4,981 results for Lincoln University

  • Draft genome sequences of two New Zealand Xanthomonas campestris pv. campestris isolates, ICMP 4013 and ICMP 21080

    Desai, D.; Li, J.-H.; van Zijll de Jong, E.; Braun, R.; Pitman, A.; Visnovsky, S.; Hampton, J. G.; Christey, M. C.

    Journal article
    Lincoln University

    Xanthomonas campestris pv. campestris is a necrotrophic bacterial pathogen of crucifers. We report here the draft genome sequences of isolates ICMP 4013 and ICMP 21080 from New Zealand. These sequences will facilitate the identification of race-specific factors in X. campestris pv. campestris.

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  • Climate change: seed production and options for adaptation

    Hampton, J. G.; Conner, A. J.; Boelt, B.; Chastain, T. G.; Rolston, P.

    Journal article
    Lincoln University

    Food security depends on seed security and the international seed industry must be able to continue to deliver the quantities of quality seed required for this purpose. Abiotic stress resulting from climate change, particularly elevated temperature and water stress, will reduce seed yield and quality. Options for the seed industry to adapt to climate change include moving sites for seed production, changing sowing date, and the development of cultivars with traits which allow them to adapt to climate change conditions. However, the ability of seed growers to make these changes is directly linked to the seed system. In the formal seed system operating in developed countries, implementation will be reasonably straight forward. In the informal system operating in developing countries, the current seed production challenges including supply failing to meet demand and poor seed quality will increase with changing climates.

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  • Using codispersion analysis to quantify temporal changes in the spatial pattern of forest stand structure

    Case, B. S.; Buckley, H. L.; Barker Plotkin, A.; Ellison, A. M.

    Journal article
    Lincoln University

    Forest development involves a complex set of ecological processes, such as dispersal and competition for light, which can generate a range of spatial patterns in forest structure that change through time. One interesting avenue of research in ecology is exploring whether spatial statistical methods can be brought to bear on such spatial patterns of forest structure to gain insight into the possible ecological processes that created them. In this study we applied a relatively new method to ecology, codispersion analysis, to investigate spatial covariation between two common measures of forest structure: tree abundance and mean basal area. We used data for four focal tree species from both a simulated and a real forest sampled at multiple time points. We assessed the significance of observed codispersion patterns using null models, in which tree diameters were iteratively and randomly reassigned to trees whose locations were kept constant. The results suggest that codispersion analysis could detect a range of spatial patterns in forest stand structure that were indicative of changing ecological processes.

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  • Survey of barley grain physical processing methods in Holstein dairy cow's ration

    Nejat, M. A.; Basaki, T; Safa, M.

    Journal article
    Lincoln University

    Barley is one of the most commonly used food grains in the diet of dairy and beef cattle. Since barley endosperm is enclosed by a sheath highly resistant to microbe degradation in Rumen, it is necessary to process dry barley grain for optimal use by dairy and beef cattle. In order to compare different methods of barley grain’s physical processing in the diet of dairy cattle and its effect on milk production, 9 Holstein cattle (in the first, second and third birth) that were at a distance of 10 ± 65 days after delivery, were selected . This experiment was performed was in a randomized complete block design with three replications (parity), four treatments (processing method) and three cattle per block. Barely grains were put in diets numbered from 1 to four, respectively through the following ways:(1) Hammer mill (with a sieve 1 mm), (2) dry roll by Index processing 73%, (3) Fusion (a mixture of first way and second way ) (4) rolling along with steam by processing index 65% of processing percent. The data included amount of milk, percent of fat and dry matter use for each of the three milking. Average milk production of cattle that were fed by diets 1, 2, 3 and 4 were respectively 33.60c, 34.23b, and 34.38b and 34.60a kg per day. Also the averages of fat percent were equal to 3.02a, 2.70c, and 2.73c and 2.84b. In both groups, the mean difference was significant at one percent level. According to the findings and production purpose (the increase of milk production) rolling machine under steam can be proposed, however, considering high cost of the device, it can be justified for large units. For small farms, dry roll with less processing index is recommended.

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  • Mycorrhizal co-invasion and novel interactions depend on neighborhood context

    Moeller, H. V.; Dickie, I. A.; Peltzer, D. A.; Fukami, T.

    Journal article
    Lincoln University

    © 2015 by the Ecological Society of America. Biological invasions are a rapidly increasing driver of global change, yet fundamental gaps remain in our understanding of the factors determining the success or extent of invasions. For example, although most woody plant species depend on belowground mutualists such as mycorrhizal fungi and nitrogen-fixing bacteria, the relative importance of these mutualisms in conferring invasion success is unresolved. Here, we describe how neighborhood context (identity of nearby tree species) affects the formation of belowground ectomycorrhizal partnerships between fungi and seedlings of a widespread invasive tree species, Pseudotsuga menziesii (Douglas-fir), in New Zealand.We found that the formation of mycorrhizal partnerships, the composition of the fungal species involved in these partnerships, and the origin of the fungi (co-invading or native to New Zealand) all depend on neighborhood context. Our data suggest that nearby ectomycorrhizal host trees act as both a reservoir of fungal inoculum and a carbon source for late-successional and native fungi. By facilitating mycorrhization of P. menziesii seedlings, adult trees may alleviate mycorrhizal limitation at the P. menziesii invasion front. These results highlight the importance of studying biological invasions across multiple ecological settings to understand establishment success and invasion speed.

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  • The effects of dietary nitrogen to water-soluble carbohydrate ratio on isotopic fractionation and partitioning of nitrogen in non-lactating sheep

    Cheng, L.; Nicol, A. M.; Dewhurst, R. J.; Edwards, G. R.

    Journal article
    Lincoln University

    The main objective of this study was to investigate the relationship between partitioning and isotopic fractionation of nitrogen (N) in sheep consuming diets with varying ratios of N to water-soluble carbohydrate (WSC). Six non-lactating sheep were offered a constant dry matter (DM) allowance with one of three ratios of dietary N/WSC, achieved by adding sucrose and urea to lucerne pellets. A replicated 3 dietary treatments (Low, Medium and High N/WSC) × 3 (collection periods) and a Latin square design was used, with two sheep assigned to each treatment in each period. Feed, faeces, urine, plasma, wool, muscle and liver samples were collected and analysed for ¹⁵N concentration. Nitrogen intake and outputs in faeces and urine were measured for each sheep using 6-day total collections. Blood urea N (BUN) and urinary excretion of purine derivative were also measured. Treatment effects were tested using general ANOVA; the relationships between measured variables were analysed by linear regression. BUN and N intake increased by 46% and 35%, respectively, when N/WSC increased 2.5-fold. However, no indication of change in microbial protein synthesis was detected. Results indicated effects of dietary treatments on urinary N/faecal N, faecal N/N intake and retained N/N intake. In addition, the linear relationships between plasma δ¹⁵N and urinary N/N intake and muscle δ¹⁵N and retained N/N intake based on individual measurements showed the potential of using N isotopic fractionation as an easy-to-use indicator of N partitioning when N supply exceeds that required to match energy supply in the diet.

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  • Faeces of generalist predators as 'biodiversity capsules': A new tool for biodiversity assessment in remote and inaccessible habitats

    Boyer, S.; Cruickshank, R. H.; Wratten, S. D.

    Journal article
    Lincoln University

    Molecular methods are increasingly used to identify prey DNA in predators' faeces to describe diet composition. However, such analysis can reveal much more ecological information. If faeces are regarded as 'biodiversity capsules', they can help describe and quantify ecological communities by containing a representative sample of the prey species occurring in the foraging area of a given predator. Here we propose to analyse these 'capsules' and infer the occurrence, distribution and minimum abundance estimate of prey communities. This novel approach goes beyond the detection of 'targeted' prey groups to inform dietary studies of predators. It is particularly suited to the study of prey communities that are difficult to sample with traditional methods because they are very small, rare and/or live in remote or inaccessible habitats. Such communities include invertebrates inhabiting the soil, deep-sea species, and small, rare flying insects. The proposed approach has the potential to inform the topical issue of biodiversity assessment and provide a new framework for the discovery of species with minimum interference to ecosystems and without the need for extensive trapping, which can be labour intensive and could kill many individuals of non-target species. Rigorous testing of this approach, and in particular direct comparison with traditional sampling methods is required to fully demonstrate its efficacy.

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  • Ammonia emissions from cattle urine and dung excreted on pasture

    Laubach, J.; Taghizadeh-Toosi, A.; Gibbs, S. J.; Sherlock, R. R.; Kelliher, F. M.; Grover, S. P. P.

    Journal article
    Lincoln University

    Twelve cattle were kept for three days in a circular area of 16 m radius on short pasture and fed with freshly-cut pasture. Ammonia (NH₃) emissions from the urine and dung excreted by the cattle were measured with a micrometeorological mass-balance method, during the cattle presence and for 10 subsequent days. Daily-integrated emission rates peaked on Day 3 of the experiment (last day of cattle presence) and declined steadily for five days thereafter. Urine patches were the dominant sources for these emissions. On Day 9, a secondary emissions peak occurred, with dung pats likely to be the main sources. This interpretation is based on simultaneous observations of the pH evolution in urine patches and dung pats created next to the circular plot. Feed and dung samples were analysed to estimate the amounts of nitrogen (N) ingested and excreted. Total N volatilised as NH₃ was 19.8 (± 0.9)% of N intake and 22.4 (± 1.3)% of N excreted. The bimodal shape of the emissions time series allowed to infer separate estimates for volatilisation from urine and dung, respectively, with the result that urine accounted for 88.6 (± 2.6)% of the total NH₃ emissions. The emissions from urine represented 25.5 (± 2.0)% of the excreted urine-N, while the emissions from dung amounted to 11.6 (± 2.7)% of the deposited dung-N. Emissions from dung may have continued after Day 13 but were not resolved by the measurement technique. A simple resistance model shows that the magnitude of the emissions from dung is controlled by the resistance of the dung crust. © Author(s) 2013.

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  • Partial proteome map of Campylobacter Jejuni strain Nctc11168 by gel-free proteomics analysis

    Shi, Z.; Dawson, C. O.; On, S. L. W.; Hussain, M. A.

    Journal article
    Lincoln University

    A proteome map of the foodborne pathogen Campylobacter jejuni NCTC11168 was analyzed using a state-of-the-art gel-free proteomic approach for the first time. A whole cell protein extract was prepared from the C. jejuni strain NCTC11168 grown in brain heart infusion (BHI) broth at 42°C under microaerobic conditions. A gel-free technique using isobaric tags for relative and absolute quantitation (iTRAQ) was employed to create a protein expression profile of the strain. Liquid chromatography-mass spectrometry (LC-MS/MS) was used to identify the proteins. Protein functionalities were searched to classify them. A total of 235 proteins were identified in the whole cell protein fraction of C. jejuni NCTC11168 cells using iTRAQ analysis. Functional grouping of the identified proteins showed that forty percent of these proteins were associated with energy metabolism, protein synthesis and genetic information processing. iTRAQ was faster, easier and proved more sensitive than two-dimensional gel-based proteomics approaches previously applied to C. jejuni, making it an attractive tool for further studies of cellular physiological response.

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  • Effect of reduced irrigation on grapevine physiology, grape characteristics and wine composition in three Pinot noir vineyards with contrasting soils

    Mejias-Barrera, Patricio

    Thesis
    Lincoln University

    The effect of water stress on grapevine performance has been extensively studied in different wine producing regions around the world, but little has ocurred in New Zealand. Pinot noir is the second most planted variety in the country and the most planted in Waipara. An improved understanding of the physiological responses of Pinot noir vines growing in different soils under a water restricted scenario is crucial for winegrowers, because vineyard irrigation is commonly practiced in Waipara and water is expected to become scarcer in future seasons. Three Pinot noir vineyards having similar characteristics, but planted in three of the most representative types of soil of the Waipara region were selected to investigate the effect of reducing irrigation by about 50% under commercial conditions. Control (CON) vines corresponded to those receiving the irrigation applied according to the viticulture manager’s criteria, and a reduced irrigation (RI) treatment was implemented by modifying the drippers spacing and flow rate. The experiment was carried out during the 2013-2014 and 2014-2015 seasons. Edapho-climatic characteristics were compared within the region and among the three sites. “Terroir” provides the link between wine composition and place of origin. Thus, soil and climatic conditions, were characterised to understand the uniqueness of Pinot noir wines produced in Waipara. Differences in soil profile available water were found between the three types of soil. Also, variations in temperatures, wind speed and evapotranspiration, among other parameters were found within the region as well as between sites. A range of analyses was used to identify differences in grapevine physiology between vines under RI and those normally irrigated. Primary leaf area abscission and stomatal closure were short-term responses to water stress, which together with the lack of differences in stem water potential suggested the isohydric behaviour of Pinot noir under the conditions of this study. Other parameters like carbon isotope ratio, leaf proline content and root carbohydrates were little affected by RI. Berry weight was reduced by the treatment, but this varied depending on the site and season. Seed water content, seed fresh and dry weight were unaffected by RI which may suggest that seeds remain “isolated” from the rest of the berry from veraison onwards, even under moderate water stress. Taurine was found in berry juice, the first time that this nitrogen compound is described in Vitis vinifera L. Wines produced during the first season showed differences in wine titratable acidity (TA), colour and aroma profile by GCMS only at the site having the lowest profile available water, while wines from those sites with high and very high profile available water did not report differences between CON and RI for most of the parameters evaluated. This study demonstrated the edapho-climatic variability within the Waipara region, as well as the adaptive responses to water stress site by site, confirming irrigation as one of the main factors modifying “terroir” expression. From a practical perspective, the findings suggest merit for the use of reduced irrigation in vineyard management, as a means to save cost whilst maintaining grape quality.

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  • Dairy replacement rearing: a comparison of an integrated management system using fodder beet and traditional rearing systems

    Cvitanovich, Ella

    Thesis
    Lincoln University

    Heifer rearing systems in New Zealand were compared in a theoretical study on weight and financial costs. The systems compared were restricted fodder beet, ad libitum fodder beet, contract grazing and on-platform pasture grazing. The aim was to identify the most cost effective rearing system to ensure heifers are grown to achieve or exceed target live weights at 15 and 22 months. Potential live weight gains were calculated through metabolisable energy in feed and daily animal intakes using reference feed standards. The pre-mating average daily weight gains were 0.59 kgLWT/day, 0.53 kgLWT/day and 0.49 kgLWT/day for the ad libitum fodder beet, restricted fodder beet and pasture grazing respectively. None of these diets meet mating live weight targets, however ad lib fodder beet was the closest at 1.8%. The weight gains between mating and calving on the ad libitum fodder beet diet and restricted fodder beet diet were 0.59 kgLWT/day and 0.53 kgLWT/day respectively, higher than 0.49 kgLWT/day seen in the pasture grazing systems. The ad libitum fodder beet diet live weights were undesired at 29.4% above target, however the other systems meet target weights. The most expensive rearing system was contract grazing at $2.85/kgLWT gained. This was followed by on-platform pasture grazing at $2.57/kgLWT gain. Fodder beet has the lowest cost of gain at $2.27/kgLWT gain. Cost analysis showed that live weight gain, not cost of crop, is the key driver of cost effective rearing systems. This research demonstrates that under careful management and feed restrictions fodder beet is a suitable and cost effective way to rear heifers in the New Zealand dairy industry.

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  • Coastal modelling of sea level rise for the Christchurch coastal environment

    Eaves, A.; Doscher, C.

    Journal article
    Lincoln University

    Predictive modelling provides an efficient means to analyse the coastal environment and generate knowledge for long term urban planning. In this study, the numerical models SWAN and XBeach were incorporated into the ESRI ArcGIS interface by means of the BeachMMtool. This was applied to the Greater Christchurch coastal environment to simulate geomorphological evolution through hydrodynamic forcing. Simulations were performed using the recent sea level rise predictions by the Intergovernmental Panel on Climate Change (2013) to determine whether the statutory requirements outlined in the New Zealand Coastal Policy Statement 2010 are consistent with central, regional and district designations. Our results indicate that current land use zoning in Greater Christchurch is not consistent with these predictions. This is because coastal hazard risk has not been thoroughly quantified during the process of installing the Canterbury Earthquake Recovery Authority residential red zone. However, the Christchurch City Council’s flood management area does provide an extent to which managed coastal retreat is a real option. The results of this research suggest that progradation will continue to occur along the Christchurch foreshore due to the net sediment flux retaining an onshore direction and the current hydrodynamic activity not being strong enough to move sediment offshore. However, inundation during periods of storm surge poses a risk to human habitation on low lying areas around the Avon-Heathcote Estuary and the Brooklands lagoon.

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  • Organic amendments for reducing the plant uptake of cadmium from New Zealand soils

    Hucker, Cameron

    Thesis
    Lincoln University

    Cadmium (Cd) is a naturally occurring element in soils. It is a non-essential trace element that can have toxic effects on fauna at relatively low concentrations. Several studies have reported above background levels of the metal in New Zealand (NZ) agricultural soils . This is thought to be due to the repeated applications of phosphate fertiliser where Cd is a commonly found impurity. Cd is taken up by plants relatively easily and can accumulate there to potentially dangerous concentrations without any effects on the plant itself. This has resulted in the NZ government imposing a 1.8 mg/kg limit on Cd in soil after which P fertiliser applications have to cease. The addition of organic amendments into the soil has been shown to reduce the plant uptake of Cd. This study has been carried out to gain better understanding of which specific organic amendment has the greatest potential for reducing plant uptake of Cd. The amendments used in the experiments were two types of peat, bio-solids from Kaikoura and Christchurch, coffee grounds, and municipal compost from Parkhouse Garden Supplies, Living Earth and Oderings. The study involved analyses of pH, conductivity, total organic carbon, water-soluble carbon (hot and cold water), elemental composition, cation exchange capacity (CEC) and the sorption potential for Cd of each amendment. Results indicated that the two bio-solid samples had Cd concentrations that were too high for potential application to the soil as this would risk accumulation at rates of up to 10 times higher than the other amendments. The findings from the Cd sorption experiment indicate that Parkhouse (PH) compost had the greatest capacity to adsorb Cd, the Kd value was 11317. This result was significantly larger than all other amendments, with Living Earth (LE) showing the second highest value of 578. This suggests the potential ability of Living Earth compost to be used as an amendment for soils contaminated with Cd. The significant sorption of Cd by PH compost could be attributed to the sulphur concentration of PH, as this was twice as high as any amendment (excluding bio solids). Parkhouse White (PHW) had the lowest S concentration but a similar CEC to PH, however the corresponding Kd was significantly lower (27). This suggests the potential addition of gypsum (CaSO4) to municipal composts can cause the associated S groups to form complexes with Cd, immobilising it and reducing plant uptake. Although, the sulphides or thiol groups are more likely to form complexes with Cd, rather than the sulphate groups. Overall, this study has indicated that the organic amendment with the greatest capacity to adsorb Cd is PH compost, with LE showing a reasonable capacity also. The next step would involve incorporating these composts into contaminated soils and to analyse the effect this has the plant uptake of Cd.

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  • Phenotypic assessment of commercial wheat (Triticum aestivum) crosses with a synthetic hexaploid incorporating wild germplasm from Aegilops tauschii

    Macalister, Jamie

    Thesis
    Lincoln University

    The wheat crop in the United States, and indeed globally, has shown high levels of genetic uniformity. A lack in genetic variation is causing dramatic fluctuations in total wheat crop yields in response to environmental conditions and has created serious production risks. This study was undertaken as a step to address this issue with an aim of develop a new high-performing line incorporating wild wheat germplasm for the Colorado State University breeding program. The purpose of using wild germplasm is to provide a source of genetic variation not currently present in the US wheat crop. This study grew 72 different crosses with eight controls and included two reps each for both an irrigated and unirrigated treatment. Traits that were assessed included grain yield, harvest index (HI), heading date, plant height, lodging and other physical features that were assessed visually. The results showed that one first generation cross (HRS2015-378) clearly stood out above all other lines, including the commercial cultivar controls. HRS2015-378 was ranked first in both treatments for HI along with third and fifth for grain yield in the dry and wet treatments respectively. The values for HI of this line were 0.34 and 0.52 with grain weights from 1m biomass strips of 118 and 150g for the dry and wet treatments, respectively. This cross along with three others, two of which were also first generation crosses and one a second generation cross, were selected for the Colorado State University breeding program for their consistently high performance compared to the commercial controls in all traits measured across both treatments. In the coming years these crosses will undergo more selective and intense breeding across multiple locations with the expectation that at least one will eventually be released as a new commercial variety.

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  • Belowground legacies of Pinus contorta invasion and removal result in multiple mechanisms of invasional meltdown

    Dickie, I. A.; St John, M. G.; Yeates, G. W.; Morse, C. W.; Bonner, K. I.; Orwin, K. H.; Peltzer, D. A.

    Journal article
    Lincoln University

    Plant invasions can change soil biota and nutrients in ways that drive subsequent plant communities, particularly when co-invading with belowground mutualists such as ectomycorrhizal fungi. These effects can persist following removal of the invasive plant and, combined with effects of removal per se, influence subsequent plant communities and ecosystem functioning. We used field observations and a soil bioassay with multiple plant species to determine the belowground effects and post-removal legacy caused by invasion of the non-native tree Pinus contorta into a native plant community. Pinus facilitated ectomycorrhizal infection of the co-occurring invasive tree, Pseudotsuga menziesii, but not conspecific Pinus (which always had ectomycorrhizas) nor the native pioneer Kunzea ericoides (which never had ectomycorrhizas). Pinus also caused a major shift in soil nutrient cycling as indicated by increased bacterial dominance, NO₃⁻N (17-fold increase) and available phosphorus (3.2-fold increase) in soils, which in turn promoted increased growth of graminoids. These results parallel field observations, where Pinus removal is associated with invasion by non-native grasses and herbs, and suggest that legacies of Pinus on soil nutrient cycling thus indirectly promote invasion of other non-native plant species. Our findings demonstrate that multi-trophic below-ground legacies are an important but hitherto largely unconsidered factor in plant community reassembly following invasive plant removal.

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  • Assessment of New Zealand's forest codes of practice for erosion and sediment control

    Pendly, M.; Bloomberg, M.; Fairweather, J. R.

    Journal article
    Lincoln University

    New Zealand's forest industry has several codes of practice available for erosion and sediment control. This article reviews conditions required for a code of practice to succeed in protecting the environment. Internal conditions – those conditions which are written into a code and can be assessed by reading the document alone – were used to assess the strengths and weaknesses of six of New Zealand's forest codes of practice. The study found that overall, the codes scored highly for objectives, communication, planning and comprehensiveness. However they did not score well for regulatory approach, monitoring, foundations and review process. Some preliminary recommendations were made about the development of future codes of practice based on these results.

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  • Predicting willingness to buy dairy functional foods: a health behaviour study

    Garg, Shweta

    Thesis
    Lincoln University

    Introduction: In recent years, obesity and other diet related health problems have been trending upwards. Consequently, functional foods, along with other healthy foods, have gradually gained prominence in our daily diet. China being a new market for dairy, and functional foods within dairy, is heavily dependent on imports to meet its growing domestic demand. Thus, this is of particular interest to New Zealand dairy exporters. Purpose: The present study focussed on the role of two of health behaviour theories- the Health Belief Model (HBM) and the Theory of Planned Behaviour (TPB), to predict willingness to buy dairy functional foods (yoghurt in this study) amongst Chinese consumers. Method: Data for this study was collected through an online survey distributed at various universities in China. The behavioural components of the models, such as perceived severity and susceptibility, perceived benefits and barriers, cues to action and self-efficacy, for HBM; and attitude, subjective norms and perceived behavioural control, for TPB, were measured. Willingness to buy was then estimated for each model using multivariate regression analysis. Cluster analysis was used to group consumers with similar characteristics. Results: Empirical investigations have suggested that for Chinese consumers, TPB was a better predictor of willingness to buy, than HBM. This implied that the sampling population from China perceived functional foods as one that promoted health and not as a disease-avoiding food category. Attitude, self-efficacy and control over one’s behaviour, as perceived by consumers, were found to be significant predictors of willingness to buy amongst Chinese. The role of health consciousness as a moderator was found to be non-significant in predicting willingness to buy yoghurt. Clustering the consumers resulted in three clusters, each significantly distinct in their attitude, willingness to buy and health consciousness. Cluster 3 was observed to be significantly different from Cluster 1 & 2, and scored highest on willingness to buy, health consciousness and attitude towards yoghurt. A further investigation of the profile of consumers grouped as Cluster 3 revealed, that this segment comprised of single, young males, with college degrees and an above average household income. They reportedly lived in a household with children. Originality value: There have been few stated preference studies on functional foods undertaken in European context, the US and a few Eastern countries. The author has found some publications investigating willingness to buy functional foods for consumers in China. However, none of these have used the theories of the Health Belief Model or the Theory of Planned Behaviour to study Chinese consumers’ willingness to buy yoghurt. The study adds to the existing body of knowledge by building on health behaviour theories to study the consumption behaviour of Chinese consumers.

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  • Oxalate content of stir fried silver beet leaves (Beta vulgaris var. cicla) with and without additions of yoghurt

    Teo, E.; Savage, G. P.

    Journal article
    Lincoln University

    Total and soluble oxalic acids were extracted and analysed by HPLC chromatography following Asian cooking methods, which involved soaking, boiling and stir frying of silver beet (Beta vulgaris var. cicla) leaves. Autumn-grown silver beet leaves contained 1658 ± 114 mg/100 g dry matter (DM) of total oxalates, 954 ± 49 mg/100 g DM of soluble oxalates and 704 ± 98 mg/ 100 g DM insoluble oxalates. Soaking and boiling before stir frying reduced the soluble oxalate contents to a mean of 455 mg/100 g DM. Addition of standard or low fat yoghurt following the pre-treatments of soaking, boiling, stir frying and soaking, boiling and stir frying further reduced the soluble oxalate content to a mean of 190.8 ± 49.8 and 227.5. ± 47.0, respectively, for the standard and low fat yoghurt mixes.

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  • Phosphorus fertilization by active dust deposition in a super-humid, temperate environment – Soil phosphorus fractionation and accession processes

    Eger, A.; Almond, P. C.; Condron, L. M.

    Journal article
    Lincoln University

    The inventory of soil phosphorus (P) is subject to significant changes over time. The main primary form, bedrock-derived apatite P, becomes progressively lost through leaching, or transformed into more immobile and less plant-accessible, secondary organic and mineral forms. Here we studied the rejuvenating effect of dust deposition on soil P along an active dust flux gradient downwind of a braided river. Along the gradient, we measured soil P fractions to 50 cm depth of six Spodosols and one Inceptisol, supplemented by tree foliage P concentrations. While an increasing dust flux correlates with a twofold increase of foliar P and soil organic P along the gradient, apatite P declines from ~50 to 3 g m⁻² and total P shows no response. Compared to dust-unaffected Spodosols, depth distribution of total P becomes increasingly uniform and organic P propagates deeper into the soil under dust flux. Further, the effect of topsoil P eluviation attenuates due to higher organic P content and the zone of high apatite P concentrations associated with un-weathered subsoil becomes progressively removed from the upper 50 cm. We interpret these patterns as being consistent with upbuilding pedogenesi and conclude that dust-derived mineral P is assimilated in the organic surface horizon and does not reach the mineral soil. Dust-derived mineral P is temporarily stored in the living biomass and returns to the soil with plant and microbial detritus as organic P, which is subsequently buried by further dust increments. We further conclude that (1) the efficiency of P fertilization of the ecosystem by dust accession is higher than through P advection in dust-unaffected Spodosols and (2) organic P may serve as an important source of labile P in a high-leaching environment. ©2013. American Geophysical Union. All Rights Reserved.

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  • Addition of calcium compounds to reduce soluble oxalate in a high oxalate food system

    Bong, W.-C.; Vanhanen, L. P.; Savage, G. P.

    Journal article
    Lincoln University

    Spinach (Spinacia oleracea L.) is often used as a base vegetable to make green juices that are promoted as healthy dietary alternatives. Spinach is known to contain significant amounts of oxalates, which are toxic and, if consumed regularly, can lead to the development of kidney stones. This research investigates adding 50 to 500 mg increments of calcium carbonate, calcium chloride, calcium citrate and calcium sulphate to 100 g of raw homogenates of spinach to determine whether calcium would combine with the soluble oxalate present in the spinach. Calcium chloride was the most effective additive while calcium carbonate was the least effective. The formation of insoluble oxalate after incubation at 25°C for 30 minutes is a simple practical step that can be incorporated into the juicing process. This would make the juice considerably safer to consume on a regular basis.

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