Journal Articles
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Item Soil C, N, and P stocks evaluation under major land uses on China’s Loess Plateau(Society for Range Management, 1/03/2017) Chen X; Hou F; Matthew C; He XZLoess Plateau covers 640 000 km2 in the central northern China. Despite a semiarid environment, harsh winters, and hot summers, agriculture has been practiced in this region for > 5 000 yr, and the food production systems are among China's oldest. The environment is fragile because the loessial soils are prone to erosion. Sound scientific information is therefore required to underpin future land use planning in the region. To this end, total soil organic carbon (SOC), N, and P stocks were measured in Huanxian County of the wider Loess Plateau, representing five major land use categories. Sites were sampled three times over 3 yr. In all, almost 2 800 soil analyses were performed. A feature of these soils is low SOC content in the A horizon but comparatively small decline with soil depth. For example, SOC levels for the 0-20 cm and 70-100 cmsoil depths averaged 6.1 and 4.1Mg ha-1, respectively. Alfalfa and rangeland sites had 5.1 Mg ha-1 (10%) more total than cropland and 7.5 t ha-1 (16%) more total SOC to 100-cm soil depth than the two silvopastoral sites. For total soil N (0- to 100-cm soil depth) the averages of alfalfa and RL siteswere 20% and 28%, respectively, higher than the cropland and silvopastoral site group means, although soil C, N, and P levels are very low, relative to those of typical soils elsewhere. When these observations are scaled up to a regional level, it can be calculated that a 5% shift in land use from cropping or silvopastoral systems to alfalfa-based systems could increase soil C sequestration by as many as 20 million t CO2 per yr, although some caution is needed in making extrapolations, as the present data are from a single locality on the Loess Plateau.Item Is glyphosate-resistant ryegrass resistant to paraquat?(Caxton Press, 2017) Ghani Zadeh H; Harrington KCSequestration of herbicide into vacuoles is considered to be the main mechanism of resistance to both glyphosate and paraquat worldwide. In New Zealand, the first case of glyphosate resistance was found in ryegrass (Lolium) species, and the restricted herbicide translocation was found to be the main mechanism of resistance in the studied populations, presumably through sequestration. Overseas researchers hypothesised that the mechanism responsible for glyphosate resistance could also cause resistance to paraquat. We examined this hypothesis by comparing a known glyphosate-resistant population of perennial ryegrass with a known susceptible population after spraying with different rates (25–800 g ai/ha) of paraquat. The glyphosate-resistant population responded similarly to the susceptible population at the different rates of paraquat application. This result suggests that the restricted glyphosate translocation mechanism does not necessarily lead to paraquat resistance. These results also suggest that paraquat could be useful for controlling ryegrass when glyphosate resistance has evolved and the application of paraquat is permitted.Item Intake of milk and pasture and growth rate of calves reared by cows with high or low potential for milk production(CSIRO Publishing, 29/11/2016) Roca Fraga FJ; Lopez-Villalobos N; Martin NP; Kenyon PR; Morris ST; Hickson REMilk production of cows influences calf weaning weight, which is the major driver for economic return in a cow–calf operation. The growth trajectory of 64 steer calves resulting from a terminal cross between Angus or Simmental bulls with Angus, Angus cross Holstein Friesian, Angus cross Jersey and Angus cross KiwiCross cows was examined during the pre-weaning period from birth (D0) to weaning (D148) and during the post-weaning period until a year of age (D365). Random regression models were used to model milk intake and liveweight of calves throughout lactation. These models were a good fit to the data (r2 = 0.77 for milk intake and r2 = 0.99 for liveweight). Total energy intake from milk was greater (P < 0.05) for the Angus cross Holstein Friesian-, Angus cross Jersey- and Angus cross KiwiCross-reared steers than for those reared by Angus dams. Additional milk intake increased liveweight of steers from D90 to D365, but the magnitude of the effect decreased as the calves aged. Simmental-sired steers had a greater liveweight response to additional milk intake than Angus-sired steers at D120 and D148, probably reflecting greater growth potential from out-crossed calves.Item An empirical analysis of the cost of rearing dairy heifers from birth to first calving and the time taken to repay these costs(Cambridge University Press, 8/02/2017) Boulton AC; Rushton J; Wathes DCRearing quality dairy heifers is essential to maintain herds by replacing culled cows. Information on the key factors influencing the cost of rearing under different management systems is, however, limited and many farmers are unaware of their true costs. This study determined the cost of rearing heifers from birth to first calving in Great Britain including the cost of mortality, investigated the main factors influencing these costs across differing farming systems and estimated how long it took heifers to repay the cost of rearing on individual farms. Primary data on heifer management from birth to calving was collected through a survey of 101 dairy farms during 2013. Univariate followed by multivariable linear regression was used to analyse the influence of farm factors and key rearing events on costs. An Excel spreadsheet model was developed to determine the time it took for heifers to repay the rearing cost. The mean±SD ages at weaning, conception and calving were 62±13, 509±60 and 784±60 days. The mean total cost of rearing was £1819±387/heifer with a mean daily cost of £2.31±0.41. This included the opportunity cost of the heifer and the mean cost of mortality, which ranged from £103.49 to £146.19/surviving heifer. The multivariable model predicted an increase in mean cost of rearing of £2.87 for each extra day of age at first calving and a decrease in mean cost of £6.06 for each percentile increase in time spent at grass. The model also predicted a decrease in the mean cost of rearing in autumn and spring calving herds of £273.20 and £288.56, respectively, compared with that in all-year-round calving herds. Farms with herd sizes⩾100 had lower mean costs of between £301.75 and £407.83 compared with farms with <100 milking cows. The mean gross margin per heifer was £441.66±304.56 (range £367.63 to £1120.08), with 11 farms experiencing negative gross margins. Most farms repaid the cost of heifer rearing in the first two lactations (range 1 to 6 lactations) with a mean time from first calving until breaking even of 530±293 days. The results of the economic analysis suggest that management decisions on key reproduction events and grazing policy significantly influence the cost of rearing and the time it takes for heifers to start making a profit for the farm.Item Pasture damage from spot-sprayed herbicides(Caxton Press, 2017) Harrington KC; Ghani Zadeh H; Moyo C; Kemp PD; Eerens JPJSpot-spraying weeds in pastures enables the use of herbicide that would be too harmful to pasture if boom-sprayed. However, some herbicides are more damaging than others. To quantify this damage, a range of spot-spraying treatments was applied to ryegrass/white clover pastures. Four herbicide treatments were compared, each at two application rates and two sizes of sprayed patch. Applications of either clopyralid or a triclopyr/picloram mix resulted in total removal of white clover from the sprayed patches but these patches remained covered in perennial ryegrass. Metsulfuron also removed all white clover but also severely damaged the perennial ryegrass, although some grass cover remained due to survival of browntop. Residues of these treatments suppressed seedlings of white clover and weeds for many weeks after application. Glyphosate treatments resulted in the most bare soil. White clover recovered most rapidly in glyphosate-treated areas, mainly by lateral spread of stolons, but weed species also established rapidly.Item Branched pectic galactan in phloem-sieve-element cell walls: Implications for cell mechanics(American Society of Plant Biologists, 6/02/2018) Torode TA; O'Neill R; Marcus SE; Cornuault VRG; Pose S; Lauder RP; Kracun SK; Rydahl MG; Andersen MCF; Willats WGT; Braybrook SA; Townsend BJ; Clausen MH; Knox JPA major question in plant biology concerns the specification and functional differentiation of cell types. This is in the context of constraints imposed by networks of cell walls that both adhere cells and contribute to the form and function of developing organs. Here, we report the identification of a glycan epitope that is specific to phloem sieve element cell walls in several systems. A monoclonal antibody, designated LM26, binds to the cell wall of phloem sieve elements in stems of Arabidopsis (Arabidopsis thaliana), Miscanthus x giganteus, and notably sugar beet (Beta vulgaris) roots where phloem identification is an important factor for the study of phloem unloading of Suc. Using microarrays of synthetic oligosaccharides, the LM26 epitope has been identified as a β-1,6-galactosyl substitution of β-1,4-galactan requiring more than three backbone residues for optimized recognition. This branched galactan structure has previously been identified in garlic (Allium sativum) bulbs in which the LM26 epitope is widespread throughout most cell walls including those of phloem cells. Garlic bulb cell wall material has been used to confirm the association of the LM26 epitope with cell wall pectic rhamnogalacturonan-I polysaccharides. In the phloem tissues of grass stems, the LM26 epitope has a complementary pattern to that of the LM5 linear β-1,4-galactan epitope, which is detected only in companion cell walls. Mechanical probing of transverse sections of M x giganteus stems and leaves by atomic force microscopy indicates that phloem sieve element cell walls have a lower indentation modulus (indicative of higher elasticity) than companion cell walls.Item Responses of rice (Oryza sativa L.) plant growth, grain yield and quality, and soil properties to the microplastic occurrence in paddy soil(Springer, 18/05/2022) Chen S; Feng Y; Han L; Li D; Feng Y; Jeyakumar P; Sun H; Shi W; Wang HPurpose: Agricultural soil has been recognized as a major sink of microplastic, an emerging pollutant to environmental biodiversity and ecosystem. However, the impacts of microplastic on soil–plant systems (e.g., crop growth, grain yield and amino acid content, nitrogen uptake capacity, and soil properties) remain largely unknown. Methods: Four typical microplastics, i.e., polythene (PE, 200 μm), polyacrylonitrile (PAN, 200 μm), and polyethylene terephthalate (PET) in diameter of 200 μm and 10 μm (PET200 and PET10), were tested to assess the consequent aforementioned responses under rice (Oryza sativa L.) paddy soil in a mesocosm experiment. Results: Microplastics multiply influenced the soil pH, NH4+-N and NO3−-N contents, which effects were depended on the rice growth stage and plastic type. Overall, microplastics significantly decreased the soil urease activity by 5.0–12.2% (P < 0.05). When exposed to PAN and PET (in both diameter of 200 μm and 10 μm), there were significantly 22.2–30.8% more grain yield produced, compared to the control (P < 0.05), which was attributing to the higher nitrogen uptake capacity of rice grain. Meanwhile, microplastics exhibited nominal influences on rice plant height, tillering number, leaf SPAD, and NDVI. The amino acids were affected by microplastic, depending on the types of plastics and amino acids. Conclusion: This study provides evidence that microplastic can affect the development and final grain yield, amino acid content, nitrogen uptake capacity of rice, and some major soil properties, while these effects vary as a function of plastic type. Our findings highlight the positive impacts that could occur when the presence of microplastics in paddy soil.Item The aetiology of wobbly possum disease: Reproduction of the disease with purified nidovirus.(2016-04) Giles J; Perrott M; Roe W; Dunowska MThe objective of this study was to investigate a role of a recently discovered marsupial nidovirus in the development of a neurological disease, termed wobbly possum disease (WPD), in the Australian brushtail possum (Trichosurus vulpecula). Four possums received 1 mL of a standard inoculum that had been prepared from tissues of WPD-affected possums, 4 possums received 1.8 mL (1 × 10(6) TCID50) of a cell lysate from inoculated cultures, and 4 possums received 1 mL (× 10(7) TCID50) of a purified WPD isolate. All but one possum that received infectious inocula developed neurological disease and histopathological lesions characteristic for WPD. High levels of viral RNA were detected in livers from all possums that received infectious inocula, but not from control possums. Altogether, our data provide strong experimental evidence for the causative involvement of WPD virus in development of a neurological disease in infected animals.Item Unilateral perivertebral fibrosis associated with lordosis, kyphosis and scoliosis (LKS) in farmed Chinook salmon in New Zealand.(27/10/2016) Munday JS; Perrott MR; Symonds JE; Walker SP; Lovett B; Preece MA; Davie PSVertebral column lordosis, kyphosis and scoliosis (LKS) can result in downgrading of farmed Chinook salmon Oncorhynchus tshawytscha in New Zealand. No cause of LKS has been identified. Radiography and histology were used to quantify LKS and perivertebral fibrosis in 27 fish with LKS visible at harvest and 30 visually normal fish from 3 New Zealand farms. Radiographic LKS was present in all 27 fish with LKS and in 18 of 30 fish without visible LKS. Quantification of the radiographic severity revealed significantly higher radiographic severity scores in fish with visible LKS (mean ± SD = 5.89 ± 2.41) than in fish with no visible, but radiographic LKS (1.44 ± 0.86, p < 0.001). The most frequent histological finding was unilateral perivertebral fibrosis that often extended into the horizontal septum and adjacent myomeres resulting in separation or loss of myocytes. Fibrosis was visible in all fish with LKS and in 12 of 30 fish without visible LKS. Fibrosis scores were higher in fish with visible LKS (3.32 ± 1.71) than in fish without visible LKS (0.35 ± 0.57, p < 0.001). The radiographic LKS severity scores were significantly correlated to the fibrosis scores (R2 = 0.59 p < 0.001) in the fish. Histology of other tissues revealed multifocal inflammation within muscle, peripheral connective tissues and myocardium which were considered most likely incidental in these fish. In this study, LKS was consistently and significantly associated with perivertebral fibrosis, suggesting that perivertebral fibrosis is an important process in the development of LKS. Further research to determine the cause of the fibrosis is required.Item Genetic characterization of equid herpesvirus type 1 from cases of abortion in Poland.(2017-08) Stasiak K; Dunowska M; Hills SF; Rola JEquid herpesvirus type 1 (EHV-1) is a common viral infection associated with varied clinical outcomes including respiratory disease, abortion and neurological disease. We have characterized EHV-1 sequences (n = 38) obtained from cases of equine abortion in Poland between 1999 and 2016, based on sequencing of PCR products from open reading frames (ORF) 30 and 68 of the EHV-1 genome. The majority (81.6%) of sequences were not classified into any of the previously described groups based on the ORF68 sequence. The remaining sequences belonged to ORF68 group III (7.9%) or IV (10.5%). A haplotype network analysis did not show any obvious structure within networks of local Polish sequences, nor within a global network of 215 EHV-1 sequences when these networks were coloured based on the geographical origin of viruses or date of detection. Our data suggest that ORF68 does not provide a reliable molecular marker for epidemiological studies of EHV-1, at least in a global sense. Its usefulness to aid local investigations of individual outbreaks remains to be established. All but two Polish EHV-1 sequences belonged to the ORF30 N752 genotype. The two ORF30 D752 viruses were obtained from abortion cases in 2009 and 2010. Hence, abortion cases that occurred in Poland between 1999 and 2016 were caused predominantly by EHV-1 with the ORF30 N752 genotype, with no indication of an increase in the prevalence of the ORF30 D752 variant.
