvertently lead to selection for increased self‐fertility, which may increase inbreeding in the long term.  相似文献   

11.
Studies on the relative effects of parents on some economic characters in sugarcane have given indications of maternal influence in the progeny performance in certain crosses with regard to millable canes at harvest, height of stalks and brix per cent in juice, irrespective of the fact that pollen parent effect was positive or negative. As judged from a study of the progeny of the direct crosses and reciprocals among the varieties studied, particularly use of Co. 678 as a pistil parent in the breeding programme for improving the mean height of the progeny and Co. 527 as a pistil parent for increasing number of millable canes at harvest and brix per cent in juice is clearly indicated. These indications should also prove useful for application in adopting the polycross method of breeding as well.  相似文献   

12.
Genetic control of alfalfa seed yield and its components   总被引：2，自引：0，他引：2  
Seed yield is of little agronomic importance in alfalfa (lucerne) but is critical in the marketing of varieties. In order to develop breeding criteria, the quantitative genetics of seed yield components must be studied. The objective of this study was (1) to evaluate combining ability for seed yield and its components and (2) to estimate the genetic control of these same characters. A 7 × 7 diallel mating design, including reciprocals, among parents from different varieties, and a 7 × 7 factorial design within the ‘Flamande’ population were evaluated. In the diallel design, where the progenies were evaluated over two growing seasons, a high genotype effect was found for seed yield and its components while genotype × year interaction was only significant for seed yield per plant. General combining ability (GCA) effects explained most of the variation due to genotype effect. Specific combining ability (SCA) and reciprocal effects were only significant for seed yield per plant. ‘Europe‐1’, ‘Rival‐5’ and ‘Medalfa‐7’ were the most promising parents, conferring the highest GCA for most of the characters evaluated, especially for seed weight per inflorescence. In the factorial design, seed weight per pod was the only character for which the year effect was not significant. Male and female effects were significant for all characters and these effects were larger than the male × female interaction variance for all the characters. These results were stable over the 2 years for most characters. Additive variance was larger than dominance variance, for all traits. This resulted in high narrow‐sense heritabilities, especially for seed yield per plant, seed weight per inflorescence and number of seeds per pod. Seed weight per inflorescence and number of seeds per inflorescence were highly correlated with seed yield per plant among the full‐sib (FS) families, in both experiments. Increase in seed yield potential in alfalfa could be achieved by the use of seed weight per inflorescence as a selection criterion.  相似文献   

13.
Half‐sib progenies of congo signal grass (Brachiaria ruziziensis Germain & Evrard, syn.: B. eminii, Urochloa ruziziensis) were analysed using a mixed model methodology. The objective was to estimate genetic and phenotypic parameters, predict individual genetic values, estimate correlations between characters associated with biomass production and forage nutritive value and use this information to determine the economic weights to compare three multiplicative selection indices. Individual narrow‐sense heritabilities corrected for inbreeding varied from 0.14 to 0.91 for characters associated with biomass production and from 0.04 a 0.24 for nutritional value characters. The correlations among characters associated with annual biomass production were of high magnitude. In contrast, biomass production characters were negatively correlated with crude protein, acid detergent fibre and lignin. Total dry matter yield, crude protein and regrowth ability were weighted separately in evaluations during wet and dry season or annually in selection indices. Index that considered characters annually resulted in better distribution of forage production along the year than indices that separated wet and dry season production.  相似文献   

14.
J. Lewis 《Euphytica》1970,19(4):470-479
Summary A genetic evaluation of S23 perennial ryegrass has been made by means of a 6 × 6 diallel cross. The characters studied were those associated with seminal reproduction and included seed yield and several of its primary components.The pattern of variation between the parents indicated a mainly additive system, itema of the Hayman analysis being significant for yield and all the other characters. Maternal effects were not a constant feature, but were evident for seed yield, plant weight and spikelet numbers/inflorescence. Dominance was a prevalent feature and invariably acted in the direction of the greater expression of the character.While a high level of incompatibility was evident from the paucity of seed setting on selfing, the variation between progeny yields following open pollination gave a range from the highly acceptable levels of commercial production to very low uneconomic levels. The results indicate that improvement in seed yield is feasible by breeding even though in this variety selection pressure has tended towards a restriction of variability for essentially agronomic features.  相似文献   

15.
Open pollinated (OP) progenies from 72 plants, selected for seed yield within a population of the Italian synthetic variety ‘Adriana’, were evaluated in 1983–1986 under dense stand conditions, both for dry matter yield (DMY) of the 1st cut and seed yield (SY) of the 2nd regrowth. Analysis of variance of the results showed the presense of significant differences in SY potential among entries, with average SY over the years of open pollinated (OP) progenies ranging between 32.1 gm-3. In contrast, the OP progenies were not significantly different in DMY, averaging between 0.61 kg m-2 and 0.77 kg m-2. The results show the possibility of selecting for SY without a negative response affecting DMY in lucerne. Furthermore, the most interesting materials appeared to be characterized both by high average SY and SY stability over the year.  相似文献   

16.
L. Frese    M. Dambroth  A. Bramm 《Plant Breeding》1991,106(2):107-113
The objective of this study was to investigate the breeding potential of the inulin-containing root chicory which has potential as a new industrial crop. Polycross families and reference varieties were grown in field experiments at 3 locations to assess their performance and the amount of variation available for breeding. Significant variation between polycross families for all characters except for glucose content and the ratio total sugar/dry matter content was observed. Compared to ‘Fredonia’, 12 out of 72 polycross families gave between 15 % and 24 % more total sugar yield. Preliminary estimates for the heritability of two yield components were calculated by means of the parent-offspring regression analysis. Additive genetic variance seems to determine the inheritance of fructose and total sugar content. All findings suggest that the total sugar yield of root chicory can be considerably increased by breeding.  相似文献   

17.
Determining unknown parentage in autotetraploid alfalfa (Medicago sativa L.) (2n = 4x = 32) can improve breeding gains. An exclusion analysis-based paternity testing SAS code, amenable to genotyping errors, is presented for autotetraploid species utilizing co-dominant molecular markers with ambiguous dosage. To demonstrate the paternity testing SAS code, 19 SSR loci were genotyped and analyzed on 1,107 progeny from a commercial, isolated, clonally replicated, 16-parent alfalfa breeding polycross which was pollinated by leafcutter bees (Megachile rotundata F.). Paternal assignment success rate was over 90 %. Among typed progeny, 45 % were the result of self-fertilization. Significant differences were detected between the 15 parents that produced seed and were observed as fathers for (1) total fertilizing pollen contribution (% deviation from expectation), (2) self-fertilization rates (%), and (3) outcrossing fertilizing pollen contribution (% deviation from expectation). Physical within-cage distance between parental plants was correlated with outcrossing fertilizing pollen frequency (negative power function). Parental seed yield was positively correlated with total fertilizing pollen contribution, particularly with self-fertilization rates (42 % self-fertilization and 17 % outcrossing). These correlations suggest that selecting for increased seed yield may result in indirect selection for increased self-fertilization rates. Parental total fertilizing pollen contribution was 62 % determined by outcrossing and 35 % by self-fertilization. This study cautions alfalfa breeders that heretofore unconsidered sources of inbreeding could be present in some breeding materials. This study also provides cost effective and easy to use molecular genetic tools for detecting, managing, and/or selecting against (through breeding) those sources of inbreeding.  相似文献   

18.
The steroid bearing medicinal plant, S. laciniatum, was bred for high solasodine yield for commercial cultivation in Thailand. Starting materials for breeding consisted of seven populations of different origin. Variability among these populations was examined using an unselected control population cultivated over three years. Additive and dominance variance were estimated from a polycross and diallel mating design. Significant genotypic variability was found for solasodine concentration, height of the plants, and total shoot length, promising successful selection for the most important yield characters. Additive variance and heritability in the narrow sense were low for all yield characters, due to previous selection of the parental plants used for the polycross and diallel mating. No dominance effects could be found for any of the characters. In conclusion, breeding S. laciniatum for quantitative yield characters by selection will be superior to hybrid breeding. As a result of selection, significant increases in the most important yield characters in the offspring of selected populations were obtained.  相似文献   

19.
Leek (Allium porrum L.) is an important outdoor vegetable in West Europe, where it is cultivated on about 30,000 ha. Most commercial cultivars of leek are open pollinated. One of the major problems with the crop is poor uniformity. Leek is an outbreeding species with up to 20% self-fertilisation. Much of the variation of open pollinated cultivars is explained by the strong sensitivity to in breeding depression after selfing. In this study we attempt to analyse in a systematic way the relationship between degree of selfing and agricultural performance in leek. The results obtained confirm a negative correlation between selfing and somea gricultural aspects important for vigour such as seedling emergence, plant growth and plant fresh yield. Also negative correlations between degree of selfing and seed individual weight and between selfing and seed individual size were found. The negative relationship between inbreeding and plant weight at harvest is further confirmed in an experiment in which the origin (cross-pollination orself-pollination) of each individual offspring plant analysed was determined using AFLP-markers. Finally, the correlation between chlorophyll deficiency genes and the loss of vigour that follows selfing was investigated. The results obtained demonstrate a significant decrease of pigment content in two generations of selfing. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
Phenotypic and genotypic variation for seed yield and associated traits (heading date, plant height, number of fertile tillers, 1000‐seed weight, panicle length, seed weight per panicle, fertility, flag‐leaf length and flag‐leaf width) were studied in a full‐sib family of meadow fescue using replicated clonal trials at two locations in Norway. Genotypic variances were highly significant for all traits and genotype × location interactions were significant for heading date, number of fertile tillers and seed yield. Seed yield and other seed component traits exhibited the largest genotypic variations. Heading date showed large genotype × location interaction, probably because of the very diverse origin of the two parents of the full‐sib family. Path coefficient analysis showed that panicle fertility, measured as seed weight per unit length of panicles, was by far the most important component trait contributing to seed yield, followed by the number of fertile tillers, plant height and flag‐leaf width. Flag‐leaf width and plant height had sizeable indirect effects on seed yield via panicle fertility. This is the first time that the importance of the size of the flag leaf for seed yield in herbage grasses has been demonstrated.  相似文献   

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