Accedi

Bibliografie tematiche / White clover / Tesi

Segui questo link per vedere altri tipi di pubblicazioni sul tema: White clover.

Tesi sul tema "White clover"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 21 febbraio 2023

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "White clover".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.

1

Youlin, Tang M. S. "Response of Leaf Protein to Ozone in Two White Clover Clones". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/46494.

Testo completo

Abstract (sommario):

A white clover ( Trifolium repens ) system, based on one ozone-sensitive (NC-S) and one ozone-resistant (NC-R) clone, has been developed as an indicator to estimate the effects of tropospheric ozone on plant biomass production. A reduction in the vegetative biomass ratio (NC-S/NC-R) of the clones was correlated with increasing concentrations of ozone during a 28-day exposure period. However, the mechanism of ozone sensitivity or tolerance at the biochemical or molecular level is not known. Superoxide dismutase isozyme activities in the two clones did not respond differently to ozone treatment. However, catalase activity increased somewhat more in the leaf tissue of NC-R, compared to NC-S, after ozone treatment. Two-dimensional polyacrylamide gel electrophoresis (PAGE) showed the presence of two proteins (Ozone-Response-Proteins, ORPs) that were more responsive to ozone in the tolerant genotype than in the sensitive one. After ozone treatment for three days, the ORPs were four-fold higher in leaf tissue of NC-R compared to NC-S. Also, the amount of the ORPs was twenty-fold higher in leaf tissue of ozone-treated NC-R than in that of control NC-R. These proteins have apparent molecular weights of 21.5 kD and 23 kD and isoelectric points of 4.1-4.4 on SDS-PAGE gels. The filtrate of a 100 kD concentrator showed that the native molecular weights of the ORPs were less than 100 kD. The results obtained from a study of field samples demonstrated that protein content in leaf tissue of both NC-R and NC-S was positively correlated with ORP content.
Master of Science

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Kuschel, Nolberto German Teuber. "Investigation of physiological factors determining white clover persistence in grass/clover swards". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333854.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Sparks, Bret Andrew. "Reduced Inputs Turfgrass Through White Clover Inclusion". UKnowledge, 2014. http://uknowledge.uky.edu/pss_etds/41.

Testo completo

Abstract (sommario):

Most managed turfgrass species require frequent inputs to maintain an acceptable level of quality. Among these inputs, nitrogen (N) fertilization is usually the most limiting in terms of growth and development. However, N fertilization is also linked to non-point source (NPS) pollution. White clover (WC) is known for its ability to provide N when mixed into stands of turfgrass, and does not pose a threat for NPS pollution. Two field studies were designed to investigate the effects of WC inclusion in stands of cool-season turfgrasses. In the first field study, three cultivation techniques were examined for establishment of WC into preexisting turfgrass stands at three different seasonal timings. Scalping during the summer was seen as providing the highest WC populations, although scalping treatments also caused the most initial damage to the turfgrass. In the second field study, mixed stands of turfgrass and WC were examined for response to several weeks of traffic simulations, with WC withstanding the traffic events. Additionally, a greenhouse study was implemented to examine the effects of several commercial broadleaf herbicides on two WC varieties. Only 2,4-D was shown to be safe for application to both WC varieties, although Microclover did show tolerance to quinclorac applications.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Baines, R. N. "Interactions between white clover and pasture grasses". Thesis, University of Reading, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383598.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Berrington, A. C. "Co-evolution of white clover to associated mycorrhizae". Thesis, Bangor University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381917.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Clark, Sonya A. "Herbicide effects on white clover growth and nodulation". Thesis, University of Canterbury. Microbiology, 1987. http://hdl.handle.net/10092/6909.

Testo completo

Abstract (sommario):

Five herbicides commonly used for suppression of weed growth in white clover seed crops were tested for toxicity against white clover (Trifolium repens), Rhizobium trifolii and the nitrogen fixing symbiosis formed between these two organisms. Trials were carried out on R.trifolii on solid and in liquid media to determine if growth of this bacterium was affected by the presence of the 5 herbicides. Paraquat and MCPB substantially inhibited bacterial growth on solid medium. Bentazone, fusilade and kerb caused very small zones of growth inhibition of R.trifolii on solid agar at high concentrations. None of the herbicides tested affected growth of R.trifolii in liquid culture. In vitro studies of herbicide toxicity toward white clover were carried out to identify interactions of herbicide activity with rhizobial inoculation and supplied nitrogen, and to attempt to identify the targets of herbicide activity. Nodules grown under in vitro conditions were excised and used for ultrastructural examination. Herbicides were applied to plants grown in vitro at two different stages of plant growth. White clover proved to be very sensitive to all herbicides at the early seedling stage. Three week old plants were more tolerant. Pot experiments in a glasshouse environment indicated the relevance of in vitro experiments of herbicide toxicity against plants and gave information on the effect of soil water levels on herbicide activity. Paraquat was extremely toxic to white clover both in vitro and in pot experiments. Nodulation is affected to some extent directly by this herbicide although dessication of foliage probably has some role in halting activity of the nitrogenise enzyme. MCPB caused severe deformation of root tissue both in vitro and in pot experiments. It must be either contaminated with the active form of this herbicide, MCPA, or is being broken down to the active form by bacterial or chemical action. Bentazone did not damage white clover or nodule activity in a consistent way in vitro. However this herbicide did have a deleterious effect on both plant weight and nodulation when applied to white clover grown in soil, particularly under conditions of low soil moisture. Fusilade showed a direct effect on the activity of nitrogenase in vitro. Fusilade also acted more severely against plants of higher nutritional status, and appeared to affect nodule activity directly rather than affecting nodules via damage to other plant parts. Kerb was very toxic to seedling white clover in vitro although older plants were not as susceptible and were stimulated by high concentration of kerb. In pots white clover was slightly inhibited by kerb at recommended concentration while 10 x this concentration did not cause any inhibition of nodulation or plant growth. Differences in results between in vitro and pot studies of toxicity of these herbicides to white clover appear to be due to the different application methods used. In vitro herbicides were applied to the whole plant while in pot experiments herbicides were foliarly applied, hence more uptake by roots would be expected. Pot experiments indicated that changes in nodulation generally reflected changes in plant growth rather than an independent activity of the herbicide on nodulation.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Enríquez, Hidalgo Daniel. "Strategies to optimise white clover (Trifolium repens L.) content in grass white clover swards to consistently replace inorganic nitrogen in grazing systems". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.673846.

Testo completo

Abstract (sommario):

Mixed perennial ryegrass white clover (WC) swards (GWc) provide a sustainable nitrogen source for grazing systems and improve herbage quality, but sward WC content and nitrogen fixation can be suppressed by fertiliser nitrogen application. Differences in structural characteristics between the species can affect dairy cow digestion process and performance. In this thesis aspects related to the effect of nitrogen fertilizer application on intensively grazed GWc and grass only swards (GO) and the effects of grazing both swards on dairy cow feeding behaviour, herbage depletion rate, rumen function, methane emissions and milk production were investigated. Regardless of nitrogen rate applied (rates up to 240 kg N/ha we applied), WC inclusion into grass wards increased herbage production, quality and nitrogen yield. These effects declined as nitrogen rate increased, due to a reduction in WC content and fixation, but less so below 120 kg N/ha. When cows rotationally grazed either a GO or GWc, both swards had similar herbage production, but GWc had slightly greater herbage quality. Sward WC contents were approximately 20%, yet cows had similar milk production and composition. Cow daily and per unit of output methane emissions were similar, but cows grazing GWc had lower methane emissions per unit of feed intake. Although cows in both groups grazed for similar times, the cows on GWc spent less time ruminating, especially in summer and autumn. Rumen volatile fatty acids were similar on both swards but isoacids and D-lactic acid percentages, ammonia content and rumen pH were higher in autumn for cows grazing GWc. Similar sward depletion rates were observed. Overall, WC related effects were more likely to occur from June onwards, when sward WC content was greatest.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Kemball, W. D. "Source-sink interrelationships in white clover (Trifolium repens L.)". Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333705.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Thompson, L. "The influence of radiation quality on the behaviour of grassland species". Thesis, Bangor University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234470.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Franzmayr, Benjamin. "Metabolic Engineering of Isoflavonoid Biosynthesis in Tobacco and White Clover". Thesis, University of Canterbury. Biological Sciences, 2011. http://hdl.handle.net/10092/5568.

Testo completo

Abstract (sommario):

Isoflavonoids are a class of plant secondary metabolites which have multiple biological roles in plants as pest feeding deterrents, phytoalexins and signals to rhizobial microbes. Some isoflavonoids, or their breakdown products, are estrogenic when ingested by animals, and pastures with high levels of the isoflavonoid formononetin can cause sterility in ewes. White clover has low levels of isoflavonoids and is susceptible to pests like the clover root weevil. The overall aim of this project was to test whether isoflavonoids could be manipulated in white clover through metabolic engineering. The genes of the key isoflavonoid biosynthesis enzymes have been cloned from a range of legumes and three major genes, chalone reductase (CHR), isoflavone synthase (IFS) and isoflavonoid O-methyltransferase (IOMT), were cloned from white clover in this study. The white clover IFS2_12 gene was expressed in transgenic tobacco. Genistein, an isoflavonoid that is not naturally present in tobacco, was detected in the IFS-expressing tobacco, thus confirming the functionality of the IFS2_12 gene. Tobacco plants were transformed with ANT1, a transcription factor that induces the production of anthocyanins that share precursors with the isoflavonoid biosynthesis pathway. When IFS was expressed in red tobacco leaves, where anthocyanin biosynthesis was occurring, the levels of genistein were greater than in anthocyanin-free green leaves. White clover was transformed to overexpress the cloned IFS2_12 gene and some transformants had greater levels of IFS gene expression, up to 12.9 times the average wild type level. However, these transformants did not produce formononetin levels greater than the wild-type. A gene fusion of alfalfa chalcone isomerase (CHI), which produces the precursors naringenin and liquiritigenin, and soybean IFS, which converts the precursors to genistein and daidzein, respectively, was received from the Noble Foundation. Transgenic white clover plants expressing IFS/CHI were produced using a novel method that also regenerated wild-type clones of the transgenic plants. When compared with their wild-type clones, two IFS/CHI transformants produced higher levels of formononetin, thus supporting the suggestion that isoflavonoid levels can be increased in white clover through overexpression of isoflavonoid biosynthesis genes.

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Nurjaya, I. Gusti Made Oka. "Studies on the competitive ability of white clover (Trifolium repens L.) in mixtures with perennial ryegrass (Lolium perenne L.) : the importance of non-structural carbohydrate reserves and plant traits /". Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09APSP/09apspi11.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Stone, Carol E. "Rhizobium strain selection by white clover under conditions of acidity stress". Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335442.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Fowbert, John A. "Nodulation and nitrogen fixation by white clover (Trifolium repens L.) in the presence of mineral nitrogen". Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329349.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Kertulis, Gina Marie. "Effects of nitrogen and cutting management on root growth and productivity of a Kentucky bluegrass (Poa pratensis L.) and white clover (Trifolium repens L.) pasture". Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1882.

Testo completo

Abstract (sommario):

Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains ix, 101 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 78-87).

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Shakeel, Mohammad Arshad. "The pest status of some invertebrate species associated with white clover Trifolium repens L". Thesis, Queen's University Belfast, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329393.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Holtham, Deborah Anne Lydia. "Enhanced soil structuring beneath white clover and its impact on nutrient transport". Thesis, University of Plymouth, 2006. http://hdl.handle.net/10026.1/2315.

Testo completo

Abstract (sommario):

Previous work at IGER has revealed that soil structural differentiation under white clover is phenomenally rapid and enhanced when compared with ryegrass. White clover is one of the most nutritious and widely distributed forage legumes. Its use is advocated in sustainable systems of livestock production because of its ability to acquire atmospheric N through biological fixation in the root nodules. It thus provides an economically viable alternative to the N-demanding conventional system, and a possible solution to reduce the environmental impacts of nitrate leaching from agricultural land. There are, however, potentially negative impacts associated with improving soil aggregation through the use of clover that need further investigation. It appears that legume-based systems are not environmentally benign: similar amounts of N and P are leached from beneath grass-clover swards as those leached from beneath fertilised grass operating at the same level of production. In some circumstances, clover rich swards can give rise to very high levels of nitrate leaching. Thus, this observation of clover induced soil aggregation has important implications for the pollutant transport qualities of soils and for the organic/conventional agriculture debate. Re-packed soil columns of four soil series and 0.5 m intact monoliths of the Crediton series were planted with white clover, perennial ryegrass and a mixture of the two species, and managed according to an organic and conventional farming regime. Visual observations revealed a rapid enhancement in soil structure beneath white clover compared to ryegrass and unplanted soil. A novel technique to determine oxygen diffusion as an indicator of soil porosity, gave a diffusion rate that was nearly nine times greater than that of the grass treatments and fifteen times greater than the unplanted control soil, with intermediate values for the mixed treatment Thus enhanced structural differentiation beneath white clover was supported by greater permeability to air and freer drainage to water. Structural stability tests suggested that white clover improved the ability of the soil to maintain its structure under the action of water, and was estimated to be three times more stable than ryegrass. There was also evidence which implied improved shear strength and resistance to mechanical forces. Differences in soil structure were verified with water retention measurements, which showed a greater proportion of macropores. The void structure was simulated with the 30 Pore-Cor network model, which also suggested a number of larger pores and a saturated hydraulic conductivity which was four times greater than ryegrass. This also highlighted inadequacies in the current standard ISO protocol for water retention. The solute transport studies showed elevated levels of nitrate and phosphate leaching. Concomitant transport of bromide inferred structural differentiation and changes in leaching dynamics. In addition, white clover allowed the passage of greater volumes of water. Most importantly, this was manifested at the soil profile scale and therefore likely to be of consequence in the field. The implications of the research are that enhanced soil structure beneath white clover alters the transport of gases, water, nutrients and other dissolved substances. Further understanding of these soil processes are needed before advocating the use of forage rich legumes in sustainable systems, and for the development of management strategies.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Crockard, Martin A. "Molecular analyses of symbiotic and defense-related responses in white clover roots". Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301737.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Gooding, Roderick F. "Cutting and grazing systems for grass/white clover Trifolium repens L. associations". Thesis, University of Glasgow, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264055.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

19

George, S. "The survival and growth of white clover (Trifolium repens) in upland soils". Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370157.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Chapman, D. F. "The assimilation and distribution of carbon in white clover (Trifoleum repens L.)". Thesis, University of Reading, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329220.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Timberlake, Caitlin. "Urea Formulations on the Productivity of Bermudagrass and Bermudagrass-White Clover Pastures". UKnowledge, 2015. http://uknowledge.uky.edu/pss_etds/70.

Testo completo

Abstract (sommario):

Bermudagrass (Cynodon dactylon L.) is a perennial warm-season grass that is very responsive to nitrogen (N) fertilization. Excessive N applications have negative environmental consequences and make maintaining mixed swards difficult. This study determined the effects of enhanced efficiency (EE) N fertilizers and fertilizer rate on bermudagrass yields, nutritive values, and white clover persistence. Nitrogen sources included urea, urea formulated with Agrotain® (U+A), urea with Agrotain® and dicyandiamide (SuperU), a polymer-coated urea (ESN), ESN+urea (75% ESN, 25% urea), and methylene urea (MU). In the urea formulation trial, SuperU and U+A maximized forage yields at lower N rates. The dicyandiamide in SuperU did not increase yields over U+A. Highest production efficiency was achieved at lower N rates. ESN had the lowest relative stimulate growth, which may increase clover persistence. In the clover persistence trial, the addition of N fertilizer began decreasing clover populations after 112 kg N/ha. Slow-release fertilizers (ESN, ESN+urea, MU) had higher clover percentage at the final harvest. Crude protein and in vitro digestible dry matter increased, while neutral detergent fiber and acid detergent fiber decreased with the addition of white clover. SuperU and U+A were more efficient and ESN had lower relative stimulated growth beneficial for mixed pastures.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Del, Pozo Ramos Manuel. "Sequential grazing of grass/white clover swards by cattle, sheep and goats". Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/16978.

Testo completo

Abstract (sommario):

Two experiments were conducted on sown grass/clover swards (Lolium perenne - Trifolium repens) to study the effect of domestic animal species (sheep, goats and cattle) on sward canopy structure and diet selection and animal performance of a subsequent grazing species. In Experiment 1, the effects of continuous grazing by sheep, goats or cattle at a sward surface height of 6 cm from mid-May to late July (Phase 1) were assessed. From late July until the end of August (Phase 2) swards were continuously grazed at 6 cm by sheep or goats. Sward composition and structure were measured by a stratified clipping technique taking account of short, medium and tall areas on the basis of their mean sward surface heights and separated into grass and clover morphological components. In Phase 2 the diet selected by oesophageally fistulated goats and sheep was measured. Swards previously grazed by cattle tended to have a higher percentage of clover than those previously grazed by sheep and by goats both in the whole sward and on the sward surface at the end of Phase 1 (sward: 11.8% versus 9.5% and 8.8% respectively; sward surface: 18.2% versus 11.1% and 7.60% respectively). This was particularly related to higher amounts of clover in short and tall areas. During Phase 2 sheep ingested a significantly higher percentage clover from cattle-grazed swards (cattle: 29.7%, sheep: 13.3% and goats: 12.6%; p<0.001) whereas the diet of the goats contained 17.3%, 14.0% and 18.9% from cattle, sheep and goats-grazed swards respectively. Furthermore, during Phase 2, there was a greater overall increase in the clover percentage on swards grazed by goats than in those grazed by sheep. Both sheep and goats ingested more clover from tall areas of the sward with 32.2% and 20.1% of the variation in the percentage of clover in their diets respectively attributed to the percentage of clover present in these areas.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Parmenter, Graeme. "The effect of soil water shortage on ryegrass and white clover growing in mixtures". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278085.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Newton, P. C. D. "The establishment, growth and fate of white clover plants : With special reference to the physiology of stolon growth". Thesis, Bangor University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379353.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Muraki, Tomohiro. "Effects of alternative grass species on grazing preference of sheep for white clover". Diss., Lincoln University, 2008. http://hdl.handle.net/10182/1095.

Testo completo

Abstract (sommario):

Despite the importance of a high white clover (Trifolium repens) content in temperate pastoral systems in terms of livestock performance and nitrogen fixation, the proportion of white clover in grass-clover pastures is often low (<20%). This thesis examined in two experiments whether the white clover content of pastures could be improved by sowing white clover with alternative grass species to diploid perennial ryegrass (Lolium perenne L.). In a pasture experiment, DM production, pasture composition and morphology of grass-clover mixtures was measured over the establishment year (January 2007 to January 2008) where white clover was sown in fine mixtures with diploid perennial ryegrass, tetraploid perennial ryegrass, timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.). Pastures were irrigated and rotationally grazed with on-off grazing with Coopworth ewe hoggets. Total annual DM production of pasture was more than 20% higher in tetraploid (12521 kg DM ha⁻¹) and diploid (11733 kg DM ha⁻¹) perennial ryegrass than timothy (9751 kg DM ha⁻¹) and cocksfoot (9654 kg DM ha⁻¹). However, timothy (5936 kg DM ha⁻¹) and cocksfoot (5311 kg DM ha⁻¹) had more than four times higher white clover annual DM production than tetraploid (1310 kg DM ha⁻¹) and diploid (818 kg DM ha⁻¹) ryegrass. Pasture growth rate at the first three harvests in autumn was significantly greater in tetraploid and diploid ryegrass than timothy and cocksfoot. Timothy and cocksfoot had a higher proportion of white clover than tetraploid and diploid perennial ryegrass throughout the entire year. This was due to more and larger white clover plants in timothy and cocksfoot plots. In a grazing preference experiment, the partial preference of sheep for white clover offered in combination with the same grass species as in the pasture experiment was measured in five grazing tests in May, September, October, November and December 2007. Pastures were sown in January 2007. Paired plots (grass and clover both 4.2 m x 10 m) were grazed by three Coopworth ewe hoggets between 9am and 5pm, and preference was recorded by decline in pasture mass and visual scan sampling for grazing time. Grazing preference for clover was generally low throughout these tests (e.g. average apparent DM intake from clover = 47%; average grazing time from clover = 44%). Several explanations are proposed for this low preference including a high N content and intake rate of the grass relative to the clover. No significant differences were found among the grass treatments in total grass grazing time, total clover grazing time, ruminating time, the proportion of grazing time on clover, selective coefficient for clover and DM intake percentage from clover at any date. There was no significant change in overall sward surface height (SSH) decline among grass treatments throughout all the tests except December 2007 when the overall SSH decline for cocksfoot was significantly lower than the other species. The study indicated that the rapid growth rate of perennial ryegrass in the early phase of pasture establishment, rather than differences in partial preference, was the key factor limiting white clover content in the mixed swards relative to cocksfoot and timothy pastures. It is concluded that high clover-containing pastures capable of delivering high per head performance can be established through the use of slow establishing pasture species such as timothy and cocksfoot.

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Evans, Thomas George. "Isolation of Cytokinin Biosynthesis and Metabolic Genes from White Clover (Trifolium repens L)". Thesis, University of Canterbury. School of Biological Science, 2009. http://hdl.handle.net/10092/4821.

Testo completo

Abstract (sommario):

The factors influencing senescence in white clover (Trifolium repens L.) are of considerable importance to the pastoral sector of New Zealand’s economy. The plant hormones, ethylene and the cytokinins, have been implicated as having opposing influences on senescence. This project focused on the cytokinins. The rate limiting step in cytokinin biosynthesis is catalysed by isopentenyl transferase (IPT) and the primary enzyme in the degradation of cytokinins is cytokinin oxidase/dehydrogenase (CKX). Both IPT and CKX genes are present as multi-gene families. A reduction in the level of active cytokinins either via a decrease in IPT expression, or an increase in CKX expression, or both, would implicate the cytokinins in developmental leaf senescence in white clover. White clover grows in a sequential pattern with leaves at all stages of development making it a good model for studying leaf development and senescence. A decrease in leaf chlorophyll is used as a marker for the onset of senescence. A micro-scale chlorophyll analysis was developed using the NanoDrop™ thus allowing tissue from the same leaflet to be used for gene expression and chlorophyll measurements. The pattern of chlorophyll changes was similar to that shown by Hunter et al.(1999) and Yoo et al.(2003) in white clover stolons used for ethylene research. Reverse transcriptase PCR (RT-PCR) and BLAST analysis was used to identify five putative IPT genes and seven putative CKX genes from white clover. RT-PCR demonstrated the expression of seven of these genes (TrIPT1. TrIPT13, TrIPT15 TrCKX1, TrCKX2, TrCKX6). Analysis with quantitative real-time PCR showed expression of TrCKX2 increased markedly during leaf expansion and was consistently high during senescence, suggesting a potential role for CKX in facilitating the progression of senescence.

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Martin, Pierre. "Genetic studies on resistance to alfalfa mosaic virus (AMV) and tolerance to white clover mosaic virus (WCMV) in red clover (Trifolium pratense L.)". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61820.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Riffkin, Penelope A. "An assessment of white clover nitrogen fixation in grazed dairy pastures of South-Western Victoria /". [Richmond, N.S.W.] : University of Western Sydney, Hawkesbury, 1999. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030528.152118/index.html.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Labuschagne, Johan. "Nitrogen management strategies on perennial ryegrass - white clover pastures in the Western Cape Province /". Thesis, Link to the online version, 2005. http://hdl.handle.net/10019.1/1385.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Riffkin, Penelope A. "An assessment of white clover nitrogen fixation in grazed dairy pastures of south-western Victoria". Thesis, [Richmond, N.S.W.] : University of Western Sydney, Hawkesbury, 1999. http://handle.uws.edu.au:8081/1959.7/31.

Testo completo

Abstract (sommario):

Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systems

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Riffkin, Penelope A., of Western Sydney Hawkesbury University e Faculty of Science and Technology. "An assessment of white clover nitrogen fixation in grazed dairy pastures of south-western Victoria". THESIS_FST_xxx_Riffkin_P.xml, 1999. http://handle.uws.edu.au:8081/1959.7/31.

Testo completo

Abstract (sommario):

Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systems
Masters Thesis

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Stephens, P. M. "Competition between strains of Rhizobium trifolii for nodulation sites on the roots of white clover". Thesis, Queen's University Belfast, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374996.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Al-Zarah, Mohamed I. "The effect of grazing management on the efficiency of utilization of grass/white clover swards". Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443113.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Scott, Gavin D. "Root system traits and root longevities in two contrasting cultivars of Trifolium repens (White clover)". Thesis, University of Aberdeen, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425002.

Testo completo

Abstract (sommario):

This study uses sequential digital imaging of rhizotron grown root systems of white clover (Trifolium repens) to evaluate the developmental differences in the architecture of two cultivars with contrasting above-ground characteristics. Root lengths and leaf areas were correlated in both cultivars, with large leaved Alice producing greater leaf area and greater root length than the small leaved S184. The key architectural difference between the two cultivars was that Alice produced a higher ratio of terminal lateral length to axial length than S184. Lateral roots had lower survival times compared with axial roots in both cultivars. Amongst lateral roots, survival was positively influenced by diameter. A 0.1 mm increase in diameter was calculated to result in between 23% and 42% reduction in the risk of lateral root mortality. Destructive investigations of the root systems were made at intervals during the experiment and roots of known age and order were excised and evaluated for C and N content and tissue density. Axial roots were found to have higher tissue density and higher C and N content than laterals, and, these traits increased with increasing axial root age. The hypothesis that axial roots are invested with additional high C compounds to increase their persistence in the soil was supported by microscopic analysis which shown a build up of lignin in axial roots as they aged. A population dynamics model was constructed showing the estimated flux of C and N from plant to soil due to root mortality. The most dynamic C and N pool was in the lateral roots. Breeding and selection of white clover cultivars should aim to maximise the ephemeral lateral root system component to enhance N flux from plant to soil.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Heshmati, Sara [Verfasser], Johannes [Akademischer Betreuer] Isselstein, Johannes [Gutachter] Isselstein, Stefan [Gutachter] Siebert e Klaus [Gutachter] Dittert. "Effect of white clover and perennial ryegrass genotype on yield and forage quality of grass-clover and grass-clover-forb mixtures / Sara Heshmati ; Gutachter: Johannes Isselstein, Stefan Siebert, Klaus Dittert ; Betreuer: Johannes Isselstein". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1186372702/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Payne, Kathryn Marie. "ENHANCED EFFICIENCY NITROGEN FORMULATION EFFECT ON GRASS-LEGUME PASTURE PRODUCTIVITY". UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/113.

Testo completo

Abstract (sommario):

The use of nitrogen (N) fertilizer is generally restricted on mixed species forage systems due to its stimulatory effect on grasses which increases competition with legume species. Reduced legume growth from this competition can compromise forage nutritive value and prospective yields. The controlled-release nature of several enhanced efficiency fertilizer N products holds the potential to improve legume persistence in mixed species pastures while providing supplemental N required by the grass component. The studies contained in this dissertation evaluated the effect of different enhanced efficiency N formulations (ATU, ESN, methylene urea, SuperU, and a 75% ESN: 25% urea blend) and untreated urea on yield, nutritive value, and legume persistence in a ‘Wrangler’ bermudagrass and ‘Durana’ white clover mixture (2014-2016 growing seasons), ‘KY-31’tall fescue and ‘Kenland’ red clover mixture (2015-2016 growing seasons), and ‘KY-31’ stockpiled tall fescue (2015-2017). The three studies were conducted at the University of Kentucky Spindletop Research Farm in Lexington, KY in a randomized complete block design. In the bermudagrass-white clover study, all enhanced efficiency N sources maintained white clover populations similar to the unfertilized grass/clover control, but only ESN caused greater clover composition than standard urea. Total forage yields increased linearly with N rate in all years, but dry weather conditions in the second and third years resulted in lower total yield. Forage nutritive value followed general trends throughout each growing season, but ESN’s ability to maintain clover resulted in higher nutritive value. In the tall fescue-red clover, total forage yields curvilinearly increased with N rate in 2015 but did not vary in 2016. ESN and ESN+urea blend treatments retained clover composition similar to that of the unfertilized control. Stockpiled forage yield increased with higher N rates. Enhanced efficiency N fertilizers with the ability to control N release can enhance forage yield while maintaining clover in mixed species swards.

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Rogers, Jacqueline Bolton. "Investigation of the role of mycorrhizas in the transfer of nitrogen from white clover to grass". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333833.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Davidson, I. A. "An investigation into the physiological basis of the effects of nitrate on grass/white clover competition". Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373466.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Febrer, Melanie. "Construction and assessment of tools for comparative structural genomic studies in white clover (Trifolium repens L.)". Thesis, Aberystwyth University, 2007. http://hdl.handle.net/2160/c0c89441-132f-41f8-80dd-2573dbd5758a.

Testo completo

Abstract (sommario):

White clover is an allotetraploid legume with a genome size of ca 960 Mb and is widely used in Irish grasslands to improve the nutritional value of the forage by increasing the relative amounts of nitrogen present. White clover is closely related to Medicago truncatula, the diploid (genome size of ca 500 Mb) model legume chosen to study the symbiotic genetic programmes of plants and facilitate the genetics and breeding of important legume crops. This thesis describes the construction of a genetic map of a white clover mapping population composed of 94 F1 progeny bred in the Institute of Grassland and Environmental Research (UK) from parents S1S4 and R3R4. The genetic map was constructed using amplified fragment length polymorphism markers and white clover microsatellite markers from previously published white clover maps. The thesis also details a glasshouse and field based phenotypic analysis carried out on morphological traits which allowed quantitative trait loci (QTL) to be detected on the genetic linkage map of white clover. Due to the high correlation between the traits measured, both conservation of QTLs across environments and co-localisation of QTLs for related traits were observed in this study. A BAC library of one of the family parents, R3R4, was constructed using pIndigo BAC-5, consisting of over 37,000 clones with an average insert size of 85 Kb, representing a threefold genome coverage. A preliminary sequence analysis was carried out where 700 BAC clones were sequenced on both ends. Results showed that over 50% of the BAC-ends had a correspondence with the Medicago genome sequence; however only 16 of the BAC-end sequence pairs had homology within a span of 20 to 200 Kb in M. truncatula. The level of synteny between white clover and M. truncatula was assessed by comparative structural genomics, where five BAC clones of the white clover library were sequenced to sixfold coverage and their sequences were compared to the corresponding M. truncatula sequences.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Kelly, Rhys Owen. "Molecular and physiological aspects of arbuscular mycorrhizal symbiosis with near-isogenic white clover : a gene expression study". Thesis, University of South Wales, 2004. https://pure.southwales.ac.uk/en/studentthesis/molecular-and-physiological-aspects-of-arbuscular-mycorrhizal-symbiosis-with-nearisogenic-white-clover-a-gene-expression-study(d43e48e0-fee7-44d0-8c9f-5d690fe185b2).html.

Testo completo

Abstract (sommario):

White clover (Trifolium repens L.) is an important component of low input pasture systems and can form effective associations with both nitrogen-fixing Rhizobium and phosphate-scavenging arbuscular mycorrhizal fungi (AMF). Understanding the genetic control of plant-AM interactions will allow clover breeders to develop genetic markers for selection of phenotypes favourable to AM symbiosis. Clover is normally an out-breeding species. Near-isogenic lines (NILs) developed from inbred lines of clover are ideal candidates for genetic studies since important agronomic traits are fixed. Four closely-related NILs provided plant material with contrasting phenotypes when inoculated with AMF Glomus mosseae. Seed-grown and clonal plants of these closely-related NILs were used to study gene expression associated with AM colonization and functioning. In order to relate plant phenotype responses specifically to changes in phosphorus availability, and ultimately to gene expression, a nutrient flowing culture system was developed in which nutrient application was constant and could be controlled. The only consistent phenotypic response discovered was a decrease in root production in response to AMF colonisation. Differential display demonstrated differences in gene expression in both leaves and roots of clover with and without AMF. These genes were mainly down-regulated in AMF plants and three were identified from a range of NILs under varying P concentrations. More apparent differences in gene expression were found in roots than in leaves, and in low rather than high AMF colonising lines. In total, 45 sequences were identified and cloned; 30 from leaves and 15 from roots. Sixteen sequences had homology with known genes, including protochlorophyllide oxido reductase and leghaemoglobin. The majority corresponded to ESTs from model legumes and from studies such as colonisation with AMF or Rhizobium, and phosphate or nitrogen starvation experiments. Six sequences were not found on any database, indicating that these corresponded to undiscovered genes either expressed or suppressed in AM white clover.

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Elorong, E. E. M. "Factors affecting the response of perennial ryegrass (Lolium perenne L.) white clover (Trifolium repens L.) swards to fertilizer nitrogen". Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332507.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Lataste, Juan Carlos Dumont. "Studies on the relationships between a ryegrass (Lolium perenne L.) - white clover (Trifolium repens L.) sward and grazing dairy cows". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276193.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

43

McAdam, James Henry. "A study of management factors affecting the contribution of white clover to swards for autumn grazing on improved hill land". Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317127.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Ennos, E. D. "An investigation of effects of management, plant selection and growth regulators on seed production of white clover (Trifolium repens L.)". Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374753.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Büker, Patrick [Verfasser], e Willy [Akademischer Betreuer] Werner. "Development of a stomatal conductance model for white clover and its application for ozone flux predictions / Patrick Büker ; Betreuer: Willy Werner". Trier : Universität Trier, 2010. http://d-nb.info/1197696423/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Assmann, Joice Mari. "Produção de forragem e sementes de trevo branco (Trifolium repens L.) em função de manejos de corte e doses de boro". Universidade Tecnológica Federal do Paraná, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/253.

Testo completo

Abstract (sommario):

CAPES
Fabáceas forrageiras têm sido consorciadas com poáceas em sistema de integração lavoura-pecuária, sendo o trevo branco (Trifolium repens L.) uma das fabáceas mais utilizadas e adaptadas no Sul do Brasil. A aplicação de boro tem resultado em benefícios ao desenvolvimento da planta, especialmente para as fabáceas. Portanto, o objetivo deste trabalho foi avaliar os efeitos da aplicação de doses de boro e da remoção da matéria aérea das plantas por meio de cortes, sobre a produção de matéria seca, produção de sementes e concentração mineral de boro e nitrogênio em plantas de trevo branco, cultivadas em um Latossolo Vermelho distroférrico. O trabalho experimental foi instalado na Estação Experimental do Instituto Agronômico do Paraná – IAPAR, localizada no Município de Pato Branco – PR, no ano de 2007 e conduzido até meados 2008. O delineamento experimental foi de blocos ao acaso com parcelas subdivididas, com quatro repetições. As parcelas tiveram como tratamento doze períodos de avaliação, nas subparcelas dois manejos (corte e retirada do material e não corte da parte vegetativa), aproximadamente a cada 60 dias e, nas subsubparcelas foram alocados cinco níveis de B (0; 0,5; 1; 2 e 4 kg ha-1). A maior produção de forragem avaliada mensalmente foi encontrada no mês de fevereiro de 2008, com incremento de 79,7% com uso 3,3 kg ha-1 em relação à testemunha. A produção de MS total acumulada e MS acumulada de folha+pecíolo no manejo com corte, foi obtida com as doses de 2,6 kg ha-1 de B, apresentando uma produção de 22.287 e 18.743 kg ha-1 de MS, respectivamente. A maior concentração de B foi observada no mês de julho, apresentando uma concentração de 48 mg kg-1 de B, com uso de 2,77 kg ha-1 de B. A maior concentração de N foi encontrada no mês de novembro, apresentando uma concentração média de 30,91 g kg-1, com o uso de 3,09 kg ha-1. O maior pico de acúmulo de N no manejo sem corte foi atingido no mês de fevereiro com um acúmulo máximo de 263,36 kg ha-1, com o uso de 4 kg ha-1 de B. No manejo com corte o N total acumulado ao final de um ano foi de 650 kg ha-1 ano-1 de N atingido com o uso de 2,50 kg ha-1 de B. A maior produção de sementes de trevo branco foi obtida no manejo sem corte com uma produção máxima de 525,81 kg ha-1 de sementes, com o uso de 2,59 kg ha-1 de B. As doses de boro influenciaram a produção de forragem, matéria seca de folha+pecíolo, estolão, inflorescência e material senescente, matéria seca acumulada, componentes de rendimento, produção de sementes, concentração de B e N foliar e acúmulo de N foliar em trevo branco, sendo que as doses de 2 a 3 kg ha- 1 de boro seriam as mais recomendadas, visto que doses acima podem diminuir o potencial máximo de produtividade pela toxidez.
Legume forages have been grown together with grass forages in a croplivestock system being the white clover one of the most used and adapted legume at the south of Brazil. The application of boron has resulted in benefits to the plant development, especially to the legumes. Due to it, the aim of this work was to evaluate the effects of increasing rates of boron and the taken out of the aerial parts by cutting the forage over the dry matter production, seed production and mineral concentration of boron and nitrogen in plants of white clover, cultivated in soil Oxisol (Latossolo Vermelho distroférrico, Brazil systems). The experiment was carried out at the Agronomist Institute of Paraná (IAPAR), experimental unit of Pato Branco from 2007 up to 2008. The experiment was laid out as random block design with divided plots and four replications. The plots composed twelve periods of evaluation and the sub-plots two managements (vegetable parts cut and uncut around each 60 days), and at the sub-subplots were allocated five levels of B (0; 0.5; 1; 2 e 4 kg ha-1). The highest forage dry matter production evaluated monthly was found in February of 2008 with an increase of 79.7% using 3.3 kg ha-1 related to the control. The accumulate total DM production and the accumulate leaf+stalk DM production at the management with cuts was obtained with the level of 2.6 kg ha-1 of boron showing a production of 22,287 e 18,743 kg ha-1 of DM respectively. The highest concentration of B was observed in July, showing a concentration of 48 mg kg-1 of B with the use of 2.77 kg ha-1 of B. The highest concentrations of N were found in November, showing an concentration of 30.91 g kg-1, with the use of 3.09 kg ha-1. The higher peak of N accumulate at the management without cuts was reached in February with an maximum accumulate of 263.36 kg ha-1, with the of 4 kg ha-1 of B. At the management with cuts the total N accumulate at the end of one year was 650 kg ha-1 year-1 of N achieved with the use of 2.50 kg ha-1 of B. The highest seed production of the white clover was obtained at the management without cuts with a maximum production of 525.81 kg ha-1 of seed using 2.59 kg ha-1 of B. The levels of N influenced the dry matter production, dry matter of leaf +stalk, stolons, inflorescence and senescent material, dry matter accumulate, yield components, seed production, leaf B and N concentration and accumulate of N in the leaves of white clover, being the rates of 2 and 3 kg ha-1 of B the most recommended ones, once highest rates can decrease the maximum production by it’s toxicity.

Gli stili APA, Harvard, Vancouver, ISO e altri

47

James, Nicola Lewis. "The management and utilisation of white clover/perennial ryegrass and perennial ryegrass swards in relation to milk production and behaviour of dairy cattle". Thesis, Bangor University, 1992. https://research.bangor.ac.uk/portal/en/theses/the-management-and-utilisation-of-white-cloverperennial-ryegrass-and-perennial-ryegrass-swards-in-relation-to-milk-production-and-behaviour-of-dairy-cattle(1a1a64ab-31af-40f0-9dcc-fd88c15e8795).html.

Testo completo

Abstract (sommario):

The literature concerning the nutritional content of white clover as a grazed herbage or conserved crop offered to dairy cattle and aspects of frothy bloat are reviewed. In the first nine week change-over design experiment the effect on milk production and behaviour of spring calving dairy cows grazing white clover/grass swards at contrasting sward heights were examined. Grazing the clover/perennial ryegrass sward to a height of 4 cm increased clover content, but reduced milk production. The 8 cm sward increased milk yields by 15.8%. This was accompanied by an increase in fat and protein yields. Grazing time and biting rate were increased on the 4 cm sward. Cows offered choice between sward types produced intermediate milk production values. A second change-over design experiment conducted over 12 weeks examined milk production and behaviour of spring calving dairy cows in early lactation grazing perennial ryegrass or White clover/perennial ryegrass swards alone or offered a choice between the two sward types or grazed on clover/perennial ryegrass during the day and perennial ryegrass at night. The inclusion of clover in the diet of the dairy cows significantly increased milk production, but reduced fat content. Protein content, fat and protein yields were increased. Cows offered a choice or mixed day and night grazing regime produced similar results, which were intermediate between the clover/ryegrass and perennial ryegrass treatments. Grazing time was increased on clover/perennial ryegrass swards. This experiment also 1 demonstrated the ability of cows to adjust their grazing time to maximise herbage intake. The third experiment compared the value in relation to milk production of three different buffer forages fed to spring calving dairy cows in late lactation grazing either clover/ryegrass or ryegrass swards. The forages were ryegrass and ryegrass/clover silages and ryegrass hay. Milk yield and composition were not affected by forage type, but intakes were higher for grass silage for cows grazing clover/ryegrass swards and visa versa. Hay OM intake was low. The final experiment conducted over the first 15 weeks of the grazing season studied the effect of energy:protein concentration of strawmix supplements on the productivity of spring calving dairy cows grazing a high white clover sward. Milk yields were increased by the provision of a strawmix supplement. The energy:protein ratio had a significant effect on milk composition except fat content. The high energy:high protein supplement tended to precipitate ruminal tympany (bloat), while the low energy:high protein supplement tended to reduce ruminal tympany on this clover based sward. These experiments have given some insight into the use of clover and stimulated questions which require further investigation to enable the farmer to safely incorporate clover into dairy farming systems.

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Roldan, Marissa B. "Expression of ACC oxidase genes in white clover (Trifolium repens L.) roots in response to phosphate supply : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Molecular Biology at Massey University, Palmerston North, New Zealand". Massey University, 2008. http://hdl.handle.net/10179/1133.

Testo completo

Abstract (sommario):

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.

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Streit, Juliane [Verfasser], Rolf [Akademischer Betreuer] Rauber, Rolf [Gutachter] Rauber e Johannes [Gutachter] Isselstein. "Biomass, root distribution and overyielding potential of faba bean/wheat and white clover/ryegrass mixtures / Juliane Streit ; Gutachter: Rolf Rauber, Johannes Isselstein ; Betreuer: Rolf Rauber". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/117811581X/34.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Coady, Juanita R. "Undersowing rutabaga (Brassica napus L.) with white clover (Trifolium repens L.) : effects on the cabbage root maggot (Delia radicum (L.)) and its parasitoid/predator (Aleochara bilineata Gyll.) /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ62377.pdf.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Offriamo sconti su tutti i piani premium per gli autori le cui opere sono incluse in raccolte letterarie tematiche. Contattaci per ottenere un codice promozionale unico!