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Summary The hullabilities of 40 inbred lines (20 male sterility maintainers and 20 male fertility restorers) and 36 hybrids were studied in several environments in France. Thousand seed weight, oil and hull contents and the quantity of hulls remaining with the kernel after hulling were also measured. Principal component analyses and a hierarchical clustering method were used to described the variation of both inbreds and hybrids. Hullability varied from 11 to 66% for inbreds and 16 to 60% for hybrids. This variation is sufficient to permit breeding programmes for this character. Hullability is correlated positively with hull content (r=0.35* to 0.69*) but negatively with oil content (r=–0.34*to–0.71**). Large seeds generally hull better than small seed (r=0.21ns to –0.66**). The value of the different classes of genotypes is discussed. Inbreds and hybrids producing achenes with a quite small hull content, a high oil content but a good hullability are the most promising for improvement of the quality of sunflower seed meal. Such genotypes are rare so that a recurrent selection programme is recommended to increase the frequency of favorable genes. 相似文献
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The widespread removal of native trees from the agricultural zone and replacement with annual crops and pastures is a major cause of dryland salinity in Australia. It has been recognised that a large proportion of the landscape needs to be replanted to trees to prevent further salinisation. However, for much of the agricultural zone, agroforestry is not an option due to lack of species that can viably generate the products currently demanded by the market. The emerging carbon market may provide a new agroforestry option for landholders, through carbon sequestration. This analysis assesses the viability of growing trees for the purpose of selling carbon credits, from a landholder’s perspective. Benefits of trees in preventing the onset of dryland salinity are accounted for. Two regions in Western Australia; a low rainfall (330 mm/year) region and a medium rainfall (550 mm/year) region, are analysed. At the expected carbon price of A$15/tCO2-e, growing trees for carbon is not a viable alternative for landholders in the low rainfall region, due to low sequestration rates. In the medium rainfall region, growing trees for carbon and timber is a viable alternative; however the opportunity costs of land mean the carbon price would still need to be higher than expected for growers to choose this alternative. Accounting for the salinity prevention benefits makes growing trees a more attractive investment for landholders in both regions. However in both regions, even after accounting for salinity benefits, the price of carbon would need to be A$25–A$46/tCO2-e higher than expected to make growing trees a worthwhile investment. 相似文献
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Felicity Hayes Katrina Sharps Harry Harmens Ieuan Roberts Gina Mills 《Journal of Agronomy and Crop Science》2020,206(2):214-228
Northern, Southern and Equatorial Africa have been identified as among the regions most at risk from very high ozone concentrations. Whereas we know that many crop cultivars from Europe, north America and Asia are sensitive to ozone, almost nothing is known about the sensitivity of staple food crops in Africa to the pollutant. In this study cultivars of the African staple food crops, Triticum aestivum (wheat), Eleusine coracana (finger millet), Pennisetum glaucum (pearl millet) and Phaseolus vulgaris (bean) were exposed to an episodic ozone regime in solardomes in order to assess whether African crops are sensitive to ozone pollution. Extensive visible leaf injury due to ozone was shown for many cultivars, indicating high sensitivity to ozone. Reductions in total yield and 1,000-grain weight were found for T. aestivum and P. vulgaris, whereas there was no effect on yield for E. coracana and P. glaucum. There were differences in sensitivity to ozone for different cultivars of an individual crop, indicating that there could be possibilities for either cultivar selection or selective crop breeding to reduce sensitivity of these crops to ozone. 相似文献
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Saïd Mouzeyar Felicity Vear Denis Tourvieille de Labrouhe 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(4):399-404
The mode of action of the fungicide metalaxyl againstPlasmopara halstedii, the causal agent of sunflower downy mildew, was studied following its application before, during and after artificial contamination of seedlings. The development of the fungus within the treated seedlings was examined microscopically and compared to that occuring in untreated genetically susceptible or resistant genotypes. Hypersensitive-like reactions and necrotic zones leading to the inhibition of fungus growth within the hypocotyl were observed for the three modes of application. This suggests that sunflower defence mechanisms activated by genetical resistance are also involved in the control of downy mildew by metalaxyl. 相似文献
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Colin Adams Felicity Huntingford Jimmy Turnbull Steve Arnott Aly Bell 《Aquaculture International》2000,8(6):543-549
Aggression in groups of 0+ Atlantic salmon (Salmo salar) was monitoredat weekly intervals in two tanks containing 100 fish each. Three 1 + salmonparr were added to one of these. After 5 weeks, fish weights were measuredin both tanks and the conditions reversed. At ten weeks, weights of fish inboth tanks were measured again. In both populations, levels of aggressionamong the smaller fish were significantly lower and growth ratessignificantly higher when the large fish were present. Although the largefish attacked the small ones, the rate at which they did so was an order ofmagnitude lower that the rate at which small fish attacked each other in theabsence of larger conspecifics. This raises the possibility that levels ofaggression among farmed salmon might be reduced by the addition of a fewlarge conspecifics. 相似文献
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Modulating immune responses with dendritic cells: an attainable goal in veterinary medicine? 总被引：3，自引：0，他引：3
Vecchione A Catchpole B D'Mello F Kanellos T Hamblin A 《Veterinary immunology and immunopathology》2002,87(3-4):215-221
Dendritic cells (DCs) are antigen presenting cells that potently modulate immune responses with varying outcomes depending on the DC sub-population involved. To understand how DC sub-types arise, it is necessary to determine which factors influence their differentiation. At least three major sub-populations of DCs have been described in mice: CD4+/CD8- "myeloid" DCs, CD4-/CD8+ "lymphoid" DCs and Langerhans cell-derived DCs. Whilst somewhat comparable populations have been described in man, in most other species very little is known. The identification of cytokines which stimulate proliferation of DC precursors, and the observation that the cytokine environment influences the phenotype and the function of the DCs that subsequently develop, has provided a useful tool for evaluating these rare cells. We describe the influence of cytokines on the phenotype of DCs generated in the rat. Using bone marrow cells as the source of precursors we generated "myeloid-type" DCs from the adherent population using granulocyte-macrophage colony stimulating factor (GM-CSF), IL-4 and Flt-3L or "lymphoid-type" DCs from the non-adherent population using cytokines which included IL-7, IL-3, SCF and TNFalpha. In order to facilitate similar approaches to the study of equine DCs we have identified the nucleotide sequence encoding GM-CSF from the m-RNA of equine PBMC stimulated with Concanavalin A, amplified the cDNA by PCR and cloned it in eukaryotic and prokaryotic expression vectors. We report on the structure and function of this molecule. 相似文献