Breeding for seedling traits in herbaceous perennial biomass feedstocks that translate into increased biomass yield or quality in established swards could accelerate the development of perennial grass cultivars for bi...Breeding for seedling traits in herbaceous perennial biomass feedstocks that translate into increased biomass yield or quality in established swards could accelerate the development of perennial grass cultivars for bioenergy or forage. In previously reported research, breeding for single large tillers (ST) or multiple tillers (MT, ≥3) six weeks after planting for two generations in big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicum virgatum L.) base populations produced ST and MT populations that differed significantly for seedling and mature plant traits including biomass yield in spaced planted nurseries. Our objective was to evaluate these ST and MT populations in sward trials to determine the effect of these genetic changes on biomass yield and quality when the plants were grown in competitive sward conditions. Big bluestem monocultures of the base, ST, and MT populations were evaluated at three locations in Nebraska in 2001 and 2002 as randomized complete block experiments with four replicates. Switchgrass monocultures of the base, ST, and MT populations were evaluated in 2003, 2004, and 2005 near Mead, NE as a randomized complete block with six replicates. In both big bluestem and switchgrass, the ST and MT populations did not consistently differ from the base population or each other for biomass yield or forage quality. These results demonstrate the importance of evaluating perennial grasses in sward trials and not relying solely on greenhouse-grown plants or space-planted nurseries to develop selection criteria and make selection decisions.展开更多
On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made b...On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.展开更多
Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period...Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period when ephemeral streams had low surface flows.Sampling was realized contiguously using belt transects.The standing crop biomass(hereafter biomass)of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity.Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams.Out of 24 herbs,only three were common for both.A peak herb biomass zone was observed in perennials in the same region where diversity peaked.In ephemerals,herb biomass increased laterally up to^1.5 m,and was constant thereafter.Seedling experiment results tallied with the field diversity observations of both stream types,and suggested that seed dispersion was the main reason for herb colonization.Furthermore,it showed sapling emergence to be significantly higher in perennials than ephemerals.Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams,and elucidated the possibility of hindcasting past flow episodes.Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters.The contents of the water nutrients were approximately the same in both stream types.While recommending further studies on eco-hydrology of ephemerals,we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.展开更多
Objective: The comparison of the remote and recent therapeutic effects on perennial allergic rhinitis was carried on among single application of acupoint-thread embedding, western medicine (certirizine+flixonase) and ...Objective: The comparison of the remote and recent therapeutic effects on perennial allergic rhinitis was carried on among single application of acupoint-thread embedding, western medicine (certirizine+flixonase) and allied therapy. Method: Ninety cases were randomized into thread-embedding group, western medicine group and embedding+western medicine group (allied-therapy group), 30 cases in each one. In thread embedding group, Yingxiang (迎香 LI 20) and Feishu (肺俞 BL 13) were selected for thread embedding, once a week, totally 4 treatments were required. In western medicine group, certirizine tablet 10 mg in combination with flixonase sprayer was applied once per day, continuously for 30 days in treatment. In allied-therapy group, both of the above methods were adopted continuously for 30 days in treatment. The therapeutic effects were in statistics at the end of treatment and 1 year later. Results: At the end of treatment, in thread-embedding group, 21 cases were remarkably effective, 3 cases effective and 6 cases no effect. In western medicine group, 20 cases were remarkably effective, 3 cases effective and 7 cases no effect. In allied-therapy group, 23 cases were remarkably effective, 2 cases effective and 5 cases no effect. It was shown in statistics that there was no significant difference in therapeutic effects among three groups ( P>0.05 ). But one year after the end of treatment, it was indicated that in thread-embedding group, 3 cases were remarkably effective, 10 cases effective and 17 cases no effect; in western medicine group, 2 cases were remarkably effective, 9 cases effective and 19 cases no effect; in allied-therapy group, 7 cases were remarkably effective, 11 cases effective and 12 cases no effect. The significant difference in the therapeutic effects had not been presented in the comparison between thread-embedding group and western medicine group (P>0.05), but that had been presented between allied-therapy group with either of the groups with single therapy applied (P<0.05). Conclusion: Quite good recent therapeutic effect of either acupoint-thread embedding or western medicine (certirizine+flixonase) was achieved on perennial allergic rhinitis. The remote therapeutic effect of allied therapy was more advantageous than that of single application of either thread embedding or western medicine.展开更多
The native prairies of the Great Plains USA are dominated by perennial C4 grasses like switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii). Spring hard freeze injury to C4 perennial grasses is rare b...The native prairies of the Great Plains USA are dominated by perennial C4 grasses like switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii). Spring hard freeze injury to C4 perennial grasses is rare but information is lacking in the literature. Our objective was to document effects of spring hard freeze damage to C4 perennial grasses native to the Great Plains USA. On 2 May at 24:00 pm, air temperature near Mead, Nebraska was below freezing and remained below freezing until 8:00 am on 3 May, with a minimum air temperature of -2.8°C. Based on 50-year of weather data for this site, a minimum threshold temperature of 0°C on or after 3 May occurred 16 times, but a minimum threshold temperature of -2.8°C on or after 3 May occurred only twice. Grass tillers were visually evaluated to determine extent of freeze damage. The terminal 3- to 5-cm of the leaf lamina was blackened 4-d after freezing and had complete browning, rolling, and desiccation 14-d after freezing. Tiller survival was not negatively affected by the freezing temperatures in May 2004. As the growing season progressed, all agronomic and livestock responses were within normal ranges for these C4 grasses. This is the first field report of multiple C4 prairie grass species responses to a spring hard freeze following significant spring growth. Plant recovery to this late-spring hard freeze demonstrates the ecological resilience of these C4 prairie grasses. These rare spring hard freezes had short-term impacts on C4 grasses but did not negatively impact agronomic performance for forage or bioenergy later in the growing season.展开更多
Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and...Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and soil moisture control plant growth and development through various complex molecular mechanisms. Crown and seed dormancy of plants are mostly influenced by day length and temperature. Genes and physiological pathways triggered by these two factors along with genotype variability are some targets to manipulate seasonal dormancy. There is genetic variation in the depth and duration of seasonal dormancy. Therefore, their genetic manipulation is possible. Manipulations of summer and fall dormancy are relatively easier compared to winter dormancy because plants require protection of their apical meristem from freezing temperatures and limited water supply. Genetic factors that regulate seed dormancy may also have regulatory role for seasonal dormancy of the maternal plants. Limited genetic and genomic information are available for seasonal dormancy in herbaceous perennial species. Knowledge of genes controlling seasonal dormancy of eudicots, forest trees, and horticultural crops could be interpolated to explore possible dormancy mechanisms in perennial forages. This study reviews current knowledge of seasonal dormancy of herbaceous forages emphasizing the genetic and physiological context that would be valuable to breeders and plant biologists to expand the production season of perennial species by developing non-dormant and semi-dormant cultivars.展开更多
In order to determine the threshold and potential distribution of climatic conditions for perennial cultivated grasses in the Northwest plateau of Sichuan, China, the niche model is used to simulate the main climatic ...In order to determine the threshold and potential distribution of climatic conditions for perennial cultivated grasses in the Northwest plateau of Sichuan, China, the niche model is used to simulate the main climatic factors affecting the distribution of perennial cultivated grasses, and to predict the current and future climate change prospects. The results show that: 1) Wet index, accumulated temperature, isothermal, and annual average temperature range are the four major climatic factors affecting the distribution of perennial cultivated grasses in the Northwest Sichuan Plateau. 2) Model training and prediction data can be achieved well under the appropriate range of major climatic factors. 3) Under the background of climate warming, from now to 2080, the potential distribution of perennial cultivated grasses in the Northwest plateau of Sichuan, China will increase. The study aims to provide scientific decision-making basis for maintaining grassland ecosystem stability and promoting desertification management and even industrial restructuring of agriculture and animal husbandry.展开更多
It has been proposed that salt-tolerant plant could be used as a feed resource for ruminants whereby salt would be removed from salinized land (Asian -Aust. J. Anim. Sci. (2002) 15:998 -1001). Ceratoides arborescens (...It has been proposed that salt-tolerant plant could be used as a feed resource for ruminants whereby salt would be removed from salinized land (Asian -Aust. J. Anim. Sci. (2002) 15:998 -1001). Ceratoides arborescens (Losinsk.) Tsien et C. G. Ma is known as a drought-and salt-tolerant plant,a kind of shrubs, growing in semi-arid land of Inner Mongolia. Because the covering effect of the perennial plant as a mulch over the soil might be expected, the optimum covering effect would be obtained after the growth period.The perennial plant produces seeds around summer and end its growth thereafter. Nutrient value of the perennial salt-tolerant plant, however,had not been reported in flowering period at different year. It is necessary to know the ruminal degradability of the plants of each growing year in order to determine the regimen to diet for ruminants. The present experiment,therefore,was undertaken to analyze the digestibility and chemical composition of Ceratoides arborescens as feed for ruminants.展开更多
Objective: The partial inferior turbinectomy and septoplasty was applied to treat the allergic perennial rhinitis (APR), and to observe the ultrastructure changes of the nasal mucosa before and after the operations. M...Objective: The partial inferior turbinectomy and septoplasty was applied to treat the allergic perennial rhinitis (APR), and to observe the ultrastructure changes of the nasal mucosa before and after the operations. Methods: For 36 cases of research objects diagnosed with APR, the partial inferior turbinectomy and septoplasty was administered. For 6 APR cases among them, the pre- and postoperative observation of anterior nasal mucosa of the inferior turbinate on the same side under the electron microscope was conducted for one year respectively. In addition, their pathological alterations of tissues were also conducted. Results: In the pre-operative observation under the electron microscope, it was found that the nasal mucosae epithelium cells were nude without cilia. The lamina propria had edema, and mesenchyme presented the infiltration of substantial eosinophilic granulocytes, basophilic granulocytes, plasmacytes and mast cells. Additionally, abundant degranulation and vacuolation of cytoplasts were observed. The plentiful glands, duct ectasia, edema and structural changes were also found. Some gland cells had degenerated. After the operation, it was found that the epithelium nudity still existed and the deficiency of cilia was not improved. Only a very small amount of microvilli existed. The edema of lamina propria was improved and eosinophilic granulocytes were rarely observed in mesenchyme. However, the infiltration of basophilic granulocytes, plasmocytes and mast cells was still observed. The particle structure was generally stable and the central crystal was clear without degranulation. Meanwhile, the amount of glands was reduced and the tissue structure tended to be recovered. Overall, the nasal mucosa showed changes as chronic inflammation. Conclusions: For the treatment of APR with the methods presented by our research institution, in one year before and after the operation, ultrastructural changes of inferior turbinate mucosa tissues were observed from the preoperatively pathological changes of typical APR to the chronic inflammation with the primary infiltration of neutrophilic granulocyte and mast cells.展开更多
In many perennial woody plants growing in the temperate and cold regions, regulation of seasonal growth cessation and floral initiation are closely integrated, both taking place in photoperiods shorter than a critical...In many perennial woody plants growing in the temperate and cold regions, regulation of seasonal growth cessation and floral initiation are closely integrated, both taking place in photoperiods shorter than a critical length. In the temperate shrub black currant (Ribes nigrum L.), the two processes proceed harmoniously in parallel under naturally decreasing autumn photoperiods, whereas an abrupt shift to photoperiods well below the critical length results in an immediate growth cessation and premature dormancy. As a result, floral initiation is suppressed and arrested. Other perennial plants such as hop (Humulus lupulus), which have the same dual short day responses, behave in the same way. In such plants, optimal flowering takes place at near-critical photoperiods, which are short enough to induce flowering and still long enough to prevent premature dormancy. These responses deviate from the situation in annual plants, which have predominated in studies on photoperiodic control of flowering. Another example of linkage between flowering and dormancy responses is the well-known dual effects of chilling temperature on vernalization and its relation to dormancy. Elucidation and disentangling of these networks of integrated processes are now awaiting joint research efforts in the areas of molecular genetics and experimental plant physiology.展开更多
Background:Tall fescue(Festuca arundinacea[Schreb.],Lolium arundinaceum[Schreb.]Darbysh)and perennial ryegrass(Lolium perenne)are important cool-season forage and amenity grasses that have a mutualistic association wi...Background:Tall fescue(Festuca arundinacea[Schreb.],Lolium arundinaceum[Schreb.]Darbysh)and perennial ryegrass(Lolium perenne)are important cool-season forage and amenity grasses that have a mutualistic association with an endophytic fungus.Endophytes confer insect and drought resistance to plants but can produce mammalian toxins.Novel endophytes that do not produce mammalian toxins have been introduced to elite cultivars for commercial production.Seed companies need to maintain adequate levels of novel endophytes within the elite forage cultivars.Endophyte detection is performed using immunochemical and molecular techniques because of their speed and reliability.Early detection in seedlings is essential to evaluate the viability of the endophyte within seed lots.Methods:This research aimed to identify the earliest growth stage in which immunochemical and molecular methods can detect viable endophyte in seedlings of tall fescue cultivars BarOptima(e34),Texoma MaxQII(584),and Jesup MaxQ(542),as well as the perennial ryegrass cultivar Remington(NEA2).Results:Immunochemical testing detected endophytes in seedlings 14 days after germination(DAG),but the detection rate increased until 42 DAG in some cultivars tested.The molecular marker Tef1exon detected endophytes at a lower rate than the immunochemical method at 28–42 DAG.However,there was insufficient DNA to detect endophytes in 14 DAG seedlings using markers.Conclusions:We conclude that the most accurate detection of viable endophytes in seedlings was 42 DAG,at which sufficient and consistent endophyte colonization occurred.展开更多
To develop a cost-effective combined phytoremediation and biological process,a combined perennial ryegrass/artificial aquatic mat biofilm reactor was used to treat synthetic wastewater.Influent ammonium loading,reflux...To develop a cost-effective combined phytoremediation and biological process,a combined perennial ryegrass/artificial aquatic mat biofilm reactor was used to treat synthetic wastewater.Influent ammonium loading,reflux ratio,hydraulic retention time(HRT) and temperature all had significant effects on the treatment efficiency.The results indicated that the effluent concentration of ammonium increased with increasing influent ammonium loading.The reactor temperature played an important role in the nitrification process.The ammonium removal efficiency significantly decreased from 80% to 30%-50% when the reactor temperature dropped to below 10°C.In addition,the optimal nitrogen removal condition was a reflux ratio of 2.The nitrate and ammonium concentration of the effluent were consistent with the HRT of the combined system.The chemical oxygen demand(COD) removal efficiency was at a high level during the whole experiment,being almost 80% after the start-up,and then mostly above 90%.The direct uptake of N by the perennial ryegrass accounted for 18.17% of the total N removal by the whole system.The perennial ryegrass absorption was a significant contributor to nitrogen removal in the combined system.The result illustrated that the combined perennial ryegrass/artificial aquatic mat biofilm reactor demonstrated good performance in ammonium,total N and COD removal.展开更多
Ratoon is the stub or root of a perennial plant that is commonly retained after harvest to produce a following crop.This paper presents a review of ratoon cotton in relation to a broader framework that has been examin...Ratoon is the stub or root of a perennial plant that is commonly retained after harvest to produce a following crop.This paper presents a review of ratoon cotton in relation to a broader framework that has been examining perennialization of agriculture for the benefit of ecology and economy.Cotton is botanically indeterminate,but has been treated as an annual after domestication,yet the habit of perenniality is retained and the plants begin to resprout after the first harvest.In some cropping systems,this tendency is exploited using the“ratooning”practice(i.e.growing one or more crops on the rootstock of the first).Ratooning has declined for various reasons such as an increase in the prevalence of pests and diseases and overwintering risk.However,ratooning has many benefits such as no annual tillage before sowing,a well-established root system,and high yield.The three methods of ratooning offer flexibility to balance the environmental and economic benefits in agriculture.The greatest environmental benefits arise from perennial ratoon cropping of semi-wild cotton,and the greatest economic benefit is obtained from biannually cropping modern annual cultivars.However,an optimum solution would be provided by perennial cropping annual cultivars.To realize both environmental and economic benefits,research is needed in the following main areas:preventing the buildup of pests and diseases,breeding the most suitable cotton cultivars for ratooning,and developing light and simplified cultivation(LSC)systems for ratoon cultivation.展开更多
Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 ...Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 perennials change over space and time.Methods:A total of 280 sites with C4 plants were surveyed in four types of grasslands in 9 years.The relative biomasses of C4 plants(PC4),C4 annuals(PA4),and C4 perennials(PP4)were calculated.Structural equation modeling was used to analyze the drivers of changes in PA4 and PP4.Results:At the regional scale,PA4 on average was 11%(±19%,SD)and PP4 was 13%(±19%,SD).Spatially,C4 annuals dominated the C4 communities within an east–west belt region along 44°N and tended to spread toward northern latitudes(about 0.5°)and higher altitudes in the east mountainous areas.The abundance of C4 annuals decreased,while that of C4 perennials increased.The patterns of C4 annuals and C4 perennials were mainly controlled by temperature,growing season precipitation,and dynamics between the two life forms.Conclusions:C4 annuals exhibited competitive advantages in normal and wet years,while C4 perennials had competitive advantages in dry years.Grazing as a main human disturbance increased C4 annuals,but had no significant effect on C4 perennials.展开更多
In Kuwait, the scarcity and irregularity of rainfall, the availability of areas of sand supply and the prevalence of strong north westerly winds significantly influence the stability of the fragile ecosystem. Naturall...In Kuwait, the scarcity and irregularity of rainfall, the availability of areas of sand supply and the prevalence of strong north westerly winds significantly influence the stability of the fragile ecosystem. Naturally, grown native shrubs and trees can provide potential shelter to soil surface in desert areas. To study the environmental indicators provided by native plant and their ability to improve quality of life, the morphological properties of the vegetated nabkhas within different areas in Kuwait desert and within protected area were assessed. The vegetated dunes can trap maximum mobile sediments from 10.5 to 0.45 ton thus cost saving per plant estimated to be from 5.5 to 0.24 USD. The arrangements of the native plant from highest efficiency in absorbing carbon dioxides to the least were as follows: Nitraria retusa, Haloxylon salicornicum, Citrullus colocynthis, Tamarix aucheriana, Lycium shawii, Convolvolus oxyphyllus, Rhanterium epapposum, Panicum turgidum, Calligonum polygonoides, Astragalus spinosus, Cyperus conglomerates. The cost saving of CO_(2) per year estimated to be from 0.95 to 1,542.1 USD. The revegetation enhanced physical and chemical quality of soil and created microenvironments for the flora and fauna. The aim of this paper is to identify the environmental indicators related to native plants for the assessment of quality of life.展开更多
To compensate for their sessile nature,plants have evolved sophisticated mechanisms enabling them to adapt to ever-changing environments.One such prominent feature is the evolution of diverse life history strategies,p...To compensate for their sessile nature,plants have evolved sophisticated mechanisms enabling them to adapt to ever-changing environments.One such prominent feature is the evolution of diverse life history strategies,particularly such that annuals reproduce once followed by seasonal death,while perennials live longer by cycling growth seasonally.This intrinsic phenology is primarily genetic and can be altered by environmental factors.Although evolutionary transitions between annual and perennial life history strategies are common,perennials account for most species in nature because they survive well under year-round stresses.This proportion,however,is reversed in agriculture.Hence,perennial crops promise to likewise protect and enhance the resilience of agricultural ecosystems in response to climate change.Despite significant endeavors that have been made to generate perennial crops,progress is slow because of barriers in studying perennials,and many developed species await further improvement.Recent findings in model species have illustrated that simply rewiring existing genetic networks can lead to lifestyle variation.This implies that engineering plant life history strategy can be achieved by manipulating only a few key genes.In this review,we summarize our current understanding of genetic basis of perenniality and discuss major questions and challenges that remain to be addressed.展开更多
文摘Breeding for seedling traits in herbaceous perennial biomass feedstocks that translate into increased biomass yield or quality in established swards could accelerate the development of perennial grass cultivars for bioenergy or forage. In previously reported research, breeding for single large tillers (ST) or multiple tillers (MT, ≥3) six weeks after planting for two generations in big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicum virgatum L.) base populations produced ST and MT populations that differed significantly for seedling and mature plant traits including biomass yield in spaced planted nurseries. Our objective was to evaluate these ST and MT populations in sward trials to determine the effect of these genetic changes on biomass yield and quality when the plants were grown in competitive sward conditions. Big bluestem monocultures of the base, ST, and MT populations were evaluated at three locations in Nebraska in 2001 and 2002 as randomized complete block experiments with four replicates. Switchgrass monocultures of the base, ST, and MT populations were evaluated in 2003, 2004, and 2005 near Mead, NE as a randomized complete block with six replicates. In both big bluestem and switchgrass, the ST and MT populations did not consistently differ from the base population or each other for biomass yield or forage quality. These results demonstrate the importance of evaluating perennial grasses in sward trials and not relying solely on greenhouse-grown plants or space-planted nurseries to develop selection criteria and make selection decisions.
基金This subject is aided financially by Chinese National Natural Science Foundation.
文摘On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.
基金funded by the Research Grants Council Fund of Hong Kong(Project number:Poly U152161/14E)Environment and Conservation Fund,Hong Kong(Project number:39/2011)。
文摘Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics.Each year,sampling was conducted during a period when ephemeral streams had low surface flows.Sampling was realized contiguously using belt transects.The standing crop biomass(hereafter biomass)of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity.Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams.Out of 24 herbs,only three were common for both.A peak herb biomass zone was observed in perennials in the same region where diversity peaked.In ephemerals,herb biomass increased laterally up to^1.5 m,and was constant thereafter.Seedling experiment results tallied with the field diversity observations of both stream types,and suggested that seed dispersion was the main reason for herb colonization.Furthermore,it showed sapling emergence to be significantly higher in perennials than ephemerals.Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams,and elucidated the possibility of hindcasting past flow episodes.Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters.The contents of the water nutrients were approximately the same in both stream types.While recommending further studies on eco-hydrology of ephemerals,we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.
文摘Objective: The comparison of the remote and recent therapeutic effects on perennial allergic rhinitis was carried on among single application of acupoint-thread embedding, western medicine (certirizine+flixonase) and allied therapy. Method: Ninety cases were randomized into thread-embedding group, western medicine group and embedding+western medicine group (allied-therapy group), 30 cases in each one. In thread embedding group, Yingxiang (迎香 LI 20) and Feishu (肺俞 BL 13) were selected for thread embedding, once a week, totally 4 treatments were required. In western medicine group, certirizine tablet 10 mg in combination with flixonase sprayer was applied once per day, continuously for 30 days in treatment. In allied-therapy group, both of the above methods were adopted continuously for 30 days in treatment. The therapeutic effects were in statistics at the end of treatment and 1 year later. Results: At the end of treatment, in thread-embedding group, 21 cases were remarkably effective, 3 cases effective and 6 cases no effect. In western medicine group, 20 cases were remarkably effective, 3 cases effective and 7 cases no effect. In allied-therapy group, 23 cases were remarkably effective, 2 cases effective and 5 cases no effect. It was shown in statistics that there was no significant difference in therapeutic effects among three groups ( P>0.05 ). But one year after the end of treatment, it was indicated that in thread-embedding group, 3 cases were remarkably effective, 10 cases effective and 17 cases no effect; in western medicine group, 2 cases were remarkably effective, 9 cases effective and 19 cases no effect; in allied-therapy group, 7 cases were remarkably effective, 11 cases effective and 12 cases no effect. The significant difference in the therapeutic effects had not been presented in the comparison between thread-embedding group and western medicine group (P>0.05), but that had been presented between allied-therapy group with either of the groups with single therapy applied (P<0.05). Conclusion: Quite good recent therapeutic effect of either acupoint-thread embedding or western medicine (certirizine+flixonase) was achieved on perennial allergic rhinitis. The remote therapeutic effect of allied therapy was more advantageous than that of single application of either thread embedding or western medicine.
文摘The native prairies of the Great Plains USA are dominated by perennial C4 grasses like switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii). Spring hard freeze injury to C4 perennial grasses is rare but information is lacking in the literature. Our objective was to document effects of spring hard freeze damage to C4 perennial grasses native to the Great Plains USA. On 2 May at 24:00 pm, air temperature near Mead, Nebraska was below freezing and remained below freezing until 8:00 am on 3 May, with a minimum air temperature of -2.8°C. Based on 50-year of weather data for this site, a minimum threshold temperature of 0°C on or after 3 May occurred 16 times, but a minimum threshold temperature of -2.8°C on or after 3 May occurred only twice. Grass tillers were visually evaluated to determine extent of freeze damage. The terminal 3- to 5-cm of the leaf lamina was blackened 4-d after freezing and had complete browning, rolling, and desiccation 14-d after freezing. Tiller survival was not negatively affected by the freezing temperatures in May 2004. As the growing season progressed, all agronomic and livestock responses were within normal ranges for these C4 grasses. This is the first field report of multiple C4 prairie grass species responses to a spring hard freeze following significant spring growth. Plant recovery to this late-spring hard freeze demonstrates the ecological resilience of these C4 prairie grasses. These rare spring hard freezes had short-term impacts on C4 grasses but did not negatively impact agronomic performance for forage or bioenergy later in the growing season.
文摘Seasonal dormancy is an adaptive mechanism where plants suspend growth and become physiologically inactive to avoid extreme environmental conditions. Environmental factors like temperature, photoperiod, nutrients, and soil moisture control plant growth and development through various complex molecular mechanisms. Crown and seed dormancy of plants are mostly influenced by day length and temperature. Genes and physiological pathways triggered by these two factors along with genotype variability are some targets to manipulate seasonal dormancy. There is genetic variation in the depth and duration of seasonal dormancy. Therefore, their genetic manipulation is possible. Manipulations of summer and fall dormancy are relatively easier compared to winter dormancy because plants require protection of their apical meristem from freezing temperatures and limited water supply. Genetic factors that regulate seed dormancy may also have regulatory role for seasonal dormancy of the maternal plants. Limited genetic and genomic information are available for seasonal dormancy in herbaceous perennial species. Knowledge of genes controlling seasonal dormancy of eudicots, forest trees, and horticultural crops could be interpolated to explore possible dormancy mechanisms in perennial forages. This study reviews current knowledge of seasonal dormancy of herbaceous forages emphasizing the genetic and physiological context that would be valuable to breeders and plant biologists to expand the production season of perennial species by developing non-dormant and semi-dormant cultivars.
文摘In order to determine the threshold and potential distribution of climatic conditions for perennial cultivated grasses in the Northwest plateau of Sichuan, China, the niche model is used to simulate the main climatic factors affecting the distribution of perennial cultivated grasses, and to predict the current and future climate change prospects. The results show that: 1) Wet index, accumulated temperature, isothermal, and annual average temperature range are the four major climatic factors affecting the distribution of perennial cultivated grasses in the Northwest Sichuan Plateau. 2) Model training and prediction data can be achieved well under the appropriate range of major climatic factors. 3) Under the background of climate warming, from now to 2080, the potential distribution of perennial cultivated grasses in the Northwest plateau of Sichuan, China will increase. The study aims to provide scientific decision-making basis for maintaining grassland ecosystem stability and promoting desertification management and even industrial restructuring of agriculture and animal husbandry.
文摘It has been proposed that salt-tolerant plant could be used as a feed resource for ruminants whereby salt would be removed from salinized land (Asian -Aust. J. Anim. Sci. (2002) 15:998 -1001). Ceratoides arborescens (Losinsk.) Tsien et C. G. Ma is known as a drought-and salt-tolerant plant,a kind of shrubs, growing in semi-arid land of Inner Mongolia. Because the covering effect of the perennial plant as a mulch over the soil might be expected, the optimum covering effect would be obtained after the growth period.The perennial plant produces seeds around summer and end its growth thereafter. Nutrient value of the perennial salt-tolerant plant, however,had not been reported in flowering period at different year. It is necessary to know the ruminal degradability of the plants of each growing year in order to determine the regimen to diet for ruminants. The present experiment,therefore,was undertaken to analyze the digestibility and chemical composition of Ceratoides arborescens as feed for ruminants.
文摘Objective: The partial inferior turbinectomy and septoplasty was applied to treat the allergic perennial rhinitis (APR), and to observe the ultrastructure changes of the nasal mucosa before and after the operations. Methods: For 36 cases of research objects diagnosed with APR, the partial inferior turbinectomy and septoplasty was administered. For 6 APR cases among them, the pre- and postoperative observation of anterior nasal mucosa of the inferior turbinate on the same side under the electron microscope was conducted for one year respectively. In addition, their pathological alterations of tissues were also conducted. Results: In the pre-operative observation under the electron microscope, it was found that the nasal mucosae epithelium cells were nude without cilia. The lamina propria had edema, and mesenchyme presented the infiltration of substantial eosinophilic granulocytes, basophilic granulocytes, plasmacytes and mast cells. Additionally, abundant degranulation and vacuolation of cytoplasts were observed. The plentiful glands, duct ectasia, edema and structural changes were also found. Some gland cells had degenerated. After the operation, it was found that the epithelium nudity still existed and the deficiency of cilia was not improved. Only a very small amount of microvilli existed. The edema of lamina propria was improved and eosinophilic granulocytes were rarely observed in mesenchyme. However, the infiltration of basophilic granulocytes, plasmocytes and mast cells was still observed. The particle structure was generally stable and the central crystal was clear without degranulation. Meanwhile, the amount of glands was reduced and the tissue structure tended to be recovered. Overall, the nasal mucosa showed changes as chronic inflammation. Conclusions: For the treatment of APR with the methods presented by our research institution, in one year before and after the operation, ultrastructural changes of inferior turbinate mucosa tissues were observed from the preoperatively pathological changes of typical APR to the chronic inflammation with the primary infiltration of neutrophilic granulocyte and mast cells.
文摘In many perennial woody plants growing in the temperate and cold regions, regulation of seasonal growth cessation and floral initiation are closely integrated, both taking place in photoperiods shorter than a critical length. In the temperate shrub black currant (Ribes nigrum L.), the two processes proceed harmoniously in parallel under naturally decreasing autumn photoperiods, whereas an abrupt shift to photoperiods well below the critical length results in an immediate growth cessation and premature dormancy. As a result, floral initiation is suppressed and arrested. Other perennial plants such as hop (Humulus lupulus), which have the same dual short day responses, behave in the same way. In such plants, optimal flowering takes place at near-critical photoperiods, which are short enough to induce flowering and still long enough to prevent premature dormancy. These responses deviate from the situation in annual plants, which have predominated in studies on photoperiodic control of flowering. Another example of linkage between flowering and dormancy responses is the well-known dual effects of chilling temperature on vernalization and its relation to dormancy. Elucidation and disentangling of these networks of integrated processes are now awaiting joint research efforts in the areas of molecular genetics and experimental plant physiology.
基金The University of Georgia Cultivar Research and Development Fund。
文摘Background:Tall fescue(Festuca arundinacea[Schreb.],Lolium arundinaceum[Schreb.]Darbysh)and perennial ryegrass(Lolium perenne)are important cool-season forage and amenity grasses that have a mutualistic association with an endophytic fungus.Endophytes confer insect and drought resistance to plants but can produce mammalian toxins.Novel endophytes that do not produce mammalian toxins have been introduced to elite cultivars for commercial production.Seed companies need to maintain adequate levels of novel endophytes within the elite forage cultivars.Endophyte detection is performed using immunochemical and molecular techniques because of their speed and reliability.Early detection in seedlings is essential to evaluate the viability of the endophyte within seed lots.Methods:This research aimed to identify the earliest growth stage in which immunochemical and molecular methods can detect viable endophyte in seedlings of tall fescue cultivars BarOptima(e34),Texoma MaxQII(584),and Jesup MaxQ(542),as well as the perennial ryegrass cultivar Remington(NEA2).Results:Immunochemical testing detected endophytes in seedlings 14 days after germination(DAG),but the detection rate increased until 42 DAG in some cultivars tested.The molecular marker Tef1exon detected endophytes at a lower rate than the immunochemical method at 28–42 DAG.However,there was insufficient DNA to detect endophytes in 14 DAG seedlings using markers.Conclusions:We conclude that the most accurate detection of viable endophytes in seedlings was 42 DAG,at which sufficient and consistent endophyte colonization occurred.
基金supported by the China National Critical Project for Science and Technology on Water Pollution Prevention and Control (No. 2008ZX07101-006)
文摘To develop a cost-effective combined phytoremediation and biological process,a combined perennial ryegrass/artificial aquatic mat biofilm reactor was used to treat synthetic wastewater.Influent ammonium loading,reflux ratio,hydraulic retention time(HRT) and temperature all had significant effects on the treatment efficiency.The results indicated that the effluent concentration of ammonium increased with increasing influent ammonium loading.The reactor temperature played an important role in the nitrification process.The ammonium removal efficiency significantly decreased from 80% to 30%-50% when the reactor temperature dropped to below 10°C.In addition,the optimal nitrogen removal condition was a reflux ratio of 2.The nitrate and ammonium concentration of the effluent were consistent with the HRT of the combined system.The chemical oxygen demand(COD) removal efficiency was at a high level during the whole experiment,being almost 80% after the start-up,and then mostly above 90%.The direct uptake of N by the perennial ryegrass accounted for 18.17% of the total N removal by the whole system.The perennial ryegrass absorption was a significant contributor to nitrogen removal in the combined system.The result illustrated that the combined perennial ryegrass/artificial aquatic mat biofilm reactor demonstrated good performance in ammonium,total N and COD removal.
基金This work was supported by the National Natural Science Foundation of China[31571600]National Key R&D Program of China[2016YFD0101413].
文摘Ratoon is the stub or root of a perennial plant that is commonly retained after harvest to produce a following crop.This paper presents a review of ratoon cotton in relation to a broader framework that has been examining perennialization of agriculture for the benefit of ecology and economy.Cotton is botanically indeterminate,but has been treated as an annual after domestication,yet the habit of perenniality is retained and the plants begin to resprout after the first harvest.In some cropping systems,this tendency is exploited using the“ratooning”practice(i.e.growing one or more crops on the rootstock of the first).Ratooning has declined for various reasons such as an increase in the prevalence of pests and diseases and overwintering risk.However,ratooning has many benefits such as no annual tillage before sowing,a well-established root system,and high yield.The three methods of ratooning offer flexibility to balance the environmental and economic benefits in agriculture.The greatest environmental benefits arise from perennial ratoon cropping of semi-wild cotton,and the greatest economic benefit is obtained from biannually cropping modern annual cultivars.However,an optimum solution would be provided by perennial cropping annual cultivars.To realize both environmental and economic benefits,research is needed in the following main areas:preventing the buildup of pests and diseases,breeding the most suitable cotton cultivars for ratooning,and developing light and simplified cultivation(LSC)systems for ratoon cultivation.
基金supported by the DFG within the DFG research group 536(MAGIM)the National Natural Science Foundation of China(31630010 and 31320103916).
文摘Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 perennials change over space and time.Methods:A total of 280 sites with C4 plants were surveyed in four types of grasslands in 9 years.The relative biomasses of C4 plants(PC4),C4 annuals(PA4),and C4 perennials(PP4)were calculated.Structural equation modeling was used to analyze the drivers of changes in PA4 and PP4.Results:At the regional scale,PA4 on average was 11%(±19%,SD)and PP4 was 13%(±19%,SD).Spatially,C4 annuals dominated the C4 communities within an east–west belt region along 44°N and tended to spread toward northern latitudes(about 0.5°)and higher altitudes in the east mountainous areas.The abundance of C4 annuals decreased,while that of C4 perennials increased.The patterns of C4 annuals and C4 perennials were mainly controlled by temperature,growing season precipitation,and dynamics between the two life forms.Conclusions:C4 annuals exhibited competitive advantages in normal and wet years,while C4 perennials had competitive advantages in dry years.Grazing as a main human disturbance increased C4 annuals,but had no significant effect on C4 perennials.
文摘In Kuwait, the scarcity and irregularity of rainfall, the availability of areas of sand supply and the prevalence of strong north westerly winds significantly influence the stability of the fragile ecosystem. Naturally, grown native shrubs and trees can provide potential shelter to soil surface in desert areas. To study the environmental indicators provided by native plant and their ability to improve quality of life, the morphological properties of the vegetated nabkhas within different areas in Kuwait desert and within protected area were assessed. The vegetated dunes can trap maximum mobile sediments from 10.5 to 0.45 ton thus cost saving per plant estimated to be from 5.5 to 0.24 USD. The arrangements of the native plant from highest efficiency in absorbing carbon dioxides to the least were as follows: Nitraria retusa, Haloxylon salicornicum, Citrullus colocynthis, Tamarix aucheriana, Lycium shawii, Convolvolus oxyphyllus, Rhanterium epapposum, Panicum turgidum, Calligonum polygonoides, Astragalus spinosus, Cyperus conglomerates. The cost saving of CO_(2) per year estimated to be from 0.95 to 1,542.1 USD. The revegetation enhanced physical and chemical quality of soil and created microenvironments for the flora and fauna. The aim of this paper is to identify the environmental indicators related to native plants for the assessment of quality of life.
基金supported by grants from the National Natural Science Foundation of China(32388201,31721001)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB27030101)the New Cornerstone Science Foundation through the XPLORER PRIZE.No conflict of interest is declared。
文摘To compensate for their sessile nature,plants have evolved sophisticated mechanisms enabling them to adapt to ever-changing environments.One such prominent feature is the evolution of diverse life history strategies,particularly such that annuals reproduce once followed by seasonal death,while perennials live longer by cycling growth seasonally.This intrinsic phenology is primarily genetic and can be altered by environmental factors.Although evolutionary transitions between annual and perennial life history strategies are common,perennials account for most species in nature because they survive well under year-round stresses.This proportion,however,is reversed in agriculture.Hence,perennial crops promise to likewise protect and enhance the resilience of agricultural ecosystems in response to climate change.Despite significant endeavors that have been made to generate perennial crops,progress is slow because of barriers in studying perennials,and many developed species await further improvement.Recent findings in model species have illustrated that simply rewiring existing genetic networks can lead to lifestyle variation.This implies that engineering plant life history strategy can be achieved by manipulating only a few key genes.In this review,we summarize our current understanding of genetic basis of perenniality and discuss major questions and challenges that remain to be addressed.
