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21.
22.
A survey of Lolium rigidum populations in citrus orchards: Factors explaining infestation levels
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Valentina Atanackovic Alejandro Juárez‐Escario Jordi Recasens Joel Torra 《Weed Biology and Management》2015,15(3):122-131
The presence of herbicide‐resistant Lolium rigidum in Mediterranean (Spanish) citrus orchards was reported in 2005 and it poses a serious threat to crop management. The main objective of this research was to investigate which components could be responsible for the persistence of annual ryegrass populations in Mediterranean mandarin and orange orchards. This is the first study regarding L. rigidum populations in Mediterranean citrus orchards. Surveys were conducted in 55 commercial citrus orchards in eastern Spain in 2013 by interviewing technicians who were working in cooperatives about crop management. The level of infestation by L. rigidum and the presence of harvester ants (Messor barbarus) then were estimated in the same orchards. The variables were subjected to a two‐dimensional analysis and both univariate and multivariate logistic regression models were fitted for each of the three L. rigidum density levels that had been established. The multivariate models showed the significant factors that were associated with various L. rigidum densities: (i) at a low density, the herbicides that were applied, the number of applications in 2013 and the type of irrigation (flood or drip); (ii) at a medium density, the presence of harvester ants; and (iii) at a high density, the herbicides that were applied in 2013. The results indicated that drip irrigation and one application of glyphosate mixed with other herbicides (or herbicides other than glyphosate) were associated with a lower L. rigidum density. The alternative management options that are presented here should help farmers to reduce weed problems in Mediterranean citrus orchards. Future research is required to better understand the presence of herbicide‐resistant populations, as well as the possible beneficial presence of granivorous ant species. 相似文献
23.
Effect of salicylic acid treatment on tomato plant physiology and tolerance to potato virus X infection 总被引:1,自引:0,他引:1
Tania Falcioni Juan Pedro Ferrio Ana Isabel del Cueto Jordi Giné María Ángeles Achón Vicente Medina 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(2):331-345
Salicylic acid (SA) is an inducer of systemic acquired resistance (SAR) and could be a potential candidate in the control of plant virus diseases. In this study we assayed under controlled conditions the potential effect of three doses of exogenous SA treatment on tomato plants infected with Potato virus X (PVX) and measured their effects on: different physiological parameters (gas exchange, stable isotopes, chlorophyll content), the activation of secondary metabolism, viral accumulation and induction of the expression of pathogenesis-related proteins (PRs) such as ß-1, 3-glucanase (PR2) and chitinase (PR3). SA treatment increased the expression of PR2, the activity of phenylalanine ammonia lyase (PAL) and the concentration of antioxidant compounds at 7 days post-treatment. Earlier expression of PR3 compared to PR2 was observed. SA treatment delayed the detection of PVX by ELISA in uninoculated leaves of mechanically infected tomato plants. Although the effect of PVX infection on physiological parameters was weak, moderate SA treatments showed enhanced photosynthesis, particularly for infected plants. The results obtained confirm that SA promotes major changes in the induction of resistance in tomato plants and suggest that treatment with exogenous SA could be considered to reduce the infections caused by PVX. 相似文献
24.
Felicitat Todolí Laia Solano-Gallego Ana Ojeda Josefina Quintana Albert Lloret Xavier Roura Jordi Alberola Alhelí Rodríguez-Cortés 《Veterinary parasitology》2009
Recently, anti-Leishmania IgG has been detected in urine samples from Leishmania-infected dogs and its concentrations have been correlated with impairment of renal function. The presence and relationship with other anti-Leishmania Ig isotypes in urine have not yet been investigated. The current study analyzed the concentrations of anti-Leishmania IgA and IgG in sera (Ig-S) and urine (Ig-U) samples by ELISA in 64 untreated dogs with clinical leishmaniasis. All 64 serum samples tested were positive for anti-Leishmania IgG. Fifty of them (78.1%) were also positive for anti-Leishmania IgA. The results showed the presence of anti-Leishmania IgA-U in 38% of the 50 dogs that were positive for specific IgA-S. Thirty-eight of the 64 dogs positive for Leishmania-specific IgG-S (59.4%) were also positive for Leishmania-specific IgG in urine (IgG-U). The concentrations of anti-Leishmania IgA-U were significantly correlated with urine protein/creatinine (uP/C) ratio (ρ = 0.542; P < 0.001) and with serum biochemical parameters, such as γ-globulins, urea and creatinine. Goldmann–Witmer coefficient (C value) indicated that detection of specific IgA in urine samples from dogs with leishmaniasis might not only be due to impairment of filtration of the glomerular barrier but also be due to local production of this isotype, which might reflect a local immunological response to the presence of the parasite in the genitourinary tract. Anti-Leishmania IgG-U concentrations were highly correlated with uP/C ratio (ρ = 0.779; P < 0.001) and C value did not support in any case local production of this isotype. IgG isotype might be a more suitable and specific tool to evaluate renal damage due to the lower IgA-U sensitivity and correlation coefficients and evidence of IgA local production. However, dogs found positive for both Ig isotypes in urine presented significantly higher specific IgG-U concentrations and higher uP/C ratios than dogs found positive only for IgG-U, thus suggesting that the first group suffered more severe renal damage. This fact makes it necessary to evaluate the prognosis of dogs showing both anti-Leishmania IgA-U and IgG-U in future studies. 相似文献
25.
Casas M Pujols J Rosell R de Deus N Peralta B Pina S Casal J Martín M 《Veterinary microbiology》2009,135(3-4):248-252
The objective of the present work was to ascertain the date in which hepatitis E virus (HEV) was introduced in the Spanish pig population. For this, a serological retrospective study was carried out using archived sera. A total of 2871 serum samples gathered between 1985 and 1997 and collected in 208 farms of Spain were tested for anti-HEV IgG by an in-house ELISA. Of the 2871 sera analyzed by ELISA, 1390 were positive for anti-HEV antibodies (48.4%, 95% CI: 46.9-49.9%) and that corresponded to 204/208 farms (98%, 95% CI: 96.1-99.9%) having at least one positive pig. Our results show that HEV was present and widespread in Spanish swine farms at least since 1985. Any significant changes in prevalence were detected from 1 year to another and therefore, HEV infection in swine should be considered endemic in Spain. 相似文献
26.
Soledad Martos Anna Andolfi Jordi Luque Laura Mugnai Giuseppe Surico Antonio Evidente 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(4):451-461
In recent years an increasing number of species of Botryosphaeriaceae have been associated with grapevine decline worldwide.
Five species isolated from declining grapevines in Spain (Botryosphaeria dothidea, Diplodia seriata, Dothiorella viticola, Neofusicoccum luteum and N. parvum) were checked for toxin production in liquid cultures. Cultural conditions for all fungi were adjusted to obtain optimal
production of phytotoxic culture filtrates, by growing the fungi in steady liquid cultures of Czapek–Dox broth for different
time intervals. Phytotoxicity of D. seriata and N. parvum reached a maximum after 14 days while the remaining species showed the highest phytotoxicity levels after 21 days in culture.
All fungi produced hydrophilic high-molecular weight compounds with phytotoxic properties. In addition, N. luteum and N. parvum produced lipophilic low-molecular weight phytotoxins, not detected consistently among the remaining species. This led to
a more exhaustive study on the phytotoxicity of N. luteum and N. parvum. Culture filtrates and corresponding extracts of both species were consistently highly phytotoxic in different assays. The
gas-chromatography analysis of the acetylated O-methyl glycosides of the phytotoxic exopolysaccharides produced by N. parvum showed these substances to be composed mainly of glucose, mannose and galactose. Results suggest that phytotoxic metabolites
could be involved in the virulence of both species in planta. 相似文献
27.
Zineb Choury Tatiana A. Shestakova Hocine Himrane Ramzi Touchan Dalila Kherchouche J. Julio Camarero Jordi Voltas 《European Journal of Forest Research》2017,136(1):139-152
The Algerian Green Barrier, mainly composed of native and artificial Aleppo pine forests, spreads along the pre-Saharan steppes and is threatened by anthropogenic and natural disturbances, including climate change. We hypothesized that the ecophysiological functioning of this conifer has been substantially modified in reaction to recent warming and drought much beyond the expected effect of CO2 fertilization. Our aim was to characterize the long-term performance (1925–2013) of native Aleppo pines thriving at their southernmost distribution. We used tree-ring width (TRW) and carbon isotope discrimination (Δ13C) to characterize basal area increment (BAI) and intrinsic water-use efficiency (WUEi) at three sites. BAI remained stable or slightly increased over time, with mean values ranging between 4.0 and 6.3 cm2 year?1. Conversely, site-Δ13C decreased from ?0.022 to ?0.014‰ year?1 along time, which translated into WUEi increases of ca. 39%. This strong physiological reaction indicated that pines were responding simultaneously to rising CO2 and drier conditions, inducing a progressively tighter stomatal control of water losses. However, WUEi increments were essentially unrelated to BAI and did not affect carbon reserves, which suggests a high resilience to climate change. This finding could be due to shifts in growing season towards earlier months in winter–spring, as suggested by temporal changes in climate factors underlying Δ13C and TRW. Our study highlights the substantial plasticity of Aleppo pine, but this species is unlikely to follow a similar pace of ecophysiological adjustments according to unprecedented low Δ13C records and lack of WUEi stimulation observed from 2000 onwards. 相似文献
28.
Esther Sanyé-Mengual Isabelle Anguelovski Jordi Oliver-Solà Juan Ignacio Montero Joan Rieradevall 《Agriculture and Human Values》2016,33(1):101-120
Urban agriculture (UA) is spreading within the Global North, largely for food production, ranging from household individual gardens to community gardens that boost neighborhood regeneration. Additionally, UA is also being integrated into buildings, such as urban rooftop farming (URF). Some URF experiences succeed in North America both as private and community initiatives. To date, little attention has been paid to how stakeholders perceive UA and URF in the Mediterranean or to the role of food production in these initiatives. This study examines the promotion and inclusion of new forms of UA through the practice of URF and contributes to the nascent literature on the stakeholder and public perceptions of UA. It seeks to understand how those perceptions shape the development of new urban agriculture practices and projects. Barcelona (Spain) was used as a Mediterranean case study where UA and URF projects are growing in popularity. Through semi-structured interviews with 25 core stakeholders, we show that UA is largely perceived as a social activity rather than a food production initiative, because the planning of urban gardens in Barcelona was traditionally done to achieve leisure and other social goals. However, several stakeholders highlighted the potential to increase urban fertility through URF by occupying currently unused spaces. As a result, the positive valuation of URF depends on the conceptualization of UA as a social or food production activity. In turn, such conceptualization shapes barriers and opportunities for the development of URF. While most UA-related stakeholders (e.g., food co-ops, NGOs) preferred soil-based UA, newer stakeholders (e.g., architects) highlighted the economic, social and environmental opportunities of local and efficient food production through innovative URF. 相似文献
29.
Apple (Malus × domestica Borkh.) fruit intended for long-term storage are frequently harvested commercially before becoming fully ripe, often resulting in poor aroma development. Since postharvest calcium dips have proved effective for the enhancement of flavor-related volatile esters after cold storage of apples, this study was undertaken in order to assess whether preharvest calcium sprays (7 weekly applications at 1.6%, w/v, 81-123 days after full bloom) could also aid in improving this important attribute at harvest. This procedure significantly increased calcium content in treated fruit. The emission of aroma-related volatile esters by untreated and calcium-treated 'Fuji' apples was then monitored during maturation and ripening over two months prior to commercial harvest. Results indicate that most of the compounds contributing to overall flavor in ripe fruit were enhanced in response to preharvest calcium applications, suggesting that this procedure may be suitable for the improvement of fruit aroma at harvest. The emission of acetate esters was particularly favored, consistent with higher acetaldehyde contents in treated fruit. These effects arose apparently from increased pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities, possibly leading to a better supply of alcohols and acyl CoAs for ester biosynthesis. 相似文献
30.