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Sativa
Kinds of Sativa Terms modified by Sativa Selected AbstractsCURRENT-STATUS SURVIVAL ANALYSIS METHODOLOGY APPLIED TO ESTIMATING SENSORY SHELF LIFE OF READY-TO-EAT LETTUCE (LACTUCA SATIVA)JOURNAL OF SENSORY STUDIES, Issue 2 2008MABEL ARANEDA ABSTRACT The objective of the present work was to develop a method for predicting sensory shelf life for situations in which each consumer evaluates only one sample corresponding to one storage time. This type of data is known as current-status data in survival analysis statistics. The methodology was applied to estimate the sensory shelf life of ready-to-eat lettuce (Lactuca sativa var. capitata cv."Alpha"). For each of six storage times, 50,52 consumers answered yes or no to whether they would normally consume the presented sample. The results were satisfactory, showing that the methodology can be applied when necessary. The Weibull model was found adequate to model the data. Estimated shelf lives ± 95% confidence intervals were 11.3 ± 1.2 days and 15.5 ± 0.9 days for a 25% and a 50% consumer rejection probability, respectively. PRACTICAL APPLICATIONS When considering shelf-life evaluations by consumers, the first idea is to have each consumer evaluate six or seven samples with different storage times in a single session. To do this, a reverse storage design is necessary, and in the case of a product such as lettuce, it would lead to different batches being confused with storage times. The methodology proposed in this article avoids this problem by having each consumer evaluate a single sample. Another issue with consumers tasting several samples in a single session is how representative this situation is of real consumption. The present methodology allows for a consumer to take home, e.g., a bottle of beer with an established storage time, and later collecting the information as to whether they found the beer acceptable or not. This is a situation much closer to real consumption. [source] The significance of a facultative bacterium to natural populations of the pea aphid Acyrthosiphon pisumECOLOGICAL ENTOMOLOGY, Issue 2 2003A. C. Darby Abstract. 1., Laboratory studies have implicated various accessory bacteria of aphids as important determinants of aphid performance, especially on certain plant species and under certain thermal regimes. One of these accessory bacteria is PABS (also known as T-type), which is distributed widely but is not universal in natural populations of the pea aphid Acyrthosiphon pisum in the U.K. 2., To explore the impact of PABS on the performance of A. pisum , the nymphal development time and fecundity of aphids collected directly from natural populations and caged on the host plant Vicia faba in the field were quantified. Over 4 consecutive months June,September 1999, the performance of PABS-positive and PABS-negative aphids did not differ significantly. 3., Deterministic modelling of the performance data showed that the variation in simulated population increase of PABS-positive and PABS-negative aphids would overlap substantially. 4., Analysis of aphids colonising five host plants ( Lathyrus odoratus , Medicago sativa , Pisum sativum , Trifolium pratense , Vicia faba ) between April and September 2000 and 2001, identified no robust differences between the distribution of PABS-positive and PABS-negative aphids on different plants and with season or temperature. 5., It is concluded that PABS is not an important factor shaping the performance or plant range of A. pisum under the field conditions tested. Reasons for the discrepancies between this study and laboratory-based studies are considered. [source] Biodiversity and biocontrol: emergent impacts of a multi-enemy assemblage on pest suppression and crop yield in an agroecosystemECOLOGY LETTERS, Issue 9 2003Bradley J. Cardinale Abstract The suppression of agricultural pests has often been proposed as an important service of natural enemy diversity, but few experiments have tested this assertion. In this study we present empirical evidence that increasing the richness of a particular guild of natural enemies can reduce the density of a widespread group of herbivorous pests and, in turn, increase the yield of an economically important crop. We performed an experiment in large field enclosures where we manipulated the presence/absence of three of the most important natural enemies (the coccinellid beetle Harmonia axyridis, the damsel bug Nabis sp., and the parasitic wasp Aphidius ervi) of pea aphids (Acyrthosiphon pisum) that feed on alfalfa (Medicago sativa). When all three enemy species were together, the population density of the pea aphid was suppressed more than could be predicted from the summed impact of each enemy species alone. As crop yield was negatively related to pea aphid density, there was a concomitant non-additive increase in the production of alfalfa in enclosures containing the more diverse enemy guild. This trophic cascade appeared to be influenced by an indirect interaction involving a second herbivore inhabiting the system , the cowpea aphid, Aphis craccivora. Data suggest that high relative densities of cowpea aphids inhibited parasitism of pea aphids by the specialist parasitoid, A. ervi. Therefore, when natural enemies were together and densities of cowpea aphids were reduced by generalist predators, parasitism of pea aphids increased. This interaction modification is similar to other types of indirect interactions among enemy species (e.g. predator,predator facilitation) that can enhance the suppression of agricultural pests. Results of our study, and those of others performed in agroecosystems, complement the broader debate over how biodiversity influences ecosystem functioning by specifically focusing on systems that produce goods of immediate relevance to human society. [source] Removal of high-abundance proteins for nuclear subproteome studies in rice (Oryza sativa) endospermELECTROPHORESIS, Issue 3 2008Guosheng Li Abstract Endosperm is a highly specialized storage organ with three sets of genomes. It is one of the most economically important organs in plants. Endosperm development involves parental imprinting and endoreduplication. A thorough study of the endosperm proteome, particularly the nuclear proteome, may provide critical insight into the regulation of seed development. Unfortunately, endosperm is extremely rich in starch grains and protein bodies of different sizes, making proteome studies on nonstorage proteins, particularly the low-abundance proteins, very challenging. Here we have developed a chromatographic method to remove large starch grains and an electrophoresis method to recover low-abundance proteins, respectively. Using these methods, we have identified 468 proteins from the nuclear enriched fraction of rice endosperm, including transcription factors, histone modification proteins, kinetochore proteins, centromere/microtubule binding proteins, and transposon proteins. Among the 468 proteins, 208 (44%) are hypothetical proteins, indicating that the endosperm proteome is poorly explored. In addition, analyses of the MS/MS data using BioWorks 3.1 have identified 59 putative acetylated proteins and 40 putative methylated proteins. Our studies have developed a method to remove starch grains and recover low-abundance proteins, respectively. The methods should be applicable to other organisms. [source] High-throughput multiplex microsatellite marker assay for detection and quantification of adulteration in Basmati rice (Oryza sativa)ELECTROPHORESIS, Issue 14 2007Sunil Archak Abstract Basmati rice is a very special type of aromatic rice known world-wide for its extra long grains and pleasant and distinct aroma. Traditional Basmati rice cultivars, confined to Indo-Gangetic regions of the Indian subcontinent, are often reported to be adulterated with crossbred Basmati varieties and long-grain non-Basmati varieties in the export market. At present, there is no commercial scale technology to reliably detect adulteration. We report here a CE-based multiplex microsatellite marker assay for detection as well as quantification of adulteration in Basmati rice samples. The single-tube assay multiplexes eight microsatellite loci to generate variety-specific allele profiles that can detect adulteration from 1% upwards. The protocol also incorporates a quantitative-competitive PCR-based analysis for quantification of adulteration. Accuracy of quantification has been shown to be ±1.5%. The experiments used to develop and validate the methodology are described. [source] Plant preference in relation to life history traits in the zoophytophagous predator Dicyphus hesperusENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2004Juan Antonio Sanchez Abstract Dicyphus hesperus Knight (Heteroptera: Miridae) is an omnivorous predator used to control pests of greenhouse vegetables. Plant preferences and life history traits were studied using nine plant species: Lycopersicon esculentum Mill. (Solanaceae), Capsicum annuum L. (Solanaceae), Verbascum thapsus L. (Scrophulariaceae), Nepeta cataria L. (Lamiaceae), Stachys albotomentosa (Lamiaceae), Nicotiana tabacum L. (Solanaceae), Vicia sativa L. (Fabaceae), Zea mays L. (Gramineae), and Chrysanthemum coronarium L. (Asteraceae). Plants were selected from among potential target crops, natural hosts, plants used for mass rearing, and plants on which D. hesperus has not been reported. Plant preference was measured by multi-choice host plant selection and oviposition assays. Development and reproduction were measured on each of the plant species on both a plant diet alone and on a plant diet supplemented with Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. Dicyphus hesperus females and nymphs expressed a preference for some plants over others. Plant preference ranged from low preference plants, such as Z. mays, V. sativa, C. coronarium, and C. annuum, to high preference plants such as V. thapsus, N. tabacum, and S. albotomentosa. When E. kuehniella eggs were supplied, there were few differences in the development time and fecundity of D. hesperus among plants, with the exception of corn and broad bean, where fecundity was lower. On a plant diet alone, nymphs were able to complete their development on V. thapsus, C. annuum, and N. cataria. However, mortality and development time were much lower on V. thapsus than on C. annuum and N. cataria. On most of the plant species D. hesperus did not lay any eggs when fed on a plant diet alone. On V. thapsus, females laid a few eggs and lived longer than when fed on prey. Dicyphus hesperus females tended to prefer host plants on which nymph survival without prey was greatest. [source] Preferential occurrence of diazotrophic endophytes, Azoarcus spp., in wild rice species and land races of Oryza sativa in comparison with modern racesENVIRONMENTAL MICROBIOLOGY, Issue 2 2000Margret Engelhard Several diazotrophic species of Azoarcus spp. occur as endophytes in the pioneer plant Kallar grass. The purpose of this study was to screen Asian wild rice and cultivated Oryza sativa varieties for natural association with these endophytes. Populations of culturable diazotrophs in surface-sterilized roots were characterized by 16S rDNA sequence analysis, and Azoarcus species were identified by genomic fingerprints. A. indigens and Azoarcus sp. group C were detected only rarely, whereas Azoarcus sp. group D occurred frequently in samples of flooded plants: in 75% of wild rice, 80% of land races of O. sativa from Nepal and 33% of modern cultivars from Nepal and Italy. The putatively endophytic populations of diazotrophs differed with the rice genotype. The diversity of cultured diazotrophs was significantly lower in wild rice species than in modern cultivars. In Oryza officinalis (from Nepal) and O. minuta (from the Philippines), Azoarcus sp. group D were the predominant diazotrophic putative endophytes in roots. In contrast, their number was significantly lower in modern cultivars of O. sativa, whereas numbers and diversity of other diazotrophs, such as Azospirillum spp., Klebsiella sp., Sphingomonas paucimobilis, Burkholderia sp. and Azorhizobium caulinodans, were increased. In land races of O. sativa, the diazotrophic diversity was equally high; however, Azoarcus sp. was found in high apparent numbers. Similar differences in populations were also observed in a culture-independent approach comparing a wild rice (O. officinalis) and a modern-type O. sativa plant: in clone libraries of root-associated nitrogenase (nifH,) gene fragments, the diazotrophic diversity was lower in the wild rice species. New lineages of nifH genes were detected, e.g. one deeply branching cluster within the anf (iron) nitrogenases. Our studies demonstrate that the natural host range of Azoarcus spp. extends to rice, wild rice species and old varieties being preferred over modern cultivars. [source] Evaluating wastewater-induced plant genotoxicity using randomly amplified polymorphic DNAENVIRONMENTAL TOXICOLOGY, Issue 1 2008K. M. Swaileh Abstract Wastewater often contains genotoxic substances that can resist different stages of the treatment process. In the present study, randomly amplified polymorphic DNA technology was applied to evaluate the genotoxic effects of wastewater (treated and raw) irrigation on oat plants (Avena sativa). RAPD profiles obtained showed that both treated and raw wastewater (RWW) were having genotoxic effects on oat plants. This was apparent by the appearance/disappearance of bands in the treatments compared with the control plants. From the 15 primers used, 186 bands were obtained with an average of 12.4 bands per primer. Irrigating plants with RWW caused 51 new bands to appear and 19 to disappear. Treated wastewater (TWW) caused only 16 new bands and the loss of 17 bands. This makes TWW less genotoxic than RWW. The Euclidean distances shown on the dendrogram, revealed the presence of two clusters according to dissimilarity values. One cluster contained the control plants and those irrigated with TWW, whereas the second contained the plants irrigated with RWW. Similarity indices calculated between the treatments and the control plants showed that the control and the plants irrigated with TWW had a similarity index of 0.87, the control and plants irrigated with RWW 0.73 and between the treatments 0.75. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Toxicity of methyl tert butyl ether to soil invertebrates (springtails: Folsomia candida, Proisotoma minuta, and Onychiurus folsomi) and lettuce (Lactuca sativa)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Matthew Dodd Abstract Experiments were conducted to assess the toxicity of methyl tert butyl ether (MTBE) to three species of Collembola (Proisotoma minuta, Folsomia candida, and Onychiurus folsomi) and lettuce (Lactuca sativa L.) using an artificial Organization for Economic Cooperation and Development (OECD) soil and field-collected sandy loam and silt loam soil samples. Soil invertebrate tests were carried out in airtight vials to prevent volatilization of MTBE out of the test units and to allow for direct head-space sampling and gas chromatography-mass spectrometry (GC-MS) analysis for residual MTBE. The use of the airtight vial protocol proved to be very successful, in that the measured MTBE concentrations at the beginning of the experiments were within 95% of nominal concentrations. The test methods used in this study could be used to test the toxicity of other volatile organic compounds to Collembola. The soil invertebrates tested had inhibitory concentration (ICx) and lethal concentration (LCx) values that ranged from 242 to 844 mg MTBE/kg dry soil. When the three test species of Collembola were tested under identical conditions in the artificial OECD soil, O. folsomi was the most sensitive collembolan, with a median inhibitory concentration (IC50; reproduction) of 296 mg MTBE/kg dry soil. The most sensitive endpoint for lettuce was an IC50 for root length of 81 mg MTBE/kg dry soil after 5 d of germination in OECD soil. Data on the loss of MTBE from the three test soils over time indicated that MTBE was retained in the silt loam soil longer than in either the sandy loam or the artificial OECD soil. Environ. Toxicol. Chem. 2010;29:338,346. © 2009 SETAC [source] Arsenate toxicity for wheat and lettuce in six Chinese soils with different propertiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Qing Cao Abstract To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination. [source] Evaluating the contribution of soil properties to modifying lead phytoavailability and phytotoxicity,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Elizabeth A. Dayton Abstract Soil properties affect Pb bioavailability to human and ecological receptors and should be considered during ecological risk assessment of contaminated soil. We used path analysis (PA) to determine the relative contribution of soil properties (pH, organic C [OC], amorphous Fe and Al oxides [FEAL], and cation-exchange capacity [CEC]) in modifying Pb bioavailability. The response of biological endpoints (bioaccumulation and dry matter growth [DMG]) of lettuce (Lactuca sativa) grown on 21 Pb-spiked (2,000 mg/kg) soils were determined. Lettuce tissue Pb ranged from 3.22 to 233 mg/kg, and relative DMG ranged from 2.5 to 88.5% of their respective controls. Simple correlation showed strong relationships between CEC and OC (p < 0.01) and weaker relationships between pH and FEAL (p < 0.05) and Pb bioaccumulation. Results of PA suggest that soil pH increased the negative surface charge of organic matter and clay, thereby increasing CEC and decreasing Pb bioaccumulation. Also, the direct effect of OC on tissue Pb can be attributed to formation of surface Pb complexes by organic matter functional group ligands. Increased OC and/or CEC reduced Pb solubility and bioavailability in the 21 soils in the present study. The relative importance of soil properties likely will vary between studies employing different soils. Soil properties should be considered during the ecological risk assessment of metal in contaminated soils. Path analysis is useful for ecological studies involving soils with a wide range of physicochemical properties and can assist in site risk assessment of metals and remediation decisions on contaminated sites. [source] Transfer of Cd, Cu, Ni, Pb, and Zn in a soil-plant-invertebrate food chain: A microcosm study,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Renaud Scheifler Abstract The transfer of Cd, Cu, Ni, Pb, and Zn was evaluated in a soil-plant (lettuce, Lactuca sativa),invertebrate (snail, Helix aspersa) food chain during a microcosm experiment. Two agricultural soils, polluted and unpolluted, were studied. Lettuce was cultivated for eight weeks before introduction of snails into the microcosms (M-snails). In a parallel experiment, snails were exposed to lettuce only (i.e., without soil) in simpler exposure devices called containers (C-snails). Snail exposure duration was eight weeks for both M- and C-snails. No effects on snail survival were found. Both M- and C-snails exposed to polluted soil showed a growth reduction, but only after two weeks of exposure. Time-dependent accumulation in M-snails exposed to the polluted environment showed a regular increase of Cd and Zn concentrations over time and a rapid increase of Pb concentrations within the first two weeks, which then remained stable. Copper and Ni concentrations did not increase during any of the experiments. Concentrations in M- and C-snails were compared to estimate the relative contribution of soil and plant to the total bioaccumulation. The results suggest that the soil contribution may be higher than 80% for Pb, from 30 to 60% for Zn, and from 2 to 40% for Cd. [source] Toward detoxifying mercury-polluted aquatic sediments with rice genetically engineered for mercury resistanceENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2003Andrew C. P. Heaton Abstract Mercury contamination of soil and water is a serious problem at many sites in the United States and throughout the world. Plant species expressing the bacterial mercuric reductase gene, merA, convert ionic mercury, Hg(II), from growth substrates to the less toxic metallic mercury, Hg(0). This activity confers mercury resistance to plants and removes mercury from the plant and substrates through volatilization. Our goal is to develop plants that intercept and remove Hg(II) from polluted aquatic systems before it can undergo bacterially mediated methylation to the neurotoxic methylmercury. Therefore, the merA gene under the control of a monocot promoter was introduced into Oryza sativa L. (rice) by particle gun bombardment. This is the first monocot and first wetland-adapted species to express the gene. The merA -expressing rice germinated and grew on semisolid growth medium spiked with sufficient Hg(II) to kill the nonengineered (wild-type) controls. To confirm that the resistance mechanism was the conversion of Hg(II) to Hg(0), seedlings of merA -expressing O. sativa were grown in Hg(II)-spiked liquid medium or water-saturated soil media and were shown to volatilize significantly more Hg(0) than wild-type counterparts. Further genetic manipulation could yield plants with increased efficiency to extract soil Hg(II) and volatilize it as Hg(0) or with the novel ability to directly convert methylmercury to Hg(0). [source] Metabolism of fluoranthene in different plant cell cultures and intact plantsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2000Marit Kolb Abstract The metabolism of fluoranthene was investigated in 11 cell cultures of different plant species using a [14C]-labeled standard. Most species metabolized less than 5% of fluoranthene to soluble metabolites and formed less than 5% nonextractable residues during the standardized 48-h test procedure. Higher metabolic rates were observed in lettuce (Lactuca sativa, 6%), wheat (Tricitum aestivum, 9%), and tomato (Lycopersicon esculentum, 15%). A special high metabolic rate of nearly 50% was determined for the rose species Paul's Scarlet. Chromatographic analysis of metabolites extracted from aseptically grown tomato plants proved that the metabolites detected in the cell cultures were also formed in the intact plants. Metabolites produced in tomato and rose cells from [14C]-fluoranthene were conjugated with glucose, glucuronic acid, and other cell components. After acid hydrolyses, the main metabolite of both species was 1-hydroxyfluoranthene as identified by gas chromatography,mass spectrometry and high-performance liquid chromatography with diode array detection. The second metabolite formed by both species was 8-hydroxy-fluoranthene. A third metabolite in tomatoes was 3-hydroxyfluoranthene. [source] Nanogold-Loaded Sharp-Edged Carbon Bullets as Plant-Gene CarriersADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Periyasamy S. Vijayakumar Abstract The higher DNA delivery efficiency into plants by gold nanoparticles embedded in sharp carbonaceous carriers is demonstrated. These nanogold-embedded carbon matrices are prepared by heat treatment of biogenic intracellular gold nanoparticles. The DNA-delivery efficiency is tested on a model plant, Nicotiana tabacum, and is further extended to the monocot, Oryza sativa, and a hard dicot tree species, Leucaena leucocephala. These materials reveal good dispersion of the transport material, producing a greater number of GUS foci per unit area. The added advantages of the composite carrier are the lower plasmid and gold requirements. Plant-cell damage with the carbon-supported particles is very minimal and can be gauged from the increased plant regeneration and transformation efficiency compared with that of the commercial micrometer-sized gold particles. This is ascribed to the sharp edges that the carbon supports possess, which lead to better piercing capabilities with minimum damage. [source] Characteristics of the Cryphonectria parasitica isolated from Quercus in SlovakiaFOREST PATHOLOGY, Issue 5 2010K. Adam, íková Summary The occurrence of chestnut blight (Cryphonectria parasitica) on oaks in mixed chestnut-oak forests was studied in 2003,2008 in Slovakia. Infections on living Quercus trees were found at four of seven localities. The disease incidence on oaks ranged from 1.3% to 15.8%. The symptoms on infected oaks were similar to those on chestnut, but less conspicuous. Cankers of C. parasitica were found only on Quercus robur and Q. petraea. A total of 22 isolates of C. parasitica, all virulent, were isolated. Each site yielded only a single vc type (EU12 or EU13). Field inoculation experiments on chestnuts with seven strains of C. parasitica from oaks and an isolate from Castanea sativa showed no differences in virulence. On Quercus robur stems, the cankered area was significantly smaller than on C. sativa and the cankers developed very slowly. [source] Distribution and severity of damage by Cryphonectria parasitica in the chestnut stands in Guilan province, IranFOREST PATHOLOGY, Issue 5 2010E. Ghezi Summary Chestnut blight caused by Cryphonectria parasitica has recently been reported from Guilan province, the only region with natural chestnut (Castanea sativa) stands in Iran. During the past few years, chestnut stands in Iran have been seriously threatened by the fungus, incidence of the disease is increasing and vast canopies are reduced to sprouts. As yet, there is no report on the disease distribution and severity in this region. Six sites from three main growing regions of chestnut in Guilan province were selected for investigation. We report occurrence and evaluation of the damage of the disease caused by C. parasitica. To evaluate the scale of damage, the investigated trees were classified into six categories based on the degree of crown damage, the number of canker wounds and the presence of the fungus. Index of health condition was calculated for all sites. During this study, a total of 250 isolates of Cryphonectria species were obtained, of which 232 isolates were C. parasitica and 18 were Cryphonectria radicalis. Castanea parasitica was observed in all regions. Index of health condition was scored from 0 to 6 with 0 being disease free and six being the most severe infection. Index results in the investigated sites varied between 0.69,5.45 and 0.93,5.55 for years 2006 and 2007, respectively. The highest damage was found in Doran (IH = 5.55), which is located some 100 km away from Shahbalutmahalleh, the site with lowest damage (IH = 0.93). This is the first extended report on aspects of chestnut blight in Iran. [source] Seasonal effect on infection and development of lesions caused by Cryphonectria parasitica in Castanea sativaFOREST PATHOLOGY, Issue 4 2003L. Guérin Summary Seasonal variation in the development of chestnut blight, caused by Cryphonectria parasitica, was investigated by inoculating in situ chestnut trees and in vitro excised chestnut segments, at either monthly or 3-monthly intervals throughout 30 months. Inoculations were made with conidia and mycelium of a virulent isolate and with mycelium of a hypovirulent isolate. Conidial inoculations of living sprouts or excised segments between May and July resulted in the greatest incidence of infection whereas inoculations in autumn and winter, in vitro as well as in situ, did not reveal any visible disease. However, from these symptomless inoculated stems, C. parasitica was isolated 3 months after inoculation. Inoculations with the mycelium of the virulent isolate always resulted in lesions, except in January 1999, and the greatest rate of lesion development occurred for inoculations made in the spring and summer. There was a significant seasonal effect on lesion development. Lesions caused by the hypovirulent isolate, smaller than those caused by the virulent isolate, followed a similar seasonal pattern. The same seasonal variations were observed for inoculations in vitro of excised segments. Relative water content (RWC) of chestnut bark significantly varied with bark sampling date. The rate of lesion development in sprouts significantly correlated with average minimum (ATn) and maximum (ATx) temperatures and the sum of rainfall during inoculation period, with the rate of lesion development measured in excised segments 10 days after inoculation (R10d) and with RWC measured on the day of inoculation. In multiple regression models, variables ATx and R10d best explained variation in lesion development. Résumé La variation saisonnière du développement de la maladie du chancre causée par Cryphonectria parasitica a étéétudiée en réalisant, une fois par mois ou par trimestre pendant deux ans et demi, des inoculations de châtaigniers in situ et des inoculations in vitro de branches coupées. Les inoculations ont été réalisées avec des conidies et du mycélium d'un isolat virulent et avec du mycélium d'un isolat hypovirulent. En Mai et Juin, les inoculations conidiennes ont provoqué le taux d'infection le plus élevé, in situ et in vitro. A l'inverse, en automne et en hiver, ces inoculations n'ont pas causé de symptômes. Cependant C. parasitica a été réisolé 3 mois plus tard, sur ces tiges ne présentant aucune lésion. Les inoculations avec du mycélium ont toujours résulté en des lésions, excepté en Janvier 1999, et le développement des lésions (R1m) a été le plus rapide au printemps et en été. La date d'inoculation a eu un effet significatif sur l'extension des lésions. Le même effet saisonnier était observé sur le développement des lésions causées par l'isolat hypovirulent, plus petites que celles causées par l'isolat virulent. Les mêmes variations saisonnières de l'extension des lésions étaient observées in vitro sur tiges excisées. Un effet saisonnier significatif a été mis en évidence sur la teneur en eau relative des écorces de châtaignier (RWC). Le développement des lésions dans les tissus vivants était significativement corrélé avec les températures moyennes minimale (ATn) et maximale (ATx) et la somme des précipitations (SR) calculées sur chaque période d'incubation, avec le développement des lésions in vitro (R10d) et avec RWC. La variation saisonnière du développement des lésions était le mieux expliquée, par un modèle de régression multiple, par ATx et R10d pour l'isolat virulent, et par ATx pour l'isolat hypovirulent. Zusammenfassung Der jahreszeitlich bedingte Einfluß auf die Entstehung von Kastanienrindenkrebs, verursacht von Cryphonectria parasitica, wurde durch Inokulation von Kastanienbäumen in situ und durch Beimpfung von geschnittenen Triebsegmenten in vitro in monatlichen oder drei-monatlichen Intervallen über dreißig Monate untersucht. Zur Inokulation wurden Myzel und Konidien eines virulenten Isolates und Myzel eines hypovirulenten Isolates verwendet. Mit Konidien wurde zwischen Mai und Juni die größte Infektionshäufigkeit auf lebenden Sprossen oder Triebsegmenten erreicht, während Inokulationen im Herbst und Winter keine sichtbaren Symptome hervorriefen. Jedoch konnte C. parastica drei Monate nach Inokulation von lebenden Sprossen isoliert werden, auch wenn keine Läsion sichtbar war. Außer im Januar 1999 führte Inokulation mit Myzel des virulenten Isolates immer zu Läsionen. Am häufigsten traten Läsionen bei Inokulationen im Frühling und im Sommer auf. Der Einfluß des Inokulationszeitpunktes auf die Ausbildung von Läsionen war signifikant. Inokulationen mit dem hypovirulenten Isolat zeigten eine ähnliche jahreszeitliche Schwankung wie jene mit dem virulenten Isolat, führten aber zu kleineren Läsionen. Die gleichen jahreszeitlichen Variationen wurden bei in vitro Inokulation von Kastanientrieben beobachtet. Der relative Wassergehalt (RWC) der Borke variierte signifikant mit dem Beprobungszeitpunkt der Borke. Die Bildung von Läsionen an lebenden Sprossen korrelierte signifikant mit den durchschnittlichen Temperaturminima (ATn) und -maxima (ATx), mit der Gesamtregenmenge (SR) während der Inokulationsperiode, mit der Bildung von Läsionen an Triebsegmenten (R10d) und mit dem am Inokulationstag gemessenen RWC. In einem multiplen Regressionsanalysenmodell zeigte sich, dass die jahreszeitliche Schwankung der Ausbildung von Kastanienrindenkrebs beim virulenten Isolat am besten durch die Variablen ATx und R10d, beim hypovirulenen Isolat durch ATx erklärt wurde. [source] Crayfish effects on seeds and seedlings: identification and quantification of damageFRESHWATER BIOLOGY, Issue 4 2005PEDRO M. ANASTÁCIO Summary 1. The red-swamp crayfish (Procambarus clarkii) is an invasive species and an important pest of wet-seeded rice fields (Oryza sativa) in California (U.S.A.) and in Portugal. Our work quantifies rice consumption and non-consumptive destruction and identifies the types of direct damage inflicted by crayfish. 2. The following fractions were quantified in the presence and absence of crayfish and at 3 and 6 days of rice development: (1) non-germinated seeds, (2) damaged seeds, (3) seeds not recovered, (4) intact rooted seedlings, (5) rooted damaged seedlings, (6) uprooted intact seedlings, (7) uprooted damaged seedlings. 3. Coarse particulate organic matter (CPOM) fragments produced during the feeding process were <2% of the material removed by crayfish. 4. Damage occurred with or without uprooting of the plants, but the incidence of uprooting without consumption was low (1.4%). 5. Consumption of recently developed parts of the rice plant was the main cause of damage and the observed effect was stronger on 6-day-old than on 3-day-old seedlings. Seedlings were more affected by crayfish than were seeds. 6. Crayfish affected the majority of seeds and seedlings available although consumption was low: 0.015 g dry weight (DW) rice g,1 wet weight (WW) crayfish per 12 h at 3 days and 0.063 g DW rice g,1 WW crayfish per 12 h at 6 days. 7. Our results are important for the mitigation of crayfish related problems in rice fields and for understanding the mechanisms of crayfish-macrophyte interactions. [source] Antihypertensive effect of Nigella sativa seed extract in patients with mild hypertensionFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2008Farshad Roghani Dehkordi Abstract Hypertension (HT) is a lifestyle-related disease and dietary modifications are effective for its management and prevention. We conducted a randomized, double-blind, placebo-controlled trial to evaluate the efficacy of treatment with an oral Nigella sativa (NS) seed extract supplement in patients with mild HT. Subjects were randomized into three groups: a placebo and two test groups that received 100 and 200 mg of NS extract twice a day. After 8 weeks, systolic blood pressure (SBP) values in both case groups were found to be significantly reduced when compared with the baseline values for each group. In addition, the decrease in SBP in the two case groups was statistically significant relative to the placebo group (P < 0.05,0.01). Meanwhile, diastolic blood pressure (DBP) values in the case groups were found to be significantly reduced from the baseline and a significant reduction was also observed in these groups (P < 0.01) when compared with the placebo group. In addition, extract administration reduced both SBP and DBP in a dose-dependent manner. Meanwhile, NS extract caused a significant decline in the level of total and low-density-lipoprotein (LDL)-cholesterol relative to baseline data. No complications caused by NS were observed. The results suggest that the daily use of NS seed extract for 2 months may have a blood pressure-lowering effect in patients with mild HT. [source] Seasonal changes in herbage mass and nutritive value of a range of grazed legume swards under Mediterranean and cool temperate conditionsGRASS & FORAGE SCIENCE, Issue 3 2007U. Sölter Summary Seasonal changes in herbage mass and herbage quality of legume-based swards under grazing by sheep or cattle were investigated at four locations in climatically different zones of Europe: Sardinia (Italy), southern France, northern Germany and south-west England (UK). At each location standard treatments were applied to legumes typical of species widely used in each locality: Medicago polymorpha in Italy, Medicago sativa in France, and Trifolium repens in Germany and in UK. At each site comparisons were made of two other legumes: Trifolium subterraneum and Hedysarum coronarium in Italy, Onobrychis sativa and Trifolium incarnatum in France, Trifolium pratense and Lotus corniculatus in Germany, and Trifolium ambiguum and L. corniculatus in UK. Legumes were sown in mixture with locally appropriate companion grasses, and measurements were made over two or three grazing periods. In Italy M. polymorpha swards gave the greatest herbage mass in grazing period 1 but H. coronarium was more persistent. At the French site all legumes established poorly with no significant herbage mass differences between treatments. At both the UK and German sites L. corniculatus maintained a high proportion of legume in the sward; T. repens showed poor persistence under continuous sheep grazing in UK but persisted under cattle grazing in Germany, while T. ambiguum was slow to establish in the UK, and T. pratense proved to be of comparable herbage mass to the standard T. repens -based sward in the last year of the experiment. The concentration of crude protein and in vitro digestibility of organic matter in the dry matter of herbage showed greater within-season variation than between treatments at each site. It is concluded that, in addition to currently used species, legume-based swards containing H. coronarium, O. sativa and L. corniculatus all have potential to contribute to forage production for low-input grazing and their use merits further consideration in systems of livestock production in Europe. [source] Environmental factors during seed development of narrow-leaved bird's-foot-trefoil (Lotus tenuis) influences subsequent dormancy and germinationGRASS & FORAGE SCIENCE, Issue 4 2003A. A. Clua Abstract Narrow-leaved bird's-foot-trefoil (Lotus tenuis) is a perennial forage legume adapted to waterlogged and heavy and infertile soils and can replace alfalfa (Medicago sativa) in areas with these soils in Argentina. Its seeds are hard and water-impermeable but the effects of environmental factors on seed dormancy and germination are not known. The objective was to evaluate the hypothesis that water availability during seed development and maturation affects the degree of hardseededness in L. tenuis by changing seed coat properties, conditioning water uptake through the seed coat; and subsequently affecting dormancy, germination and speed of germination. Seeds were harvested in December/January and in February in both 1993/1994 and 1994/1995 from a permanent pasture of L. tenuis growing in a Hapludol soil in San Miguel del Monte province of Buenos Aires. Environmental conditions of each anthesis-harvest period were determined. Seeds of each harvest were subjected to chilling, washing and mechanical scarification. After 12 months seeds from each harvest were observed in a scanning electron microscope. The water deficit of the soil and relative humidity were greater in the second than the first anthesis-harvest period in both seasons. In 1993/1994 the control treatment in December had a higher germination rate than the February control seeds (0·40 vs. 0·20) and a faster germination rate. Mechanical scarification and chilling significantly enhanced the germination rate (0·95) and its speed in seeds of both harvests. Low temperatures significantly enhanced germination rate, starting after 60 d for the seeds harvested in December, and 90 d for the seeds harvested in February. In 1994/1995 the results were similar but both the January and February control treatments had higher germination rates (0·60 vs. 0·40) than in the previous year. Seeds harvested in February were more dormant in both years. These differences could be explained by the conditions in February anthesis-harvest period in both years that could have hastened the natural dehydration process of seed, changing integument structure and enhancing its impermeability. [source] Selecting and evaluating native plants for region-specific phytotoxicity testingINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2008David Olszyke Abstract In this study, we evaluated methodology to determine risks to terrestrial native plant species from potential herbicide drift, focusing on 1) selection of native species for testing, 2) growth of these species, and 3) variability in herbicide response among native species and compared with crop plants. Native plant species were selected for initial testing on the basis of spatial analysis, which indicated that species from Illinois, USA, were at potential risk for off-target effects of herbicide drift. On the basis of preliminary seed germination tests, 5 native plant species (Andropogon gerardi, Polygonum lapathifolium, Solidago canadensis, Symphyotrichum lateriflorum, and Tridens flavus) were selected for comparison with crops grown in Illinois, normally used in the US Environmental Protection Agency's (USEPA's) Vegetative Vigor Test (Avena sativa, Daucus carota, Glycine max, Solanum lycopersicon, and Zea mays), or both. When treated with low concentrations of a test herbicide, sulfometuron methyl, 2 native species, P. lapathifolium and S. canadensis, were as sensitive as the 5 crop species. The effective herbicide concentrations producing a 25% reduction in shoot dry weight (EC25) for these species, ranged from 0.00015 to 0.0014 times a field application concentration of 52 g/ha active ingredient of sulfometuron methyl. S. lateriflorum and T. flavus were less sensitive than the other native species, whereas A. gerardi was tolerant to sulfometuron methyl with no growth reduction at any herbicide concentration tested. This study indicated that native species can be successfully selected and grown, used in the suite of species used in the USEPA's phytotoxicity test to assess risks of chemical herbicides to nontarget plants. It also showed (with a limited number of species) that native species varied more in sensitivity to simulated herbicide drift than crop species often used in phytotoxicity testing and that a Weibull function was useful to calculate EC25 values when low concentrations of herbicides was used. [source] Seedling Growth of Agronomic Crops in Crude Oil Contaminated SoilJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2006I. Issoufi Abstract Phytoremediation of hydrocarbon-contaminated soil shows promise as a low-cost alternative to most remediation methods. This study evaluated seedling growth of six crop species in crude oil contaminated soils. The experiments were conducted in a greenhouse. Weathered crude oil was added to an Ipava silt loam soil at the rate of 0 (control), 10, 50 and 100 g of crude oil kg,1 of soil, which was then placed into pots. Irrigation was used to maintain soil moisture at approximately field capacity. Five seeds of Zea mays, Meticago sativa, Lolium perenne, Triticum aestivum, Glycine max or Vicia villosa were sown per pot. The experimental design was completely randomized with five replications per treatment. Germination and seedling height data were recorded on day 7, 14, 21 and 28. Plants were harvested on day 28, separated into shoots and roots and dried to measure biomass. Analysis of variance was used to determine treatment significance. Significant treatment mean values were separated using Tukey's Honestly Significant Difference Test. Based upon percent emergence and plant biomass production in contaminated soil, Z. mays and G. max seedlings show the greatest potential to enhance remediation. [source] Variation in Crown and Root Organic Reserves Among Lucerne Genotypes of Different Morphology and Flower ColourJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2003F. Fornasier Abstract Previous evidence indicates that differences in the concentration of underground organic reserves can drive the survival and growing ability of lucerne under cold and defoliation stresses. In order to provide the selection process with further information on compounds that may influence plant performance under grazing, we assessed variations in cold-season concentrations of nitrogen and carbon reserves on genotypes that had been identified for morphological features that possibly enhance grazing tolerance. The selected genotypes encompassed distinct morphological patterns (defined as ,models') and different taxa within the Medicago sativa complex, as shown by different flower colours. Crown concentrations of reserves were determined on 90 genotypes, whereas root concentrations were measured on a subsample of 15 genotypes. Wide intergenotypic variation was observed for all reserve substances. Comparisons among models and among flower colour classes highlighted the high concentrations of crown carbohydrates and root and crown-soluble proteins of the model coded as ,D1', characterized by prostrate, rhizomatous habit and long dormancy, which largely corresponded to plants with yellow or variegated flowers, typical of ssp. falcata and ×,varia, respectively. There was a strong ,flower colour × storage organ' interaction for sugar concentration, and the results suggested a preferential compartment of sugars in the roots of purple-flowered genotypes that belonged to the ssp. sativa. A rank correlation analysis indicated a positive relationship between persistence after two years under grazing of half-sib progenies deriving from 19 genotypes out of the 90 and crown concentrations of carbohydrates of the 19 mother plants. [source] Response of Photosynthesis and Water Relations of Rice (Oryza sativa) to Elevated Atmospheric Carbon Dioxide in the Subhumid Zone of Sri LankaJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 2 2003W. A. J. M. De Costa Abstract The objective of the present paper is to determine the response of the physiological parameters related to biomass production and plant water relations in a standard Sri Lankan rice (Oryza sativa) variety (BG-300) to elevated CO2 (i.e. 570 µmol/mol). During two seasons, rice crops were grown under three different experimental treatments; namely, at 570 µmol/mol (i.e. ,elevated') and 370 µmol/mol (,ambient') CO2 within open top chambers, and at ambient CO2 under open field conditions. Leaf net photosynthetic rate in the elevated treatment increased by 22,75 % in comparison to the ambient. However, the ratio between intercellular and ambient CO2 concentrations remained constant across different CO2 treatments and seasons. CO2 enrichment decreased individual leaf stomatal conductance and transpiration rate per unit leaf area, and increased both leaf and canopy temperatures. However, the overall canopy stomatal conductance and daily total canopy transpiration rate of the elevated treatment were approximately the same as those achieved under ambient conditions. This was because of the significantly greater leaf area index and greater leaf,air vapour pressure deficit under CO2 enrichment. The leaf chlorophyll content increased significantly under elevated CO2; however, the efficiency (i.e. photochemical yield) of light energy capture by Photosystem II (i.e. Fv/Fm) in chlorophyll a did not show a significant and consistent variation with CO2 enrichment. [source] Vegetable and animal food sorts found in the gastric content of Sardinian Wild Boar (Sus scrofa meridionalis)JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5-6 2007W. Pinna Summary Authors report results emerging from gastric content analysis from n. 96 wild boars hunted in Sardinia isle, during the hunting tide (2001,2005), from November to January. Mean pH of the gastric content was 3.77 ± 0.69. Mean total capacity (TC) of each stomach was 1702 ± 680 g. Mean Stuff ratio (CW/TC) between the content weight (CW) and stomachs TC was 0.45. Food categories found in animal stomachs were: 19 categories of vegetal species (Allium spp., Arbutus unedo, Arisarum vulgare, Avena fatua, Avena sativa, Castanea sativa, Ceratonia siliqua, Chamaerops umilis, Cichorium intybus, Hordeum sativum, Juniperus oxycedrus, Myrtus communis, Olea europea, Pirus amygdaliformis, Pistacia lentiscus, Quercus spp., Rhamnus alaternus, Triticum durum, Zea mais); 11 categories of animal species (Agriotes lineatus, Apodemus sylvaticus dicrurus, Chalcides chalcides, Chalcides ocellatus tiligugu, Crematogaster scutellaris, Forficula auricularia, Helix aspersa, Lumbricus terrestris, Ovis aries, Podarcis tiliguerta tiliguerta, Scolopendra cingulata); three categories were identified in general terms (insects larvae, hairs of mammals, feathers of birds). Food categories found in the stomach contents of Sus scrofa meridionalis confirm observations by other researchers who report the prevalence of vegetables in spite of animal food sorts in the wild boar diet in Italian regions. [source] Demographic vital rates determine the performance advantage of crop,wild hybrids in lettuceJOURNAL OF APPLIED ECOLOGY, Issue 6 2005DANNY A. P. HOOFTMAN Summary 1Hybridization seems possible for many crop species after pollen transfer from crops to wild relatives in the surrounding vegetation. Subsequent introgression of crop-specific traits into wild relatives could lead to invasive introgressants. This process has become a public concern following the introduction of genetically modified (GM) crops. Until now, few studies have used demographic vital rates to compare the performance of hybrids with their wild relatives. 2We created second-generation (S1 and BC1) hybrids between the non-transgenic crop Lactuca sativa and its entirely cross-fertile wild relative Lactuca serriola. Seeds of parents and hybrids were individually sown in field plots at three different locations. Next to germination and survival, we measured a range of single fitness components and morphological traits. We also compared observed phenotypes to phenotypes theoretically expected, according to different inheritance scenarios. 3Phenotypes of both hybrid classes resembled L. serriola closely, and more than theoretically expected. However, demographic vital rates, i.e. germination and survival of hybrids were much higher than in L. serriola. 4Our results indicate that hybrids between crop and wild Lactuca are phenotypically indistinguishable from the wild relative and thus will largely remain unnoticed when they occur. However, these hybrids could potentially become invasive because of substantial differences in vital rates and seeds returned per seed sown. 5Synthesis and applications. A comparative study on single fitness components, such as seed production, alone would not have revealed the performance advantage of crop,wild hybrids in Lactuca. Therefore, studying demographic vital rates of hybrids and back-crosses to test for long-term consequences of hybridization should be part of any risk assessment of GM crops. Demographic vital rates are also important for the development of predictive modelling tools that can be employed to test the individual- and population-level consequences of new-to-add traits. [source] Utilisation of morphological features in life table studies of Liriomyza huidobrensis (Dipt., Agromyzidae) developing in lettuceJOURNAL OF APPLIED ENTOMOLOGY, Issue 7-8 2002J. Head The growth ratios of cephalopharyngeal skeletons between first and second and second and third instar larvae were 1.80 and 1.47, respectively, enabling clear separation to be achieved for experimental work. Using this method the development rates of the immature stages of L. huidobrensis feeding on Lactuca sativa were determined under constant temperatures of 11, 16, 19, 26 and 28 ± 1°C and were shown to increase linearly with temperature over the range investigated. The theoretical lower threshold temperatures for development from oviposition to the end of each larval instar or pupal stage were 5.35, 6.30, 6.20 and 5.70°C, respectively. The overall threshold temperature for development from oviposition to 50% adult emergence (5.70°C) was used to calculate degree-day (DD) requirements for development from oviposition to each larval instar or pupal eclosion, which were 84.3, 30.1, 58.9, 143.7 DD, respectively. The use of these data for optimizing the timing of application of control agents which are effective against specific developmental stages is discussed. [source] The host plant range of the pea aphid subspecies Acyrthosiphon pisum ssp. destructor (Johnson) (Hom., Aphididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2002R. I. K. McVean The plant species used were: Lotus uliginosus, Medicago sativa, Melilotus officinalis, Ononis repens, Sarothamnus scoparius, Trifolium hybridum, Trifolium pratense, Trifolium repens, Vicia cracca and Vicia faba. Vicia faba and Trifolium hybridum were the plants on which aphids reached the greatest size, took the least time to reach maturity, and experienced the lowest mortality. The time taken for the aphids to develop to maturity was negatively correlated with adult size, whereas survival to maturity was positively correlated with adult size. The host preference of the aphids was also assessed. The plant species selected as hosts by alatae were those on which their offspring performed best. [source] | |||||||||||||||||||||||||||||||||||||||||||