ABSORPTION OF RADIO–ACTIVE PHOSPHORUS FROM TAP–AND NODAL ROOTS OF WHITE CLOVER (TRIFOLIUM REPENS L.)     

M. Ueno  R. Dorrington  Williams 《Grass and Forage Science》1967,22(3):165-169

Absorption by the tap-root and by different nodal roots of white clover S100 and translocation of ³²P were investigated to find to what extent nodal roots can compensate for the absence of a tap-root. ³²P absorbed from the tap-root was distributed evenly within the whole plant. When translocation from the 2nd and 7th nodal roots was studied, similar distribution was obtained only from the nodal root closer to the centre of the plant. The backward movement of ³²P absorbed from nodal roots at the base of the plant increased as the root size increased. Removal of tap-roots resulted in temporary depression of translocation; its effect disappeared within 3 weeks.
It is concluded that the ability of nodal roots to compensate for loss of the tap-root depends on their position and size.  相似文献   

MICROENVIRONMENT IN RELATION TO EXPERIMENTAL TECHNIQUES     

StellaS.  Williams 《Grass and Forage Science》1951,6(4):207-217

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The Prince Edward Islands: A sanctuary for seabirds in the Southern Ocean     

A.J. Williams  W.R. Siegfried  A.E. Burger  A. Berruti 《Biological conservation》1979,15(1):59-71

This paper reviews the breeding distribution and numerical status of selected species of seabirds at 23 oceanic island groups in the Southern Ocean (between latitudes 35 and 70°S), based on census data and population estimates which have become available through increased scientific endeavour in the region during the last 15 years or so. The paper focuses on the avifauna of the Prince Edward islands, in the southern Indian Ocean, and points to the importance of these islands as a breeding station and sanctuary for seabirds. Only one oceanic island group, the Crozets, contains more species of breeding seabirds than the Prince Edward islands. Substantial segements (about 10% and greater) of the world breeding populations of the king and macaroni penguins, and the wandering, grey-headed, yellow-nosed and sooty albatrosses are based at the Prince Edward group. We recommend that Prince Edward Island (sensu stricto) should be a wilderness area, and that development at Marion Island should be kept to an absolute minimum.  相似文献   

Gas-liquid chromatographic determination of ethylenediaminetetraacetic acid in pickled vegetables     

D T Williams 《Journal of the Association of Official Analytical Chemists》1974,57(6):1383-1385

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Gas chromatographic determination of low levels of di-(2-ethylhexyl)phthalate in soy oil     

D T Williams 《Journal of the Association of Official Analytical Chemists》1973,56(1):181-183

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Studies on the ecology of actinomycetes in soil—VIII: Distribution and characteristics of acidophilic actinomycetes     

M.R. Khan  S.T. Williams 《Soil biology & biochemistry》1975,7(6):345-348

Acidophilic actinomycetes, growing between pH 3.5 and 6.5, were isolated from 17 natural soils and mine wastes. Most isolates were Streptomyces spp. and selected ones were compared with some established neutrophilic species by assessment of overall similarity. Acidophilic and neutrophilic strains clustered separately, differing in a number of cultural and physiological characters, in addition to pH requirements. The possible importance of acidophilic actinomycetes in soil is discussed.  相似文献   

THE EFFECTS OF HARVEST DATE ON THE YIELD AND QUALITY OF SEED OF TETRAPLOID HYBRID RYEGRASS     

S. Williams 《Grass and Forage Science》1972,27(4):221-228

The ripening process in a tetraploid ryegrass is described in terms of seed moisture content changes. The heavier seeds of tetraploids appear to be shed at an earlier stage in the ripening process than those of diploid ryegrass. The seed moisture level at which a tetraploid ryegrass seed crop is harvested is shown to be a critical factor determining the yield and quality of from the crop harvested seed.  相似文献   

Thin layer chromatographic separation of two chlorodibenzo-p-dioxins from some polychlorinated biphenyls and organochlorine pesticides     

D T Williams  B J Blanchfield 《Journal of the Association of Official Analytical Chemists》1971,54(6):1429-1431

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Growth-regulating Substances in Laminaria agardhii     

Williams LG 《Science (New York, N.Y.)》1949,110(2850):169

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Nitrous oxide fluxes and denitrification sensitivity to temperature in Irish pasture soils     

M. Abdalla  M. Jones  P. Smith  M. Williams 《Soil Use and Management》2009,25(4):376-388

Nitrous oxide (N₂O) emissions from grazed pastures constitute approximately 28% of total global anthropogenic N₂O emissions. The aims of this study were to investigate the effect of inorganic N fertilizer application on fluxes of N₂O, quantify the emission factors (EFs) for a sandy loam soil which is typical of large areas in Ireland and to investigate denitrification sensitivity to temperature. Nitrous oxide flux measurements from a cut and grazed pasture field for 1 year and denitrification laboratory incubation were carried out. The soil pH was 7.3 and had a mean organic C and N content at 0–20 cm of 44.1 and 4.4 g/kg dry weight, respectively. The highest observed peaks of N₂O fluxes of 67 and 38.7 g N₂O‐N per hectare per day were associated with times of application of inorganic N fertilizer. Annual fluxes of N₂O from control and fertilized treatments were 1 and 2.4 kg N₂O‐N per hectare, respectively. Approximately 63% of the annual flux was associated with N fertilizer application. Multiple regression analysis revealed that soil nitrate and the interaction between soil nitrate and soil water content were the main factors controlling N₂O flux from the soil. The derived EF of 0.83% was approximately 66% of the IPCC default EF value of 1.25% as used by the Irish EPA to estimate greenhouse gases (GHGs) in Ireland. The IPCC‐revised EF value is 0.9%. A highly significant exponential regression (r² = 0.98) was found between denitrification and incubation temperature. The calculated Q₁₀ ranged from 4.4 to 6.2 for a temperature range of 10–25 °C and the activation energy was 47 kJ/mol. Our results show that denitrification is very sensitive to increasing temperature, suggesting that future global warming could lead to a significant increase in soil denitrification and consequently N₂O fluxes from soils.  相似文献