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71.
通过S342省道(沪宜)无锡市区段3标段湿喷桩处理软基的施工实践,总结湿喷桩的施工工艺参数,质量控制手段,质量检测方法。湿喷桩处理后的软基加固见效快,耐久性好,施工工期短等优点。 相似文献
72.
Addition of nitrogen (N) to the field layer of boreal forests has been shown to increase the occurrence of the parasitic fungus Valdensia heterodoxa on Vaccinium myrtillus plants. We investigated whether N addition to soil alters the levels of polyamines in V. myrtillus shoots, and discuss here whether such changes could promote the spread of the parasitic fungus on V. myrtillus. Using HPLC, we analyzed the concentrations of free and conjugated polyamines in healthy and naturally V. heterodoxa-infected V. myrtillus plants, which had received a moderate or high dose of N fertilizer, or no additional N. Fertilization with N increased the concentrations of free diamines (putrescine and diaminopropane), but had no significant effect on conjugated amines. Thus, N-induced changes in the constitutive levels of soluble conjugated amines do not seem to explain the increased parasite susceptibility of V. myrtillus under N enrichment. Generally, the concentrations of free diamines and insoluble conjugated putrescine were higher in diseased than in healthy shoots, suggesting parasite-induced accumulation of diamines. Free spermine seemed to accumulate in unfertilized, diseased plants, but in fertilized plants this induction was dampened, suggesting that N-induced alterations in spermine metabolism may promote the spread of parasites on V. myrtillus under N-enrichment. 相似文献
73.
Maria P Geneva Ira V Stancheva Madlen M Boychinova Nadezhda H Mincheva Petranka A Yonova 《Journal of the science of food and agriculture》2010,90(4):696-702
BACKGROUND: The effect of foliar fertilization and Glomus intraradices inoculation on the growth, qualitative and quantitative pattern of essential oil in Salvia officinalis was determined. Sage plants were grown in a glass house on a soil/sand mixture (w/w = 3:1). Agroleaf® total, N:P:K = 20:20:20 + microelements, was used at the whole vegetative growth stage as a 0.3% solution. Inoculation with Glomus intraradices was done at the sowing stage. RESULTS: Application of foliar fertilization and/or mycorrhizal colonization improved dry biomass accumulation and increased the content of antioxidant metabolites (ascorbate and reduced glutathione). Applied treatments lowered the activities of the antioxidants enzymes catalase, ascorbate peroxidase and superoxide dismutase, while guaiacol peroxidase increased. The relative quantity of essential oil pattern was also altered as a result of the applied treatments. Combined application (FF + Gi) significantly promoted 1,8‐cineole and α‐thujone, mycorrhizal colonization enhanced bornyl acetate, 1,8‐cineole, α‐ and β‐thujones, while foliar fertilization increased bornyl acetate and camphor. The favorable effect of root colonization by Glomus intraradices was determined both on quantitative and qualitative pattern of sage essential oil. CONCLUSION: We conclude that inoculation with Glomus intraradices resulted in improved essential oil yield and quality, while combined application of foliar fertilizer and mycorrhizal fungi predominantly enhanced shoot biomass accumulation. Copyright © 2010 Society of Chemical Industry 相似文献
74.
Xiaopeng Gao Fardausi Akhter Mario Tenuta Donald N Flaten Eugene J Gawalko Cynthia A Grant 《Journal of the science of food and agriculture》2010,90(5):750-758
BACKGROUND: A 3‐year field trial was conducted to investigate the effect of agricultural management practices including tillage, preceding crop and phosphate fertilization on root colonization by arbuscular mycorrhizal (AM) fungi and grain cadmium (Cd) concentration of durum wheat (Triticum turgidum L.). The relationship between grain Cd and soil and plant variables was explored to determine the primary factors affecting grain Cd concentration. RESULTS: Mycorrhizal colonization of the roots was reduced by conventional tillage or when the preceding crop was canola (Brassica napus L.), compared to minimum tillage or when the preceding crop was flax (Linum usitatissimum L.). In contrast, grain Cd was not consistently affected by any treatment. Grain Cd was generally below the maximum permissible concentration (MPC) of 100 µg Cd kg?1 proposed by WHO. Grain Cd varied substantially from year to year, and could be predicted with 70% of variance accounted for by using the model: grain Cd concentration = ? 321.9 + 44.5× ln(grain yield) + 0.26× soil DTPA‐Cd + 182.5× soil electrical conductivity (EC)? 0.98× grain Zn concentration. CONCLUSIONS: These common agricultural management practices had no effect on grain Cd concentration in durum wheat though they impacted mycorrhizal colonization of roots. Grain yield and to a lesser extent soil conditions of EC and DTPA‐Cd and grain Zn influenced grain Cd, whereas mycorrhizal colonization levels did not. Copyright © 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd 相似文献
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Nitrous oxide emissions from an Uruguayan argiudoll under different tillage and rotation treatments 总被引:1,自引:0,他引:1
Lack of local data limits estimation of nitrous oxide (N2O) emissions from different land uses of Uruguay. As a first step towards obtaining local information, we measured from August
2003 to September 2004 N2O fluxes from a rotation-by-tillage experiment established in 1993 and from a nearby natural pasture (NP). Nitrous oxide emission
rates were measured on an event-driven basis by using the closed chamber technique with six replicates per treatment. Fluxes
varied considerably with time and the higher rates (more than 30 g N ha−1 day−1) were generally associated with periods of high soil water content, high temperature, and/or decreasing soil nitrate. We
could not identify, however, any statistically significant correlation between flux and these variables. Throughout the evaluation
period, fluxes from crops or cultivated pastures tended to be higher than those from NP, but the effects of tillage (no-till
and conventional tillage) or rotation (continuous tillage and rotation with pasture) were not consistent. The application
of 112 kg N ha−1 to barley did not increase N2O fluxes probably due to a high fertilizer use efficiency caused by the recommended three-split application and by the lack
of rain during this period. The annual cumulative flows of different treatments compared well with those estimated using IPCC
methodology, but the high spatial and temporal variability observed in this one-year study indicate that further research
is needed to obtain reliable data on N2O fluxes from agricultural soils of Uruguay. 相似文献
78.
有机无机肥不同施用方式对鄂西南植烟土壤有效氮动态的影响 总被引:1,自引:0,他引:1
在鄂西南烟区研究了化肥不同施用方式对植烟土壤有效氮时空动态的影响。结果表明,在降雨量较大年份,烟叶移栽后一个月内化学肥料带入的有效氮基本全部损失,有机肥料带入的氮素(有机态氮)则在移栽后45~70 d内在0~20 cm土层内发挥作用;移栽后60 d左右土壤自身有机氮开始矿化加速导致土壤有效氮升高。揭膜可以使化学氮素大量淋失,而全生育期覆膜则使后期土壤有效氮升高。提前施肥可能会使无机肥料氮素转化为有机氮,使氮素淋失的风险大幅度降低。 相似文献
79.
在鄂西南植烟土壤上研究了不同施肥方式对土壤有效氮、烟株氮累积量以及氮累积速率的影响。结果显示,在不栽烟情况下,施肥后40 d内肥料养分损失完毕,60 d后土壤有机氮矿化量高于有效氮损失量,土壤有效氮出现净累积;全生育期覆膜方式下移栽后63 d内化肥处理(D)土壤有效氮明显高于有机无机配施处理(G),烟株氮累积和土壤有效氮下降成显著负相关,且G处理相关程度(-0.935)高于D处理(-0.661);前期覆膜团棵揭膜方式下,移栽后42 d内化肥处理(E)土壤有效氮明显高于有机无机配施处理(F),烟株氮累积量和累积速率F处理均高于E处理;提前施肥起垄方式下,化肥处理(I)和有机无机配施处理(H)土壤有效氮变化基本一致且烟株氮累积量和累积速率H处理均高于I处理。不论何种施肥方式,移栽后前期化肥处理土壤有效氮含量明显高于有机无机配施处理,而烟株氮累积则相反,证明施用有机肥可以使烟株对氮素吸收累积高峰提前,且提高烟株氮累积量和氮累积速率。提前施肥可明显弱化不同肥料处理之间土壤有效氮的差异。 相似文献
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