Physiological and Biochemical Responses of Perennial Ryegrass Mixed Planting with Legumes under Heavy Metal Pollution

In artificially controlled pot experiments,perennial ryegrass was mixed with other leguminous plants(white clo-ver and alfalfa)and treated with lead,zinc and cadmium(337 mg·kg^(-1),648 mg·kg^(-1),and 9 mg·kg^(-1),respectively)to simulate compound pollution conditions.The results showed that the concentrations of heavy metals,trans-port factors,and bioconcentration factors in mixed planting of ryegrass decreased compared with those in mono-culture.Regardless of whether heavy metal pollution was introduced,mixed planting increased the aboveground and underground biomasses of ryegrass.The different mixed planting treatments had no significant impact on the chlorophyll concentration of ryegrass.The mowing time,mixed planting treatment,and heavy metal treatment had impacts on antioxidant and osmotic adjustment substances,and there were some interactions.The mixed planting treatment did not significantly affect glutathione concentration,cysteine concentration,or nonprotein thiol.Mixed planting generally increased the nitrogen and phosphorus concentrations of ryegrass while reducing the stoichiometric ratio of carbon,nitrogen,and phosphorus.These results suggest that the mixed planting of ryegrass with legumes promotes the growth of ryegrass in the presence of high concentrations of heavy metal pollution.However,it does not enhance the ability of ryegrass to remediate heavy metal pollution in the soil.

AHP-based Landscape Value Evaluation of Perennial Flower Border Application in Hefei City

An analytic hierarchy process(AHP)was employed to establish a landscape value evaluation model for 20 common species of perennial flowers in the flower border of Hefei City.With the overarching objective of determining the application value of the flower border,10 evaluation factors were identified and subsequently classified into 3 distinct grades.Grade I(L>2.5)was defined as perennial flower resources with the highest development and utilization value,including only one species of Salvia farinacea.Grade II(2.0≤L≤2.5)was defined as perennial flower varieties suitable for most areas,encompassing 9 species of plants,such asTaraxacummongolicum.Grade III(L<2.0)was defined as perennial flower varieties with low application value,encompassing 10 species of plants,such asRuellia brittoniana,but lacking the value of further popularization and application.Consequently,the proportion of their application in the flower border should be reduced.The evaluation results can serve as a theoretical foundation for the implementation of perennial flowers in urban flower borders.

Does Selection for Seedling Tiller Number in Perennial Biomass Feedstocks Translate to Yield and Quality Improvements in Mature Swards?

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.

Callus Induction and Plant Regeneration from Mature Seeds of Perennial Ryegrass

Objective The aim was to explore callus induction and plant regeneration of perennial ryegrass, as well as provide the foundation for transgenic research on perennial ryegrass.[ Methed] Mature seeds of perennial ryegrass were used as explants to study the effects of different hormone compositions on callus induction, proliferation and plant differentiation. Result The result showed that the induction rate achieved its highest on 2,4-D of 8 mg/L combining with 6-BA of 0.025 mg/L, which was up to 56.42%. Callus were differentiated after two to three generations, the highest differentiation rate 34.14% was achieved in the medium contained MS medium with 6-BA of 2 mg/L, and the differentiation rate was obviously affected by the callus condition after proliferation. The root inducing medium, containing 0.5 mg/L NAA and MS medium with half of macroelement, gained 98% root inducing rate. Conclusien A high frequency genetic regeneration system was established.

Effects of Fragmentation Intensity of Perennial Roots and Their Burial Depth on Sprouting and Early Growth of Alternanthera philoxeroides(Mart.)Griseb

[Objective] The aim was to provide theoretical basis for the prevention and control of the invasion of Alternanthera philoxeroides（Mart.）Griseb.[Method] Effects of fragmentation intensity of fresh roots and their burial depth on sprouting and early growth of A.philoxeroides were studied by control test.[Result] More sprouts of A.philoxeroides emerged when the fragmentation intensity of fresh roots was higher,while if the fragmentation intensity of fresh roots was lower,the early growth of A.philoxeroides was more rapid.The soil buried depth had significant effect on fresh root sprouts＇ emergence,but once fresh root sprouts could reach the soil surface and were given enough growth time,even if the fresh roots were buried in different depths,soil buried depth had no significant effect on its young plant growth.[Conclusion] If different fragmentation intensities of fresh roots present,there is a kind of trade-off strategy between root sprouts＇ emergence and plant＇ early growth,by which A.philoxeroides can invade new habitat successfully.To control the invasion of A.philoxeroides,it is critical to prevent its fresh root sprouts from emerging to soil surface,that is,to bury the fresh roots at a further soil depth.

Scarabaeid Larvae- and Herbicide-Resistant Transgenic Perennial Ryegrass (Lolium perenne L.) Obtained by Agrobacterium tumefaciens-Mediated Transformation of cry8Ca2, cry8Ga and bar Genes

Insect pest and weeds are two major problems for forage and turf grasses. In this study, scarab larvae- and herbicide-resistant transgenic perennial ryegrass （Lolium perenne L.） was obtained by transforming it with cry and bar genes simultaneously via the Agrobacterium-mediated method. To optimize the callus induction and plant regeneration conditions, various concentrations of 2,4-dichlorophenoxyacetic acid and 6-benzylaminopurine were assayed. The transformation efficiencies of different Agrobacterium suspension media, used during Agrobacterium-mediated transformation, were compared. Then, plasmids of pCAMBIA3301 containing cry gene （cry8Ca2 or cry8Ga） and bar gene, driven by ubiquitin promoter, were transformed into perennial ryegrass. The transformants were generated and confirmed by both Southern hybridization analysis and Western hybridization analysis. Further, the resistance of transgenic perennial ryegrass plants to scarab larvae and herbicide were analyzed. After 30 d of co-cultivation with scarab larvae, the damage to the root system of transgenic plants was less than that of non-transgenic control plants. Additionally, the leaves of transgenic plants were resistant to Basta, while leaves of the wild plants wilted after Basta spraying. These results show that cry gene and bar gene were successfully transferred into perennial ryegrass by the Agrobactgerium-mediated method, and convey resistance to scarab larvae and herbicide in transgenic perennial ryegrass plants.

Vegetation dynamics of ephemeral and perennial streams in mountainous headwater catchments

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.

Monitoring Perennial Sub-Surface Waterlogged Croplands Based on MODIS in Jianghan Plain, Middle Reaches of the Yangtze River

Perennial waterlogged soil（PWS） is induced by the high level of groundwater, and has a persistent impact on natural ecosystems and agricultural production. Traditionally, distribution information regarding PWS is mainly collected from in situ measurements through groundwater level surveys and physicochemical property analyses. However, in situ measurements of PWS are costly and time-consuming, only rough estimates of PWS areas are available in some regions. In this paper, we developed a method to monitor the perennial waterlogged cropland using time-series moderate resolution imaging spectroradiometer（MODIS） data. The Jianghan Plain, a floodplain located in the middle reaches of the Yangtze River, was selected as the study area. Temporal variations of the enhanced vegetation index（EVI）, night land surface temperature（LST）, diurnal LST differences（ΔLST）, albedo, and the apparent thermal inertia（ATI） were used to analyze the ecological and thermodynamic characteristics of the waterlogged croplands. To obtain pure remote sensing signatures of the waterlogged cropland from mixed pixels, the croplands were classified into different types according to soil and land cover types in this paper, and a linear mixing model was developed by fitting the signatures using the multiple linear regression approach. Afterwards, another linear spectral mixing model was used to get the proportions of waterlogged croplands in each 1 km×1 km pixel. The result showed an acceptable accuracy with a root-mean-square error of 0.093. As a tentative method, the procedure described in this paper works efficiently as a method to monitor the spatial patterns of perennial sub-surface waterlogged croplands at a wide scale.

Insights into Seasonal Dormancy of Perennial Herbaceous Forages

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.

Development of Perennial Wheat Through Hybridization Between Wheat and Wheatgrasses： A Review

Wheatgrasses （Thinopyrum spp.）, which are relatives of wheat （Triticum aestivum L）, have a perennial growth habit and offer resistance to a diversity of biotic and abiotic stresses, making them useful in wheat improvement. Many of these desirable traits from Thinopyrum spp. have been used to develop wheat cultivars by introgression breeding. The perennial growth habit of wheatgrasses inherits as a complex quantitative trait that is controlled by many unknown genes. Previous studies have indicated that Thinopyrum spp. are able to hybridize with wheat and produce viable/stable amphiploids or partial amphiploids. Meanwhile, efforts have been made to develop perennial wheat by domestication of Thinopyrum spp. The most promising perennial wheat-Thinopyrum lines can be used as grain and/or forage crops, which combine the desirable traits of both parents. The wheat-Thinopyrum lines can adapt to diverse agricultural systems. This paper summarizes the development of perennial wheat based on Thinopyrum, and the genetic aspects, breeding methods, and perspectives of wheat-Thinopyrum hybrids.

Assessment of severity of acute pancreatitis:a comparison between old and most recent modalities used to evaluate this perennial problem

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OBSERVATION OF REMOTE AND RECENT THERAPEUTIC EFFECTS OF ACUPOINT-THREAD EMBEDDING, WESTERN MEDICINE OR ALLIED THERAPY ON PERENNIAL ALLERGIC RHINITIS

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.

Root proliferation in native perennial grasses of arid Patagonia,Argentina

Pappophorum vaginatum is the most abundant C4 perennial grass desirable to livestock in rangelands of northeastern Patagonia, Argentina. We hypothesized that （1） defoliation reduce net primary productivity, and root length density and weight in the native species, and （2） root net primary productivity, and root length density and weight, are greater in P. vaginatum than in the other, less desirable, native species （i.e., Aristida spegazzinfi, A. subulata and Sporobolus cryptandrus）. Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons. Root proliferation was measured using the cylinder method. Cylindrical, iron structures, wrapped up using nylon mesh, were buried diagonally from the periphery to the center on individual plants. These structures, initially filled with soil without any organic residue, were dug up from the soil on 25 April 2008, after two successive defoliations in mid-spring 2007. During the second growing season （2008-2009）, cylinders were destructively harvested on 4 April 2009, after one or two defoliations in mid- and/or late-spring, respectively. Roots grown into the cylinders were obtained after washing the soil manually. Defoliation during two successive years did reduce the study variables only after plants of all species were defoliated twice, which supported the first hypothesis. The greater root net primary productivity, root length den- sity and weight in P. vaginatum than in the other native species, in support of the second hypothesis, could help to explain its greater abundance in rangelands of Argentina.

A Review on Reasons of Increasing Perennial Weeds and Control Technology of Perennial Weeds in Heilongjiang Province

The main reasons that perennial weeds has becoming the dominant weeds in Heilongjiang Province were summarized. The biological mechanism that explained why it was difficult to control perennial weeds was analyzed. During dormancy course, variation regularity of some inner matters in perennial weeds was researched and new tentative for controlling the perennial weeds was pointed out.

Selection of Rhizosphere Phosphate-solubilizing Bacteria of Perennial Ryegrass

The research isolated phosphorus-soluble bacteria from different parts of ryegrasses and selected 7 bacteria performing better in solbilizing capacity. The test results showed that the capacity of phosphorus-solubilizing tended to be volatile in the range from 135.27 to 187.87 μg/ml and the secreting capacity of IAA was in3.47-24.27 μg/ml. It is believed that Lp59, Lp61, Lp65, Lp69, Lp70 and Lp72 are potential for further development.

Observations of Spring Hard Freeze Injury to C₄Perennial Grasses Native to the Great Plains, USA

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.

Prediction of the Distribution of Perennial Cultivated Grasses in the Northwest Sichuan Plateau, China under Climate Change

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.

Chemical Composition and Ruminal Digestibility of Ceratoides, a Salt-tolerant Perennial Plant,at Different Years

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.

Observation of Ultrastructure in Nasal Mucosa on Allergic Perennial Rhinitis Cases before and after the Operations

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.

Dormancy Interferes with Flowering in Perennial Plants with Short Day Regulation of Both Processes:A Mini-Review

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.