Water sources of Populus euphratica and Tamarix ramosissima in Ejina Delta,the lower reaches of the Heihe River China北大核心CSCD

Aims: We aim to evaluate the water sources of typical riparian arbor species (Populus euphratica) and shrub species (Tamarix ramosissima), and analyze the spatial and temporal dynamics of plant water source in Ejina Delta, the lower reaches of the Heihe River. China. Methods: Eight sampling sites were selected in the riparian zones along the East River and West River in Ejina. The plant xylem water, soil moisture, rainwater, stream water and groundwater were taken and pretreated during the growing season in 2015-2016, and the stable oxygen isotope ratio (δ18O) for each water sample was measured. The δ18O of plant xylem water and soil moisture were compared to estimate the dominant depth of root water uptake, and the linear-mixed model called "IsoSource" were applied to determine plant water sources and quantify their proportions. Important findings: This study indicated that the main recharge sources for P. euphratica and T. ramosissima were stream water and groundwater. The contributions of rain water to them was negligible due to the limited amount and the shallow infiltration depth of local rainfall. As affected by groundwater level fluctuation, soil physical properties, as well as lateral and vertical recharge of stream water on soil moisture, the dominant depth of root water uptake spatially varied. However, the relative contributions of stream water or groundwater to plant water sources did not change significantly across space. Populus euphratica used more stream water (68%), while T. ramosissima used more groundwater (65%). Plant water sources were sensitive to environmental flow controls. The contributions of stream water to the water sources of the two species went up to 84% and 48% for P. euphratica and T. ramosissima respectively during the discharge period, but dropped to 63% and 30% during the non-discharge period. On the other hand, the contributions of groundwater decreased to 16% and 52% during the discharge period, but increased to 37% and 70% during non-discharge period. It is noteworthy that the high similarity of δ18O between stream water and groundwater due to extensive water exchange in the riparian zone made increase the uncertain in quantifying plant water sources.     

The Dutch N-cascade in the European perspective

The Netherlands is "well known" for its nitrogen problems; it has one of the highest reactive nitrogen (Nr) emission densities in the world. It is a small country at the delta of several large European rivers. Ever since the industrial revolution, there has been a growing excess of nutrients and related emissions into the atmosphere (ammonia, nitrogen oxides and nitrous oxide) and into groundwater and surface water (nitrate), leading to a large range of cascading environmental impacts. Vehicular traffic, sewage and animal husbandry are the main sources of oxidized and reduced forms of Nr. This paper provides an overview of the origin and fate of nitrogen in the Netherlands, the various reported impacts of nitrogen, the Dutch and European policies to reduce nitrogen emissions and related impacts. In addition, ways are presented to go forward to potentially solve the problems in a European perspective. Solutions include the improvement of nitrogen efficiencies in different systems, technological options and education.     

Screening landraces for additional sources of field resistance to cassava mosaic disease and green mite for integration into the cassava improvement program

Twelve cassava landraces were evaluated for sources of resistance genes to diseases and pests of major economic importance in Africa. The objective was to assess their levels of field resistance to mosaic disease （ACMD）, bacterial blight （CBB）, anthracnose （CAD）, and green mite （CGM）, compared to TMS30572, an elite cultivar widely adopted in Africa. Considerable genotypic variation was observed among cultivars for resistance to ACMD and CGM but not for CBB and CAD. The lowest mean incidence of 12% and severity of 1.8 on a scale of 1-5 for ACMD was recorded for Atu, a landrace with farmer acceptable qualities. In comparison, the improved cultivar, TMS 30572, had a mean disease incidence of 72% and a severity score of 2.8. Another landrace, MS-20 had the lowest CGM damage score （2.1） while TMS 30572 emerged as one of the susceptible cultivars with a damage score of 3. Additional sources of resistance to ACMD and CGM that may possibly be better than the popular improved cultivar, TMS 30572, were identified in this study. These could serve as novel sources of additional genes to complement existing resources for elite cassava breeding in Africa.     

Phenotypic analysis of Phytophthora parasitica by using high throughput phenotypic microarray北大核心CSCD

［Objective］We studied the phenotypic characterization of Phytophthora parasitica Dastur var.nicotianae．［Methods］Phenotypic characterization of the pathogen was studied to provide information for disease management program by using BIOLOG phenotype MicroArray(PM).Using PM plates 1 to 10,950 different phenotypic characterizations were tested.［Results］P．parasitica was able to metabolize 74% of tested carbon sources,96% of nitrogen sources,100%of sulfur sources,and 98%of phosphorus sources.Most informative utilization patterns for carbon sources of P．parasitica were organic acids and carbohydrates,and for nitrogen were various amino acids.The pathogen presented 285 different nitrogen pathways.It had wide range adaptabilities in osmolytes with up to 1%sodium chloride,up to 3%potassium chloride,up to 5%sodium sulfate,up to 20%ethylene glycol,up to 2%sodium formate,up to 5% urea,and up to 2% sodium lactate.It also exhibited active metabolism under pH values between 3.5 and 10,with optimal pH of around 7.0.The pathogen showed both decarboxylase and deaminase activities in the presence of various amino acids.［Conclusion］These phenotypic characterizations of P．parasitica provided the theoretical basis for the next study of the pathogen in physiology and metabolism,and provided potential new way for tobacco black shank management.     

COMPARATIVE DEMOGRAPHICS OF A GENERALIST PREDATORY LADYBIRD ON FIVE APHID PREY： A LABORATORY STUDY

Prey driven demographic parameters of an aphidophagous ladybird, Propylea dissecta (Mulsant) were studied in attempt to answer how ladybird overcomes the problem of seasonally fluctuating food base. The ladybird reared for five generations in laboratory derived differential nutrition from five food sources (i.e. aphid species, Rhopalosiphum maidis (Fitch), Aphis craccivora Koch, Aphis gossypii Glover, Uroleucon compositae (Theobald) and Lipaphis erysimi (Kalt.)). The order of relative prey suitability was A. gossypii, A. craccivora, R. maidis, U. compositae and L.erysimi. Neonates suffered maximum mortality followed by eggs. Estimates of net reproductive rate,intrinsic rate of increase and finite rate of increase were highest (407.18, 0.2274 day^-1, 1.2553 day^-1) on A. gossypii and lowest (176.02, 0.1533 day^-1, 1.1657 day^-1) on L. erysimi. Generation time was shortest (26.43 days) on A. gossypii and longest (33.73 days) on L. erysimi. The present study thus,provides an explanation to the high incidence of P. dissecta on A. gossypii, as it experienced high intrinsic rate of increase and optimal values for related demographic parameters.     

Identification of neurons responsible for feeding behavior in the Drosophila brain

Drosophila melanogaster feeds mainly on rotten fruits,which contain many kinds of sugar.Thus,the sense of sweet taste has evolved to serve as a dominant regulator and driver of feeding behavior.Although several sugar receptors have been described,it remains poorly understood how the sensory input is transformed into an appetitive behavior.Here,we used a neural silencing approach to screen brain circuits,and identified neurons labeled by three Gal4 lines that modulate Drosophila feeding behavior.These three Gal4 lines labeled neurons mainly in the suboesophageal ganglia(SOG),which is considered to be the fly’s primary taste center.When we blocked the activity of these neurons,flies decreased their sugar consumption significantly.In contrast,activation of these neurons resulted in enhanced feeding behavior and increased food consumption not only towards sugar,but to an array of food sources.Moreover,upon neuronal activation,the flies demonstrated feeding behavior even in the absence of food,which suggests that neuronal activation can replace food as a stimulus for feeding behavior.These findings indicate that these Gal4-labeled neurons,which function downstream of sensory neurons and regulate feeding behavior towards different food sources is necessary in Drosophila feeding control.     

Water sources of dominant species in three alpine ecosystems on the Tibetan Plateau, China

Plant water sources were estimated by two or three compartment linear mixing models using hydrogen and oxygen isotope （δD and δ^18O） values of different components such as plant xylem water, precipitation and river water as well as soil water on the Tibetan Plateau in the summer of 2005. Four dominant species （Quercus aquifolioides, Pinus tabulaeformis, Salix rehderiana and Nitraria tangutorum） in three typical ecosystems （forest, shrub and desert） were investigated in this study. Stable isotope ratios of the summer precipitations and the soil water presented variations in spatial and temporal scales. δ^18O values of N. tangutorum xylem water were constant in the whole growth season and very similar to those of deep soil water. Water sources for all of the plants came from both precipitations and soil water. Plants switched rapidly among different water sources when environmental water conditions changed. Rainwater had different contributions to the plants, which was influenced by amounts of precipitation. The percentage of plant xylem water derived from rainwater rose with an increase in precipitation. Water sources for broad-leaved and coniferous species were different although they grew in the same environmental conditions. For example, the broad-leaved species Q. aquifolioides used mainly the water from deep soil, while 92.5% of xylem water of the coniferous species P. tabulaeformis was derived from rainwater during the growth season. The study will be helpful for us to fully understand responses of species on the Tibetan Plateau to changes in precipitation patterns, and to assess accurately changes of vegetation distribution in the future.     

Landscape hydrogeomorphic conditions determine structure and species composition of an ephemeral floodplain wetland

Wetlands are major sources of habitat heterogeneity, with certain environmental variables controlling wetland structure and composition. There is very little information on the heterogeneity of ephemeral floodplain wetland patch mosaics and how hydrogeomorphic circumstance affects composition and structure. Structure (wetland size) and composition (herbaceous species) are two attributes of an ephemeral wetland that are easily quantifiable using a moving window analysis. The moving window analysis is a statistical technique that identifies significant changes in parameters (i.e., structure and composition) along gradients. An analysis of changes in wetland structure and composition longitudinally identified two hydrogeomorphic types and laterally delineated wetland boundaries. The wide–flat type had a wide (131.2 ± 50.4 m) wetland patch and a mean lateral slope of 0.008 ± 0.003, in contrast the narrow–deep type had a significantly smaller (80 ± 40.2 m) and steeper (0.048 ± 0.06) wetland patch. Changes in hydrogeomorphology had distinct effects on the species composition of the wetland. Facultative wetland species such as Sporobolus pyrimidalis and Ischaemum afrum were associated with the wide–flat type, while, the narrow–deep type was characterized by more obligate, flood dependent species such as Phragmites australis, Mariscus congestus, and Eriochloa meyeriana. Internally, the structure and composition of ephemeral wetlands on the northern plains of Kruger National Park were spatially heterogeneous and correlated to hydrogeomorphic conditions, that are identifiable when examined at the wetland scale. Results add knowledge to wetlands as sources of landscape heterogeneity and highlight how environmental variation can result in increases in wetland heterogeneity.     

Offshore wave energy generation devices: Impacts on ocean bio-environment

As the crisis of petroleum-based energy is aggravating and the carbon emission is elevating, the search and exploitation of renewable energy sources such as solar, wind and oceanic powers, are of global interest and underway in some developed countries. In western countries pioneering the oceanic energy utilization, wave is currently an attractive energy source due to the predictability and the ease to be absorbed into power grid. As wave-energy generators (WEGs) and the associated devices interact with the surrounding environment, they would have impacts on the biological components within the ecosystem in the vicinity of WEGs. However, the environmental effects of offshore WEGs on local fauna and flora have yet to be evaluated in a comprehensive way. This article discusses several aspects, including influence of offshore WEGs on marine macrofaunal communities, interactions between offshore WEGs and biofouling organisms, impacts of offshore WEGs on marine birds and of electromagnetic fields (EMFs) on marine animals as well as “artificial reef” effects. If precaution is taken with the planning and construction of offshore WEGs, and environmental monitoring is performed with operation of these devices, marine wave energy can become a desirable alternative to fossil fuels.     

Light quality influences germination, root growth and hypocotyl elongation in somatic embryos but not in seedlings of norway spruce

Summary We studied how light from different light sources influences germination and postgerminative growth of plants from somatic embryos and seeds of Norway spruce (Picea abies [L.] Karst). Somatic embryos of three spruce genotypes and seeds were subjected to light from commercially available light sources: Philips TLD Blue 18W/18 (BL), Osram Fluora (FL), Philips Cool White TL 50W/33 (CW), Osram Warm White 18W/30 (WW), Philips Yellow 36W/16 (YE) and Philips TLD Red 36W/15 (RE), 18 h a day, with a photon flux (PAR) at 30 μmol m⁻² s⁻¹. After 6 wk the germination frequencies of the somatic embryo-derived plantlets were 50% under BL and 98% under RE. The corresponding mean root lengths were 6.7 and 15.4 mm. In somatic embryo-derived plantlets cultured under BL, FL, CW and WW, both roots and hypocotyls turned brown, presumably due to production of phenolic substances. Browning was less severe in somatic embryo-derived plantlets cultured under RE and YE. Under RE, the epicotyl elongated in 37% of the plantlets after 6 wk, compared with 70% under the other light sources. Seed germination and postgerminative seedling growth was modestly influenced by light from these light sources. RE and WW initially delayed germination as compared with BL, FL and CW, but after 2 wk, more than 90% of the seeds had germinated under all light sources. In conclusion, germination and postgerminative growth of somatic embryos of spruce is sensitive to differences in light quality, whereas seed germination and seedling growth is not.     

Changes in a deep lake following sewage diversion – a challenge to the orthodoxy of external phosphorus control as a restoration strategy?

1. The restoration of deep lakes has traditionally focused on reducing the external phosphorus loading. 2. Following the diversion of sewage effluent, that led to marked reductions in nutrient concentrations in its main inflow, Rostherne Mere has shown no reduction in phosphorus or chlorophyll a concentrations. A shallow lake upstream (Little Mere), however, has shown a marked response to effluent diversion. 3. Nutrient budgets for Rostherne Mere reveal that sewage effluent was by far the most significant external source of total phosphorus and that diffuse drainage from the catchment was the most significant external source of dissolved inorganic nitrogen. Phosphorus loads from groundwater and a bird roost were insignificant. Internal sources of phosphorus were, however, considerable and were largely responsible for the observed delay in recovery. 4. Phosphorus limitation of phytoplankton biomass may never be attainable because of substantial internal and diffuse sources of phosphorus, combined with a long retention time. Nitrogen is likely to be more important in limiting phytoplankton biomass. Control of diffuse nitrogen sources may therefore be more effective in the restoration of the deeper lakes of this region.     

茶薪菇菌丝液体培养的营养需求

探索茶薪菇菌丝液体培养所需的营养条件,并测定了供试氛源和碳源所培养的菌丝的粗蛋白。结果表明：氨源以玉米浆、蛋白胨最佳;碳源以玉米粉、可溶淀粉最适宜;最佳的碳氮比为20．8：1;有机酸中仅富马酸对其生长有促进作用;磷和锌为菌丝生长的必需矿质元素。     

Variable responses of old-field perennials to arbuscular mycorrhizal fungi and phosphorus source

If arbuscular mycorrhizal fungi (AMF) promote phosphorus partitioning of plant hosts, they could provide one mechanism for the maintenance of plant community diversity. We investigated whether AMF improved the ability of old field perennials to grow on a range of phosphorus sources and whether AMF facilitated differential performance of plant species on different phosphorus sources (phosphorus niche partitioning). We manipulated form of phosphorus (control versus different inorganic and organic sources) and AM fungal species (control versus four individual AMF species or an AMF community) for five old field perennials grown in a greenhouse in individual culture. Based on biomass after four months of growth, we found no evidence for phosphorus niche partitioning. Rather, we found that effects of AMF varied from parasitic to mutualistic depending on plant species, AMF species, and phosphorus source (significant Plant × Fungus × Phosphorus interaction). Our results suggest that the degree of AMF benefit to a plant host depends not only on AMF species, plant species, and soil phosphorus availability (as has also been found in other work), but can also depend on the form of soil phosphorus. Thus, the position of any AMF species along the mutualism to parasitism continuum may be a complex function of local conditions, and this has implications for understanding plant competitive balance in the field.     

Metabolic Factors Affecting Enhanced Phosphorus Uptake by Activated Sludge

Activated sludges obtained from the Rilling Road plant located at San Antonio, Tex., and from the Hyperion treatment plant located at Los Angeles, Calif., have the ability to remove all of the orthophosphate normally present in Tucson sewage within 3 hr after being added to the waste water. Phosphorus removal was independent of externally supplied sources of energy and ions, since orthophosphate and (32)P radioactivity were readily removed from tap water, glass-distilled water, and deionized water. Phosphorus uptake by Rilling sludge in the laboratory appears to be wholly biological, as it has an optimum pH range (7.7 to 9.7) and an optimum temperature range (24 to 37 C). It was inhibited by HgCl(2), iodoacetic acid, p-chloromercuribenzoic acid, NaN(3), and 2, 4-dinitrophenol (compounds that affect bacterial membrane permeability, sulfhydryl enzymes, and adenosine triphosphate synthesis). Uptake was inhibited by 1% NaCl but was not affected by 10(-3)m ethylenediaminetetraacetic acid disodium salt (a chelating agent for many metallic ions).     

Phosphate starvation-inducible gene ushA encodes a 5' nucleotidase required for growth of Corynebacterium glutamicum on media with nucleotides as the phosphorus source

Phosphorus is an essential component of macromolecules, like DNA, and central metabolic intermediates, such as sugar phosphates, and bacteria possess enzymes and control mechanisms that provide an optimal supply of phosphorus from the environment. UDP-sugar hydrolases and 5' nucleotidases may play roles in signal transduction, as they do in mammals, in nucleotide salvage, as demonstrated for UshA of Escherichia coli, or in phosphorus metabolism. The Corynebacterium glutamicum gene ushA was found to encode a secreted enzyme which is active as a 5' nucleotidase and a UDP-sugar hydrolase. This enzyme was synthesized and secreted into the medium when C. glutamicum was starved for inorganic phosphate. UshA was required for growth of C. glutamicum on AMP and UDP-glucose as sole sources of phosphorus. Thus, in contrast to UshA from E. coli, C. glutamicum UshA is an important component of the phosphate starvation response of this species and is necessary to access nucleotides and related compounds as sources of phosphorus.     

Physiological Aspects of Cluster Root Function and Development in Phosphorus-deficient White Lupin (Lupinus albus L.)

Cluster root formation in white lupin (Lupinus albus L.) isinduced mainly by phosphorus (P) starvation, and seems to beregulated by the endogenous P status of the plant. Increasedformation of cluster roots, when indole acetic acid is suppliedto the growth medium of P sufficient plants, and inhibitoryeffects of kinetin application suggest the involvement of endogenousphytohormones (auxins and cytokinins), which may act in an antagonisticmanner in the P-starvation response. Phosphorus deficiency-inducedadaptations of white lupin, involved in P acquisition and mobilizationof sparingly available P sources, are predominantly confinedto the cluster roots, and moreover to distinct stages duringtheir development. Increased accumulation and exudation of citrateand a concomitant release of protons were found to be mainlyrestricted to mature root clusters after prolonged culture (3–4weeks) under P-deficient conditions. Inhibition of citrate exudationby exogenous application of anion channel antagonists such asethacrynic- and anthracene-9-carboxylic acids may indicate involvementof an anion channel. Phosphorus deficiency-induced accumulationand subsequent exudation of citric acid seems to be a consequenceof both enhanced biosynthesis and reduced turnover of citricacid in the cluster root tissue, indicated by enhanced expressionof sucrose synthase, fructokinase, phosphoglucomutase, phosphoenol-pyruvatecarboxylase, but reduced activity of aconitase and slower rootrespiration. The release of acid phosphatase and of phenoliccompounds (isoflavonoids) as well as the induction of a putativehigh-affinity P uptake system was more highly expressed in juvenile,mature and even senescent cluster regions than in apical zonesof non-proteoid roots. An AFLP-cDNA library for cluster root-specificgene expression was constructed to assist in the identificationof further genes involved in cluster root development. Copyright2000 Annals of Botany Company Acid phosphatase, auxin, citric acid, cluster roots, cytokinin, Lupinus albus L., P acquisition, P uptake, root exudates     

Nutrient Reabsorption Mechanism Adapted to Low Phosphorus in Wild and Cultivated Soybean Varieties

Journal of Plant Growth Regulation - Phosphorus (P) plays an important role in soybean growth and reproduction. Wild soybean (Glycine soja) expressed higher tolerance to P-limited environment...     

Species and Biogeochemical Cycles of Organic Phosphorus in Sediments From a River With Different Aquatic Plants Located in Huaihe River Watershed,China

The results of phosphorus fractionation in the sediments from a contaminated river containing different aquatic plants, analyzed by solution ³¹P-NMR for Organic Phosphorus, showed that the concentration of Inorganic Phosphorus dominated in all species and Organic Phosphorus accounted for over 20% of Total Phosphorus. In general, orthophosphate was dominant in all the sampling sites. The proportion of Organic Phosphorus accounting for the Total Phosphorus in the sediments with different plant decreased in the following order: Paspalum distichum > Typha orientalis > Hydrilla verticillata. Phosphorus-accumulation ability of Paspalum distichum was obviously stronger than Typha orientalis and Hydrilla verticillata. The Organic Phosphorus was in aquatic plants dominated by humic-associated P (Hu-P), which converted to Inorganic Ohosphorus more significantly in submerged plants than in emerged plants. The sediment dominated by Paspalum distichum abundantly accumulated Organic Phosphorus in the orthophosphate monoester fraction. The degradation and mineralization of orthophosphate monoester was the important source of high Inorganic Phosphorus concentration and net primary productivity in Suoxu River. The Organic Phosphorus derived from Typha orientalis and Hydrilla verticillata was dramatically converted to Inorganic Phosphorus when the environmental factors varied.     

The response of Solanum melongena L. to different phosphorus levels and sowing dates

In order to harvest potential yield of eggplant and to find a suitable sowing time and phosphorus level for eggplant, an experiment was conducted at Ornamental Nursery, Department of Horticulture, The University of Agriculture Peshawar in February 2013. The experiment was laid out in randomized complete block (RCB) design with split plot arrangements. There were two factors i.e. Phosphorus levels and dates of Sowing. Phosphorus levels were assigned to the main plot while sowing dates were kept in the subplot. The data on Number of branches plant⁻¹, Days to flowering^, Days to fruiting, Number of fruits plant⁻¹ and Yield Plot⁻¹were significantly affected by phosphorus level and date of sowing. While the data on plant height was not significant, and overall results showed that early sowing date (February 25) produced significantly good results as compared to the rest of the sowing dates. Moreover, phosphorus level was also significantly affected the experimental parameters. Phosphorus level (70 kg ha⁻¹) produced significantly best results in all the parameters followed by Phosphorus level (100 kg ha⁻¹) in almost all the parameters. Thus it is concluded that early sowing of bringel (eggplants) is recommended with phosphorus level (70 & 100 kg ha⁻¹).     

Localisation of phosphomonoesterase activity in ectomycorrhizal fungi grown on different phosphorus sources

Phosphorus (P) is a major limiting nutrient for plants in boreal forest ecosystems where a substantial part of the total P is sequestered in organic compounds. Some ectomycorrhizal (ECM) fungi are known to produce phosphomonoesterases, enzymes that degrade organic P sources. Here, we test 16 ECM species for this enzymatic activity by growing them on media containing orthophosphate, phytic acid or apatite. A method with an overlay gel that determined both phosphomonoesterase activity and its spatial distribution was developed. The phosphomonoesterase activity was not significantly higher when growing on organic P; conversely some isolates only produced measurable enzyme activity when grown on apatite. Species-specific variations with respect to phosphomonoesterase activity as well as growth responses to different substrates were found. The production of phosphomonoesterases was found to be widespread in ECM fungi and the enzyme activity did not need induction by organic P. The enzyme activity was highest in the central parts of the mycelia, potentially reflecting breakdown and recycling of phospholipids from old hyphae or potentially higher mycelial density.