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81.
Takahiro Noda Nisha Sulari Kottearachchi Shogo Tsuda Motoyuki Mori Shigenobu Takigawa Chie Matsuura-Endo Sun-Ju Kim Naoto Hashimoto Hiroaki Yamauchi 《Carbohydrate polymers》2007,68(4):793-796
The research presented herein provides valuable data with respect to the phosphorus content of starches from many potato (Solanum tuberosum L.) cultivars using an energy-dispersive X-ray fluorescence technique. In all starches examined, the phosphorus content ranged from 308 to 1244 ppm. Furthermore, the estimation of the starch characteristics of representative samples differing manifestly in their phosphorus content indicated that enhancing the starch phosphate resulted in significant increases in the swelling power, peak viscosity, and breakdown and significant but small increases in the onset and peak temperatures of gelatinization. Other starch quality parameters, such as the amylose content, median granule size, and the gelatinization enthalpy, did not change significantly due to the degree of phosphate substitution of starch. 相似文献
82.
Soil Organic Phosphorus Transformations During Pedogenesis 总被引:2,自引:0,他引:2
Benjamin L. Turner Leo M. Condron Sarah J. Richardson Duane A. Peltzer Victoria J. Allison 《Ecosystems》2007,10(7):1166-1181
Abstract
Long-term changes in soil phosphorus influence ecosystem development and lead to a decline in the productivity of forests
in undisturbed landscapes. Much of the soil phosphorus occurs in a series of organic compounds that differ in their availability
to organisms, but changes in the relative abundance of these compounds during pedogenesis remain unknown. We used alkaline
extraction and solution phosphorus-31 nuclear magnetic resonance spectroscopy to assess the chemical nature of soil organic
phosphorus along a 120,000-year post-glacial chronosequence at Franz Josef, New Zealand. Inositol phosphates, DNA, phospholipids,
and phosphonates accumulated rapidly during the first 500 years of soil development characterized by nitrogen limitation of
biological productivity, but then declined slowly to low concentrations in older soils characterized by intense phosphorus
limitation. However, the relative contribution of the various compounds to the total organic phosphorus varied along the sequence
in dramatic and surprising ways. The proportion of inositol hexakisphosphate, conventionally considered to be relatively recalcitrant
in the environment, declined markedly in older soils, apparently due to a corresponding decline in amorphous metal oxides,
which weather to crystalline forms during pedogenesis. In contrast, the proportion of DNA, considered relatively bioavailable
in soil, increased continually throughout the sequence, due apparently to incorporation within organic structures that provide
protection from biological attack. The changes in soil organic phosphorus coincided with marked shifts in plant and microbial
communities, suggesting that differences in the forms and bioavailability of soil organic phosphorus have ecological significance.
Overall, the results strengthen our understanding of phosphorus transformations during pedogenesis and provide important insight
into factors regulating the composition of soil organic phosphorus. 相似文献
83.
通过对福建三明27年生杉木(Cunninghamia lanceolata)-观光木(Tsoongiodendron odorum)混交林(混交比例2:1)及杉木纯林群落N、P养分循环进行为期2年的研究。结果表明,混交林中杉木和观光木地上各组分的N、P含量大小均为叶>活枝(或皮)>枯枝>干,而根系的则随径级的减小而增大,且观光木各组分的N含量均高于杉木的;混交林群落的N、P总积累量达585.223 kg·hm-2和128.784 kg·hm-2,分别是纯林群落的1.5倍和1.3倍。混交林群落N、P养分年归 相似文献
84.
M. Estrada M.M. Sala M. Alcaraz M.J.W. Veldhuis 《Journal of experimental marine biology and ecology》2008,355(1):1-11
A microcosm approach was used to test whether: a) growth under unbalanced nutrient conditions (varying N:P ratios) affected the susceptibility of a phytoplankton community including the dinoflagellate Alexandrium catenella (a paralytic shellfish toxin producer) to mesozooplankton grazing, and b) the potential effects of unbalanced nutrient conditions were mediated by changes in toxicity of A. catenella or by other mechanisms. The experimental setup consisted of fifteen 30 l microcosms, filled with water from the Barcelona Harbour and subjected to treatments combining nutrient inputs at three different N:P ratios (Redfield N:P ratio or nutrient-balanced, high N:P and low N:P), addition or omission of A. catenella (an estimated initial concentration of 38 A. catenella cells ml− 1, a value typical for blooms in harbours of the Catalan coast), and selective addition of a cultured population of Acartia grani. P sufficiency had a strong positive effect on the growth of A. grani, both with or without A. catenella addition, presumably due to enhanced food quality of the prey community. The presence of this copepod resulted in lower concentrations of ciliates, A. catenella, and other dinoflagellates, suggesting active grazing by the copepods. No noxious effects of A. catenella on the copepods were detected at the relatively low cell concentrations of that dinoflagellate used in the experiment. 相似文献
85.
Summary Effects of calcium phosphate supply on plant dry matter and phosphorus concentrations of parts of jarrah (Eucalyptus marginata) seedlings grown in a lateritic topsoil from the jarrah forest were examined in two glasshouse trials. Phosphorus deficiency
depressed root and shoot dry weights and severely deficient leaves were smal and purple with prominent red major veins. Phosphorus
deficiency severely reduced stem phosphorus levels (0.5% to 0.02%, experiment 1). Phosphorus concentrations were higher in
bark than wood and the amount of phosphorus in the bark was sensitive to stem age and phosphate supply. Phosphorus adequate
plants had bark phosphorus concentrations in the range 0.2–0.9% compared to <0.1% in deficient plants (experiment 2).
Jarrah leaves accumulated dry matter up to 80 days after expansion and some leaves exported phosphorus during this period.
Bark analysis may therefore be preferable to leaf analysis for detecting phosphorus deficiency in this species. 相似文献
86.
PAN Li-juan YANG Xiao-cheng 《现代生物医学进展》2008,(12)
水体中氮磷营养物质不断积累,部分藻类及水生生物的过度繁殖,导致了水体的富营养化。水体富营养化防治的关键是减小水中氮、磷的含量。人工湿地是一项新型的废水处理技术,近年来在脱除富营养化水体氮磷中获得广泛研究和应用。本文在简述脱氮除磷机理的基础上,较系统地阐述了影响人工湿地脱除氮磷的因素及工艺的在改善水体富营养化的研究进展,以便在构建人工湿地中对各项因素综合考虑及兼顾利用,提高人工湿地修复富营养化水体的综合效能。 相似文献
87.
Effects of agricultural production on phosphorus losses from paddy soils: a case study in the Taihu Lake Region of China 总被引:6,自引:0,他引:6
Huanchao?ZhangEmail author Fuliang?Cao Shengzuo?Fang Gaiping?Wang Hongai?Zhang Zhihong?Cao 《Wetlands Ecology and Management》2005,13(1):25-33
A field plot experiment was conducted on two types of paddy soils in the Taihu Lake Region of China from June 2000 through 2002 to assess phosphorus (P) losses by runoff and drainage flow and the effectiveness of rice–wheat double cropping on reducing P losses from paddy soils. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 30, 150, and 300 kg P ha–1 for rice season trials, and 0, 20, 80, and 160 kg P ha–1 for wheat season trials. The experiments consisted of four replicates (plots of 5 × 6 m in a randomized block design) of each treatment in Argic stagnic anthrosols (Anzhen site) and six replicates in Cumulic stagnic anthrosols (Changshu site). P30 and P20 treatments (30 and 20 kg P ha–1 in rice and wheat seasons, respectively) were considered as conventional P application rates in this area. Higher P treatments, such as P150 and P300 for rice and P80 and P160 for wheat, were intended to simulate the status of soil P in ~10–20 years with an application of P30 or P20 kg P ha–1 each season. Results revealed that the average concentration of total P (TP) in runoff samples was 0.870 mg P l–1 from P30 plots during the rice season, and 0.763 mg P l–1 from P20 plots during the wheat season in both years at the Anzhen site, while it was 0.703 and 1.292 mg P l–1, respectively, at the Changshu site. Average TP load (mass loss) at the Anzhen site with conventional P application rates was 220.9 and 439.5 g P ha–1 during rice season in 2000/2001 and 2001/2002, respectively, but was 382.3 and 709.4g P ha–1 during wheat season, respectively. Mass loss at the Changshu site was 140.4 and 165.7 g P ha–1 during the rice season and 539.1 and 1184.6 g P ha–1 during the wheat season, respectively. P losses from paddy soils were significantly greater during the wheat season, especially at the Changshu site, indicating that planting rice reduced P. Phosphate fertilizer levels significantly affected P concentrations and P loads in runoff both seasons. Both mean concentrations and average seasonal P loads from the P150/P80 plots were lower than that from the P300/P160 plots, but significantly higher than that from the P30/P20 and P0 plots. This implied that runoff P loads would be greatly increased in 10–20 years as a result of the accumulation of soil P if 50 kg P ha–1 (rice season plus wheat season) is applied each year. 相似文献
88.
89.
Cellulase, an enzymatic complex that synergically promotes the degradation of cellulose to glucose and cellobiose, free or adsorbed onto Si/SiO2 wafers at 60 °C has been employed as catalyst in the hydrolysis of microcrystalline cellulose (Avicel), microcrystalline cellulose pre-treated with hot phosphoric acid (CP), cotton cellulose (CC) and eucalyptus cellulose (EC). The physical characteristics such as index of crystallinity (IC), degree of polymerization (DP) and water sorption values were determined for all samples. The largest conversion rates of cellulose into the above-mentioned products using free cellulase were observed for samples with the largest water sorption values; conversion rates showed no correlation with either IC or DP of the biopolymer. Cellulose with large water sorption value possesses large pore volumes, hence higher accessibility. The catalytic efficiency of immobilized cellulase could not be correlated with the physical characteristics of cellulose samples. The hydrolysis rates of the same cellulose samples with immobilized cellulase were lower than those by the free enzyme, due to the diffusion barrier (biopolymer chains approaching to the immobilized enzyme) and less effective contact between the enzyme active site and its substrate. Immobilized cellulase, unlike its free counterpart, can be recycled at least six times without loss of catalytic activity, leading to higher overall cellulose conversion. 相似文献
90.
Summary Greenhouse experiments were done with two purposes: (1) to identify strains of rhizobia effective and acid-tolerant in symbiosis withLablab purpureus, and (2) to determine whether soil acidity or the symbiotic condition increased the phosphate requirement for growth.Five rhizobial strains were tested in one neutral soil, two acid soils, and the two acid soils limed to pH 6.6. In the neutral and limed soils, three of the strains were effective (CB1024, CB756, TAL169), but only two strains (CB756, TAL169) remained effective in acid soil.Strain CB756 and plus-N treatments were further compared in a factorial trial involving combinations of five levels of P with lime, no lime and CaCl2 treatments, applied to an acid soil. Some of the treatments were also applied to plants inoculated with CB1024. Between the N-fertilized and CB756 treatments there was no clear difference in growth response to applied P, and the critical internal concentration of P for 95% of maximal growth was the same (0.22% shoot dry weight). Increasing P beyond levels needed for maximal growth increased nodulation and N concentration in plants inoculated with CB756. It lowered N concentration in N-fertilized plants. There was evidence suggesting that the P requirement of symbiotic plants increased if the soil was acid, or if CB756 were replaced by CB1024 as microsymbiont; but the critical statistical interactions were not significant. 相似文献