摘要:

AbstractA total of 45 tetraploid‐diploid (4x—2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. A relatively low degree of determination (R2) of both 4x and 2x parents on the performance of their 4x—2x hybrid progenies was found for all six traits studied. This implies that test crossing and subsequent progeny analysis is necessary before such parents can be used in a breeding program. Since marketable yield was found to have a higher predictability than total yield, it is the preferred yield trait to be measured. Diploids which produce 2n gametes via FDR usually give rise to 4x progenies with a greater amount of heterosis than similar progenies derived from diploids which produce 2n gametes via SDR, although such heterosis is not necessarily expressed in terms of marketable

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01204.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA total of 45 tetraploid‐diploid (4x—2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. Means of six traits of the 45 progenies obtained from a two‐year experiment were used in progeny analysis. A new mathematical model is developed for analyzing the incomplete two‐way table. It is modified from the conventional model for factorial mating design. The aim of the model is to evaluate the potential of 2x parents in terms of their mean effects (μi) and sensitivity measures (Bi) to the 4x parents. The 4x parents were treated as testers in the model. They were compared by the estimates of the magnitude of tester effects (gi). The mean effects of 2x parents showed a dominant influence on variation of tuber number and mean tuber weight of the hybrid progenies. They also demonstrated a substantial influence on the variation of total and marketable yield, chipping score and specific gravity. The linear response of 2x parents to 4x parents, however, also showed a substantial influence on the variation of the latter traits. The information on μiand Biare useful in terms of choosing superior 2x parents and, together with gj of 4x parents, 4x—2x progenies for specific traits. The μiand Biestimates of the six traits showed a complicated interrelationship t

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01205.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTo facilitate testing large numbers of tomato soma‐clones for resistance to bacterial canker, a fast screening procedure was developed. Two inoculation methods were investigated, i.e. excision with an infected scalpel of I) one cotyledon of 2‐week‐old seedlings, and II) the first true leaf of 3‐week‐old seedlings, followed by applying a drop of inoculum on the wound. Inoculation by method II discriminated well between populations of partially resistant and susceptible tomato genotypes. A criterion for the selection of single, putatively resistant plants, based on rating scores of the severity of wilting symptoms, was proposed and tested with plants of aLycopersicon peruvianumaccession with a relatively high level of resistance to bacterial canker. Progenies of 279 somaclones, derived from tissue explants of the susceptible tomato cultivar ‘Moneymaker’, were evaluated for resistance. The presence of somaclonal variation for morphological characters in these populations was previously shown. However, no differences were detected between the somaclone population and controls in either mean susceptibility or distribution of plants over disease severity categories. Moreover, plants with major increases in resistance were not detected. These results suggest that the potential of somaclonal variation as a source of resistance to bacterial canker m

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01206.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractGenetic variation in two commercial varieties, ‘Liwally’ and ‘Barok’, and two Swedish natural populations of sheep's fescue,Festuca ovina s.l., was studied by means of starch gel electrophoresis. Variation in allele frequencies was found at theDial, Gpi2, Got2, Pgdl, Pgm, Tpil and Tpi2loci. ‘Liwally’, belonging to ssp.vallesiaca, showed clear differences compared to the other samples which belong to ssp.capillataand ssp.vulgaris.Genetic diversity, as measured by per cent polymorphic loci, number of alleles per locus and frequency of heterozygotes, was high in all samples in agreement with what has been found in other perennial, outcrossing mono‐cotyledonous species with a wide distribution. The bred varieties and the wild populations did not statistically differ with respect to frequency of heterozygotes or number of alleles, though the last value was lower in the domesticated lines than in the natural populations. No significant deviation from the expected Hardy‐Weinberg proportions was found in any

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01207.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThere is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungusAcremonium coenophialumhas resulted in substantial acceptance of new endophyte‐free cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. ‘Kentucky 31’ populations from 18 to 38 year‐old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within‐population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r2= 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r2= 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among ‘Kentucky 31’ tall fescue ecotypes

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01208.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWheat, rye and wheat‐rye addition lines have been investigated regarding their developmental and organ‐specific isozyme patterns of aspartate amino‐transferase (AAT) and endopeptidase (EP). Evidence is given, that development‐specific isozymes of AAT are encoded by chromosomes 3R and 4R of ‘Imperial’ rye which can be used as biochemical markers up to leaf age of 14 days. Organ‐specific increase of intensity of bands for AAT in stems could be assigned to genes or alleles of chromosome 3A of ‘Chinese Spring’ wheat. For EP new markers were localized on chromosomes 4R and 6R of ‘Imperial’ rye showing variability. Utilization of these markers is possible at all developmental stages of the leaves. Mechanisms of gene reg

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01209.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe N‐ and C‐banding patterns of the chromosomes of the hexaploid wheat cultivar ‘Viking’, and the hairy‐necked line derived from it, were described. Except for chromosome 4B (formerly 4A), no significant variation in banding patterns were found between the two genotypes. In addition to a 5BS.7BS (5BL.7BL) translocation in both genotypes, the presence of a small 5RL rye segment in a terminal position on the long arm of chromosome 4B was suggested by banding and confirmed by meiotic analysis, and by thehairy neckmarker as well as by rye‐specific leaf esterase bands in the translocation line. The translocation breakpoint is presumed to be located in the distal 4BL2.2 and/or 5RL2.3 band. The hairy‐necked ‘Viking’ was shown to be copper efficient. Its utilization in wheat breeding progr

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01210.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThis study was made to determine the reactions of sunflower genotypes to artificial infections ofBotrytis cinereaunder netting tunnels with irrigation. The genotypes were the parents and F1hybrids of a factorial cross between 5 female (male sterile) and 5 restorer lines. Their resistance levels were measured by the mean delay between infection and symptom appearance on the capitulum. Significant genotypic differences in reaction toB. cinereawere shown. The ratio of general combining ability to specific combining ability was 2.9, indicating that additive effects are important. However, there were some significant interactions between male and female parents. The mean parent‐hybrid and parent‐progeny regressions were both significant with correlation coefficients of r = 0.57 and r = 0.66 respectively. It is concluded that breeding programmes with tests forB. cinerearesistance in early generations should be effective in the development of sunflower hybrids with improvedB. cinerearesista

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01211.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractSugarcane leaves and calli from highly susceptible and resistant varieties to eyespot disease were used to evaluate theDrechslera saccharitoxin effect at different concentrations and incubation times by measuring electrolyte leakage. This expression of disease resistance was observed not only in the leaf but also in the callus. Furthermore, the growth of resistant calli MS medium supplemented with DS toxin, was higher when compared to the susceptible ones. The possibility of obtaining resistant somaclones is confirmed.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01212.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractFour clones of palisade grass,Brachiaria brizantha(Hochst. Ex. A. Rich.) Stapf., were studied in a diallel competition trial to investigate their competitive relationship in clonal mixtures. Clone X associate interactions were observed for plant height, number of tillers per plant and dry matter yield per plant. Both general and specific competitive abilities were observed for tiller number and dry matter yield. Clone X associate interaction for plant height was mainly due to the specific competitive ability of individual combinations. The most competitive clone observed was CIAT 6387. Competitive abilities of local clones were low compared to the imported clones. Local clones (RU 127 and RU 139) yielded more than imported clones (CIAT 6387 and PI 292185) under low competitive stresses. General and specific competitive abilities should be taken into consideration when mixing clones of palisade grass.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1991.tb01213.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY