Partitioning of Phosphorus in White Clover Populations with Different Nodulation Patterns

The objective of this study was to see if a white clover (Trifolium repens L.) population selected for development of relatively few, but large nodules, differed in the way it used absorbed phosphorus, compared to a white clover population selected for many small nodules. Plants of both populations were grown in minus-nitrogen sand culture and the dry weights and phosphorus contents of shoots, roots and nodules were measured. There were no differences in growth or partitioning of dry matter or phosphorus between the clover lines

Effect of Tannin in Animal Diet on Nitrification Rate of Pasture Soil Under Dung Patches

The rate of formation of nitrate and ammonium in the soil under dung patches was compared for dung from animals fed either ryegrass (Lolium perenne)/white clover (Trifolium repens) or ryegrass/Lotus pedunculatus forage. Tannin derived from the Lotus did not inhibit ammonification in the soil under dung but nitrate formation was strongly inhibited. The results support the theory that polyphenolics may bind to nitrite in acid soils and cause immobilisation of mineral nitrogen. Apart from their effect of reducing the proportion of dietary nitrogen excreted in urine, tannins in animal diets may make a further contribution to reducing nitrate leaching from grazed pasture by slowing down nitrification of dung nitrogen

A Quantitative Trait Locus Analysis of Root Distribution in Perennial Ryegrass (\u3cem\u3eLolium Perenne\u3c/em\u3e L.)

Root system architecture impacts perennial ryegrass performance, with deeper roots potentially contributing to drought tolerance, nutrient interception, and anchoring of plants. Root mass in a perennial ryegrass sward is typically shallow, concentrated in the top 10 cm of soil (Troughton 1957). Phenotypic selection for deeper root systems in breeding programmes is limited by the inaccessibility of underground plant components. We aim to use quantitative trait locus (QTL) analysis to discover genetic factors influencing root architecture traits, including vertical root distribution, in perennial ryegrass. Ultimately, markers linked to root architecture QTL may be used in a marker-assisted selection strategy that would alleviate the limitations of conventional selection, and lead to ryegrass cultivars with improved production and environmental performance

Efficient Use of Phosphorus in Temperate Grassland Systems

Phosphorus (P) fertilisers are important for high production in many grassland systems. However, there are increasing environmental, economic and strategic issues associated with using P, which is a non-renewable and “effectively finite” global resource. We review the P balance of temperate pastures to identify the factors that contribute to inefficient P use and discuss ways to improve P use efficiency. The most immediate gains can be made by ensuring that pastures are not over-fertilised. Plants with low critical P requirements, particularly as a result of better root foraging, will be important. Root traits such as fine roots (root diameter), branching, length and root hairs, and mycorrhizal associations all contribute to improved root foraging; some are amenable to plant breeding. Plants that can “mine” sparingly-available P in soils by producing organic anions and phosphatases are also needed; as are innovations in fertiliser technology. Soil microorganisms play a crucial role in P acquisition by pastures but are not particularly amenable to management. Selection of pasture species for root characteristics offers a more realistic approach to improving P efficiency but progress, to date, has been minimal. Traditional plant breeding, augmented by marker assisted selection and interspecific hybridisation, are likely to be necessary for progress. Inevitably, P efficient pastures will be achieved most effectively by a combination of plant genetic, fertiliser innovation and management responses. Success will bring economic and environmental benefits from reduced P fertiliser use, with consequent benefits for global resource and food security

The Clover Root Weevil Invasion: Impact and Response of the New Zealand Pastoral Industry 1996-2012

Clover root weevil, Sitona lepidus Gyllenhall (Curculionidae: Coleoptera), was first reported in New Zealand in 1996. With few natural enemies or competitors, it rapidly became a major pest of white clover. Its strong flight capability, tendency to be transported in agricultural machinery and vehicles, and wide climatic tolerance enabled it to spread the length of the country (1,600 km) by 2010. The most damaging stage is the larva, which attacks the roots, root nodules and stolons of clovers, reducing herbage production (particularly in spring), pasture clover content, and nitrogen fixation. From the time of the initial invasion, the pastoral industry supported research into management as insecticides were not a viable option. Nitrogen fertiliser applications after grazing were recommended to maintain production. Field evaluations showed that white clovers with good general agronomic adaptation survived better under weevil pressure than less-adapted clovers. In 2006, a parasitic wasp, Microctonus aethiopoides Loan (Braconidae: Hymenoptera), was introduced from Ireland for biological control of S. lepidus. It has also established and dispersed very rapidly, and often suppresses weevil populations within 2 – 3 years of its establishment in a new locality. Involvement of industry field consultants was an essential aspect of the biological control release programme in the North Island where the weevil was already widespread before M. aethiopoides was introduced

CT densitometry as a predictor of pulmonary function in lung cancer patients.

Purpose: Preoperative pulmonary assessment is undertaken in patients with resectable lung cancer to identify those at increased risk of perioperative complications. Guidelines from the American College of Chest Physicians indicate that if the FEV1 and DLCO are ≥60% of predicted, patients are suitable for resection without further evaluation. The aim of our study is to determine if quantitative measures of lung volume and density obtained from pre-operative CT scans correlate with pulmonary function tests. This may allow us to predict pulmonary function in patients with lung cancer and identify patients who would tolerate surgical resection. Materials and Methods: Patients were identified retrospectively from the lung cancer database of a tertiary hospital. Image segmentation software was utilized to estimate total lung volume, normal lung volume (values -500 HU to -910 HU), emphysematous volume (values less than -910 HU), and mean lung density from pre-operative CT studies for each patient and these values were compared to contemporaneous pulmonary function tests. Results: A total of 77 patients were enrolled. FEV1 was found to correlate significantly with the mean lung density (r=.762, p<.001) and the volume of emphysema (r= -.678, p<.001). DLCO correlated significantly with the mean lung density (r =.648, p<.001) and the volume of emphysematous lung (r= -.535, p<.001). Conclusion: The results of this study suggest that both FEV1 and DLCO correlate significantly with volume of emphysema and mean lung density. We now plan to prospectively compare these CT parameters with measures of good and poor outcome postoperatively to identify CT measures that may predict surgical outcome preoperatively

Perplexing plain abdominal x-ray.

Editor's quiz: GI snapshot: Clinical presentatio

Medical student knowledge regarding radiology before and after a radiological anatomy module: implications for vertical integration and self-directed learning.

Objectives: To examine the impact that anatomy-focused radiology teaching has on non-examined knowledge regarding radiation safety and radiology as a specialty. Methods: First-year undergraduate medical students completed surveys prior to and after undertaking the first-year anatomy programme that incorporates radiological anatomy. Students were asked opinions on preferred learning methodology and tested on understanding of radiology as a specialty and radiation safety. Results: Pre-module and post-module response rates were 93 % (157/168) and 85 % (136/160), respectively. Pre-module and post-module, self-directed learning (SDL) ranked eighth (of 11) for preferred gross-anatomy teaching formats. Correct responses regarding radiologist/radiographer roles varied from 28-94 % on 16 questions with 4/16 significantly improving post-module. Identification of modalities that utilise radiation significantly improved for five of eight modalities post-module but knowledge regarding relative amount of modality-specific radiation use was variable pre-module and post-module. Conclusions: SDL is not favoured as an anatomy teaching method. Exposure of students to a radiological anatomy module delivered by senior clinical radiologists improved basic knowledge regarding ionising radiation use, but there was no improvement in knowledge regarding radiation exposure relative per modality. A possible explanation is that students recall knowledge imparted in didactic lectures but do little reading around the subject when the content is not examined. Teaching Points: Self-directed learning is not favoured as a gross anatomy teaching format amongst medical students; An imaging anatomy-focused module improved basic knowledge regarding ionising radiation use; Detailed knowledge of modality-specific radiation exposure remained suboptimal post-module; Knowledge of roles within a clinical radiology department showed little change post-module