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Recent lysimeter studies have demonstrated that the nitrification inhibitor, dicyandiamide (DCD), can reduce nitrate (NO) leaching losses from cow urine patches in grazed pasture systems. The objective of this study was to quantify the effects of fine particle suspension (FPS) DCD on soil mineral N components, pasture yield, nutrient uptake and pasture quality under grazed pasture conditions. A field study was conducted on the Lincoln University dairy farm, Canterbury, New Zealand, from 2002 to 2006. FPS DCD was applied to grazed pasture plots at 10 kg ha?1 in early May in addition to applied cow urine patches at a nitrogen (N) loading rate of 1000 kg N ha?1, with DCD reapplied in early August. Soil mineral N levels in the urine patches were monitored. Pasture yield, N and cation concentrations and uptake were measured in treatment urine patches and inter‐urine areas of the pasture. Comparisons were made with control plots which did not receive DCD. NO levels under the DCD‐treated urine patches (0–7.5 cm) were in the order of 10 kg N ha?1 compared with 40–80 kg N ha?1 under untreated patches, and soil ammonium (NH) levels were consistently higher under the DCD‐treated patches. The DCD significantly and consistently increased pasture yield in both the urine patches, and inter‐urine areas of the pasture in all 4 years of the trial. Mean annual dry matter (DM) yields over 4 years were inter‐urine areas, 10.3; inter‐urine + DCD, 12.4; urine, 12.4 and urine +DCD 16.0 t DM ha?1, representing an average DM yield increase of 20 and 29% in inter‐urine and urine patch areas, respectively. On a whole paddock basis, the increase in annual DM yield resulting from DCD application was estimated to be 21%. N, calcium (Ca), magnesium (Mg) and potassium (K) concentrations in pasture were unaffected by treatment with DCD; however, total annual uptake of these nutrients by pasture was significantly higher in all years where DCD had been applied. Pasture DM, protein, carbohydrate, metabolizable energy and fibre levels and sward clover content were not affected by treatment with DCD. The results demonstrate the agronomic value of the DCD treatment in addition to the environmental benefits in a grazed pasture system. 相似文献
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Heterologous protein secretion from yeast 总被引:25,自引:0,他引:25
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Patel AK Singh VK Moir AJ Jagannadham MV 《Journal of agricultural and food chemistry》2008,56(19):9236-9245
A novel heme peroxidase MGP from the latex of Ipomoea carnea subsp. fistulosa (morning glory) belonging to the Convolvulaceae family was purified to homogeneity using ammonium sulfate precipitation, anion exchange, hydrophobic interaction, and gel filtration chromatography. The enzyme is glycosylated and has a molecular mass of 42.06 kDa (MALDI-TOF) and an isoelectric point of pH 4.3. The enzyme has high yield, broad substrate specificity, and a high stability toward pH, temperature, chaotrophs, and organic solvents. The extinction coefficient (epsilon 280 (1%)) of the enzyme was estimated as 20.56 and it consists of 13 tryptophan, 9 tyrosine, and 8 cysteine residues forming 4 disulfide bridges. There is significant effect of inhibitors targeting S-S bridges (mercaptoethanol, l-cysteine, glutathione), as well as of inhibitors targeting heme (sodium azide and hydroxylamine) on peroxidase activity, whereas inhibition was not observed with ethylmaleinimide due to the absence of reduced cysteine in the enzyme. Polyclonal antibodies against the enzyme have been raised in rabbit, and immunodiffusion suggests that the antigenic determinants of MGP are unique. The N-terminal sequence of MGP (D-E-A-C-I-F-S-A-V-K-E-V-V-D-A) exhibited considerable similarity to the sequence of other known plant peroxidases. Spectroscopic studies (absorbance, fluorescence, and circular dichroism) reveal that MGP has secondary structural features with alpha/beta type with approximately 20% alpha-helicity. 相似文献
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B. J. Malcolm K. C. Cameron H. J. Di G. R. Edwards J. L. Moir 《Soil Use and Management》2014,30(1):58-68
Nitrate () leaching can cause elevated concentrations of ‐N in water, which can have adverse impacts on water quality and human health. In grazed pasture systems, most of the ‐N leaching occurs beneath animal urine‐N deposits. The objective of this study was to investigate the effect of four different pasture species compositions [perennial ryegrass/white clover (P. ryegrass WC), tall fescue/white clover (T. fescue WC), Italian ryegrass/white clover (It. ryegrass WC) and perennial ryegrass/Italian ryegrass/white clover/red clover/chicory/plantain (Diverse)] on ‐N leaching losses from animal urine patches, and to examine the relative importance of root system architecture and seasonal activity to reduce ‐N leaching losses. The results show that ‐N leaching losses were 24–54% lower beneath It. ryegrass WC than other pasture species. Total dry matter (DM) yield in the season following establishment was 11–58% greater in the It. ryegrass WC pasture, while average winter daily N uptake rate of It. ryegrass WC over the two seasons was on average 58% greater than P. ryegrass WC and T. fescue WC. In the second season, the P. ryegrass WC and T. fescue WC pastures had up to 140 and 82% more roots between 0 and 40 cm depth, respectively, than the other pasture species compositions. These results suggest that in grazed pasture systems, high plant winter activity (plant growth/root metabolic activity) is more important than specific root architecture (e.g. deep roots) to reduce ‐N leaching losses. 相似文献
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