Erträge und n‐bilanzen im IOSDV Madrid im laufe von vier rotationen     

Cristina López‐Fando  Maria Teresa Pardo Fernandez  Hans‐Richard Wegener 《Archives of Agronomy and Soil Science》2013,59(6):489-505

Im IOSDV Madrid wird seit 1984 die kombinierte Wirkung von Stallmist, Stroh, Zwischenfrucht und mineralischer N‐Düngung in der Fruchtfolge Sorghum‐Weizen‐Gerste auf einem semiariden Standort in der zentralspanischen Meseta auf einem Calcic Luvisol geprüft.

Die Ergebnisse zeigen, dass die Witterungsbedingungen die Erträge wesentlich stärker beeinflussen als die Behandlungsvarianten. Durch die sehr geringen Niederschläge während der dritten Rotation waren die Gersten‐ und Weizenerträge unabhängig von der Düngung sehr niedrig, während unter optimalen Niederschlagsbedingungen in der ersten und zweiten Rotation die Weizen‐ und Gerstenerträge mit steigender N‐Düngung zunahmen und ihr Optimum bei der Stickstoffdüngungsstufe N₃ aufwiesen; allerdings zeigte nur die Gerste eine Reaktion auf die gleichzeitige Anwendung organischer Dünger. Während der vierten Rotation wurden die Trockenmasse‐Erträge bei Weizen und Gerste durch organische Düngung bis zur Stufe N₂ erhöht, während höhere Mineral‐N‐Gaben die Erträge negativ beeinflussten. Bei Sorghum traten, bedingt durch die extremen Niederschlagsbedingungen, erhebliche Schwierigkeiten auf, die sich in einem sehr niedrigen Korn‐Stroh‐Verhältnis widerspiegelten und keinerlei signifikanten Zusammenhang zu den Behandlungsvarianten erkennen liessen.  相似文献   

Short-term effects of organic and inorganic fertilizers on soil microbial community structure and function   总被引：1，自引：0，他引：1  

Cristina Lazcano  María Gómez-Brandón  Pedro Revilla  Jorge Domínguez 《Biology and Fertility of Soils》2013,49(6):723-733

A field study was carried out to analyze the short-term impacts of replacing mineral by organic fertilizers on the microbial and biochemical parameters relevant for soil fertility and crop yield. Three types of fertilization regimes were compared: (1) conventional fertilizer regime with inorganic fertilizer, and combined integrated fertilizer regimes in which 25 % of the nutrients were supplied by either (2) rabbit manure or (3) vermicompost. The effects on microbial community structure and function (phospholipid fatty acid [PLFA] profiles, bacterial growth, fungal growth, basal respiration, β-glucosidase, protease and phosphomonoesterase activities), soil biochemical properties (total C, dissolved organic carbon [DOC], N-NH₄ ⁺, N-NO₃ ^?, PO₄, total K) and crop yield were investigated in the samples collected from the experimental soil at harvest, 3 months after addition of fertilizer. The integrated fertilizer regimes stimulated microbial growth, altered the structure of soil microbial community and increased enzyme activity relative to inorganic fertilization. Bacterial growth was particularly influenced by the type of fertilizer regime supplied, while fungal growth only responded to the amount of fertilizer provided. The use of manure produced a fast increase in the abundance of PLFA biomarkers for Gram-negative bacteria as compared to inorganic fertilizer. Nutrient supply and crop yield with organic fertilizers were maintained at similar levels to those obtained with inorganic fertilizer. The effects of the organic amendments were observed even when they involved a small portion of the total amount of nutrients supplied; thereby confirming that some of the beneficial effects of integrated fertilizer strategies may occur in the short term.  相似文献   

Nitrogen,Phosphorus, and Sulfur Nutrition in Broccoli Plants Grown Under Salinity     

Carmen López-Berenguer  Micaela Carvajal  Cristina Garcéa-Viguera  Carlos F. Alcaraz 《Journal of plant nutrition》2013,36(11):1855-1870

Broccoli (Brassica oleracea L. var. ‘Italica’) is a recognized health-promoting vegetable and shows a moderate sensitivity to salinity. As very little is known about the effect of salt stress on broccoli plants, the objective was to evaluate nitrogen (N), phosphorous (P), and sulfur (S) nutrition in plants grown under saline conditions. For this objective, the contents of nitrate, phosphate, and sulfate, and total nitrogen, phosphorus, and sulfur, as well as related metabolic enzymes, were determined for plants grown with 0, 20, 40, 60, 80, or 100 mM sodium chloride (NaCl) for two weeks. Nitrate, phosphate, and sulfate concentration in leaves and roots showed a maximum at 40–60 mM NaCl. Up to these salt levels, broccoli plants showed a normal development, but over these salt levels, broccoli plants showed a decrease of nitrate reductase and an increase of the acid phosphatase. From 60 to 100 mM NaCl, the nutritional disorders indicated that the threshold of resistance was exceeded.  相似文献   

A tree distance-dependent growth and yield model for naturally regenerated pure uneven-aged maritime pine stands in central inland of Portugal     

Cristina Alegria  Margarida Tomé 《Annals of Forest Science》2013,70(3):261-276

? Context

Maritime pine (Pinus pinaster Aiton) is one of the most important Portuguese species, growing in pure stands ranging from even-aged to multi-aged structures. Current growth and yield models were developed only for even-aged, managed stands and/or for very specific regions of Portugal.

? Aims

This paper focuses on the validation of the existing size-class model PBRAVO, adapted to even-aged stands, and on the subsequent development of a single tree distance-dependent growth and yield model (PBIRROL), both in distance-independent and distance-dependent versions, for uneven-aged stands.

? Methods

The new model is composed of four modules, each with a set of sub-models for: tree variable prediction, tree volume prediction, future tree list prediction and growth projection.

? Results

The evaluation of the PBRAVO and PBIRROL models showed that the new model gives more accurate predictions. Moreover, medium-term simulations provided consistent and logical predictions.

? Conclusion

It was verified that individual tree models are more suited to simulate poorly managed uneven-aged stands than diameter distribution models. No clear superiority of distance-dependent models was found over models using just distance-independent measures of inter-tree competition.  相似文献   

Increasing the use of expert opinion in forest characterisation approaches based on LiDAR data     

Cristina Pascual  Luis G. Garc��a-Montero  Lara A. Arroyo  Antonio Garc��a-Abril 《Annals of Forest Science》2013,70(1):87-99

Context

Forest structure characterisation approaches using LiDAR data and object-based image analysis remain scarce to forestry agencies as these automated procedures usually require the use of expensive software and highly skilled analysts. The integration of forest expert opinion into semi-automated approaches would simplify the access of forest managers to new technologies and would allow the incorporation of personal experience and the introduction of specific forest management criteria.

Aim

The aim of this study is to explore new alternatives to a previously published automated approach based on LiDAR data and object-based image analysis.

Methods

We compare four approaches, ranging from null to high incorporation of expert opinion and from fully automated to fully manual. These four approaches consist of three stages: (1) forest stand identification from LiDAR models, (2) forest stand classification into forest structure classes (manual and based on cluster analysis), and (3) validation.

Results

Quantitative attributes for validation (i.e. hypsographs and percentiles) provided slightly lower degree of separability for forest structure classes, in the mixed procedures with increasing incorporation of expert opinion than for the fully automated approach.

Conclusions

The new mixed approaches proposed are comparable to the automated procedures for the characterisation of forest structure in heterogeneous pine forest stands. They also offer additional advantages: (1) they make it possible to give a specific management focus and (2) they provide accessibility by the forest managers to the source of LiDAR information.  相似文献   

Geographic variability in response to azinphos‐methyl in field‐collected populations of Cydia pomonella (Lepidoptera: Tortricidae) from Argentina     

Jimena Soleño  Olga L Anguiano  Liliana B Cichón  Silvina A Garrido  Cristina M Montagna 《Pest management science》2012,68(11):1451-1457

BACKGROUND: Resistance to insecticides has been related to application history, genetic factors of the pest and the dynamic within the treated area. The aim of this study was to assess the geographic variation in azinphos‐methyl response and the role of esterase and cytochrome P450 monooxygenase enzymes in codling moth populations collected within different areas of the Río Negro and Neuquén Valley, Argentina. RESULTS: Diapausing field‐collected populations showed resistance ratios at the LC₅₀ that were 0.7–8.7 times higher than that of the susceptible strain. Mean esterase (EST) and cytochrome P450 monooxygenase activities (expressed as α‐N min^?1 mg^?1 prot^?1 and pg 7‐OHC insect^?1 min^?1 respectively) were significantly correlated with LD₅₀ values from the field‐collected populations. In addition, azinphos‐methyl response was associated with the geographic area where the insect population was collected: populations from isolated and more recent productive areas presented significantly lower resistance ratios in comparison with populations from older and more intensive productive areas. CONCLUSION: The populations assayed presented different resistance levels to azinphos‐methyl. The response was highly correlated with the orchard's geographic location. EST and ECOD activities were involved in azinphos‐methyl response in the given region. Copyright © 2012 Society of Chemical Industry  相似文献   

Mating disruption for the control of Aonidiella aurantii Maskell (Hemiptera: Diaspididae) may contribute to increased effectiveness of natural enemies     

Vacas S  Vanaclocha P  Alfaro C  Primo J  Verdú MJ  Urbaneja A  Navarro-Llopis V 《Pest management science》2012,68(1):142-148

BACKGROUND: New directives on sustainable use of pesticides have encouraged research on efficient alternative pest control methods. In the case of the California red scale (CRS), Aonidiella aurantii (Maskell), this imperative, along with the many difficulties in controlling this pest, have led to the investigation of new approaches. Previously developed mating disruption (MD) dispensers, together with the augmentative releases of the parasitoid Aphytis melinus DeBach, are here considered as a combined strategy for use against A. aurantii. RESULTS: Efficacy of MD was demonstrated by a mean reduction of 80% in CRS male catches and a mean fruit damage reduction of 83% compared with the control. A delay in the development of A. aurantii instars was observed in the MD plot. This delay increased the period of exposure of the susceptible instars to natural enemies, which resulted in higher predation and parasitism levels in the MD plot. Under laboratory conditions, A. melinus mating behaviour and effects on A. aurantii were not significantly altered in a CRS-pheromone-saturated environment. CONCLUSION: Mating disruption pheromone did not affect the behaviour or level of parasitism by A. melinus or the incidence of other generalist predators. Therefore, A. aurantii pheromone appears to be compatible with augmentative releases and biological control, making its use a good strategy for CRS management. Copyright © 2011 Society of Chemical Industry  相似文献   

Plant species richness and ecosystem multifunctionality in global drylands     

Maestre FT  Quero JL  Gotelli NJ  Escudero A  Ochoa V  Delgado-Baquerizo M  García-Gómez M  Bowker MA  Soliveres S  Escolar C  García-Palacios P  Berdugo M  Valencia E  Gozalo B  Gallardo A  Aguilera L  Arredondo T  Blones J  Boeken B  Bran D  Conceição AA  Cabrera O  Chaieb M  Derak M  Eldridge DJ  Espinosa CI  Florentino A  Gaitán J  Gatica MG  Ghiloufi W  Gómez-González S  Gutiérrez JR  Hernández RM  Huang X  Huber-Sannwald E  Jankju M  Miriti M  Monerris J  Mau RL  Morici E  Naseri K  Ospina A  Polo V  Prina A  Pucheta E 《Science (New York, N.Y.)》2012,335(6065):214-218

Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.  相似文献   

Fate-restricted neural progenitors in the mammalian cerebral cortex     

SJ Franco  C Gil-Sanz  I Martinez-Garay  A Espinosa  SR Harkins-Perry  C Ramos  U Müller 《Science (New York, N.Y.)》2012,337(6095):746-749

During development of the mammalian cerebral cortex, radial glial cells (RGCs) generate layer-specific subtypes of excitatory neurons in a defined temporal sequence, in which lower-layer neurons are formed before upper-layer neurons. It has been proposed that neuronal subtype fate is determined by birthdate through progressive restriction of the neurogenic potential of a common RGC progenitor. Here, we demonstrate that the murine cerebral cortex contains RGC sublineages with distinct fate potentials. Using in vivo genetic fate mapping and in vitro clonal analysis, we identified an RGC lineage that is intrinsically specified to generate only upper-layer neurons, independently of niche and birthdate. Because upper cortical layers were expanded during primate evolution, amplification of this RGC pool may have facilitated human brain evolution.  相似文献   

Yeast Flora in Oropharyngeal and Rectal Mucous Membranes of Healthy and Critically Ill Neonatal Foals     

Alessandro Pirrone  Carolina CastagnettiJole Mariella  DVM  PhD  Cristina BonoliLaura Stancampiano  DVM  Maria Paola TampieriRoberta Galuppi  DVM 《Journal of Equine Veterinary Science》2012

Little is known about the normal or pathologic yeast flora in healthy and critically ill neonatal foals. The aims of this study were to evaluate the yeast flora colonizing the mucous membranes of the digestive tract (oropharynx and rectum mucous membranes) of healthy and hospitalized foals and to find out risk factors involved in yeast colonization of foals referred to a neonatal intensive care unit. A total of 240 swabs were collected from 21 healthy (group A) and 39 sick (group B) foals. In 14 of the 60 foals, yeast was isolated in at least one sample (23.3%): 3 of the 21 foals (14.3%) were positive in group A and 11 of 39 foals (28.2%) were positive in group B. The yeasts were isolated from rectal swabs obtained from none in healthy foals, whereas 5 of the 39 sick foals were positive; however, this difference was not statistically significant. No significant difference was also detected regarding oropharyngeal swabs between healthy (3/21) and sick (10/39) foals. The risk factors significantly associated with the isolation of yeasts from rectal swabs were female sex, treatment with oral antibiotics, and stressful diagnostic–therapeutic procedures. The only risk factor significantly associated with the isolation of yeast from oropharyngeal swabs was the treatment with antacids and gastroprotectants. The results show that fungi present in the gastrointestinal tract of neonatal foals were mainly environmental yeasts and suggested the absence of a stable fungal colonization. Candida was the genus frequently isolated in hospitalized foals, just as it is isolated in critically ill human neonates.  相似文献