A conceptual framework and an empirical test of complementarity and facilitation with respect to phosphorous uptake by plant species mixtures     

Chunjie LI  Thomas W. KUYPER  Wopke VAN DER WERF  Junling ZHANG  Haigang LI  Fusuo ZHANG  Ellis HOFLLAND 《土壤圈》2022,32(2):317-329

Plant species have different traits for mobilizing sparingly soluble phosphorus (P) resources, which could potentially lead to overyielding in P uptake by plant species mixtures compared to monocultures due to higher P uptake as a result of resource (P) partitioning and facilitation. However, there is circumstantial evidence at best for overyielding as a result of these mechanisms. Overyielding (the outcome) is easily confused with underlying mechanisms because of unclear definitions. We aimed to define a conceptual framework to separate outcome from underlying mechanisms and test it for facilitation and complementarity with respect to P acquisition by three plant species combinations grown on four soils. Our conceptual framework describes both mechanisms of complementarity and facilitation and outcomes (overyielding of mixtures or no overyielding) depending on the competitive ability of the species to uptake the mobilized P. Millet/chickpea mixtures were grown in pots on two calcareous soils mixed with calcium-bound P (CaP) and phytate P (PhyP). Cabbage/faba bean mixtures were grown on both acid and neutral soils mixed with P-coated iron (hydr)oxide (FeP) and PhyP. Wheat/maize mixtures were grown on all four soils. Rhizosphere carboxylate concentration and acid phosphatase activity (mechanisms) as well as plant P uptake and biomass (outcome) were determined for monocultures rhizosphere and species mixtures. Facilitation of P uptake occurred in millet/chickpea mixtures on one calcareous soil. We found no indications for P acquisition from different P sources, neither in millet/chickpea, nor in cabbage/faba bean mixtures. Cabbage and faba bean on the neutral soil differed in rhizosphere acid phosphatase activity and carboxylate concentration, but showed no overyielding. Wheat and maize, with similar root exudates, showed overyielding (the observed P uptake being 22% higher than the expected P uptake) on one calcareous soil. We concluded that although differences in plant physiological traits (root exudates) provide necessary conditions for complementarity and facilitation with respect to P uptake from different P sources, they do not necessarily result in increased P uptake by species mixtures, because of the relative competitive ability of the mixed species.  相似文献   

Photosynthetic inhibition in Phaseolus vulgaris II. The influence of light on herbicidal action     

J. L. P. VAN  OORSCHOT P. H. VAN  Leeuwen 《Weed Research》1974,14(2):81-86

The influence of pre-treatment and post-treatment illumination upon the herbicidal effect produced in Phaseolus vulgaris L. cv. Berna by simeton, diuron, diquat and ioxynil was examined. The increased effect noted at lower pre-treatment and higher post-treatment levels of illumination was correlated with increased inhibition of net photosynthesis. This increased effect was ascribed to enhanced photo-oxidation.  相似文献   

VASCULAR ANOMALY CAUSING SUBCLAVIAN STEAL AND CERVICAL MYELOPATHY IN A DOG: DIAGNOSIS AND ENDOVASCULAR MANAGEMENT     

DICCON R. WESTWORTH  KAREN M. VERNAU  SEAN P. CULLEN  CRAIG D. LONG  VAN V. HALBACH  RICHARD A. LECOUTEUR 《Veterinary radiology & ultrasound》2006,47(3):265-269

A 3-year-old dog with cervical myelopathy resulting from a vascular anomaly is described. Marked intradural-extramedullary spinal cord compression was observed, in association with multilevel ectatic anastomotic radicular arterial branches connecting the left and right vertebral arteries. A nonpatent proximal segment of the right subclavian artery had resulted in compensatory enlargement of the left vertebral artery. Flow within the right vertebral artery was retrograde and fed into the patent distal segment of the right subclavian artery. Multiple imaging techniques including myelography, computed tomography, magnetic resonance imaging, and selective digital angiography were used to document this anomaly. To reduce spinal cord compression the largest collateral vessel was embolized without complication. Good clinical response was observed within 6 weeks and improved clinical neurologic function was maintained at the time of a 12-month re-evaluation.  相似文献   

Lidocaine decay and hepatic extraction in the Pig     

B. METS  R. ALLIN  J. VAN DYKE  R. HICKMAN† 《Journal of veterinary pharmacology and therapeutics》1993,16(1):8-14

Plasma lidocaine decay after injection was studied in five anaesthetized pigs and fitted to a two compartment open model. Derived pharniacokinetic paranieter-s were eniployed to rapidly achieve plateau concentrations within 60 min of starting a two stage infusion of lidocaine hydrochloride. Hepatic extraction and clearance of lidocaine at steady state were determined in 10 pigs by transhep;ttic: sampling and nieasurenient of hepatic arterial and portal venous blood flow using perivascular ultrasonic flow probes placed at laparotomy. These data were compared with siniilar studies performed in man as well as the sheep, (log, monkey and cat. The lidocaine extraction ratio of 0.60 in the pig was found t o be similar to that determined by others in man.  相似文献   

Sulphadimidine metabolism in vitro: I. sex differences in acetylation and hydroxylation in cultured rat hepatocytes     

G. A. E. VAN T KLOOSTER  F. M. A. WOUTERSEN-VAN NIJNANTEN  B.J. BLAAUBOER†  J. NOORDHOEK†  A. S.J. P. A. M. VAN MIERT 《Journal of veterinary pharmacology and therapeutics》1993,16(3):343-349

The hydroxylation and acetylation of 0.5 mM sulphadimidine (SDD) was studied in primary cultures of hepatocytes from male and female rats, and from castrated male and sham operated male rats. In addition, SDD metabolism was investigated in hepatocytes from castrated male rats treated with testosterone, prior to liver cell isolation. In male rat hepatocytes a significantly higher hydroxylation activity was observed than in hepatocytes from female and castrated male rats. Acetylation activity was higher in females. Testosterone induced hydroxylation but did not affect acetylation. These results correlate well with data from previous in vivo studies, showing the relevance of this in vitro model.  相似文献   

Phenology of arable and hedgerow populations of Galium aparine L. in relation to climate and soil conditions     

R. Y. VAN DER  WEIDE 《Weed Research》1992,32(4):249-258

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Bioavailability of ketoprofen in horses after rectal administration     

S. CORVELEYN  P. DEPREZ†  G. VAN DER WEKEN‡  W. BAEYENS‡  J. P. REMON 《Journal of veterinary pharmacology and therapeutics》1996,19(5):359-363

Six healthy mares ranging in age from 6 to 12 years and weighing from 415 to 540 kg were used to determine the rectal bioavailability of ketoprofen. For the rectal administration, three different formulations, each containing 1 g of ketoprofen, were administered in a fatty and a hydrophilic suppository base and as a liquid suspension. An average elimination half-life of 1.3 h (±1.2) was found. The average value for the total plasma clearance ( Cl _T) was 131.9 mL/min.kg (range 95-183.5). The volume of distribution V _d(area) was 255 mL/kg and the mean residence time (MRT)P = 0.05; Friedman test). Despite the low rectal bioavailability obtained in this study, there was some evidence for the clinical effectiveness of the rectal formulations.  相似文献   

Mechanical Properties of Four Suture Patterns for Transected Equine Tendon Repair     

K. J. EASLEY DVM  MS    T. S. STASHAK DVM  MS  DiplomateACVS    F. W. SMITH PhD  G. VAN SLYKE BVSC 《Veterinary surgery : VS》1990,19(2):102-106

Thirty-six superficial digital flexor tendons from nine fresh equine cadavers were transected and sutured with size 2 monofilament nylon. Nine tendons were repaired with each of four suture patterns: single-locking loop, double-locking loop, triple-locking loop, or three-loop pulley. The times required for application, tensile strengths, resistance to distraction (gap), and modes of failure were analyzed. The mean times required were: single-locking loop, 3 mins, 15 secs; double-locking loop, 4 mins, 15 secs; triple-locking loop, 10 mins, 50 secs; and three-loop pulley, 4 mins. The double-locking loop, triple-locking loop, and three-loop pulley suture patterns were stronger than the single-locking loop. The triple-locking loop and three-loop pulley patterns were close in strength and only the triple-locking loop was stronger than the double-locking loop. The three-loop pulley had the greatest resistance to gap formation and its mode of failure was different from the others. The three-locking loop suture patterns failed by suture breakage but the three-loop pulley failed first by suture pull-out and then by suture breakage.  相似文献   

Sources and inheritance of resistance to stemphylium leaf spot of lettuce     

D. Netzer  D. Globerson  CH. Weintal  R. Elyassi 《Euphytica》1985,34(2):393-396

Summary None of the tested cultivars of lettuce was found resistant to Stemphylium leaf spot, a common disease in Israel. Within a Lactuca saligna population collected in wild lettuce in Israel, resistance was traced. Interspecific crosses of L. saligna x L. sativa were made and the mode of inheritance of resistance to this disease was studied. Resistance is apparently controlled by two genes: one dominant (Sm₁) and one recessive (sm₂).Contribution No. 1176-E 1984 series, from the ARO.  相似文献   

Floras and oxygen     

VAN Valen L 《Science (New York, N.Y.)》1979,205(4412):1302

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