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  • 1
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Seed production in perennial ryegrass, Lolium perenne L., is low. Early selection for high seed yield carried out in spaced plants would be valuable for breeders, but only if this potential is also expressed in derived progenies sown later in drilled plots. Therefore, spaced-plant traits assessed on clonal ramets of 31 genotypes in each of two perennial ryegrass varieties in four environments were related to seed production characteristics in drilled plots of open-pollinated progenies of these plants.Significant differences were found among these half-sib families for seed yield, thousand-grain weight, spring performance and earliness. The number of spikelets per ear in the maternal plants was negatively correlated with the seed yield of the progenies, explaining 17 % of the variation for seed yield in the cv. ‘Barenza’ and 14 % in the cv. ‘Wendy’. Multiple regression analyses revealed that no combinations of plant traits consistently explained a major portion of the variation for seed yield of the progenies.The results indicate that in these varieties, spaced-plant data are of limited value in predicting seed production. Direct selection for seed yield in drills of progenies in later stages of the breeding programme remains the best method for obtaining varieties with sufficient seed production.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Plants from a Festuca pratensis variety which had caused‘eczema solare’among lambs in The Netherlands revealed the presence of endophytic Acremonium after microscopic evaluation. Combined gas chromatographic-mass spectrometric analysis of extracts from seeds of these plants showed the occurrence of N-formyl- as well as N-acetyl-loline which are formed as a result of the plant-fungus association.Endophyte-infected Lolium perenne plants produced lolines only at elevated temperatures while non-infected plants failed to synthesize these alkaloids under identical environmental conditions. Results indicate that presence of endophytic fungi together with growth at temperatures above 23°C is a prerequisite for induction of alkaloids detected in perennial ryegrass
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 2 (1989), S. 225-230 
    ISSN: 1432-2145
    Keywords: Lolium perenne ; Pollen tube ; Genotype ; Temperature ; Self-incompatibility ; Seed production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Low yield in seed crops of perennial ryegrass is related to low fertilization efficiency and low temperature during anthesis. To study the effect of genotype and temperature on pollen performance, we conducted greenhouse experiments at controlled temperatures. Individual florets of four genotypes that are known to differ in seed production were hand pollinated at four temperatures (14°, 18°, 22°, 26° C) both in vivo and via a semiin-vitro method involving excised florets on agar. Pollen germination and tube growth were determined with UV-fluorescence microscopy and scored in six classes at 2 h after pollination in vitro and after 0.5, 2 and 5 h in vivo. In vitro, both genotype and temperature had a significant effect on the performance of self-pollen. Pollen tube growth increased with temperature. In cross-pollinations, the pistil parent had a significant effect on pollen tube growth, and there was also a significant pistil-by-temperature interaction. In vivo, genotype and temperature significantly affected pollen performance. The genotype-by-temperature interaction was only significant 5 h after pollination. One genotype with low seed yield was pseudoself-compatible and was a relatively poor mother after cross-pollination. The effects of genotype and temperature on the growth of self-pollen might be exploited in a breeding programme.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2242
    Keywords: Key wordsMalus pumila Mill ; Molecular linkagemap ; Marker-assisted selection ; Fruit tree breeding ; Outbred progeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 163 (1989), S. 133-146 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cucurbitaceae ; Cucumis ; C. sativus ; C. melo ; C. metuliferus ; C. anguria ; C. zeyheri ; C. myriocarpus subsp.leptodermis ; comb. nov. ; Crossing experiments ; meiosis of hybrids ; polyploidy ; isozymes ; DNA analysis ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Meiosis in seven interspecificCucumis hybrids has been analysed i.a. inC. metuliferus ×C. zeyheri, where the parents belong to different sections. In the triploid hybrids a remarkably high number of trivalents has been found. Additional data from literature on geographical distribution, cucurbitacins, flavonoid patterns, isozymes, C-banding, genome size, DNA amount and chloroplast DNA are used to discuss species relationships and evolution. The African cross-compatible group is divided into theMyriocarpus subgroup with the diploid speciesC. africanus, C. myriocarpus subsp.leptodermis and subsp.myriocarpus, and theAnguria subgroup withC. anguria, C. dipsaceus, C. ficifolius, C. prophetarum, C. zeyheri and all polyploids (exceptC. heptadactylus). It is argued that the Asian subg.Melo with x = 7 is derived from the African subg.Cucumis with x = 12; the latter contains all the polyploid species and has the most common basic chromosome number of theCucurbitaceae. This phylogenetic advance is interpreted with concepts of the quantum model of evolution.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 151 (1985), S. 31-41 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cucurbitaceae ; Cucumis sativus L. — Giemsa C-banding ; heterochromatin ; infraspecific classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Infraspecific cytogenetical variation was studied in a diverse collection of five non-cultivated and cultivatedCucumis sativus accessions. The individual chromosomes of different accessions could be identified by the C-banding pattern and chromosome measurements. About 40–50% of the genomic area are made up of heterochromatin inC. sativus. The non-cultivated accessions exhibit more heterochromatin and lower chiasma frequencies per pollen mother cell than cultivated accessions. There is infraspecific variation in C-banding pattern, karyomorphology and multinucleolate cells. The use of C-banding in infraspecific classification is discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5060
    Keywords: Cucumis ; biosystematics ; interspecific hybridization ; genetic variation ; crossability barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The genetic variation in pickling and slicing cucumbers (C. sativus L.) seems insufficient to enable the breeder to solve serious cultivation problems. Wild allies of C. sativus possess a wide range of interesting characters which could be incorporated by means of species crosses. In the past, attempts to achieve such crosses have failed. Important characters of Cucumis species are mentioned and biosystematic problems discussed. Results of previous research on species crosses prompted an examination of the prospects of further research.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5060
    Keywords: Cucumis sativus ; cucumber genotypes ; growth analysis ; night temperature ; breeding for low energy conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth of four breeding lines and two cultivars of slicing cucumber with different growth at low temperature and light intensity was analysed in relation to night temperature. Plants were grown from 17 days after sowing at 20°C day temperature and 20, 15 or 10°C night temperature (NT), a light intensity of 24 W/m2 visible radiation and a daylength of 8 hours. Data from six successive harvests, ending 47 days after sowing, were analysed according to a MANOVA procedure. RGR, NAR, LAR, SLA and LWR generally decreased with time. Ln W and RGR were largely similar at 20 and 15°C NT, but reduced at 10°C NT. LAR and SLA decreased at each lower NT, whereas LWR increased. NAR was only marginally affected by NT. Significant genotypic differences occurred for 1n W, LAR, SLA, LWR, stem length and percentage of dry matter in leaves and stems at all NT's and for RGR and NAR only at 20°C. Genotypic differences for 1n W could not be explained by differences for RGR, but by differences for initial plant weight. Significant genotype × night temperature interactions were present for LWR. Breeding lines increased LWR in response to lower NT, while that of cultivars remained fairly constant. Implications for breeding are discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 32 (1983), S. 677-684 
    ISSN: 1573-5060
    Keywords: Cucumis sativus ; mentor pollen ; gamma-radiation ; pollen germination ; cucumber ; Cucumis species ; fertilization ; double pollination ; competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pollen of 4 Cucumis sativus genotypes and of the related species C. metuliferus and C. zeyheri 2x was irradiated with four doses of γ-rays: 1, 2, 4 and 5 kGy. Higher radiation doses were found to inhibit germination and pollen tube growth in vitro with C. sativus, the most sensitive species. Irradiated pollen of cucumber never performed normal fertilization. However, after radiation with 1 kGy, cucumber pollen was able to occupy all available ovules, of which about 50% developed into empty seeds without embryo. This makes 1 kGy-irradiated maternal pollen less suitable to serve as mentor pollen in interspecific hybridizations. Doses of 2 kGy and more appeared to eliminate the ability to compete for ovules, while fruit set after a 2 kGy radiation was still high.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-5060
    Keywords: Cucumis L. ; interspecific hybridization ; pre-fertilization crossing barriers ; genetic variation for crossability ; aminoethoxyvinylglycine (AVG)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It was attempted to overcome crossing barriers between the cucumber (Cucumis sativus L.), the melon (C. melo L.) and two wild Cucumis spp. (C. metuliferus Naud. and C. zeyheri 2x Sond.) by application of aminoethoxyvinylglycine (AVG) and by limiting the amount of rooting substrate. The reciprocal crosses between both wild species were used as a model system. Crosses between C. metuliferus and C. zeyheri 2x succeeded well if the maternal plants were grown in containers of 10 or 25 1 instead of in open soil. This treatment also improved crossability in the cross C. metuliferus x C. melo. It strongly enhanced the number of female flowers per plant in C. metuliferus. Application of AVG to pollinated flowers initially seemed also to improve crossability in these cross combinations, but later on this effect was not found again. Significant genetic variation for crossability was found in C. zeyheri 2x. Rare plants yielded numerous fruits with embryos after crosses with C. metuliferus and also with C. sativus. Clones from these plants gave similar results. Excessive temperature and radiation decreased crossability especially in crosses with C. metuliferus and C. sativus as maternal parent.
    Type of Medium: Electronic Resource
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