摘要:

AbstractSix accessions belonging to four subspecies ofBrassica rapa, including three accessions ofB. rapasubsp.sylvestris, were crossed withB. oleraceasubsp.alboglabrain order to develop a series of syntheticB. napuslines with a common C genome but contrasting A genomes. Different A genomes had significant effects on the efficiency ofB. napusresynthesis and the sexual compatibility of the synthetic lines with oilseed rape cultivars. The synthetic lines were used to investigate the effect of A genome substitution on the resistance ofB. napusto infection byLeptosphaeria maculans, and to explore the potential for the use of wild forms ofB. rapain oilseed rape breeding programmes. Synthetic lines derived from two wild accessions ofB. rapa, and their F1hybrids with oilseed rape cultivars, expressed high levels of resistance toL. maculansin glasshouse experiments. One of these lines also expressed high levels of resistance in field experiments in England and Australia when exposed to a genetically diverse pathogen population. All other synthetic lines and cultivars were highly susceptible in both glasshouse and field experiments. F1hybrids between oilseed rape cultivars and synthetic lines derived fromB. rapasubsp.chinensiswere significantly more susceptible than either parent.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00684.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIsoelectric focusing (IEF) and immunoblotting were used to detect genetic variants of malt endopeptidase (MEP1), an enzyme related to malting quality in barley and coded by theCepBlocus on barley chromosome 3 (= 3H). A variant was found in a Turkish accession of wild barley (Hordeum vulgaressp.spontaneum). The self progeny of a hybrid between this accession and the barley cultivar ‘Clipper’ were analyzed for recombination between theCepBlocus and other isozyme loci. The estimates of recombination linked theCepBlocus to an NADH diaphorase locus (Ndh2), which in turn was linked to the seedling esterase complex (Est1, Est2, andEst4) situated near the distal end of the long arm of chromosome 3. TheNdh2locus was independent of two other NADH dehydrogenase loci (Ndh3, Ndh5) which were mapped on barley chromosome 5 (= 1H) in relation to the three hordein loci (Hor1, Hor2, andHo

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00685.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractProfound hardening is the prerequisite for survival of a cultivar over winter. In the present study, hardening abilities of 13 winter wheat, 10 rye, 3 triticale and 6 winter barley cultivars were determined in field samples collected during the autumns of 1990 and 1991 by measuring the amount of ion leakage from frost‐treated leaf segments. The cultivars tested were selected from the Inter‐Nordic Winterhardiness Project, in which Field Survival Indices were determined for a total of 23 winter wheat, 13 rye, 5 triticale and 11 winter barley cultivars in order to estimate winter survival potentials under Finnish conditions. The winter survival of the materials studied correlated well with their hardening ability assessed by using the electrolyte leakage met

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00686.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSeveral statistical methods were investigated for improving yield estimation for 72 genotypes of winter wheat tested in a single‐row‐plot (SRP) trial. The different analytical models were compared using several criteria: the residual mean square fit; the standard error of differences of genotype means; the correlations of genotype means with means from six‐row‐plot (6RP) reference trial; the expected genetic gains relative to 6RP trial from selecting the 10 top yielding genotypes.There was no significant correlation between the unadjusted genotype means for SRP and 6RP. Genotype yields were positively correlated with height in SRP, but this correlation was reversed in 6RP. Using the mean height difference of a plot with its two neighbours as a covariate to adjust for competition in SRP reduced the standard error of difference of genotype means and substantially increased their correlation with the 6RP means. The predicted selection efficiency in SRP trial increased from zero, before adjustment, to 83 % of 6RP trial. Including the difference in heading date and the effect of guards at borders as covariates in the SRP analysis improved the residual mean square fit but had no effect on correlation with 6RP means or selection efficiency. A producer‐competitor model in which individual competitor effects were estimated for each genotype gave a substantial improvement in fit over the covariate models but a much lower correlation with 6RP means and selection efficiency.Yield selection in early generation wheat trials based on single‐row plots could be considerably strengthened by use of a plot covariate derived from height difference between

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00687.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSeptoria tritici blotch constitutes a major disease problem of wheat world‐wide. To efficiently breed wheat for resistance to this disease, an understanding is required of the inheritance of resistance. Our objective was to study the quantitative inheritance of resistance under field conditions. A nine‐parent diallel and a generation mean experiments were conducted at Toluca, México in 1986 and 1987, respectively, to investigate gene effects. General combining ability effects accounted for most of the variation although specific combining ability effects were detected in some crosses. Ias20*5/H567.71, Thornbird, and RPB709.71/Coc contributed the most to reduced disease severity. Reciprocal effects were detected in two of 36 crosses, where RPB709.71/Coc contributed additional reduced disease severity when used as female. The analysis of generation means confirmed results obtained from the diallel. Additive effects were also most important. Dominance effects and epistasis, mostly of the additive × additive type, were found in some crosses. Hence, substantial genetic progress for resistance can be expected among progeny from crosses with resistant parents. However, selection would be most effective if delayed to later generations because of dominance, and choice of the specific female parent may produce a higher level of resis

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00688.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this investigation, genotypes with branched, tetrastichon (two spikelets per node of the rachis), and normal spikes were used in order to induce changes in sink capacity, while high‐yielding domestic and foreign varieties served as donors of other traits. These materials were crossed by the methods of single‐, back‐, and top crossing and the desirable genotypes were selected by the pedigree method. After 10 years of breeding for the desired ideotype, whose main features had been a highly fertile spike of normal structure, short straw, curved leaves, and reduced tillering, 229 lines were tested in comparative yield trials. Among them, four lines were superior in yield and other traits to the highest yielding standards. Regarding the expected changes in sink capacity, considerable progress was made in spike length, number of grains per spike, number of grains per spikelet, and the weight of grains per

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00689.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSeveral studies have indicated a possible link between genome size and earliness in maize. In this study, an original maize population, South African photo‐period insensitive maize composite II (C0) and several selected generations were analyzed for days to flowering, plant height, ear height, and yield. The selection criterion was earliness. Over six cycles of selection a 14‐day decrease in days to flowering was obtained with no significant reduction in grain yield. In the initial population (C0) and the most advanced selection (C6) 101 plants were analyzed for nuclear DNA content. A significant decrease in the mean nuclear DNA content of the C0population (102 AU) was observed with respect to the C0population (105 AU). This reduction was the result of a decrease in frequency of plants in the C6population with large genome sizes. Therefore it was concluded that selection for earliness resulted in selection against plants with large genome sizes. Hence, the nucleotype of a maize plant can be modified by selection such as early flowering t

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00690.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractResistance toV. inaequalis, derived from the small‐fruited speciesMalus floribunda821, is determined by a major dominant gene, assigned asVf.The material used in this paper is based on the introgression of theVfgene fromM. floribundainto commercial apple varieties. Comparing RAPD patterns of a genomic DNA sample ofM. floribundawith a pooled DNA sample of resistant individuals and that of 10 susceptible commercial apple varieties, fragments were identified which are derived fromM. floribunda.One of them, the fragment OPD20/600, proved to be linked to theVfgene with a recombination value of about 0.20—0.25. It is the first DNA marker so far for scab resista

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00691.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFifty‐five doubled haploids (DH) ofCoffea canephorawere crossed with either heterozygous genotypes or DH in order to study their combining ability. Three agronomic trials were established. Marked hybrid vigour was observed for all characters analyzed including yield. Large differences were evident among top‐crosses involving different DH produced from the same parental clone reflecting the high level of heterozygosity of clones. Factorial mating design analysis indicated that all genetic variance was attributable to additive effects in estimates of yield as well as plant height and leaf characteristics. The general combining ability variance component was also predominant for stem girth and susceptibility to leaf rust, although effects due to interaction were detected. Some hybrid combinations had yield comparable to standard clonal varieties. The implications of such results for breeding ofCoffea canephoraare discussed. Particularly, the development of F1hybrid varieties is envisa

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00692.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn order to identify 1B/1R translocations and substitutions by simple means in breeding materials, the efficiency of using starch gel electrophoresis of isoenzymes was evaluated. GPI (glucose phosphate isomerase) and MDH (malate dehydrogenase) were tested in 17 lines of wheat which had previously been identified for their 1B/1R status by C‐banding. By electrophoresis of these two enzymes the rye substitution of only one wheat chromosome arm could be identified with high accurac

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1994.tb00693.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY