共查询到20条相似文献,搜索用时 15 毫秒
1.
Annelies J. Veraart Maurício R. Dimitrov Arina P. Schrier-Uijl Hauke Smidt Jeroen J. M. de Klein 《Ecosystems》2017,20(5):928-943
Drainage ditches are ubiquitous yet understudied features of the agricultural landscape. Nitrogen pollution disrupts the nutrient balance of drainage ditch ecosystems, as well as the waterbodies in which they drain. Denitrification can help ameliorate the impact of N-fertilization by converting reactive nitrogen into dinitrogen gas. However, factors affecting denitrification in drainage ditches are still poorly understood. In this study, we tested how within-ditch and regional environmental conditions affect denitrifier activity, abundance, and community structure, to understand controls on denitrification at multiple scales. To this end, we quantified in situ denitrification rates and denitrifier abundance in 13 drainage ditches characterized by different types of sediment, vegetation and land-use. We determined how denitrification rates relate to denitrifier abundance and community structure, using the presence of nirS, nirK and nosZ genes as a proxy. Denitrification rates varied widely between the ditches, ranging from 0.006 to 24 mmol N m?2 h?1. Ditches covered by duckweed, which contained high nitrate concentrations and had fine, sandy sediments, were denitrification hotspots. We found highest rates in ditches next to arable land, followed by those in grasslands; lowest rates were observed in peatlands and nature reserves. Denitrification correlated to nitrate concentrations, but not to nirK, nirS and nosZ abundance, whereas denitrifier-gene abundance correlated to organic matter content of the sediment, but not to nitrate concentrations. Our results show a mismatch in denitrification regulators at its different organizational scales. Denitrifier abundance is mostly regulated at within-ditch scales, whereas N-loads, regulated by landscape factors, are most important determinants of instantaneous denitrification rates. 相似文献
2.
To determine the differences in the ditch environments and mussel composition between floodplains and alluvial fans, two geomorphic types in a Lake Biwa river basin were surveyed. An intrinsic Gaussian conditional autoregressive (CAR) model was applied to assess the relationship between the density of Nodularia douglasiae biwae, the dominant species in the floodplain area, and ditch environment. Relative to the alluvial fan area, ditches in the floodplain area had higher percentages of muddy and sandy substrates, a lower percentage of pebble substrates, greater sediment softness, faster flow velocity, and deeper water depth. N. d. biwae and Pronodularia japanensis were collected in both the floodplain and alluvial fan areas. Lanceolaria grayana and Sinanodonta japonica were captured only in the floodplain area, and Sinanodonta lauta was found only in the alluvial fan area. The differences in the ditch environments between the two geomorphic types and the drought tolerance of the mussel species may explain why the mussel composition differs between the two geomorphic types. The CAR model indicated that N. d. biwae was more abundant in ditches with sandy and soft sediment and with deeper water. It also points to the importance of microhabitat-scale sampling to determine the relationship between unionid density and ditch environment. 相似文献
3.
The damselfly Coenagrion ornatum represents a threatened species of lowland headwater streams. Although the species is threatened in Western and Central Europe, it is known at a system of post-mining drainage ditches in the Radovesicka spoil heap (northwestern Bohemia, Czech Republic). This study aimed to estimate its population size in this post-mining stream system, and to explore habitat preferences of both its larvae and adults with respect to various environmental factors. The adults were captured-recaptured along 5.2 km of the ditches in June 2012; larvae were sampled in 64 study sites (i.e., 27-meter-long sections of the same ditches) in April 2012. The adult population size was estimated via log-linear models with the robust design on 4544 individuals (1560?±?391 females and 2983?±?298 males). Larvae were present in a third of the sections. GLMs revealed that both larvae and adults required emergent vegetation with a high proportion of Eleocharis spp. plants. The adults preferred the slow-flowing and shallow streams with 2-meter-high banksides covered by intermediately tall vegetation (~40 cm), whereas the larval abundance was supported by a high in-stream vegetation heterogeneity and a patchy cover of rocks on the streambeds. These results indicate that the post-mining streams could represent a valuable secondary habitat for the complete life cycle of this relatively large population of the endangered headwater specialist. Therefore, we recommend consideration of the conservation potential of such ditches during post-mining sites restoration and their subsequent management. 相似文献
4.
Stephen P. Jennewein Robert A. Gilbert Diane L. Rowland Alan L. Wright Barry Glaz Jerry M. Bennett 《Bioenergy Research》2017,10(3):688-699
Rising energy costs, decreasing soil depth, and best management practices that require on-farm water retention have led to interest in flood-tolerant bioenergy crops for production in the Everglades Agricultural Area (EAA) of Florida. Information on the effects of high water tables on sugarcane (Saccharum spp. L.) is available; however, little is known about the bioenergy crops elephant grass (Pennisetum purpureum Schumach.), energycane (Saccharum spp. L.), and giant reed (Arundo donax L.). The objective of this study was to evaluate the role of water-table depth on the yields, morphology, physiology, and early season growth of these three bioenergy species in relation to sugarcane. The species were grown in a greenhouse and subjected to three water management strategies, ?40 or ?16 cm constant water-table depths, and bi-weekly flooding with drainage to ?40 cm. The experiment was conducted in plant-cane, first-ratoon, and successive plant-cane crop cycles. Periodic flooding relative to a ?40 cm constant water table significantly reduced dry weights and leaf area index and increased aerenchyma development. Averaged among crops, dry weight declined by 32, 49, 37, and 52% while leaf area index (LAI) decreased by 31, 50, 46, and 57% for giant reed, elephant grass, energycane, and sugarcane, respectively, in response to flooding. Aerenchyma proportional area of the stalk increased by 52, 90, and 95% for elephant grass, energycane, and sugarcane, respectively, but aerenchyma in giant reed decreased by 11%. High yields and stalk populations for all water tables were observed in energycane and elephant grass. These two species show potential for bioenergy production in the EAA. Field trials are recommended to confirm production scale yield. 相似文献
5.
Rodney A. Chimner David J. Cooper Marcie D. Bidwell Anthony Culpepper Kay Zillich Koren Nydick 《Restoration Ecology》2019,27(1):63-69
Ditching is a common practice to dewater wetlands, including peatlands, and ditch blocking is a common method for restoring wetlands because substrate is often unavailable for filling the ditches. However, filling has many advantages compared to blocking ditches. Our goal was to test whether ditches could be filled in a Colorado sloping fen (Chattanooga Fen) using bales created from shredded aspen (Populus tremuloides) tree‐fiber. We monitored water table levels before and after we filled two ditches (combined length of approximately 165 m × 3 m wide) as well as an undisturbed reference portion of Chattanooga fen. The reference site had stable water tables that rarely dropped more than 20 cm below the soil surface. The ditches had been dewatering large areas of the fen for at least 100 years. Filling the ditches with fiber bales resulted in a water table increase between 2 and 22 cm in an area up to 150 m below the ditch. Native sedges now cover the area where we filled the ditches, with no erosion or compression/settling of the ground observed and no water backing up behind the filled ditches. Filling the ditches with shredded fiber bales is a good option for restoration in wilderness areas, or areas lacking peat or mineral soil fill because it is a natural material that is easily transported and placed in the ditches. 相似文献
6.
Jeny Adina Larrea-Murrell Marcia Maria Rojas-Badia Ivette García-Soto Beatriz Romeu-Alvarez Tristano Bacchetti Annika Gillis Ana Karina Boltes-Espinola Mayra Heydrich-Perez Daysi Lugo-Moya Jacques Mahillon 《World journal of microbiology & biotechnology》2018,34(2):28
Genotypic and phenotypic characterization of Bacillus spp. from polluted freshwater has been poorly addressed. The objective of this research was to determine the diversity and enzymatic potentialities of Bacillus spp. strains isolated from the Almendares River. Bacilli strains from a polluted river were characterized by considering the production of extracellular enzymes using API ZYM. 14 strains were selected and identified using 16S rRNA, gyrB and aroE genes. Genotypic diversity of the Bacillus spp. strains was evaluated using pulsed field gel electrophoresis. Furthermore, the presence of genetic determinants of potential virulence toxins of the Bacillus cereus group and proteinaceous crystal inclusions of Bacillus thuringiensis was determined. 10 strains were identified as B. thuringiensis, two as Bacillus megaterium, one as Bacillus pumilus and one as Bacillus subtilis. Most strains produced proteases, amylases, phosphatases, esterases, aminopeptidases and glucanases, which reflect the abundance of biopolymeric matter in Almendares River. Comparison of the typing results revealed a spatio-temporal distribution among B. thuringiensis strains along the river. The results of the present study highlight the genotypic and phenotypic diversity of Bacillus spp. strains from a polluted river, which contributes to the knowledge of genetic diversity of Bacilli from tropical polluted freshwater ecosystems. 相似文献
7.
Katherine M. Laushman Sara C. Hotchkiss Bradley M. Herrick 《Biological invasions》2018,20(7):1671-1685
Because Upper Midwest temperate forests lack native earthworms, the invasions of European and Asian earthworms can significantly alter soils and understory vegetation. Earthworms’ ability to increase leaf litter decay, alter nutrient cycling by mixing the organic layer with mineral soil, and decrease plant species richness leads to concern about the Asian ‘jumping earthworm’ (Amynthas agrestis and A. tokioensis) species that were recorded in the University of Wisconsin—Madison Arboretum in 2013. In 2015, we found A. agrestis and A. tokioensis in a distinct 8-ha region of a 23-ha hardwood forest surveyed in the Arboretum; by 2016 A. agrestis and A. tokioensis had spread over an additional 7 ha. Plots also contained the European earthworm species Lumbricus terrestris, L. rubellus, and Apporectodea spp., whose distributions decreased from 2015 to 2016. While leaf litter, plant species richness, and tree and shrub seedling abundance were generally reduced in areas with European earthworms, they were typically slightly increased in areas with A. agrestis and A. tokioensis versus those without. Although our results do not show substantial impacts of A. agrestis and A. tokioensis on vegetation in the initial years of invasion, the rapid replacement of European earthworms by A. agrestis and A. tokioensis suggests continued monitoring of these new invasive species is important to better understand their potential to change the Upper Midwest’s forests. 相似文献
8.
Richard Hardi Gergely Babocsay Dennis Tappe Mihály Sulyok Imre Bodó Lajos Rózsa 《EcoHealth》2017,14(4):743-749
African pythons (Pythonidae) and large vipers (Bitis spp.) act as definitive hosts for Armillifer armillatus and Armillifer grandis parasites (Crustacea: Pentastomida) in the Congo Basin. Since the proportion of snakes in bushmeat gradually increases, human pentastomiasis is an emerging zoonotic disease. To substantiate the significance of this threat, we surveyed snakes offered for human consumption at bushmeat markets in the Kole district, Democratic Republic of the Congo, for the presence of adult pentastomids. In Bitis vipers (n = 40), Armillifer spp. infestations exhibited an 87.5% prevalence and 6.0 median intensity. Parasite abundance covaried positively with viper length, but not with body mass. In pythons (n = 13), Armillifer spp. exhibited a 92.3% prevalence and 3.5 median intensity. The positive correlations between parasite abundance and python length or mass were statistically nonsignificant. Ninety-one percent of A. grandis were discovered in vipers and 97% of infected vipers hosted A. grandis, whereas 81% of A. armillatus specimens were found in pythons and 63% of infected pythons hosted A. armillatus. Thus, challenging the widespread notion of strict host specificity, we found ‘reversed’ infections and even a case of coinfection. In this study, we also gathered information about the snake consumption habits of different tribal cultures in the area. Infective parasite ova likely transmit to humans directly by consumption of uncooked meat, or indirectly through contaminated hands, kitchen tools or washing water. 相似文献
9.
Tomáš Peterka Michal Hájek Daniel Dítě Petra Hájková Salza Palpurina Irina Goia Vít Grulich Veronika Kalníková Zuzana Plesková Anna Šímová Táňa Štechová 《Folia Geobotanica》2018,53(3):265-276
Quaking rich fens dominated by boreal semi-aquatic brown-mosses such as Scorpidium scorpioides and Calliergon trifarium are extremely rare in the Carpathians. These fens harbour endangered species persisting at few localities in the region. However, their phytosociological classification has not been sufficiently solved yet, because they lack Sphagnum species as well as calcicole species characteristic for the Caricion davallianae alliance. A recent pan-European synthesis on fen vegetation suggests that these fens belong to the Stygio-Caricion limosae alliance (boreal rich fen vegetation). The isolated occurrence of this alliance southward of the boreal zone and outside the Alps is rather exceptional and might represent a relict from an early post-glacial period. In this study, we compared phytosociological data for the Stygio-Caricion limosae alliance between Northern Europe and the Carpathians plus adjacent regions (the Bohemian Massif, the Dinaric Alps) using NMDS and cluster analysis. We found that the species composition of brown-moss quaking rich fens in Central and Southeastern Europe corresponds well with that in Northern Europe, confirming their assignment to Stygio-Caricion limosae. We further reconstructed the potential past distribution of the alliance in Czech Republic and Slovakia using available floristic and macrofossil data. Macrofossil data suggest that this vegetation type had been much more common in Central Europe and that today it persists only in ancient fens, showing the long-term stability of environmental conditions. The main causes of its present-day rarity are Middle-Holocene woodland phases in fens and recent water table decreases caused by anthropogenic deterioration of the water regime in the landscape. 相似文献
10.
Significant differences were revealed in the taxonomic structure of the epiphytic yeast communities formed on Sphagnum mosses and on the leaves of vascular plants. On mosses, low abundance of red yeasts was found (the most typical epiphytes on vascular plant leaves), along with a relatively high content and diversity of nonpigmented dimorphic basidiomycetes related to the order Leucosporidiales. The species composition of epiphytic yeasts from mosses is different from that of both forest and meadow grasses and of the parts of vascular plants submerged in the turf. The specific composition of the Sphagnum mosses yeast community is probably determined by the biochemical characteristics of this environment, rather than by the hydrothermal regime in the turf. 相似文献
11.
Peat bogs are regarded as extreme environments due to their low pH and low nutrient concentration, and thus hold a unique biota adapted to these particular conditions. The island of Tierra del Fuego encompasses the southernmost extensive peat bog area in the world, and is therefore particularly interesting from a biogeographical viewpoint. Within the same peat bog, different environment types can be identified: clear ponds, vegetated ponds and Sphagnum patches. In this study we compare the abundance, richness and species diversity of microinvertebrates (Copepoda, Cladocera and Rotifera) in these three types of environments from two peat bogs (Andorra and Rancho Hambre). Out of the 29 taxa recorded, 19 were common to both peat bogs, including four cladocerans endemic to Southern Patagonia and three rotifers endemic to Fuegian peat bogs. The rotifers were the dominant group in all environment types from Rancho Hambre, while in Andorra the Sphagnum moss was dominated by copepods, particularly harpacticoids. The results revealed that the environment type rather than peat bog was the key factor at explaining differences in species richness and diversity among microinvertebrate communities. This study highlights the importance of Sphagnum moss as a low diversity extreme environment which supports highly endemic species. 相似文献
12.
Edivani V. Franceschinelli Marcos A. S. Elias Leonardo L. Bergamini Carlos M. Silva-Neto Edison R. Sujii 《Journal of Insect Conservation》2017,21(4):715-726
Evidence shows that pollinator abundance has declined and, consequently, so has their services, which has possible negative impacts on ecosystem functioning. The goal of this study was to evaluate the influence of landscape context at multiple spatial scales on the abundance of bee pollinators of tomato crops in Brazil. Pollinator abundance was obtained from tomato crops grown in a conventional system in the Cerrado region. Around each tomato field circular buffers of 0.75, 1, 1.5, 2, and 3 km radius were defined. Inside each buffer the landscapes were manually classified into native and non-native cover and, the proportion of native vegetation, the relative largest patch size, and the distance of the nearest native vegetation to each field were calculated. Pollinator species were categorized into five groups: Exomalopsis, Centris, Bombus/Eulaema, Halictidae, and all buzz pollinators combined (Buzzers). The results showed that the landscape context influenced the abundance of the five groups of tomato pollinators. Bees with a smaller body size, such as Exomalopsis spp., responded at smaller scales, while bees with a larger body size, such as the Centris and Bombus/Eulaema groups, responded at larger scales. The abundance of all pollinator groups increased with native vegetation cover. Most groups showed higher abundances in landscapes with similar-size fragments. The results reinforce the recommendation for maintaining natural habitats around crop areas, even if fragmented, for the conservation of the tomato pollinator assemblage. These findings are valuable for planning landscape management in the studied area to improve bee conservation, ecosystem services, and food production. 相似文献
13.
Dimphna Nneka Ezike Catherine V. Nnamani Oluwatoyin T. Ogundipe Olushola H. Adekanmbi 《Aerobiologia》2016,32(4):697-707
The ambient atmosphere is dominated with pollen and spores, which trigger allergic reactions and diseases and impact negatively on human health. A survey of pollen and fungal spores constituents of the atmosphere of Garki, Abuja (North-Central Nigeria) was carried out for 1 year (June 1, 2011–May 31, 2012). The aim of the study was to determine the prevalence and abundance of pollen and fungal spores in the atmosphere and their relationship with meteorological parameters. Airborne samples were trapped using modified Tauber-like pollen trap, and the recipient solutions were subjected to acetolysis. Results revealed the abundance of fungal spores, pollen, fern spores, algal cysts and diatoms in decreasing order of dominance. The atmosphere was qualitatively and quantitatively dominated by pollen during the period of late rainy/harmattan season than the rainy season. Numerous fungal spores were trapped throughout the sampling periods among which Alternaria spp., Fusarium spp., Cladosporium spp. and Curvularia spp. dominated. These fungi have been implicated in allergic diseases and are dermatophytic, causing diverse skin diseases. Other pathogenic fungi found in the studied aeroflora were Dreschlera spp., Helminthosporium spp., Torula spp., Pithomyces spp., Tetraploa spp., Nigrospora ssp., Spadicoides spp., Puccinia spp. and Erysiphe graminis. Total pollen and fungal spores counts do not show significant correlation with meteorological parameters. 相似文献
14.
Thomas R. Newman Neal Wright Barbara Wright Sofie Sjögersten 《Wetlands Ecology and Management》2018,26(5):763-774
Peatlands are a critical carbon store comprising 30% of the Earth’s terrestrial soil carbon. Sphagnum mosses comprise up to 90% of peat in the northern hemisphere but impacts of climate change on Sphagnum mosses are poorly understood, limiting development of sustainable peatland management and restoration. This study investigates the effects of elevated atmospheric CO2 (eCO2) (800 ppm) and hydrology on the growth of Sphagnum fallax, Sphagnum capillifolium and Sphagnum papillosum and greenhouse gas fluxes from moss–peat mesocosms. Elevated CO2 levels increased Sphagnum height and dry weight but the magnitude of the response differed among species. The most responsive species, S. fallax, yielded the most biomass compared to S. papillosum and S. capillifolium. Water levels and the CO2 treatment were found to interact, with the highest water level (1 cm below the surface) seeing the largest increase in dry weight under eCO2 compared to ambient (400 ppm) concentrations. Initially, CO2 flux rates were similar between CO2 treatments. After week 9 there was a consistent three-fold increase of the CO2 sink strength under eCO2. At the end of the experiment, S. papillosum and S. fallax were greater sinks of CO2 than S. capillifolium and the ? 7 cm water level treatment showed the strongest CO2 sink strength. The mesocosms were net sources of CH4 but the source strength varied with species, specifically S. fallax produced more CH4 than S. papillosum and S. capillifolium. Our findings demonstrate the importance of species selection on the outcomes of peatland restoration with regards to Sphagnum’s growth and GHG exchange. 相似文献
15.
Brian M. Hoven David L. Gorchov Kathleen S. Knight Valerie E. Peters 《Biological invasions》2017,19(10):2813-2836
Invasive insects and plants are major threats to the health and viability of North American forests. Emerald ash borer (Agrilus planipennis) (EAB) may cause extensive changes to forest composition due to rapid ash (Fraxinus spp.) mortality. Invasive shrubs like Amur honeysuckle (Lonicera maackii) may benefit from EAB and have negative effects on woody seedlings. We predict that ash mortality has positive effects on seedling abundance, recruitment, and survival, but that these effects are influenced by L. maackii basal area and/or cover. We sampled 16 sites, representing a chronosequence of ash mortality throughout western Ohio. We tested whether L. maackii growth and fecundity varied in relation to ash decline. We also investigated effects of ash decline, stand basal area (BA), L. maackii BA and percent cover on woody seedling abundance, recruitment, and survival using linear mixed models evaluated with Akaike’s Information Criterion. These same responses were also investigated for four seedling groups: L. maackii, invasive plants (excluding L. maackii), shade tolerant natives, and shade intolerant natives. We found a significant positive relationship between ash decline and L. maackii BA growth. Lower seedling species richness corresponded with greater L. maackii BA and better ash condition. Greater L. maackii BA was also associated with lower seedling abundance and recruitment, as well as abundance and recruitment of shade-tolerant species, and recruitment of shade-intolerant species. Sites with poorer ash condition and greater L. maackii BA had more L. maackii seedlings. These findings indicate that the negative effects of L. maackii are more important to future forest composition than ash decline; however ash decline increases L. maackii growth, hence exacerbating the effects of this invasive shrub. 相似文献
16.
Maritime Spartina spp. are powerful ecosystem engineers that accrete sediment, define shorelines, create habitat, and generate prodigious primary productivity both where they are native and where they have been introduced. Invasive Spartina spp. can compete vigorously with native species, diminish biota, change hydrology, and confound human uses of estuaries. Herbicides have been effective in controlling several Spartina spp. invasions. One of the most recent successes is a 15-year campaign that has virtually eliminated S. alterniflora from the large, century-old invasion in Willapa Bay, WA, USA. Hybridization between native and introduced Spartina spp. has created new species and hybrid swarms. In San Francisco Bay, CA, USA (SF Bay) a complicated situation continues to play out from the purposeful introduction of S. alterniflora, which hybridized with native California cordgrass, S. foliosa. The hybrids spread rapidly and led to a long list of environmental problems, which led to an herbicide program that was successful in greatly diminishing the hybrid and saving the open mud habitat of migratory shorebirds. However, it was belatedly realized that the non-migratory, endangered Ridgeway’s rail uses the tall, dense hybrid Spartina as a surrogate for habitat that was lost during the twentieth century to urbanization and agricultural transformation of marshes around SF Bay. This realization has made difficult the simultaneous management of hybrid Spartina, wildlife conservation, and marsh restoration in San Francisco Bay. Restoration of native vegetation could satisfy the multiple goals of preserving open mud and conserving Ridgeway’s rail. 相似文献
17.
Jeong Soo Park Deokjoo Son Yoo Kyung Lee Jong Hak Yun Eun Ju Lee 《Journal of Plant Biology》2018,61(1):33-39
We investigated multivariate relationships among snowmelt, soil physicochemical properties and the distribution patterns of Arctic tundra vegetation. Seven dominant species were placed in three groups (Veg-1, 2, 3) based on niche overlap (Pianka’s Index) and ordination method, and a partial least squares path model was applied to estimate complex multivariate relationships of four latent variables on the abundance and richness of plant species. The abundance of Veg-1 (Luzula confusa and Salix polaris) was positively correlated with early snowmelt time, high soil nutrients and dense moss cover, but the abundance of Veg-2 (Saxifraga oppositifolia, Bistorta vivipara and Silene acaulis) was negatively correlated with these three variables. Plant richness was positively associated with early snowmelt and hydrological properties. Our results indicate that the duration of the snowpack can directly influence soil chemical properties and plant distribution. Furthermore, plant species richness was significantly affected by snow melt time in addition to soil moisture and moss cover. We predict that L. confusa and S. polaris may increase in abundance in response to early snowmelt and increased soil moisture-nutrient availability, which may be facilitated by climate change. Other forb species in dry and infertile soil may decrease in abundance in response to climate change, due to increasingly unfavourable environmental conditions and competition with mosses. 相似文献
18.
Debjani Basu Bharat Bhusan Majhi Rajasekaran Sripriya Karuppannan Veluthambi 《Journal of plant biochemistry and biotechnology.》2017,26(4):395-405
We report a new T-DNA-tagged rice plant chi7, which displays a severe dwarf phenotype, reduced plant vigour, and impaired panicle development in the homozygous state. By chromosome walking, T-DNA integration was mapped in chromosome 2, 1054-bp upstream of the translation start site of a gene (Os02g0820400), which we designate as DWARF SHOOT AND DEFECTIVE PANICLE1 (DSDP1). DSDP1 expression was unexpectedly higher in the homozygous mutant leaves than in the hemizygous mutant and control plant leaves. Mutant dsdp1 seeds, stored for 24 weeks, failed to germinate in soil. The growth vigour of the dsdp1 mutant reduced with increasing seed storage period. The dsdp1 mutant plants, grown in vitro on MS medium, formed short, stout, and ageotropic roots with lesser number of root hairs. The findings suggest that DSDP1 may function as a negative regulator of many developmental processes in rice. 相似文献
19.
Anuraag Boddupalli Rameshwar Tiwari Anamika Sharma Surender Singh Radha Prasanna Lata Nain 《Folia microbiologica》2017,62(3):253-262
There is a growing interest in the use of bioinoculants to assist mineral fertilizers in improving crop production and yield. Azotobacter and Pseudomonas are two agriculturally relevant strains of bacteria which have been established as efficient bioinoculants. An experiment involving addition of graded concentrations of zinc oxide (ZnO) nanoparticles was undertaken using log phase cultures of Azotobacter and Pseudomonas. Growth kinetics revealed a clear trend of gradual decrease with Pseudomonas; however, Azotobacter exhibited a twofold enhancement in growth with increase in the concentration of ZnO concentration. Scanning electron microscopy (SEM), supported by energy-dispersive X-ray (EDX) analyses, illustrated the significant effect of ZnO nanoparticles on Azotobacter by the enhancement in the abundance of globular biofilm-like structures and the intracellular presence of ZnO, with the increase in its concentration. It can be surmised that extracellular mucilage production in Azotobacter may be providing a barrier to the nanoparticles. Further experiments with Azotobacter by inoculation of wheat and tomato seeds with ZnO nanoparticles alone or bacteria grown on ZnO-infused growth medium revealed interesting results. Vigour index of wheat seeds reduced by 40–50% in the presence of different concentrations of ZnO nanoparticles alone, which was alleviated by 15–20%, when ZnO and Azotobacter were present together. However, a drastic 50–60% decrease in vigour indices of tomato seeds was recorded, irrespective of Azotobacter inoculation. 相似文献
20.
This study assessed the microbial diversity, activity, and composition of methane-oxidizing communities of a subarctic wetland in Russia with mosaic cover of Sphagnum mosses and lichens of the genera Cladonia and Cetraria. Potential methane-oxidizing activity of peat sampled from lichen-dominated wetland sites was higher than that in the sites dominated by Sphagnum mosses. In peat from lichen-dominated sites, major bacterial groups identified by high-throughput sequencing of the 16S rRNA genes were the Acidobacteria (35.4–41.2% of total 16S rRNA gene reads), Alphaproteobacteria (19.1–24.2%), Gammaproteobacteria (7.9–11.1%), Actinobacteria (5.5–13.2%), Planctomycetes (7.2–9.5%), and Verrucomicrobia (5.1–9.5%). The distinctive feature of this community was high proportion of Subdivision 2 Acidobacteria, which are not characteristic for boreal Sphagnum peat bogs. Methanotrophic community composition was determined by molecular analysis of the pmoA gene encoding particulate methane monooxygenase. Most (~80%) of all pmoA gene fragments revealed in peat from lichen-dominated sites belonged to the phylogenetic lineage represented by a microaerobic spiral-shaped methanotroph, “Candidatus Methylospira mobilis”. Members of the genus Methylocystis, which are typical inhabitants of boreal Sphagnum peat bogs, represented only a minor group of indigenous methanotrophs. The specific feature of a methanotrophic community in peat from lichen-dominated sites was the presence of uncultivated USCα (Upland Soil Cluster alpha) methanotrophs, which are typical for acidic upland soils showing atmospheric methane oxidation. The methanotrophic community composition in lichen-dominated sites of a tundra wetland, therefore, was markedly different from that in boreal Sphagnum peat bogs. 相似文献