Switchgrass, Panicum virgatum, is being developed as an economically and ecologically sustainable biomass crop. Nitrogen is considered one of the most limiting inputs of switchgrass. Alternatives to synthetic nitrogen fertilization may be nitrogen-fixing legumes interseeded into switchgrass. The objectives of this research were: (1) develop efficient legume management strategies for switchgrass production systems, (2) evaluate and identify cool and warm-season legumes that can be grown compatibly with switchgrass, (3) determine whether switchgrass yields are increased by legume N-fixation, and (4) determine N-fixation of common (Vicia sativa) and hairy vetch (Vicia villosa). This study examined the establishment and persistence of ten different legume species in ‘Alamo’, a lowland variety of switchgrass in two switchgrass production systems: a one-cut biomass harvest and a two-cut forage/biomass harvest. Cool-season legumes were alfalfa (Medicago sativa), arrowleaf clover (Trifolium vesiculosum), common vetch, crown vetch (Securigera varia), red clover (Trifolium pretense), hairy vetch, and crimson clover (Trifolium incarnatum). Warm-season legumes were Illinois bundle flower (Desmanthus illinoensis), trailing wild bean (Strophostyles helvula), and partridge pea (Chamaechrista fasciculata). Red clover showed the highest plant densities and increase in switchgrass yields when interseeded into existing switchgrass stands in both harvest systems. Crude protein levels were highest in the 135 kg N ha-1 treatment in the forage cut of the two-cut harvest system. Arrowleaf clover, crimson clover, and red clover had high stand densities with annual reseeding. A combination of cool-season legumes, crimson clover and common vetch, in combination with warm-season partridge pea, were established in existing switchgrass stands after one year. Common vetch was evaluated for its nitrogen fixing capacity, seed germination, establishment, and effects on yield of switchgrass. Scarification by sulfuric acid had higher seed germination than other scarification treatments, except 100 grit sandpaper treatment for one minute at 0.7 kg of pressure. Common and hairy vetch nitrogen contributions were 59.3 and 43.3 kg N ha-1 respectively at seeding rates of 6.7 kg PLS ha-1. Switchgrass yields can increase with common and hairy vetch seeding rates of 7.6 and 10.4 kg PLS ha-1 to achieve 67 kg N ha-1, the recommended rate of N-fertilization for switchgrass stands.

Hairy prairie-clover (Dalea villosa Nutt. (Spreng) var. villosa), a rare plant species, grows in the Canadian Prairies. Populations of Dalea in Canada are threatened by the loss of sand dune habitat because of changes in land use and altered ecological processes such as grazing and fire. Local populations of Dalea are further threatened by one or more specific threats, including herbivory from native and domestic ungulates and invasion of habitats by exotic plants. The overall objective of this thesis was to gain more knowledge about Dalea and to determine the impact of threats and management practices to the Saskatchewan populations and their habitats. Observational studies were conducted at each of two sites in Saskatchewan supporting Dalea. First, at the Dundurn Sandhills site, structural equation modeling was used to examine landscape, ecological, and management factors associated with high rates of herbivory on Dalea and with reductions in the long-term survival and productivity of Dalea. The conditions which deer (Odocoileus hemionus and Odocoileus virginianus) or cattle (Bos taurus) were responsible for the most intense rates of herbivory to Dalea plants and patches were determined. Generally, deer appeared responsible for the most herbivory, whereas cattle grazing on Dalea increased with stocking densities. At the same time, new hypotheses about ecological processes affecting Dalea productivity in the Dundurn Sandhills were explored. In particular, it appeared that deer may be responding to cattle grazing in Dalea habitat by avoiding those areas, and that mid-season germination and recruitment of many Dalea plants may occur following precipitation events. Second, at the Mortlach site, the costs and benefits of using grazing management to control leafy spurge (Euphorbia esula L. var. esula) were assessed, especially in consideration of the potential negative effects of intense herbivory on Dalea productivity. Aspects of the grazing regime including stocking density and the livestock species influenced herbivory on Dalea and its reproductive output, but there were no apparent links between the abundance of leafy spurge abundance and the reproductive output of Dalea. The findings of these two studies are relevant for the conservation and management of Dalea in Saskatchewan.

No description available.

Kura clover was successfully established via sod-seeding in different environments. Its establishment and yields were initially inferior to that of red clover and white clover. But, its presence slowly increased in the sward and, by the first harvest of the second post seeding season, it was yielding significantly more than the legume species presently recommended for pastures. Clover establishment increased with increasing intensity of herbicide suppression. Best overall results were obtained with glyphosate at low rate (0.8 kg a.i. ha-1). Paraquat (0.9 kg a.i. ha -1) did not suppress sufficiently the grass population for clovers to establish while glyphosate applied at high rates (3.3 kg a.i. ha -1) led to excessive grass suppression, excessive legume content and temporary weed encroachment. N fertilization at seeding did not consistently increase establishment of sod-seeded Kura clover. Forage quality was positively correlated with clover content.

No description available.

Herbicide sod suppression during pasture renovation by legume sod-seeding often results in the loss of potentially usable forage, weed encroachment, and inadequate glass-legume ratios. A study was conducted to investigate the viability of sod suppression by sheep grazing or mowing, as alternatives to herbicide, during pasture renovation with no-till seeding of red clover (Trifolium pratense L.) or white clover (Trifolium pratense L.). Sod suppression methods evaluated were: strategically timed mowing or sheep grazing to 5 or 10 cm at seeding and during legume establishment, or similarly managed mowing or sheep grazing with an additional defoliation to 5 cm the previous fall. Additional treatments included suppression by herbicide and, unsuppressed and unseeded controls. Treatments were evaluated by determining clover plant population, botanical composition, forage yield and quality. Physical (mowing or grazing) and herbicide sod suppression resulted in similar clover plant populations; clover yields tended to be higher with herbicide suppression. However, increasing the intensity of physical suppression increased clover yields. Forage quality was increased only with sod suppression by grazing or herbicide when compared with the unimproved control. Although, for grazing this was attributed to a more frequent defoliation regime and not to the renovation itself. Unlike suppression with herbicide, physical suppression did not decrease total seasonal forage yields in the renovation year when compared with controls.

Plant species were assessed for recolonization of a brownfield in Muncie, IN. In a greenhouse study, soil was seeded to perennial ryegrass (Lolium perenne), red clover (Trifolium pratense) and sunflower (Helianthus annuus). Selected pots were amended with leaf compost and mycorrhizal fungi. Soil and plant tissue were analyzed after 30 and 90 days. Ryegrass and compost were studied at the brownfield site. In the greenhouse, red clover was capable of concentrating the greatest quantity of Cd, Cu, Cr, Ni, and Pb in above-ground biomass (all soil treatments combined). Compost + mycorrhizal fungi treatment resulted in highest Cd, Cu, and Zn plant concentrations (all plant treatments combined). Compost resulted in the highest tissue Cr and Ni concentrations. The reported study demonstrates that this brownfield is capable of being revegetated by turf and legume species. Each infertile and/or toxic site must be assessed for revegetation species on a case-by-case basis. / Department of Natural Resources and Environmental Management

Darbo tikslas – apžvelgti Lietuvoje augančių antilipideminėmis savybėmis pasižyminčių augalų pritaikymo galimybes mažinti cholesterolio kiekį kraujyje bei pagrįsti raudonųjų dobilų terapinį potencialą. Tyrimo metodai. Bendrasis flavonoidų kiekis raudonųjų dobilų žolėje nustatytas UV spektrofotometrijos metodu. Raudonųjų dobilų veikliųjų medžiagų ADME savybių prognozė atlikta panaudojant ACD/ADME suite 5.0 programą. Statistinė analizė atlikta naudojant „Microsoft Office Excel 2003“ programą. Apskaičiuotas aritmetinis vidurkis ir standartinis nuokrypis. Tyrimo rezultatai. Daugiausia flavonoidų raudonųjų dobilų žaliavoje yra birželio mėn. pradžioje ir viduryje (0,46 ± 0,07 proc.). Liepos mėn. pradžioje flavonoidų kiekis sumažėja 2–3 kartus, o vasaros viduryje padidėja iki 0,33 ± 0,05 proc. Rugpjūčio mėnesį flavonoidų kiekis žaliavoje vėl sumažėja iki 0,29 ± 0,03 proc. Remiantis programos prognozėmis raudonųjų dobilų žolės veikliosios medžiagos pasižymi gana palankiomis ADME savybėmis, kurios leistų šio augalo preparatus vartoti per os. Dauguma veikliųjų junginių, ypač flavonoidų aglikonai ir kumarinai turėtų labai gerai absorbuotis pasyviosios absorbcijos būdu, o didžiausias bioprieinamumas per os (> 70 proc.) prognozuojamas biochaninui A, daidzeinui, formononetinui ir kumestroliui. Beveik visoms veikliosioms medžiagoms, kaip ir statinams, prognozuojamas nedidelis pasiskirstymo tūris: nuo 0,7 l/kg iki 1,6 kg/l. Visiems junginiams prognozuojamos labai mažos tikimybės, kad jie... [toliau žr. visą tekstą] / Objectives – to overview the possibility to use plants with antilipidemic properties growing in Lithuania to reduce cholesterol in blood and to substantiate therapeutic potential of the red clover. Methods. Total flavonoid amount in red clover was determined by using UV spectroscopy. ADME properties of red clover active substances were predicted by using ACD/ADME suite 5.0 software. Statistical analysis was carried out using “Microsoft Office Excel 2003” software. Arithmetical average and standard deviation were calculated. Results. The biggest amount of flavonoids in red clover raw material is detected in the beginning and middle of June (0.46 ± 0.07 %). The content of flavonoids decreases two-three times in the beginning of July, and increases to 0.33 ± 0.05 % in the middle of the summer. The flavonoid content of raw material decreases to 0.29 ± 0.03 % again in August. Based on program predictions the active substances present in the herb of red clover have beneficial ADME properties affording the preparations of this herb to use per os. Majority of active substances, especially flavonoid aglycones and coumarins should have very good absorption by passive route of absorption, and the highes oral bioavailability (>70 %) is predicted for biochanin A, daidzein, formononetin and coumestrol. Almost all active compounds, the same as statins, were predited to have low volume of distribution: from 0.7 l/kg to 1.6 l/kg. All compounds were prognosed not to be strong inhibitors of CYP... [to full text]

Overall soil productivity is declining in the U.S. due to loss of soil organic matter (SOM). Decreased SOM lowers soil water storage, reduces water infiltration, slows aggregate formation, and depletes soil of nutrients. In many systems, crop nutrients are replaced by expensive synthetic fertilizers that can lead to environmental concerns. This practice is not economically or environmentally sustainable in the long term. To secure future soil use and crop production, sustainable management practices are needed to prevent further SOM depletion. Incorporating legumes into cropping systems is one alternative that can bolster soil organic C (SOC) (key indicator of SOM) and reduce N fertilizer applications through symbiotic legume N fixation. Three studies were conducted over multiple years at the Texas A&M AgriLife Research and Extension Center near Overton, TX. Annual cool- and warm-season legumes were evaluated as potential green manure crops and intercrops under grain sorghum [Sorghum bicolor (L.) Moench], high-biomass sorghum [Sorghum bicolor (L.) Moench], and annual forage cropping systems. These studies quantified legume soil moisture usage and C and N contributions to the soil and subsequent crop yields in East Texas. Primary project objectives were to maintain or maximize primary crop yields at reduced N fertilizer rates and to build SOC through the integration of legume green manures and intercrops. Green manuring cool-season legumes showed the most beneficial effect on SOC, soil total N, and crop yields; however, significant increases in yield were only detected after three years in rotation. Intercropping Iron-and-Clay cowpea (Vigna unguiculata L. [Walp]) decreased yield of both high-biomass sorghum and grain sorghum due to competitive vegetative growth. Iron-and-Clay did however improve biomass yields of high-biomass sorghum in two subsequent years when implemented as a green manure. Despite large N yields as high as 310 kg ha-1, impacts of legumes on annual forage crops was limited. Poor response was likely a result of previous field history in which a permanent warm-season grass pasture was cultivated for site preparation and mineralized SOC released substantial amounts of available N. Under low soil N conditions, legume green manures produce enough N to likely reduce N fertilizer requirements cost-effectively for subsequent crops in East Texas.

The differential expression of members of the Trifolium repens ACC oxidase (TR-ACO) gene family and accumulation of TR-ACO proteins in white clover roots, and the temporal TR-ACO gene expression and TR-ACO protein accumulation in response to phosphate (Pi) stress has been investigated. Four-node stolon cuttings of wild type and transgenic white clover (designated TR-ACOp::GUS and TR-ACO1p::mGFP5-ER) plants were rooted and acclimatised in Hoagland’s solution, and then subjected to either a Pi sufficiency (1 mM Pi) treatment or a Pi depletion (10 µM Pi) treatment over a designated time course. Using semi quantitative Reverse Transcriptase-Polymerase Chain Reaction (sqRT-PCR) and gene-specific primers it has been determined that the TR-ACO genes are differentially expressed in the roots of white clover. The TR-ACO1 transcript abundance was greater in the lateral roots when compared to the main roots. By immunodetection analysis using antibodies raised against TR-ACO1, recognition of a protein of expected size (ca. 36 kDa) was also greater in the lateral roots. The tissue-specific localisation of TR-ACO1 promoter activity was investigated first by light microscopy using a single genetic line of white clover transformed with a TR-ACO1p::GUS gene construct, and results then confirmed by confocal microscopy using several genetically independent lines of transgenic plants transformed with a TR-ACO1p::mGFP5 ER gene construct. In these lines, the TR-ACO1 promoter activity was primarily located in the meristem of the main and lateral roots, lateral root primordia as well as in the pericycle of the root with nodes of expression in the emerging lateral roots, suggesting a role for ethylene in the development of young tissues where cells are actively dividing. In terms of TR-ACO2, greater transcript abundance and protein accumulation of TR-ACO2 were also observed in the lateral roots when compared to the main roots. Histochemical GUS staining of roots of a single genetically-independent line transformed with a TR-ACO2p::GUS construct showed predominant promoter activity in the mature tissues of both the main and lateral roots but not in the meristematic tissues. In contrast, TR-ACO3 showed greater transcript abundance in the main roots relative to the lateral roots, and the promoter activity, as determined using a single genetically- independent line of TR-ACO3p::GUS transformed plants was predominantly in the mature tissues of the main roots In response to Pi depletion, the members of TR-ACO gene family were temporally expressed in the white clover roots. Using sqRT-PCR, the TR-ACO1 transcript abundance was greater in Pi depleted roots at 12 h and 24 h after Pi depletion in both wild type plants and in the one genetically-independent line of white clover transformed with the TR-ACO1p::mGFP5-ER construct examined. Similarly, by western analysis using both a-TR-ACO1 and commercially available a-GFP antibodies (for the transformed line), a greater accumulation of proteins was consistently observed in Pi depleted roots from the first up to the seventh day after Pi depletion. By confocal microscopy, it was determined for several genetically-independent line of white clover transformed with TR-ACO1p::mGFP5-ER that under Pi depletion more intense GFP fluorescence over a time course of 1 d, 4 d, and 7 d was observed, when compared to plants grown under Pi sufficiency. For TR-ACO2, there was no significant difference in transcript accumulation and protein accumulation in response to short term Pi depletion of up to seven days. However, at 15 d and 21 d after Pi depletion there was a greater protein accumulation in the roots of Pi depleted plants relative to the Pi sufficient roots. Further, when main and lateral roots were compared, a greater protein accumulation occurred in the lateral roots. For TR-ACO3, there was no consistent trend of transcript accumulation in response to Pi depletion over a 24 h period. While a marked reduction in transcript accumulation was noted in Pi depleted roots at 1h, 12 h, 24 h, there was an increase in transcript accumulation at 6 h and 18 h after Pi depletion, indicating that factors other than Pi supply may be affecting gene regulation. Root morphological studies revealed an increase in the main root length and lateral root production in white clover in response to Pi depletion with a greatest growth rate noted between the sixth and ninth day after Pi depletion, and this period overlapped with accumulation of TR-ACO1 protein suggesting a role for ethylene in the Pi stress induced lateral root production in white clover. The differential regulation of the three TR-ACO genes in white clover roots in response to Pi depletion further suggests the divergence in terms of regulation of the ethylene biosynthetic pathway, which may play an important role in fine tuning the responses of plants to particular environmental cues.