The influence of NH4 +‐N vs. NO3 ‐‐n nutrition on root reductant release by fe‐stressed sorghum 1

The effect of NH₄ ⁺ ‐N on root reduction capacity developed during Fe stress was investigated in plants grown in a CaCO₃ buffered nutrient solution. After a 3‐day period of Fe stress, reduction capacity was not increased by the presence of NH₄ ⁺ ‐N in the growth medium or in the extracting solution. Since reductant degradation over time was pH dependent, experiments measuring root reductant release into nutrient solution would be confounded by treatments with different solution pH values. In an unbuffered nutrient solution a differential NH₄ ⁺ uptake due to the cultivar would affect solution pH and interfere with a reliable interpretation of reductant measurements.     

Root reductant release as a measure of sorghum cultivar iron efficiency

Measurement of root reductant levels developed during plant Fe stress was tested as a possible assay for sorghum cultivar Fe‐efficiency screening. Iron‐stressed sorghum was shown to release reductants into CaCO₃ buffered nutrient solution; however, considerably more plants could be tested by extracting reductants from excised roots of Fe‐stressed sorghum in 35 ml of pH 3 nutrient solution and 1 mM glucose. An Fe‐efficient cultivar, RT×2536, and an Fe‐inefficient cultivar, BT×378, could be separated by measurement of reductants released into CaCO₃ buffered nutrient solution and by an excised root extraction method; however, neither method was as effective as visual rating methods.     

Cultivar response to bacterial ring rot infection in Maine

An account of several years of testing cultivars for response to bacterial ring rot (BRR) infection is reported. Inoculum was prepared by grinding infected tuber tissue and adding distilled water to make a slurry. Seedpieces of cultivars to be tested were dipped in the slurry, planted and covered immediately in the field. Five hill plots were arranged in a RCB design with four replications and cultivars of known reaction to BRR were included as checks. Assessment of symptom expressions was begun when symptoms were first observed in any entry and repeated weekly for the remainder of the growing season. Results of tests on named cultivars and a few advanced, numbered selections are presented for the years 1983 through 1986.     

Can scale-dependent landcover relationships explain canid community composition independent of intraguild occupancy?

Landscape Ecology - Niche theory is frequently used as a framework to integrate environmental variables and species interactions to describe species geographic distribution. Yet, the scale at which...     

Initial Experience with Norepinephrine Infusion in Hypotensive Critically III Foals

Seven critically ill foals that continued to be hypotensive despite fluid resuscitation and the infusion of dobutamine and/or dopamine were treated with an infusion of norepinephrine (noradrenaline). The norepinephrine was administered concurrently with dobutamine, and the combination therapy was titrated by use of indirect mean arterial pressure measurements. The highest dose of norepinephrine used was 1.5 mcg/kg/min. In six foals the administration of norepinephrine was associated with an increase in blood pressure. In one foal the mean arterial pressure did not increase in response to the doses of norepinephrine administered. All of the foals experienced an increase in urine output coincident with the start of the norepinephrine infusion. Three of the foal survived to hospital discharge.     

Influence of single applications of nitrogen on white clover nitrogen fixation in autumn and winter dairy pastures in south‐west Victoria,Australia

Abstract

Effects of nitrogen (N) (0, 15, 30, 45 and 60 kg N ha^?1) applied at five different times during autumn and early winter on the N fixation of Trifolium repens L. (white clover) in Lolium perenne L. (perennial ryegrass) / white clover pastures were examined (Experiment 1). Effects of applying different N fertilisers (e.g. urea and ammonium nitrate) at 45 kg N ha^?1 in autumn, with and without phosphorus (P), potassium (K) and sulphur (S) on N fixation were also tested (Experiment 2). In Experiment 1, percentage N derived from the atmosphere (percent Ndfa) by white clover varied between 87% and 91% in the period after (24 to 36 days) N application. Increasing rates of N and time of application did not influence percent Ndfa. The amount of N fixed by white clover ranged from 0.8 to 3.7 kg N ha^?1 in the period after N application. Increasing rates of applied N produced a significant (P<0.05) linear increase in the amount of N fixed. In Experiment 2, percent Ndfa and amount of N fixed (1.9 to 4.1 kg N ha^?1) were unaffected by different N fertilisers, with and without P, K and S, in the period after (37 days) fertiliser application. For both experiments, fertiliser N increased dry matter yield while having no effect on white clover composition. It is concluded that single applications of N during the autumn and early winter benefit pasture growth without adversely affecting white clover N fixation or clover composition. This finding, however, will require further investigation.     

Left atrial rupture in dogs: 14 cases (1990–2005)

Objective: To describe the clinical parameters, treatment, and prognosis of dogs with left atrial rupture secondary to chronic mitral valve insufficiency. Design: Retrospective study. Setting: University referral hospital. Animals: 14 dogs with left atrial rupture. Interventions: None. Measurements and main results: Mixed breed dogs (n=6, 43%) and Shetland Sheepdogs (n=3, 21%) were most commonly affected. The median age was 12 years (range 5.8–18 y). The median weight was 11 kg (range 4–30 kg). Eight dogs had been previously diagnosed with chronic valvular disease. The most common presenting complaints included collapse (13/14), cough (9/14), and dyspnea (8/14). Four dogs were presented in either respiratory or cardiac arrest. Pericardial effusion was present in 13 dogs. The median left atrium:aortic outflow ratio was 2.66 (range 1.66:1–5.52:1). Pericardiocentesis was performed to alleviate tamponade in 3 dogs. Five dogs were discharged from the hospital, 3 of which were euthanized within 35 days of initial diagnosis for recurrence of clinical signs (n=2) and for hematochezia and lethargy (n=1). Five dogs were euthanized while in the hospital for a variety of reasons including DIC, progressive azotemia, collapse and recurrence of pericardial effusion, or possible seizure episode. Conclusions: Although rare, left atrial rupture resulting in pericardial effusion should be considered in older small‐ to medium‐sized dogs presenting with collapse, cough, and dyspnea. The overall prognosis appears poor.     

Variation in Surrogate Breeding Habitat Quality Between Continuously Grazed Rangelands and Late-Cut Hayfields for a Threatened Grassland Birds

Rangelands and hayfields provide a large portion of remaining surrogate habitat for many species of declining grassland birds in North America. We compared late-cut hayfields and continuously grazed pastures at low to moderate cattle densities for providing suitable breeding habitat in eastern Canada for the nationally threatened Bobolink (Dolichonyx oryzivorus). To examine the quality of both habitats, we conducted point counts and monitored 87 nests during the 2015 and 2016 breeding seasons. Bobolink abundance and daily survival rate (DSR) of nests were modeled sequentially by habitat and sex as a function of vegetation structure, prey availability, and agricultural management. Year and habitat were the strongest predictors of abundance. When analyzed separately for pastures and hayfields, vegetation height was most important for female abundance in pastures while pasture size was most important for males. Nests in hayfields had significantly higher daily survival (DSR = 0.98 ± 0.01) than nests in pastures (DSR = 0.94 ± 0.01). Nesting success was highest in hayfields with taller vegetation, while in pastures, no microhabitat variable showed a clear relationship with DSR. Within pastures, cattle stocking densities of ≤ 1 animal units (AU) · ha^? 1 were not related to DSR. This study provides evidence that late-cut hay is of highest quality, but that small-scale beef farms with low to moderate stocking densities are suitable targets for conservation efforts of Bobolinks in eastern North America.