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991.
Chemical and biological indicators of soil quality in organic and conventional farming systems in Central Italy 总被引:5,自引:0,他引:5
Sara Marinari Roberto Mancinelli Enio Campiglia Stefano Grego 《Ecological Indicators》2006,6(4):701-711
In the past decade, there has been increased scientific interest in the so-called organic farming, especially in comparison with conventional agriculture. Many recent studies compare these two fundamentally different systems for soil properties, in different regions of the world. In this study, two adjacent fields in Central Italy, one managed according to organic, and the other according to conventional farming methods, were studied to determine the effects of these two agricultural systems on soil quality indicators at the farm level. Chemical and microbiological properties were chosen as indicators of soil quality and were measured at soil depth intervals of 5–20 and 20–35 cm, after 7 years of organic certified and conventional management methods. The field under organic management showed significantly better soil nutritional and microbiological conditions; with increased level of total nitrogen, nitrate and available phosphorus, and an increased microbial biomass content, and enzymatic activities (acid phosphatase, protease and dehydrogenase). No consistent increase in total organic carbon was observed. Results of the study suggest that, over the period of 7 year, organic management method strongly affects soil quality indicators. Large differences between the two soils were found in terms of microbiological properties, which are sensitive soil indicators of changes occurred under the different farming systems. 相似文献
992.
酿酒葡萄品质评价及其对气象条件的响应 总被引:26,自引:0,他引:26
根据2004~2005年我国北方6省酿酒葡萄主要产区葡萄取样和宁夏芦花台园艺场田间试验葡萄化验结果,运用层次分析方法(AHP)对酿酒葡萄主要品质因子总糖、糖酸比pH、单宁进行综合评价,运用主成分分析方法和因子分析法研究影响每个地区酿酒葡萄综合品质的主要气象因子和影响时段。结果表明:2004~2005年贺兰山东麓的御马、玉泉营、广夏三基地、贺东在庄园;河西走廊的高台、武威;新疆石河子酿酒葡萄品质优良,渤海湾的烟台、蓬莱、昌藜等地酿酒葡萄品质表现一般。酿酒葡萄综合品质主要受果实着色期、全生育期和7~8月的降水量和水热系数的影响,其中降水量起主导作用。果实着色期气温日较差和全生育期平均相对湿度对酿酒葡萄综合品质的形成也有重要影响,影响相对较小的是果实着色期的最低气温。采样地区的光照、温度等气象条件基本适宜酿酒葡萄品质形成,对优质酿酒葡萄形成没有大的限制作用。 相似文献
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995.
1. We examined the role of flooding on the leaf nutrient content of riparian trees by comparing the carbon : nitrogen : phosphorus (C : N : P) ratio of leaves and litter of Rio Grande cottonwood (Populus deltoides ssp. wislizenii) in flood and non‐flood sites along the Middle Rio Grande, NM, U.S.A. The leaf C : N : P ratio was also examined for two non‐native trees, saltcedar (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia), and six species of dominant riparian arthropods. 2. Living leaves and leaf litter of cottonwoods at flood sites had a significantly lower leaf N : P ratio and higher %P compared with leaves and litter at non‐flood sites. A non‐flood site downstream from wastewater effluent had a significantly lower litter C : N ratio than all other sites, suggesting N fertilisation through ground water. The non‐native trees, saltcedar and Russian olive, had higher mean leaf N content, N : P ratio, and lower C : N ratio compared with cottonwoods across study sites. 3. Riparian arthropods ranged from 5.2 to 7.1 for C : N ratio, 56–216 for C : P ratio, and 8.9–34 for N : P ratio. C content ranged from 25 to 52% of dry mass, N content from 4.7 to 10.8%, and P content from 0.59 to 1.2%. Differences in stoichiometry between high C : nutrient leaf litter and low C : nutrient invertebrates suggests possible food‐quality constraints for detritivores. 4. These results suggest that spatial and temporal variation in the C : N : P ratio of cottonwood leaves and leaf litter is influenced by surface and subsurface hydrologic connection within the floodplain. Reach‐scale variation in the elemental composition of riparian organic matter inputs may have important implications for decomposition, nutrient cycling, and food webs in river floodplain systems. 相似文献
996.
997.
H G Wiener P Klinkhamer U Schenck M Arbyn J Bulten C Bergeron A Herbert 《Cytopathology》2007,18(2):67-78
The quality of a cervical cytology laboratory depends on adequate handling and staining of the samples, screening and interpretation of the slides and reporting of the results. These guidelines give an overview of procedures recommended in Europe to manage the balance between best patient care possible, laboratory quality assurance and cost effectiveness and will be published as a chapter 4 in the European Guidelines for Quality Assurance in Cervical Cancer Screening. The laboratory guidelines include protocols for personnel and organisation, material requirements, handling and analysing cervical samples, recording of results, quality management and communication. The section on quality management is comprehensive and includes protocols for all aspects of internal and external quality assurance. The guidelines are extensively referenced and as far as possible the recommendations are evidence-based. 相似文献
998.
A. Herbert C. Bergeron H. Wiener U. Schenck P. Klinkhamer J. Bulten M. Arbyn 《Cytopathology》2007,18(4):213-219
There are many different systems of cytology classification used in the member states of the European Union (EU) and many different languages. The following short annexe to Chapter 3 of the European Guidelines for Quality Assurance in Cervical Cancer Screening provides a framework that will allow different terminologies and languages to be translated into standard terminology based on the Bethesda system (TBS) for cytology while retaining the cervical intraepithelial neoplasia (CIN) classification for histology. This approach has followed extensive consultation with representatives of many countries and professional groups as well as a discussion forum published in Cytopathology (2005;16:113). This article will describe the reporting of specimen adequacy, which is dealt with in more detail elsewhere in Chapter 3 of the guidelines, the optional general categorization recommended in TBS, the interpretation/cytology result and other comments that may be made on reports such as concurrent human papillomavirus testing and the use of automation review and recommendations for management. The main categories in TBS will be described in the context of CIN, dyskaryosis and dysplasia terminologies so that all may be translated into the same framework. These guidelines should allow European countries to adapt their terminology in such a way as to make their screening programmes comparable with each other as well as with programmes elsewhere in the world. 相似文献
999.
Assessment of patch quality by ladybirds: role of larval tracks 总被引:7,自引:0,他引:7
Gravid females of the two-spot ladybird, Adalia bipunctata (L.), were deterred from ovipositing when kept in petri dishes that had previously contained conspecific larvae but not conspecific
adults, or the larvae of another two species of ladybird, Adalia decempunctata (L.) and Coccinella septempunctata L. The deterrent effect was density dependent and mediated via a chloroform-soluble contact pheromone present in the larval
tracks. Similarly, gravid females of C. septempunctata were deterred from ovipositing by conspecific larval tracks and chloroform extracts of these tracks, but not by the tracks
or extracts of tracks of A. bipunctata larvae. That is, in ladybirds the larvae produce a species-specific oviposition-deterring pheromone. In the field, the incidence
of egg cannibalism in ladybirds increases very rapidly with the density of conspecific eggs or larvae per unit area. Thus,
in responding to the species specific oviposition deterring pheromone female ladybirds reduce the risk of their eggs being
eaten and spread their offspring more equally between patches.
Received: 14 March 1997 / Accepted: 26 August 1997 相似文献
1000.
Seston quality controls zebra mussel (Dreissena polymorpha ) energetics in turbid rivers 总被引:3,自引:1,他引:2
Daniel W. Schneider Sharook P. Madon James A. Stoeckel Richard E. Sparks 《Oecologia》1998,117(3):331-341
Feeding processes and energetic balance of zebra mussels were both related to the quantity and quality of natural seston.
Filtration rate and pseudofeces production increased while clearance rate remained constant with increasing seston concentration.
Ingestion rate, assimilation efficiency, and assimilation rate all increased with increasing food quality, measured as the
ratio of organic to inorganic material in the seston. Respiration rate did not change with either food quantity or quality.
As a result, scope for growth declined with decreasing food quality, and fell below 0 cal mg−1 h−1 at an organic:inorganic ratio of 0.5. The association between feeding processes and food quality appears related to a breakdown
in the ability of zebra mussels to selectively ingest high-quality organic particles when the organic content of the seston
is low. Ingestion, assimilation efficiency, assimilation rate and scope for growth were all higher when seston was amended
with an addition of a natural assemblage of algae. Food quality may be a better indicator of environmental conditions suitable
for growth than food quantity. These results suggest that the conditions of high suspended inorganic sediment concentrations
in large turbid rivers represent a difficult growth environment for the zebra mussel.
Received: 12 May 1997 / Accepted: 7 July 1998 相似文献