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Taek-Ryoun Kwon Zamin Shaheed Siddiqui Phil J.C. Harris 《Journal of plant nutrition》2013,36(4):644-667
ABSTRACT Effects of three supplemental calcium (Ca++; 2.5, 5.0, and 10 mole m?3) concentrations on ion accumulation, transport, selectivity, and plant growth of salt-sensitive species, Brassica rapa ‘Sani’ in saline medium were investigated. Supplemental Ca++ in the presence of 125 mol m?3 sodium chloride (NaCl) did not improve the dry weight and leaf area indicating no role played by Ca++ in the alleviation of salinity induced growth inhibition. However, calcium chloride (CaCl2) did significantly affect sodium (Na+), potassium (K+), and Ca++ contents of roots and shoots. The ion contents of shoots were significantly greater than those of roots per g dry weight, indicating ion transportation to shoots is greater than ion accumulation in roots. Use of CaCl2 in 125 mol m?3 NaCl reduced the Na+ content but increased K+ and Ca++ contents in shoots. Sodium contents in shoots differed among the supplemental Ca++ treatments indicating the role of CaCl2 in Na+ ions transportation. Calcium content in shoots declined significantly in the control treatment (0 CaCl2) but increased significantly in 10 mol m?3 CaCl2. The root also showed the effects of Ca++ on the reduction of Na+ content and the increase of K+ and Ca++ content. Unexpectedly, 5 mol m?3 CaCl2 induced the highest Na+ content in roots at 16 days after treatment. Supplemental CaCl2 application influenced the K+ or Ca++ selectivity over Na+ in two ways, ion accumulation at roots and transport to shoots. However, high CaCl2 treatments allowed greater Ca++ selectivity over Na+ than low CaCl2. Likewise, high supplemental CaCl2 showed higher K+ selectivity over Na+ than low CaCl2. A marked increase in K+ versus Na+ selectivity for the transport process occurred at 10 mol m?3 CaCl2 treatments. The roots and shoots exhibited higher K+/Na+ and Ca++/Na+ ratios in high CaCl2 treatment than in low. The results are discussed in context to supplemental Ca++ concentrations, ions accumulation, transportation and selectivity of salt sensitive Brassica rapa cultivar. 相似文献
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Penny R. Hirsch Lucy M. Gilliam Saran P. Sohi Jennie K. Williams Ian M. Clark Phil J. Murray 《Soil biology & biochemistry》2009,41(9):2021-2024
If soil communities rely on plant-derived carbon, is biodiversity lost when this primary source is removed? Soil microbial and mesofaunal communities at the Rothamsted Highfield site were compared under a mixed grass sward, arable rotation and a section maintained as a bare-fallow for the past 50 years by regular tillage. Organic matter reserves have been degraded and microbial and mesofaunal numbers and mite diversity have declined in this unique bare-fallow site, where fresh carbon inputs have been drastically reduced. However, it supports a species-rich metabolically active bacterial community of similar diversity to that in soil maintained as grass sward. Thus in contrast to soil mesofauna, bacterial diversity (but not abundance) is apparently independent of plant inputs. 相似文献
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Thomas J. Drinan Phil McGinnity Jamie P. Coughlan Tom F. Cross Simon S.C. Harrison 《Ecology of Freshwater Fish》2012,21(3):420-432
Abstract – The morphologies of sympatric juvenile Atlantic salmon Salmo salar parr and brown trout Salmo trutta parr were compared between Irish rivers with contrasting hydraulic environments – a high‐gradient and a low‐gradient tributary from the River Barrow catchment, south‐east Ireland and a high‐gradient river from the Burrishoole catchment, west of Ireland. The two catchments differ markedly in mean annual precipitation (849.0 mm year?1 and 1370.3 mm year?1 for the Barrow and Burrishoole catchments, respectively). Parr of both species demonstrated morphological variation between and within catchments. Changes in metrics such as pectoral fin length, body depth and body length between and within catchments suggest that hydraulic forces were a major determinant of morphological variation. Both species from the Burrishoole catchment had relatively larger pectoral fins, longer heads, larger eyes and shallower bodies than conspecifics from the Barrow catchment. In rivers subject to frequent rainfall‐driven high discharges, such as those in the Burrishoole catchment, a more fusiform body and head shape coupled with larger pectoral fins may reduce the energetic cost of maintaining position in the water column, as well as increase stability and manoeuvrability. The larger eyes in both parr species in the Burrishoole catchment could further be a response to the lower visibility of the more turbid and peat‐stained waters or to the reduced prey availability. The results of this study demonstrate that local adaptation to flow conditions can yield morphologically distinct populations and that multiple species can exhibit parallel phenotypic responses to changing environmental conditions. 相似文献
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The questionnaire survey of Hart and Hart (1985, Journal of the American Veterinary Medical Association 186, 1811-1815) ranked the 56 most popular breeds of dog in the USA on 13 behavioural traits and is compared here with results of a similar survey conducted on the 49 most popular breeds in the UK. Of the 36 breeds in common between the studies, 24 were similar for the traits aggressivity, reactivity and ease of housetraining between the two countries. However, the characteristics of nine breeds (Airedale Terrier, Old English Sheepdog, Welsh Corgi, Irish Setter, Standard Poodle, Beagle, Samoyed, Boxer, Dalmatian) differed markedly between the two countries, and a further three (Chihuahua, Scottish Terrier, Standard Dachshund) showed smaller, but probably meaningful, shifts. These differences should be recognised when giving advice to prospective owners, and when treating unwanted behaviour in these breeds. 相似文献
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R. E. Bradshaw 《Forest Pathology》2004,34(3):163-185
Dothistroma (red‐band) needle blight has been a problem in plantations of exotic pines in the southern hemisphere for many decades. The prevalence of this disease is currently increasing in the northern hemisphere and is now affecting trees in their native ranges. The fungal pathogen Mycosphaerella pini with its anamorph Dothistroma pini, which is responsible for the disease, produces a toxin, dothistromin, that is closely related to the potent carcinogen, aflatoxin. Understandably this has provoked concern about possible effects on the health of forestry workers. This review gives a broad coverage of literature on both disease and toxin. The fungus has a complicated taxonomy with many synonyms and in most countries only the anamorph is found. It is a necrotrophic pathogen that kills needle tissue and completes its life cycle in the lesion thus formed. Dispersal of the disease is normally by rain splash of conidiospores but there is evidence that long range dispersal has occurred by transport of contaminated plant tissue and by wind/cloud dispersal of spores in air currents. The severity of disease is affected by humidity, temperature and light. There is variation in susceptibility of different Pinus species and some achieve increased resistance with age. The current method of control in southern hemisphere plantation forests is through spraying with copper fungicides and, with P. radiata, increased disease resistance has been achieved through a breeding programme. The dothistromin toxin is a difuroanthraquinone and is similar in structure to the aflatoxin precursor versicolorin B. Part of a gene cluster encoding dothistromin biosynthetic genes has been cloned and this has confirmed parallels between the dothistromin and aflatoxin biosynthetic pathways. Dothistromin produces damaging oxygen radicals by reductive oxygen activation rather than by photosensitization, but is also thought to exert its toxic effects on specific cellular targets. Studies have shown that dothistromin is a weak mutagen and clastogen and is therefore a potential carcinogen. Although the risks to forest workers are considered very low it is prudent to avoid unnecessary exposure during periods when dothistromin levels are likely to be at their peak. 相似文献
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Proanthocyanidins (PAs) in the hot water extract prepared from Pinus radiata bark were isolated by a Sephadex LH-20 chromatography. The PAs were characterized using UV/Visible, FT-IR and 13C nuclear magnetic resonance (NMR) spectroscopic techniques, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF)
mass spectrometry (MS), and gel permeation chromatography (GPC) analysis. Bate-Smith acidic alcoholysis and FT-IR spectrum
of the PAs indicated the predominant presence of the procyanidin (PC) structure. The 13C NMR spectrum revealed that the PAs comprise PC (94%) together with a small amount of prodelphinidin (PD, 6%), and also that
they contain the higher trans configuration rather than the cis configuration of C2–C3. The MALDI-TOF MS results obviously proved the presence of PD units, but the maximum degree of polymerization
(DP) was limited to octamer. The average molar mass (Mw, Mn), polydispersity (Mw/Mn), and DP of the pine bark PAs were 3,800
(Mw), 1,200 (Mn), 3.2, and 13, respectively. 相似文献
10.
Thomas P. Howard Brendan Fahy Fiona Leigh Phil Howell Wayne Powell Andy Greenland Kay Trafford Alison M. Smith 《Journal of Cereal Science》2014
The effects on barley starch and grain properties of four starch synthesis mutations were studied during the introgression of the mutations from diverse backgrounds into an elite variety. The lys5f (ADPglucose transporter), wax (granule-bound starch synthase), isa1 (debranching enzyme isoamylase 1) and sex6 (starch synthase IIa) mutations were introgressed into NFC Tipple to give mutant and wild-type BC2F4 families with different genomic contributions of the donor parent. Comparison of starch and grain properties between the donor parents, the BC2F4 families and NFC Tipple allowed the effects of the mutations to be distinguished from genetic background effects. The wax and sex6 mutations had marked effects on starch properties regardless of genetic background. The sex6 mutation conditioned low grain weight and starch content, but the wax mutation did not. The lys5 mutation conditioned low grain weight and starch content, but exceptionally high β-glucan contents. The isa1 mutation promotes synthesis of soluble α-glucan (phytoglycogen). Its introgression into NFC Tipple increased grain weight and total α-glucan content relative to the donor parent, but reduced the ratio of phytoglycogen to starch. This study shows that introgression of mutations into a common, commercial background provides new insights that could not be gained from the donor parent. 相似文献