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1.
Summary The effectiveness of the honeycomb selection method for yield in spring wheat (Triticum aestivum L.) was evaluated using progenies from two wheat crosses, Glenlea x NB131 and Glenlea x Era. Honeycomb selection was carried out in the F2 and F3 generations, grown at the University of Manitoba in the summers of 1980 and 1981, respectively. In both generations, divergent selection was made for both high and low yield. Plants selected in the F3 generation were entered in an F4 yield test in the summer of 1982. Results of the experiment showed that honeycomb selection for yield in the F2 and F3 generations was effective in identifying parents of high- and low-yielding lines. F3 plants from highyielding F2 selections gave higher yields than those from low-yielding F2 selections by 11.5% and 13.0% for Glenlea x NB131 and Glenlea x Era crosses, respectively. The F4 yield test showed that high yielding selections from both crosses significantly outyielded by 8.9% low yielding selections and by 14.4% the unselected composite lines. It is concluded that the honeycomb selection method can be used for early generation selection in spring wheat.  相似文献   

2.
H. G. Nass 《Euphytica》1979,28(1):161-167
Summary Three methods were evaluated as potential aids in identifying superior crosses early in the breeding program: (1) F1 yield, (2) F2 yield, and (3) midparental yield. Two sets of spring wheat (Triticum aestivum L. em. Thell.) crosses and parents were evaluated in replicated single row plots in F1 and in replicated multi-row plots in F2 over a period of five years. On the basis of F1 yields, two of the highest yielding and two of the lowest yielding crosses in each set were chosen for a more detailed selection study in subsequent generations.In Set 1, random F2 head selections for each of the selected four crosses were evaluated in 3-row yield plots in F4. In Set 2, F2 plant selections were made on the basis of head weight and the highest yielding 10% evaluated for yield in F4.Lines of crosses identified as high yielding in F1 had significantly greater mean yields in F4 than those of crosses that were low yielding in F1. The high yielding crosses had three to four times as many lines yielding in the top 10% in F4 than did the low yielding crosses.Correlations for yield were obtained between F1 and F2 in different years, F2 and midparents in the same year, lower or no correlations between F1 and midparents in the same year, and no correlations between F1 and midparent and F2 and midparent in different years. It is suggested that larger plot sizes rather than single rows be used to evaluate parents.Midparental yield, F1 yield and F2 yield tests are recommended as a progressive set of screening tests for a given set of crosses to effectively maintain the superior crosses in the breeding program.  相似文献   

3.
Yields of large-seeded Andean (A) common bean (Phaseolus vulgaris L.) cultivars of Chile and Nueva Granada races are 40 to 60% lower compared to their Middle American (M) counterparts of small-seeded Mesoamerica and medium-seeded Durango races. Our objective was to use the concept of congruity backcrossing between Andean x Middle American inter-gene pool [AM 11833 = A 483 (A)///// A 686 (M) //// PVA 800A(A)/// ‘Carioca’ (M)// Carioca (M)/ G 19833 (A)] and between races within Andean gene pool [i.e., intra-gene pool Andean, AA 11834 = A483 (A)//// ‘Cardinal’(A) /// ‘Blanco Español’(A) // BlancoEspañol (A) / ‘Taylor’ (A)] to compare selection for seed yield improvement of large-seeded Andean beans. Seven hundred sixty seven F2-derived F3 (F2:3) families were produced for each population. Visual appraisal for total plant performance, combined with seed yield from non-replicated plots was used for selection of 551 families in F2:3, 182 families in F2:4, and 91 families in F2:5 in each population. Eight hundred twenty three F5:6 lines were developed from the 91 F2:5 families in each population. Visual selection, combined with seed yield in non-replicated plots was again used to select 294 lines in F5:6 in each population. Similarly, 44 highest yielding F5:7 lines were selected in AM 11833 and 39 F5:7 lines in AA 11834. Thus, single plant selections were made in the F2 and F5, and plants within each plot were harvested in bulk in F3, F4, F6, and F7. Thirty nine F5:8 lines from AA 11834 and 44 lines from AM 11833, parents, and checks were evaluated at Popayán and Quilichao, Colombia in 1998 and 1999. Selected lines in both populations, on average, out-yielded the mean of their large-seeded Andean parents. Mean yield of the lines selected from AM 11833 was 50% higher than AA 11834 lines. Twelve F5:8 lines out-yielded the highest yielding Andean parents G 19833 and A 483 in AM 11833, whereas only one line yielded significantly higher (p < 0.05) than the highest yielding parent A 483 in AA 11834. However, none of selected lines out-yielded small-seeded Middle American parents used in AM 11833 (A 686 and ‘Carioca’). The mean 100 seed-weight of AA 11834 was 36 g compared to 28 G for AM 11833 F5:8 lines. Selected lines had similar days to maturity as parents in AM 11833, and matured 3 d later in AA11834. Correlation coefficients between yield and 100 seed-weight were negative in both populations. Yield and days to maturity were positively correlated in AA 11834.  相似文献   

4.
Summary Aspects of selection for yield and harvest index were investigated by simulating selection using data from random pedigreed F2, F3, F4 and F5 derived lines from two crosses grown in plots at two sites over two years.Improvement in yield through selection was obtained when the response was measured at the same site and in the same year as the selection. Selecting the best 10 per cent of F2 to F4 derived lines gave F5 derived lines that outyielded random selections by 19 to 53 per cent for one cross and 5 to 23 per cent for the second cross. These lines were 41 to 50 per cent better than the mid-parent in one cross, but were less than the mid-parent in the other cross.However, the response to selection when measured in a different year was little better than random selection. The effect of different sites also reduced the effectiveness of selection.Selection of harvest index in early generations for improvement of yield was ineffective when response was measured at the same site in the same year, or in different years.Contrary to some theoretical proposals, the same improvement in yield was obtained by selecting in early or late generations. While high yielding genotypes may be lost by delaying selection, this is counteracted by the better predictive value of late generations due to their greater homozygosity and homogeneity.  相似文献   

5.
Approaches are needed to broaden the genetic base and improve earliness and yield potential of large-seeded beans under sustainable cropping systems. The objective of this research was to develop adapted dwarf bean populations having a commercial seed quality and yield suitable for the production in the South of Europe. The original base populations were produced from crosses between genotypes within each Mesoamerica, Nueva Granada and Peru races, and between Peru and Nueva Granada, and Mesoamerica and Nueva Granada races. Visual mass selection for plant performance was practised in the F2 and F3 generations. In the F4 and F5, single plants were harvested under two cropping systems (sole cropping and intercropping with maize). From F4, selection was based on precocity, combined with seed yield and seed commercial type. The F4:7 selected lines from each original population were compared with their parents and five checks at four environments and two cropping systems. Differences among environments, populations, parents and checks were observed for all traits. Under intercropping with maize, there was a 50% reduction in seed yield. Yield of parents and checks belonging to Andean South American races, intraracial (Nueva Granada × Nueva Granada) and interracial (Nueva Granada × Peru) populations, was higher than that of those of Middle American origin. Intraracial crosses within large-seeded Andean South American (Peru race) and Middle American gene pools (Mesoamerica race) did not produce lines yielding more than the highest yielding parent. Only two large-seeded lines selected from crosses between small- and large-seeded gene pools out-yielded the best parent and check cultivar.  相似文献   

6.
Crosses were made between two widely grown U.S. peanut (Arachis hypogaea L.) cultivars, ‘Florunner’ and Florigiant’, and two genotypes adapted to growing conditions on the plateau of tropical Africa, ‘Makulu Red’ and 486 GKP. F2 seed populations were equally divided between Georgia and Zimbabwe. Subsequently, pedigree selection was practised simultaneously at both locations in the early segregating generations. The highest yielding pureline selections were then interchanged, and combined yield evaluations were determined over three growing seasons at each location. ‘Florunner’, ‘Florigiant’, and the Georgia pureline selections tested at the Georgia location had significantly higher pod yields than ‘Makulu Red’, 486 GKP, and the Zimbabwe selections. Conversely, the mean yield of the Zimbabwe selections tested m Zimbabwe was significantly higher than that of the Georgia selections. Thus, the breeding environment under which selection is conducted among cross populations strongly influences the yield adaptability of selected peanut genotypes.  相似文献   

7.
The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency. Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection schemes were: pedigree, modified bulk (F2 and F1-top as pedigree, selected lines in F3, F4, F2-top, F3-top as bulk; and pedigree in F5 and F4-top populations), selected bulk (selected plants in F2, F3, F4, F1-top, F2-top and F3-top as bulk; and pedigree in F5 and F4-top populations), and nonselected bulk (bulk in F2, F3, F4, F1-top, F2-top and F3-top; and pedigree in F5 and F4-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore, a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
A fragment of chromosome 1DL of breadwheat (Triticum aestivum L.) with the locus Glu-D1 encoding high molecular weight glutenin subunits 5+10 was translocated in hexaploid triticale (× Triticosecale Wittmack) to chromosome 1RL of rye (Secale cereale L.) where it replaced a corresponding fragment containing locus Sec-3 encoding rye secalins. The translocated chromosome 1R was transferred to diploid rye through backcrosses. During the transfer, at least two crossover events must have taken place that reduced the lengths of the 1DL inserts to about 5–8% of 1RL. These short inserts were selected on the basis of normal male transmission from heterozygotes and by low pairing with chromosome 1D in the F1 hybrids with wheat, and tested by the in situ hybridization with total genomic DNA. While the wheat introgression in rye did not affect plant morphology or fertility, preliminary observations of the first population of homozygotes suggested that grain yield was lower, probably as a result of about 15% reduction of the 1000 kernel weight. The presence of a single wheat glutenin locus was insufficient to create rye with wheat-like breadmaking properties. However, relative to controls, the SDS-sedimentation value increased by about 75% and loaf volume was greater in test bakes using the procedure adapted for wheat-rye blends. Loaf volume for bread baked using the procedure for rye flour was not affected. Ryes with various glutenin subunits could be used in wheat-rye blends. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

9.
S.R. Verma  M. Yunus  S.K. Sethi 《Euphytica》1998,100(1-3):15-18
Three populations of an intervarietal durum wheat cross IWP5308/PDW208, F5, F5BIP1 (population derived after intermating in F2) and F5BIP2 (population derived after intermating in BIPF1), were evaluated under three different agronomic environments for mean performance and stability of genotypes for grain yield, yield components and protein content. Though the biparental progenies indicated a higher mean performance, they did not differ significantly from progenies of the pedigree method for almost all characters. The biparental progenies, however, produced a higher number of stable genotypes for grain yield per plant, grains per ear and protein content. The F5 population had a higher number of stable genotypes for 1000 grain weight and number of tillers per plant. The BIP progenies also had a higher number of genotypes with above average mean performance, and many were significantly higher than the checks WH896 and WH542, compared with F5 progenies. Hence, in spite of high G x E interactions, the use of cycles of biparental mating and selection of top yielding lines on the basis of yield components can enable selection of stable genotypes with high protein content. Number of tillers per plant and 1000 grain weight were the yield component characters which made maximum contribution to phenotypic stability of the genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

10.
Summary Water is often the most limiting factor to winter wheat (Triticum aestivum L.) production in the southern Great Plains of the U.S.A., yet the lack of reliable screening criteria has precluded direct selection for drought resistance in breeding programs. Previous work showed that leaf relative water content (RWC) was highly heritable when measured under field-drought conditions, but its adoption as a screening tool for yield improvement requires further investigation of the genetic relationship between grain yield and RWC. Plants representing high and low yield potential under drought stress, and a random group of plants, were selected from an F2 population having the pedigree, TAM W-101/Sturdy. Two sets of entries, each comprised of the two parents and 24 F2-derived lines, were evaluated under a rainshelter in the F3 (1986) and F4 (1987) generations to determine differences in leaf RWC during reproductive development. One set of entries did not receive any water after the jointing stage, and the other set was grown under well-watered conditions. A positive relationship was observed between grain yield and RWC measured during anthesis and mid-grain fill, as the high-yield selections maintained a significantly higher RWC than the low-yield selections. Grain yield and RWC were also positively associated among random selections segregating for both traits. Subsequent adjustment of genotype means for differences in reproductive development at time of sampling underscored the need to consider differences in maturity when RWC is the selection criterion.  相似文献   

11.
An essential quality improvement of rapeseed oil can be obtained by reduction of its linolenic acid (C18:3) content from about 10% to less than 3% of the total fatty acids. Genotypes low in C18:3 have been developed by mutagenesis. The initial summer rapeseed mutant had been low yielding and highly susceptible to various diseases. It has been debated whether the low C18:3 character can be successfully combined with high seed yield for physiological reasons. Therefore, the low linolenic character of mutant M48 was transferred into high-yielding genotypes by repeated backcrossing to well-adapted low erucic acid, low glucosinolate (00-) winter rapeseed cultivars. Lines with low C18:3 content were selected from BC3 and BC4 generations and examined in 1990–95. Positive selection response for seed yield was shown to continue over the years. Presently, the best lines are yielding as well as the control cultivars being equivalent also in oil and glucosinolate contents. In order to test the effect of a low C18:3 content on seed yield, plants with low and with high C18:3 content, respectively, were selected from 16 segregating BC5-F2 populations and bulked to form 32 F3 populations. These ‘isogenic’ bulk populations were tested for field performance at four locations in 1995. The results show that C18:3 content of the seed oil is not associated with seed yield, oil content, beginning of flowering, plant height and disease resistance. Means of relative seed yield for the high and the low linolenic F3 bulk populations were not significantly different with 88.0% and 86.9% of the control cultivars, respectively. There was a significant interaction between genotypes with high or low C18:3 content and location. This shows that under specific environmental conditions a low C18:3 content may be either favourable or unfavourable. The results indicate that the low C18:3 character of the original mutants per se does not cause a decrease in seed yield, oil content or general field performance.  相似文献   

12.
Divergent Selection for Heading Date in Barley   总被引:1,自引:0,他引:1  
Divergent selection for heading time was performed in two F2 barley population. Five populations were obtained for each cross: F5 SSD (unselected control), 3E and 3L (from three cycles of selection for earliness or lateness), 2E1L and ZL1E (from two cycles of direct and one of reverse selection). These populations, together with corresponding parents and F2 generations, were evaluated over two years. The response to selection was 5.6 and 6.5 days inane direction (earlier heading) and 7.7 and 6.7 clays in the other direction (later heading) in the two crosses, respectively. 3E and 3L populations were highly transgressive as compared to their parents. A sizeable amount of genetic variability was still present after two cycles of selection. Heading was probably controlled by a polygenic system with prevailing additive effects and alleles for earliness and earliness somewhat equally distributed in the parents. Selection fur heading time led to significant changes in plant height, yield and kernel weight. Early progenies were higher yielding than lace ones.  相似文献   

13.
Summary Significant advances in increasing tolerance to the leafhopper Empoasca kraemeri Ross & Moore in common bean have been obtained using a new breeding scheme where yield under leafhopper attack is the principal selection criterion in the evaluation of progenies. However, to further refine this breeding scheme, a study was conducted to determine whether selection for nonprotected yield would be more effective in early versus late generations. Two selection strategies were compared. In Strategy I, early generation selections in the F2 and F3 were compared to Strategy II where late generation selections were made in the F4 and F5, with the F2 and F3 generations advanced using single pod descent and bulk practices, respectively. Yield trials of the F6 lines from both selection strategies were conducted under nonprotected and insecticide protected treatments. No significant differences were detected between the two selection strategies. However, Strategy II did produce advanced lines with greater nonprotected yields than did Strategy I, with the best F6 line, in three out of four crosses, coming out of Strategy II. Late generation selection is recommended over early generation selection. Results of the new leafhopper breeding scheme, based on yield, are compared to the old breeding scheme where selections were made using visual selection practices in early generations.  相似文献   

14.
Selection for yield in early generations is difficult, mainly due to a shortage of seed. In the breeding company Fr. Strube the breeder uses three-way crosses and first selects for yield between F2′-derived lines in the F4′. The generations are called F1, F2′, etc., because the first generation is already segregating. The efficiency of this selection was checked in the F5′ and F6′. For this purpose F3′-derived progenies, corresponding to poor and good yielding bulks in F4′, were selected. In later generations the average yield of the group of strains with good yield in the F4′ was 4 % (F5′) and 3 % (F6′) higher, respectively, than the mean of the strains with low yield in the F4′. Strains with very low yielding potential can easily be discarded in the F4′. The risk of discarding lines with a very high yield is minimal. Selection for yield in the F4′ was as effective as in the F5′. The importance of testing F2′-derived bulks in the F4′ is not only based on the assessment of yield but also on the possibility of reliable intensive selection through recording visual characters (height, resistance against diseases) in a second environment in parallel to the single plant progenies.  相似文献   

15.
Summary Independent but simultaneous selection by two breeding teams of the same segregating two-row winter barley material at Cambridge, England and Fiorenzuola, Italy was carried out over the years 1978–1982 with the objective of comparing the individual selection of the two breeding teams and assessing the adaptation of the surviving selections. Visual selection in the generations F3 to F5 did not result in any clear cut compartmentalisation of the material and both teams were as likely to select from families previously selected only by the other team as from families they had themselves previously selected. Lines with specific adaptation to each site as well as lines well adapted to both sites were identified from yield trials carried out in F5 and F6. The former showed only a very small yield advantage over lines with general adaptation to both sites.  相似文献   

16.
Summary Relationships among the traits protein percentage, grain yield, and protein yield of oats were studied with F2-derived lines in F3 and F4 from 27 matings obtained by crossing high-protein with high-yield oat lines. High-protein parents were (a) selections from an Avena sativa bulk, (b) selections from three-way matings in which an initial parent was A. sterilss, and (c) cultivars. High-yield parents were derived from backcross populations involving A. sterilis accessions as donor parents.Significnnt genetic variation existed among F2-derived lines for grain and protein yield in all matings and for protein percentage in all but one mating.Protein percentage had a highly significant negative correlation with grain yield (r=–0.33**) when pooled over all matings, but in five, these two traits were not correlated. Overall, protein percentage showed a small negative correlation with protein yield (r=–0.09*), and protein and grain yields had a high positive association (r=0.98**). F2-derived lines with both high protein percentage and high grain yield were obtained.High transgressive segregates for protein percentage occurred in two matings, for grain yield in nine, and for protein yield in 14. Most high transgressive segregates for protein yield were high because of high grain yield only, but in four matings, lines were found where protein yield was increased by concurrent increases in both protein percentage and grain yield.Only a few specific parental combinations between high-protein and high-yield parents produced segregates in which increased protein percentage contributed materially to high-protein yields.Journal Paper No. J-11264 of the Iowa Agriculture and Home Economics Experiment Stn., Ames, Iowa 50011. Project 2447.  相似文献   

17.
Parental lines, F1 and F2 hybrids from a 7×7-diallel of topless faba beans and eight standard cultivars were grown in single-rows for two years at four sowing dates on a highly fertile loam soil near Göttingen. In grain yield, F1 hybrids showed 21 to 54% advantage over the higher yielding parent. Compared with the midparental value an average heterosis of 50% was observed for grain yield. Corresponding heterosis mean values ranged from 3 to 37% for yield components and up to 11% for phenological traits. The grain yield of the highest yielding topless F1 hybrid was equal to that of Alfred, the highest yielding indeterminate standard cultivar. High grain yield in the topless hybrids was closely correlated with high biomass yield, late ripening and tall plants generally having a high number of podded nodes and pods on the main stem. Due to their agronomic advantages, i.e., lower plant length, reduced lodging sensitivity and earlier ripening, efforts at breeding topless hybrids seemed to be worth-while in faba beans. However, their yielding ability must be improved further before they can compete with normal, semi-dwarf and stiff-strawed cultivars.  相似文献   

18.
Summary Two breeding procedures were compared in two cowpea crosses. Both procedures were started from the same selected F2 plants in each cross. For the early generation yield testing, the F3 lines were yield tested and a pedigree and bulk methods followed in F4 and F5. Each F5 line was bulked to provide seed for a yield test in F6. In the Single Seed Descent (SSD) procedure, a single seed was taken from each F2 plant to produce the F3 generation. The procedure was repeated for the F4 and F5. The F6 SSD lines and the F6 yield testing lines were compared in yield tests.The results showed that differences in yielding ability of F3 lines persisted over generations indicating that selection was effective. This was confirmed by the high significant correlations between F3 yields and those of later generations which ranged from r=0.51* to 0.85**.The grain yields of lines derived by the single seed descent procedure were as good as those derived from early generation yield testing.Significant linear correlation between visual rating of F3 and F6 yields with actual yields revealed that it is possible to identify promising lines of cowpea visually.  相似文献   

19.
Summary Four hundred sesame (Sesamum indicum L.) lines selected by five methods from five crosses were tested for yield and other agronomic characters in F6 and F7. More high yielding lines were isolated by the bulk method and in the cross involving two local cultivars when two seasons means and performance in each individual season were considered. The cross involving two exotic cultivars did not produce a single line superior to local recommended variety. The 80 highest yielding lines recorded a 10.8% increase in yield compared to the mean of 400 lines. Thirty five lines were among the top 20% both seasons with a 13.2% increase in yield. Highly significant seasonal and population effects were recorded. There were no significant differences among the methods of selection although the yield differences among lines were highly significant. Interactions of seasons × populations, seasons × methods, populations × methods and seasons × populations × methods were highly significant. The results indicate that simple and less expensive bulk method may be used with equal success as the pedigree, single seed descent or early generation testing methods when selecting for yield in segregating sesame populations. The importance of inclusion of a high yielding, locally adapted cultivar in the crossing programmes for yield breeding of sesame has also been revealed.Abbreviations BM Bulk method - EGT Early generation testing - G × E Genotype × environment - MSS Modified single seed descent - PM Pedigree method - SSD Single seed descent  相似文献   

20.
Most of the Brazilian soils, especially in Cerrado biome, have high acidity and toxic aluminium, making the application of limestone an indispensable technique to obtain high yield in soybean crop. The hypothesis of this study was that contrasting base saturation provides changes in water-use efficiency (WUE) and agronomic traits of soybean populations. Thus, we evaluated the WUE and agronomic performance of F3 soybean populations under different base saturation levels. Each experiment was conducted in a randomized complete blocks design with three replicates and 10 F3 populations (P1, P2, P3, P4, P5, P6, P7, P8, P9 and P10) for two crop seasons. Segregating populations were obtained by bulk method. In the first experiment, F3 populations were evaluated without correction of base saturation (V = 30%), while in the second experiment, limestone was applied three months before sowing to increase base saturation to 60%. The traits evaluated were as follows: calcium, magnesium and potassium contents, water-use efficiency (WUE), plant height, first pod height, main stem diameter and grain yield. Our findings indicate that WUE and agronomic performance of F3 soybean populations depends on the saturation condition. We identified the P4 and P9 populations as the most promising for use in breeding programmes aiming at higher tolerance to abiotic stress caused by low base saturation in soil.  相似文献   

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