首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Increases in the groat-oil content of oat (Avena sativa L.) increase the energy value of the grain and improve the feasibility of extracting oat oil for use as a vegetable oil. Nine cycles of recurrent selection for greater groat-oil content conducted in a genetically broad-based oat population resulted in dramatic increases in groat-oil content. Our objectives were todetermine if selection for greater groat-oil content affected fatty acid composition, grain quality traits (test weight and seed weight), or agronomic traits (straw yield, biomass, harvest index, heading date, and height). We evaluated 100 random lines from the base (C0) population and each of the nine selection cycle populations in three environments in order to estimate means, genetic variances, heritabilities, and genotypic and phenotypic correlations of grain quality and agronomic traits. We also evaluated 20 random lines from each population to estimate changes in fatty acid contents. Oleate and stearate contents increased over cycles of selection, as did the ratio of unsaturated to saturated fatty acids. Palmitate, linoleate, and linolenate contents and all grain quality and agronomic traits except harvest index decreased over cycles of selection. There was no evidence for reduced genetic variance or heritability in C9 for any trait, but the genotypic and phenotypic correlations between agronomic traits and oil content fluctuated over cycles. Selection for increased groat-oil content improved oil quality but reduced grain quality and agronomic performance of the population. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

2.
The objective of this study was to evaluate the genetic progress after four cycles of recurrent selection in common bean. The base segregating population was obtained from 10 parents, and derived the S0:1 and S0:2 families that were evaluated. The S0:3 families with higher grain yield and grain color, like the standard carioca were selected, and were intercrossed to generate the population of the following cycle. This process was repeated for four cycles. The best families were evaluated in each cycle by many generations and locations, and the five best lines of each cycle were identified. The 20 lines thus obtained were evaluated in two growing seasons, sown in July and November 2002. The grain yield (kg/ha) and grain type (scale of scores) were evaluated. Genetic progress was confirmed for both traits. The mean annual gain with selection for the grain type was 10.5% and 5.7% for grain yield, with no evidence of variability reduction in the population. These results show that recurrent selection is a good alternative for improving common bean quantitative traits.  相似文献   

3.
Inter‐population hybrids of pearl millet, Pennisetum glaucum (L.) R. Br., have a substantial grain yield advantage over open‐pollinated varieties that makes them an appropriate and economically viable proposition for many African agricultural situations, provided that stable male‐sterile populations can be developed for use as seed parents. The objective of this research was to examine the feasibility of breeding stable male‐sterile populations, using the d2 dwarf version of Nigerian Composite NCD2 and the A4 cytoplasmic‐nuclear male sterility system as a test case. Results showed that two cycles of recurrent selection for sterility maintenance ability led to the development of a fully effective maintainer version of NCD2. There was no significant difference between the original C0 cycle bulk and the C3 cycle bulk (developed from the third and final cycle of recurrent selection) for grain yield and other agronomic traits. The male‐sterile population at the third backcross stage, developed from the maintainer version of NCD2, had as high a level of stable male sterility as the A1 system commercial inbred male‐sterile line 841A1. Thus, it is concluded that with the use of the A4 cytoplasmic male‐sterile system, it would be possible rapidly to develop a maintainer version of any population without detrimental effects on grain yield and agronomic traits. Male sterility of populations developed from these maintainers will be highly stable, paving the way for their effective utilization as seed parents in breeding inter‐population hybrids.  相似文献   

4.
Crop strains with high values for the selected trait but unacceptable agronomic characteristics are not useful as varieties. In this study, we determined whether selection for groat-oil content in oat (Avena sativa L.) via three recurrent selection regimes caused associated changes in 10 agronomic traits. Random lines of each cycle of selection of each regime were evaluated in a replicated field experiment at two locations. Biomass, grain yield, groat yield, and test weight decreased in all three regimes. Seed weight and plant height decreased in two regimes, and groat fraction in one. Oil yield increased in two regimes and decreased in the other. Plants headed earlier in one and later in another regime over cycles of selection. No changes in harvest index occurred. Heritabilities and genetic variances were relatively high for all traits in each regime. Factor analysis of the phenotypic correlation matrices indicated that simultaneous increases in grain yield and in groat-oil content are possible, that continuous selection for groat-oil content decreases groat fraction and test weight, and that seed weight is strongly and negatively associated with groat-oil content. A new recurrent selection regime for increasing groat-oil content of oat that may overcome the negative responses of agronomic traits was proposed.  相似文献   

5.
Maize (Zea mays L.) is a very important cereal to world-wide economy which is also true for Brazil, particularly in the South region. Grain yield and plant height have been chosen as important criteria by breeders and farmers from Santa Catarina State (SC), Brazil. The objective of this work was to estimate genetic-statistic parameters associated with genetic gain for grain yield and plant height, in the first cycle of convergent–divergent half-sib selection in a maize population (MPA1) cultivated by farmers within the municipality of Anchieta (SC). Three experiments were carried out in different small farms at Anchieta using low external agronomic inputs; each experiment represented independent samples of half-sib families, which were evaluated in randomized complete blocks with three replications per location. Significant differences among half-sib families were observed for both variables in all experiments. The expected responses to truncated selection of the 25% better families in each experiment were 5.1, 5.8 and 5.2% for reducing plant height and 3.9, 5.7 and 5.0% for increasing grain yield, respectively. The magnitudes of genetic-statistic parameters estimated evidenced that the composite population MPA1 exhibits enough genetic variability to be used in cyclical process of recurrent selection. There were evidences that the genetic structure of the base population MPA1, as indicated by its genetic variability, may lead to expressive changes in the traits under selection, even under low selection pressure.  相似文献   

6.
Summary One hundred random oat (Avena sativa L.) lines from a base (C0) and each of three populations (C1, C2, and C3) improved for groat (caryopsis) oil content by phenotypic recurrent selection were evaluated for correlated changes in several unselected agronomic traits. In addition, the parents of the base population and four check varieties were evaluated for the same traits. Phenotypic recurrent selection for high groat-oil content resulted in no significant correlated response in mean expression of any trait. Mean grain yield, biomass, groat yield, and harvest index of the improved populations were equal or superior to the mean of the parents and, with the exception of harvest index, equivalent to the mean of the check varieties. Mean test weight and seed weight of all populations were lower than for parents or check varieties. Selection for high groat-oil content caused a decline in genotypic variance for test weight and groat fraction, but reductions in genotypic variance for heading date and plant height may have resulted from culling for good agronomic type. Broad-sense heritability remained moderate to high for all traits except groat fraction. Phenotypic and genotypic correlation coefficients revealed negative, though mostly nonsignificant, relationships between groat-oil content and several traits, which may reflect a purported bioenergetic limitation to increasing groat-oil content in oats. Oil yield, however, was positively correlated with grain and groat yield, groat fraction, biomass, and harvest index. Results suggest that development of high-oil oat cultivars with current levels of production traits via phenotypic recurrent selection is possible.Journal Paper no. J-13038 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2447.  相似文献   

7.
In order to test if selection can improve a population's adaptation to diverse environments simultaneously, three cycles of recurrent selection based on grain yield in Iowa, Idaho, and Norway were practiced in an oat (Avena sativaL.) population developed from North American, Scandinavian, and wild species (A. sterilis L.) germplasm sources. Specific objectives were to determine if selection: increased mean yields across environments and within all environments; changed the genetic correlation of yields in different environments; and changed genetic variation for yield within the population. We evaluated 100 to 210 randomly-chosen families from each cycle of selection at three Iowa locations, in Idaho, and in Norway for two years. Grain yield within each location and mean yields across locations increased significantly over cycles of selection. Mean yields across locations expressed as a percent of the original population mean increased at a rate of 2.6% per year. Several families from the third cycle population exhibited both high mean yields across locations and consistently high yields within all locations. Average genetic correlations of yield in different environments were higher in the second cycle than in the original population. A trend of reduced genetic variation and heritability was observed in Iowa only. These results suggest that we successfully improved mean population yield both within and across locations, and yield stability across environments, and in developing families with outstanding adaptation to diverse environments. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

8.
Yield response to honeycomb selection in maize   总被引：1，自引：0，他引：1  
Summary This research evaluated the response to three cycles of mass honeycomb selection based on the grain yields of widely-spaced plants from the F2 generation of a maize (Zea mays L.) single cross hybrid. Frequency distributions of individual plant yields in the selection plots showed strong positive skewness. A significant linear yield increase of 11.23% per cycle compared to the check was obtained. Correlated responses were the significant reduction in days to mid-silking, increases in ear and plant heights and in prolificacy. The selected population was similar to the original hybrid in days to mid-silking, ear and plant heights, but had significantly more ears per plant. It is concluded that mass honeycomb selection at wide spacings was effective in improving grain yield and prolificacy but may produce correlated responses in some other agronomic traits similar to those obtained with other selection schemes.  相似文献   

9.
Summary During the last decades extensive progress has been achieved in winter barley breeding with respect to both, yield and resistance to fungal and viral diseases. This progress is mainly due to the efficient use of the genetic diversity present within high yielding adapted cultivars and – with respect to resistance – to the extensive evaluation of genetic resources followed by genetic analyses and introgression of respective genes by sexual recombination. Detailed knowledge on genetic diversity present on the molecular level regarding specific traits as well as on the whole genome level may enhance barley breeding today by facilitating efficient selection of parental lines and marker assisted selection procedures. In the present paper the state of the art with respect to virus diseases, i.e. Barley mild mosaic virus, Barley yellow mosaic virus, and Barley yellow dwarf virus is briefly reviewed and first results on a project aiming on a genome wide estimation of genetic diversity which in combination with data on yield and additional agronomic traits may facilitate the detection of marker trait associations and a more efficient selection of parental genotypes are presented. By field tests of 49 two-rowed and 64 six-rowed winter barley cultivars the genetic gain in yield for the period 1970–2003 was estimated at 54.6 kg ha−1 year−1 (r2 = 0.567) for the six-rowed cultivars and at 37.5 kg ha−1 year−1 (r2 = 0.621) for the two-rowed cultivars. Analysis of 30 SSRs revealed a non-homogenous allele distribution between two and six-rowed cultivars and changes of allele frequencies in relation to the time of release. By PCoA a separation between two and six-rowed cultivars was observed but no clear cut differentiation in relation to the time of release. In the two-rowed cultivars an increase in genetic diversity (DI) from older to newly released cultivars was detected.  相似文献   

10.
对ZZ4完成了4轮MS1-HS和MS1选择.结果表明,经4轮选择的群体,两种方法均有效地保留了各主要性状的遗传方差.MS1-HS选择的群体遗传方差下降速率更慢,C4群体的单株籽粒产量的遗传方差仅减少3.7%.穗长、穗粗、粒行数、行粒数、出籽率、百粒重的遗传方差的变化与单株籽粒产量一致,MS1C4的遗传方差减少了8%～15%,MS1-HSC4的遗传方差仅减少了4%～15%.株高、穗位高、抽丝期、植株保绿度、抗倒性等相关选择性状的遗传方差的变化与产量性状基本一致.MS1-HS法对改良玉米群体籽粒产量与测验种间的特殊配合力十分有效,呈逐轮上升的趋势;改良群体与测验种综系140间的杂交后代产量平均每轮提高6%,杂种优势平均每轮提高6.9%.两种方法在改良群体产量性状一般配合力方面,均得到了良好的效果.同时,穗部性状及株高、穗位、抽丝期、散粉期、抗性等田间农艺性状的一般配合力也获得了同步改良.通过ZZ4改良群体与6个测验种间杂交组合产量及杂种优势的比较研究,得出ZZ4与黄早四类种质为杂种优势模式对.  相似文献   

11.
Summary Maize (Zea mays L.) breeders are interested in the effects of recurrent selection for grain yield on other traits. Changes in plant traits could alter agronomic acceptability of the populations under selection, and observed improvements in grain yield could be explained by changes in ear traits. We evaluated changes in combining ability for plant and ear traits of BS10(FR), BS11(FR), BSSS(R), BSCB1(R), and Lancaster Surecrop associated with recurrent selection for grain yield.Recurrent selection procedures generally did not change plant and ear heights or date of silking of testcrosses of populations or of the population crosses, BS10(FR)×BSS11(FR) and BSSS(R)×BSCB1(R). Grain yield improvements, however, were associated with increases in ear-sink size.Journal Paper No. J 9517 of the Iowa Agriculture and Home Economics Exp. Stn., Ames, Iowa. Project 2152.  相似文献   

12.
Growing in Central Europe winter instead of spring durum wheat would substantially increase yield potential but is currently hampered by the lack of knowledge of frost tolerance present in elite material. The objectives of our survey were to (i) study the genetic variability and heritability of frost tolerance and its association with other important agronomic and quality traits in durum wheat, (ii) examine the potential to combine frost tolerance with high quality and high grain yield and (iii) investigate the consequences of the heritabilities and associations among traits on the optimum design of a multistage selection programme for winter durum wheat. We investigated 101 elite winter durum wheat lines and four commercial checks in field trials at four locations. Four agronomic as well as nine quality traits were recorded. In addition, frost tolerance was evaluated using a semi‐controlled test resulting in high‐quality phenotypic data. Genotypic variances (σ²G) were significantly larger than zero for all traits, and heritabilities were moderate to high. Several elite durum wheat lines exhibited a frost tolerance comparable to that of two frost‐tolerant Triticum aestivum varieties. Frost tolerance was not negatively associated with other important agronomic and quality traits. The high quality of the phenotypic data for frost tolerance evaluated in a semi‐controlled test suggests that this is a cost‐efficient approach to consider frost tolerance at early stages of a multistage durum wheat breeding programme.  相似文献   

13.
YLM, a codaominant polymerase chain reaction (PCR) marker linked to Yd2, could substantially improve the precision and efficiency of barley yellow dwarf virus (BYDV) resistance breeding. The aim of this study was to assess the effectiveness of YLM in a marker‐assisted introgression programme and to quantify associations between the presence of Yd2 and other agronomic and quality traits. The Yd2 gene was introgressed into a BYDV‐susceptible background through two cycles of marker‐assisted backcrossing. BC2 F2‐derived lines, either carrying or not carrying the YLM allele associated with resistance, were compared in the presence and absence of BYDV. The YLM marker was shown to be effective in the introgression of Yd2. Lines carrying the YLM allele associated with resistance produced significantly fewer leaf symptoms and showed a reduction in yield loss when infected with BYDV. There were no deleterious effects associated with the introgression of Yd2 on grain yield, grain size or malting quality. The implications of marker‐assisted selection for Yd2 on barley improvement are discussed.  相似文献   

14.
Long-term selection experiments provide germplasm to study the effects of selection in a closed population. Recurrent selection to enhance grain yield in oat has been ongoing at the University of Minnesota since 1968. The objectives of this study were: (i) estimate the GCA and SCA effects for three agronomic traits in the seventh cycle of selection, (ii) assess the effect of the current methods of selection on parental contribution and unselected traits, and (iii) determine the direct and indirect responses to seven cycles of recurrent selection for grain yield. Progeny of the Cycle 6 parents and parents for Cycles 0 through 7 were grown in two separate tests. Grain yield, heading date and plant height were evaluated in each test. Grain yield was increased by 21.7% after seven cycles of selection. Evaluation of Cycle 6 progeny showed that GCA effects were significant for all three traits studied, and SCA effects were significant only for grain yield. Four Cycle 6 parents did not have any progeny selected as Cycle 7 parents. Results from this study indicate that long term recurrent selection has continued to increase grain yield. Alternative selection strategies may be necessary to maintain the genetic variability in this population, particularly when improvement of secondary traits is required. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

15.
Improvement of maize populations for resistance to downy mildew   总被引：1，自引：0，他引：1  
Upgrading levels of disease resistance are a primary objective of maize breeding programmes. Efficacy of S1 recurrent selection in improving levels of resistance to downy mildew (DM) infection was assessed in Nigeria from 1997 to 2000 in six maize populations. Improvement procedures consisted of evaluating S1 progenies under artificial infection with DM spores and in disease‐free environments and using a selection index to combine selection for reduced DM infection with appropriate agronomic characters from more than one environment. Three to four cycles of selection were completed in each of the populations. Products from the different cycles of selection were evaluated and data collected on DM infection parameters and agronomic traits. Result obtained showed 3–4 cycles of selection were adequate to reduce DM infection levels significantly and increase grain yield. Downy mildew infection decreased by between 58 and 100% while grain yield increases ranged from 10 to 98% for the 2‐4 cycles of selection relative to the C0 (original). Selection increased grain yield with acceptable changes in plant height while maintaining maturity in disease‐free environments.  相似文献   

16.
A recurrent selection program for adaptation to diverse environments was successful in improving mean oat (Avena sativa L.) grain yield within and across testing environments. The objectives of this research were to determine if this selection program also resulted in changes in other agronomic traits or altered yield stability. Additionally, we investigated how selection modified the response of genotypes to climatic conditions. We evaluated random samples of 100 families from the original population and each of three selection cycle populations in replicated yield trials in Idaho, Iowa, and Norway for two years. Yield stability was assessed via joint regression analysis and superiority analysis. For each cycle, genetic relationships among yields observed indifferent environments were assessed by estimating phenotypic correlations between pairs of target environments. The effect of climate variables on genotype-by-environment interaction (GEI) responses was determined with partial least squares regression. Selection resulted in a small increase in mean heading date, a decrease in mean test weight, and no change in total above-ground biomass or plant height. Genotypic regression coefficients on environmental indices and deviations from regression were larger in the last cycle population, but superiority analysis demonstrated that selection significantly improved the adaptability of the population to the target testing environments. Improved adaptation was also demonstrated by increased phenotypic correlations among the most divergent pairs of environments in the later cycles. Partial least squares regression of GEI effects on climate variables suggested that later cycle families tended to respond more favorably to cooler than average conditions than the original population. Selection resulted in improved yield stability as well as improved mean yield. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
Summary Two spring barley composites, one based on eight West-European two-rowed cultivars (A) and one, the predominantly six-rowed composite XXI, based on several thousands of barley cultivars (B), formed the starting point of a recurrent selection procedure. The aim was to study whether recurrent selection in early generations is an effective procedure to improve barley populations for agronomic characteristics, especially grain yield.After two cycles of recurrent selection in the two populations A and B separately, and consisting of single plant selection followed by line selection, one cycle of recurrent selection was applied to the population produced by intercrossing the selected A and selected B lines.The selection for grain yield in the F2 single plant stages and the F3 line stages was carried out by selecting the plants or lines with the largest mean head weight provided that they did not tiller too poorly. Also some selection was applied against extremes in heading date and against tall plants.After two cycles of recurrent selection the grain yield, tested over two years and two locations, had increased with 16.5% in population A and with 27.0% in population B. Both the single plant selection and the line selection had contributed significantly to this response.The population created by crossing the selected A with the selected B lines showed a significant reduction in yield compared to the mean yield of the A and B lines constituting this population. Single plant selection, followed by line selection did raise the yield level 5.7% above that of the mean of these A and B lines. Several lines produced from this intercross combined an excellent grain yield with outstanding resistance to barley leaf rust and powdery mildew. However, these lines like the entire intercross population suffered from susceptibility to lodging, a characteristic derived from population B.In five experimental situations mixtures of genotypes were compared with the mean of the monocultures of the constituting genotypes. The mixture yielded always more, the average mixture effect being 4.5%.  相似文献   

18.
I. H. Khalil    B. F. Carver    E. L. Smith 《Plant Breeding》1995,114(2):117-120
Genetic gain in field crops is usually estimated as the collective contribution of several breeding programmes. Critical to an individual breeder, however, is the genetic gain realized within a single programme. Our objective was to quantify per-annum genetic gains from 1969 to 1993 within two successive phases of experimental line testing in the wheat (Triticum aestivum L.) breeding programme of the Oklahoma Agricultural Experiment Station. Data for grain yield (Phases I and II), volume weight and heading date (Phase II) were analysed according to the procedure developed by St. Martin and McBlain (1991). Genetic gains for grain yield were indistinguishable between phases, averaging 4.6 ± 1.1 and 4.2 ± 1.3% of the control mean across the 24-year period. Genetic gain for volume weight averaged only 0.2% of the check mean, reflecting lower selection pressure for that trait compared to grain yield. Inconsistent genetic gains in heading date reflect a preference for a window of desirable heading dates rather than difficulties in selecting uni-directionally for maturity. The absence of a decline in genetic gain in recent years indicates that future improvement in grain yield is likely; however, increased attention must be given to volume weight to maintain US domestic and export standards for hard winter wheat. The statistical procedure was useful in monitoring long-term trends in genetic gains and identifying gaps in programme efficiency.  相似文献   

19.
Choosing germplasm based on elite and diverse genetic sources is essential for the genetic improvement of maize (Zea mays L.) hybrids. The objectives of this research were to evaluate the agronomic and economic potential of maize population and single-cross hybrids and whether significant maternal (ME) and reciprocal effects (RE) reside in elite population hybrids for seed production purposes. Seven elite maize populations currently under recurrent selection at North Dakota State University (NDSU) [NDSCD(M-S)C11, NDSAB(MER-FS)C14, BS21(R)C7, BS22(R)C7, LEAMING(S)C4, CGL(S1-S2)C5 and CGSS(S1-S2)C5] were crossed in a diallel mating design to form 42 population hybrids, including their reciprocals. The 42 population hybrids with eight single-cross hybrids were evaluated at six U.S. North Central locations in 2005. Data collected across locations indicated that differences across genotypes were significant (P ≤ 0.05) for all traits observed, except for grain yield ear components. General combining ability (GCA) effects were on average larger than specific combining ability (SCA) effects. ME and RE were not significant for all traits, except for ear height. The large grain yield differences between macro-environments were reflected in the ranking of genotypes, with BS21(R)C7 × BS22(R)C7 being the top performer in eastern environments and CGSS(S1-S2)C5 × NDSAB(MER-FS)C14 being the top one across western environments where drought is the major limitation. The increased ethanol production and demand from maize make test weight (and grain quality), earliness, lodging resistance, and drought tolerance as important as grain yield for maintaining a sustainable maize-ethanol relationship. Part of the thesis submitted by McDonald B. Jumbo in partial fulfillment of the requirements for a MS degree at North Dakota State University.  相似文献   

20.
This research was conducted to study the genetic diversity in safflower (Carthamus tinctorius L.) using agro-morphological traits and RAPD markers. Sixteen selected lines derived from landraces growing in various agro-climatic regions of Iran along with four exotic genotypes were evaluated in a randomized complete block design with three replications under field conditions. Days to emergence, days to initial flowering, days to flowering, days to maturity, plant height, branches per plant, capitula per plant, seeds per capitulum, 1,000-seed weight, seed yield per plant, seed yield, and reaction to powdery mildew (Leveillula taurica Arnaud) were evaluated in this study. Genetic diversity of the genotypes was assessed by RAPD markers. The results indicated significant differences among genotypes for the agro-morphological traits and clustering based on these traits classified the genotypes into five groups. Analysis of the RAPD markers revealed 15 polymorphic primers out of 50 used primers. Based on RAPD data, the highest genetic similarity was observed between the cultivars of “AC Sunset,” “AC Sterling” from Canada and the lowest relatedness observed between a local breeding line “E2428” and genotype “GE62923” from Germany. Cluster analysis based on RAPD markers and 54% coefficient of similarity divided the genotypes into five distinct groups. Comparing the clusters based on agro-morphological traits with those from molecular markers showed slight similarities. The finding of high genetic variation for agro-morphological traits and polymorphism at DNA level reveal that agronomic traits can be improved by selection programs.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号