Monitoring of soil organic carbon over 10 years in a Mediterranean silvo-pastoral system: potential evaluation for differential management     

J.?M.?SerranoEmail author  S.?Shahidian  J.?Marques?da?Silva  M.?Carvalho 《Precision Agriculture》2016,17(3):274-295

Soil organic carbon (SOC) plays a vital role in determining the susceptibility to land degradation. The recommended procedure for the recovery of the characteristic poor soils of the Southern region of Portugal is the installation of grazed permanent pastures and increase of soil fertility. The objectives of this study were: (i) to identify the spatial and temporal patterns of soil nutrients at four points in time over a 10-year period in a perennial pastureland; (ii) to test new tools for survey of the spatial variability of soil nutrients; (iii) to evaluate the potential for differential organic management. A 6 ha permanent bio-diverse pasture field, grazed by sheep and improved by annual application of super phosphate fertilizer, was installed on a shallow soil in Mediterranean conditions. Spatial variability and temporal stability of topsoil macronutrients (phosphorus, nitrogen and potassium), SOC and pH were measured. The results indicate that SOC and pH have great potential for implementing differential management. In the case of SOC, the management classes map shows that over 80 % of the area has temporal stability, while more than 50 % of the area has low levels of SOC (<10 g kg^?1), justifying the potential for differential application of C-rich organic soil amendments. The geospatial measurements of apparent soil electrical conductivity (EC_a) and NDVI index showed significant correlation between these parameters and soil properties, revealing the potential of these tools for producing detailed soil maps, decisive for understanding the changes in soil properties under sustainable management systems.  相似文献   

Novel application of square-wave adsorptive-stripping voltammetry for the determination of xanthohumol in spent hops     

Moreira MM  Carvalho AM  Valente IM  Goncalves LM  Rodrigues JA  Barros AA  Guido LF 《Journal of agricultural and food chemistry》2011,59(14):7654-7658

This paper reports the development of a novel electrochemical assay for xanthohumol (XN) by square-wave adsorptive-stripping voltammetry (SWAdSV) with a hanging mercury drop electrode. The method showed good repeatability (CV < 2%) and linearity (between 10 and 250 μg L(-1)), as well as suitable limits of detection (2.6 μg L(-1)) and quantification (8.8 μg L(-1)). The method was applied for the quantification of this compound in spent hops, and the results obtained were compared with the HPLC-UV method. XN contents determined by the SWAdSV method were 16 ± 1 and 100 ± 4 μg L(-1) for aqueous and methanolic extracts, respectively. The developed new methodology considerably reduces the analysis time, approximately from 25 min (HPLC-UV method) to 7 min, enabling a high sample throughput. In addition, the detection and quantification limits were approximately 5-fold lower than those obtained with the chromatographic method.  相似文献   

Soybean cultivar performance in the presence of soybean Asian rust,in relation to chemical control programs     

Junia Vianna Corrêa da Silva  Fernando César Juliatti  João Renato Vaz da Silva  Fernanda Carvalho Barros 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(3):409-418

Soybean rust is caused by an obligate parasite (Phakopsora pachyrhizi) which has spread in Brazil in each new season since 2001 and, despite the efforts to control the disease, losses have occurred every year. Its control demands several tactics amongst which chemical control with fungicides is the main method and remains indispensable. Control strategies such as the use of cultivars with partial resistance are desirable, but are not yet commercially available. The present study analyzed the existing differences in the reactions of short, medium and long cycle soybean cultivars against Asian rust and their responses to fungicide sprays. The experiment was conducted at Uberlandia-MG, Brazil, under field conditions from December 2007 to May 2008, in the Syngenta Seeds Experimental Station. The high pressure of the disease in the experiment simulated the natural pressure that the disease often reaches in Brazil. The studied variables were: visual severity (percentage of infected leaf area), percentage defoliation and productivity (kg ha⁻¹). Disease severity was expressed as AUDPC (area under disease progress curve). Variance analysis and comparison of means by the Tukey test (5% significance) were done for all variables studied. Significant differences were observed between cultivar effects and chemical control programs. The results obtained here indicate that the cultivars M-Soy 8199RR and Emgopa 315RR were less susceptible to disease, and that a control program termed “monitoring” (in which the appearance of new pustules of the pathogen were monitored to make the decision at each fungicide spray) was the most effective.  相似文献   

Convergence of developmental mutants into a single tomato model system: 'Micro-Tom' as an effective toolkit for plant development research     

Carvalho RF  Campos ML  Pino LE  Crestana SL  Zsögön A  Lima JE  Benedito VA  Peres LE 《Plant methods》2011,7(1):18-14

Background

The tomato (Solanum lycopersicum L.) plant is both an economically important food crop and an ideal dicot model to investigate various physiological phenomena not possible in Arabidopsis thaliana. Due to the great diversity of tomato cultivars used by the research community, it is often difficult to reliably compare phenotypes. The lack of tomato developmental mutants in a single genetic background prevents the stacking of mutations to facilitate analysis of double and multiple mutants, often required for elucidating developmental pathways.

Results

We took advantage of the small size and rapid life cycle of the tomato cultivar Micro-Tom (MT) to create near-isogenic lines (NILs) by introgressing a suite of hormonal and photomorphogenetic mutations (altered sensitivity or endogenous levels of auxin, ethylene, abscisic acid, gibberellin, brassinosteroid, and light response) into this genetic background. To demonstrate the usefulness of this collection, we compared developmental traits between the produced NILs. All expected mutant phenotypes were expressed in the NILs. We also created NILs harboring the wild type alleles for dwarf, self-pruning and uniform fruit, which are mutations characteristic of MT. This amplified both the applications of the mutant collection presented here and of MT as a genetic model system.

Conclusions

The community resource presented here is a useful toolkit for plant research, particularly for future studies in plant development, which will require the simultaneous observation of the effect of various hormones, signaling pathways and crosstalk.  相似文献   

Arsenic Contamination and Dispersion in the Engenho Inlet,Sepetiba Bay,SE, Brazil     

Magalhães  V. F.  Carvalho  C. E. V.  Pfeiffer  W. C. 《Water, air, and soil pollution》2001,129(1-4):83-90

Arsenic distribution and dispersion in sediments of the EngenhoInlet and the Sepetiba Bay were investigated in order to evaluate the extent of the contamination caused by a metallurgical plant installed in the Sepetiba Bay watershed. The ore used in the smelting process, the soil around the plant, and ore waste collected inside the plant were also analyzed for As. Very high As concentrations in the stronglyand weakly bound fractions (up to 63 000 and 52 700 μgg^-1, respectively) were found in the ore waste. The soilsalso contained high concentrations of both the strongly andweakly bound fractions (748 and 636 μg g^-1, repectively), although the ore itself contained lower levelsof the two fractions (63 and 13 μg g^-1, respectively).The sediments of the Engenho Inlet had a high degree of contamination (up to 347 μg g^-1) decreasing toward Sepetiba Bay where the lowest concentrations were found (up to 50 μg g^-1). Altough lower concentrations were found in the Sepetiba Bay sediments, they are 5 times higher than the world average. The results showed that there is an As transport from the Engenho Inlet to the Sepetiba Bay. These results suggests that the bay's fish and mollusk stock my be contaminated. This contamination may adversely affect the health of the local population, whose main protein supply is seafood.  相似文献   

Heavy metal contamination of the marine biota along the Rio de Janeiro coast,SE-Brazil     

Carvalho  C. E. V.  Lacerda  L. D.  Gomes  M. P. 《Water, air, and soil pollution》1991,(1):645-653

A survey is presented on the heavy metal contamination of benthic organisms of the Rio de Janeiro coast, SE Brazil. Metal concentrations were different depending on major pollution sources, element, and species analyzed. The highest concentrations of Zn and Cd occurred in moderately industrialized Sepetiba Bay, while Cu presented its highest content in areas receiving urban wastes. The metals Pb, Ni and Mn did not show any difference among areas. The highest concentration of metals, regardeless of site, occurred in barnacles and oysters, due to the high filtering capacity of these organisms, while the lowest concentrations of all metals occurred in algae species.  相似文献   

Virulence factors in Escherichia coli strains isolated from pigs in the Ribeirao Preto region, State of Sao Paulo, Brazil.     

A C Carvalho  F A Avila  R P Schocken-Iturrino  J L Quintana  P E Albertini 《Revue d'élevage et de médecine vétérinaire des pays tropicaux》1991,44(1):49-52

Three-hundred faecal swabs were obtained from pigs with diarrhoea in farms located in different areas of the Ribeirao Preto region in the State of Sao Paulo. One-hundred Escherichia coli strains were isolated and tested for production of thermolabile (TL) and thermostable (STRa and STb) enterotoxins, and for the presence of colonization factors F4, F5 and F6. The strains were also tested for sensitivity to 14 antibiotics and chemotherapeutic agents. Twenty-four Escherichia coli strains produced enterotoxin STb, 5 produced LT and 3 produced STa. In the mannose-resistant haemagglutination reaction, one strain reacted positively with sheep, chicken, horse and human red blood cells and another reacted positively with guinea pig, sheep, chicken, horse and human red cells. However, both strains were negative for colonization factors F4, F5 and F6 when submitted to the slide agglutination test. All Escherichia coli strains were resistant to at least one antibiotic, the highest percentages being obtained for resistance to penicillin, tetracycline and cephalotin. In addition to the importance of the virulence factors normally encountered in enterotoxigenic Escherichia coli strains from pigs, the present results show the possible existence of new colonization factors other than F4, F5 and F6 participating in E. coli-induced pigs colibacillosis in the Ribeirao Preto region.  相似文献   

Influence of Water Stress on the Chemical Composition of Seeds of Two Lupins (Lupinus albus and Lupinus mutabilis)     

I. S. Carvalho  M. Chaves  C. Pinto Ricardo 《Journal of Agronomy and Crop Science》2005,191(2):95-98

We have performed chemical proximate analysis and determined the carbohydrate profile of mature seeds of Lupinus albus, cv. Rio Maior and Lupinus mutabilis, cv. Potosi plants, either well watered (ww) or subjected to a water-stress period (imposed from the 15th to 35th day after anthesis). Protein content from lupin seeds was 450 and 320 g kg⁻¹ of seed on dry weight basis, for ww plants, respectively, of L. albus and L. mutabilis. Water stress did not affect protein content. The oil content of ww plants was about 120 g kg⁻¹ of seed dry weight for L. albus and 180 g kg⁻¹ of seed dry weight for L. mutabilis. Water stress reduced those values of half. The sugar content was about 90 g kg⁻¹ for L. albus and 50 g kg⁻¹ of seed dry weight for L. mutabilis, in ww plants. Water stress led to an increase in sugar content to 200 and 130 g kg⁻¹ of seed dry weight, respectively, for L. albus and L. mutabilis. The α-galactosides amounted to 70 % of the total sugars (raffinose being 30 % and stachyose, 40 %) and sucrose was about 20 % of the total sugars. Water stress increased total carbohydrates and increased the sucrose/α-galactoside ratio, although reducing raffinose content and increasing sucrose content.  相似文献   

Efficacy of topically applied ivermectin against Boophilus microplus (Canestrini, 1887) in cattle     

L G Cramer  L A Carvalho  A A Bridi  N K Amaral  R A Barrick 《Veterinary parasitology》1988,29(4):341-349

Systemic efficacy of ivermectin applied topically was evaluated against the cattle tick, Boophilus microplus. Twenty cattle with induced infestations were randomly allocated to five groups of equal size based on the numbers of engorged female ticks which fell through the slatted floor of individual pens during the 3 days prior to treatments. Control cattle were non-medicated. Cattle in three groups were given ivermectin at 200, 500 or 1000 mcg kg-1 in a topical formulation applied along the backline from the withers to the rump; cattle in the fifth group were given ivermectin in an injectable formulation subcutaneously at 200 mcg kg-1. Individual 24-h tick collections were made three times weekly for 5 weeks after treatment. Engorged female B. microplus were incubated to determine effects on reproduction. Based on the numbers of engorged female B. microplus collected following treatments, overall efficacy of ivermectin applied topically at 200, 500 and 1000 mcg kg-1 was 50, 85 and 91%, respectively, whereas ivermectin given at 200 mcg kg-1 subcutaneously was 80% effective. The index of reproduction for ivermectin given topically was reduced by 84, 94 and 95%, respectively, and that for ivermectin subcutaneously was 94%. No significant differences (P greater than 0.05) were found for these variables between ivermectin given topically at 500 or 1000 mcg kg-1 versus 200 mcg kg-1 given subcutaneously.  相似文献   

Seasonal reproduction in the mare: possible role of plasma leptin, body weight and immune status   总被引：1，自引：0，他引：1  

Ferreira-Dias G  Claudino F  Carvalho H  Agrícola R  Alpoim-Moreira J  Robalo Silva J 《Domestic animal endocrinology》2005,29(1):203-213

The primary objective of this study was to evaluate the possible role of leptin, body weight and immune status on reproductive activity throughout the transition period from cyclicity to seasonal anestrus, during anestrus and resumption of ovarian activity in Lusitano mares. Mares in good body condition were monthly monitored throughout 2 years (10 mares in each year) for evaluation of their reproductive status by sequential ultrasonography and plasma progesterone determinations. On the second year, all mares were weighed. Progesterone and leptin were assayed by radioimmunoassay (RIA). Parameters of the immune status (phagocytosis and oxidative burst of neutrophils, characterisation of circulating lymphocyte subsets) were also evaluated. Phagocytosis and oxidative burst in blood neutrophils were measured by flow cytometry using commercially available kits. Lymphocyte subsets were assessed by indirect immunofluorescence staining after incubation with monoclonal antibodies specific for CD2, CD19, CD4, CD8 cells markers by flow cytometry. Natural killer cells and B cells were estimated mathematically. No significant difference was found in phagocytosis, oxidative burst and circulating lymphocyte subsets at anestrus and at either phase of the estrous cycle (p>0.05), suggesting that the immune status of the mare was not influenced by the seasonal changes in ovarian activity. This study also suggests that body weight has a direct relationship with plasma leptin levels. Increased concentrations of this hormone in circulation might be associated with the restart or maintenance of ovarian cyclicity in Lusitano mares.  相似文献