摘要:

AbstractThe agronomic performance of transgenicBrassica napuslines carrying chimeric 2S albumin seed protein genes was studied under field conditions. A total of 37 transgenic lines were compared to non‐transformed lines. Plant development, morphological characteristics, yield parameters and seed composition were considered. Only a few transgenic lines differed from the control, and then only for particular parameters: four lines had altered leaf morphology, two differed in germination efficiency, one differed in yield, and three differed in some parameters of seed composition. These differences were not correlated with the presence or expression of the transgene and, thus, were more probably linked to cell‐ or tissue‐culture effects, or to residual variation present in cv. ‘Drakkar’. A statistical interaction between variations in a limited number of seed composition parameters and cell haploid culture was observed.While the expression of the chimeric 2S albumin gene was not as high as hoped, this study demonstrates that transgenic lines can be isolated in which the intrinsic morphological and agronomic properties of the original lines are m

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00771.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo field experiments were carried out with seven wheat cultivars (three of them, including a commercial hybrid, released during the last 10 years) representing different eras of plant breeding, to evaluate genetic improvement over the last century in grain yield, height, biomass, harvest index and grain yield components. Plots were fertilized and irrigated, and lodging and diseases were prevented.Main culm height was negatively correlated with the year of release of the cultivars, probably as a consequence of selection for increased lodging resistance. There was no significant association between total above‐ground biomass and year of release of the cultivars. On the other hand, grain yield increased as newer cultivars were released. Results indicate that during recent years harvest index has been kept as the main attribute responsible for increases in grain yield. In general, number of grains/m2was associated with increases in grain yield during the century. However, the newest cultivars showed an increased grain weight. In both growing seasons, cultivars released before 1980 showed a trend towards reduced grain weight, but cultivars released after 1987 had a similar number of grains per m2with a higher grain weight than their predecessors. This was probably because the most modern cultivars have a longer grain‐filling duration with a similar length of growth cy

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00772.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA gibberellic acid‐insensitive dwarfing gene in rye (ct1) was mapped in an F2population on chromosome 7R close to the centromere. Two RFLP markers were found, which flank the gene at distances of 1 and 3 cM, respectively. A total of 11 markers were mapped on 7R of which six cluster around the centromere and show segregation distortion in the case of the codominant markers. Thect1gene is closely linked to copies of both α‐amylase and EmBP, as is thect2gene on chromosome 5R. Because of the different chromosomal locations of the GA3‐insensitive dwarfing genes in rye and wheat it is concluded that these genes are not homoeologous. This is supported by further differences in their phenotypic and genotypic expre

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00773.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractGenetic 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 aestivumL.) 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 e

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00774.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe inheritance of resistance to powdery mildew was investigated in 20 accessions ofHordeum spontaneumand in 20 F4lines derived from crosses between the variety ‘Aramir’ and 13 accessions ofH. spontaneum.Two resistance genes were detected in 17 accessions, and three resistance genes in one accession. In two accessions, only one resistance gene was present. The 20 breeding lines showed a large variation in infection type and infection level. The genetic relationship between the resistance genes detected was investigated in the seven most resistant F4lines. These F4lines were divided into three groups which carried different resistance genes. In two lines, the detected resistance gene was shown to be race‐spe

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00775.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of powdery mildew on the photosynthesis and grain yield of partially resistant spring barley was investigated. The effect of powdery mildew on the CO2exchange rate (CER) of inoculated and non‐inoculated leaves was measured in several glasshouse experiments. Grain yield reduction by powdery mildew was determined in three field experiments. The CER of the inoculated leaves was reduced by infection but that of the non‐inoculated leaves was not significantly different from that of the corresponding leaves of the control plants. The reduction in CER of the different genotypes was closely related to the percentage leaf area infected with powdery mildew.The correlation between degree of mildew infection and grain yield reduction varied between r = 0.84 (significant at P = 0.01) and r = 0.41 (not significant). Differences in greenness of the crop were correlated better with grain yield reduction (r = 0.66, P = 0.01) than powdery‐mildew infection itself. Low percentages of powdery‐mildew infection did not lead to significant reduction in grain yield. Partial resistance to powdery mildew could thus be a valuable attribute of future barley va

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00776.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDoubled‐haploid breeding systems are typically based on sampling gametes from F1plants. However, in the case of repulsion linkages, additional recombination could be advantageous. Pre‐selection of gamete donors might also shift progeny performance in a desired direction. The objectives of this study were to quantify the effects of an additional round of recombination and assess the effectiveness of pre‐anthesis selection in the production of barley doubled haploids. Assessments were conducted on: 1. 100 F1‐derived lines representing a subset of lines used in previous genome‐mapping studies; 2. 100 random F2‐derived lines; and 3. 50 F2‐derived lines from gamete donors selected for early heading. An additional round of recombination had only a modest effect on generating more favourable genotypes. Pre‐anthesis selection was ineffective in generating an earlier heading population. According to published quantitative‐trait locus (QTL) analyses based on the F1‐derived population, there are few repulsion linkages between QTL determining the traits measured in this experiment. Any advantages to be gained from postponing the generation of derivation of doubled haploids must be weighed against the delay

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe objectives of this research were to gather hybridization information about crosses between tetraploid and synthetically derived octoploid lines ofAvenaand their reciprocals, and to study the cytology of the hybrids obtained. When the octoploid plants were used as females, only 2.6% of the pollinated florets set seed, while seed set increased to 39.0% in reciprocal crosses. However, germination was 95.7% for the first group of hybrids and only 18.2% for the reciprocals. These diverse results can be explained by the paternal: maternal endosperm genomic ratios and the hypothesis of polar nuclei activation. The tetraploid‐octoploid hybrids did not always contain 42 chromosomes. Octoploid lines derived indirectly from tetraploid (AABB) × hexaploid (AACCDD) crosses were found to retain their A and B genome chromosomes. Univalents in the above hybrids averaged 15.44 in 1990 and 15.15 in 1991, indicating the presence of C and D genome chromosomes inherited from the octoploid lines. Directly synthesized octoploids from diploid (AcAc) × hexaploid (AACCDD) crosses were found to form 20.44 univalents, 5.30 bivalents, and 2.69 trivalents when crossed with AABB tetraploid species. The high number of univalents indicates that chromosomes from at least three genomes, i.e. B, C, and D, remain unpaired, while trivalents are the result of homology between the A and Acgenomes. Hybrids between tetraploid and octoploid lines can be obtained at low frequencies but, regardless of the direction of the cross, these hybrids are highly ster

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractGenetic variation in the feeding efficiency of maize genotypes was evaluated from experiments with dairy cows. Maize genotypes were chosen to represent a range of digestibilities from previous experiments with standard sheep.The variation in milk yield observed with dairy cows fed genotypes with low or high digestibilities or energy values was about 1.0–2.0 kg per animal per day. Moreover, the range of variation in body weight was about 10–30 kg during the 3 months of the experiments. Hybrids with similar energy values had a similar effect on milk yield, but the intake of each hybrid could be very different when they were fed to dairy cows, even if no difference in intake had been observed in sheep. The higher silage maize intake of ‘DK265’ was mostly converted into a body weight gain rather than an increased milk yield, probably because the milk yield potential of the animals was soon reached. It appeared that those hybrids whose predicted energy value from sheep measurements was low led to relatively low performances in cows. Dairy cow performances also appeared to be related to the enzymatic solubility values of the whole plants.For maize breeders, the prediction of hybrid efficiency in dairy cow rearing must include digestibility and ingestibility factors. The most important challenge for maize breeders now will probably be the adjustment of a criterion for predicting intake because the stover digestibility and the starch content can be predicted reliably with the use of NIRS calib

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00779.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractProgenies of 110 diploid R0plants regenerated from haploid protoplasts derived from microspore callus cell suspension culture of rice (cv. Miara) were evaluated for 6 traits, along with control lines, in a replicated field trial. Complementary post‐harvest observations were carried out for four panicle or grain characters. A wide range of variation was observed for all traits under study among the protoclonal lines. The mean of the protoclonal population was significantly different from that of the control for most traits and 64.5% of the lines differed from the control for at least one field‐evaluated trait. A unidirectional shift towards later‐maturing, taller, and lower‐tillering lines was observed. Of all the lines, 39% were taller than the control by at least 10 cm, 31 % had flowering delayed by at least 5 days, and 13% exhibited significantly longer panicles (P = 0.05). As to the agronomical value of the lines, the variation resulted in a global negative drift although favourable variations were found in a few lines. All but two lines were homogeneous, suggesting that most variations existed in a homozygous form in the R0plants. R2lines grown from seeds of 17 R1protoclonal lines stably inherited the changes and did not segregate, thereby confirming that variations ar

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1995.tb00780.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY