Climate Change And Variability: Impacts On New Zealand Pastures,
2024
NIWAR
Climate Change And Variability: Impacts On New Zealand Pastures, M J. Salinger, A S. Porteous
IGC Proceedings (1977-2023)
Climate change and variability influence the productivity and distribution of New Zealand pasture species. Temperature and rainfall scenarios are used to explore the sensitivity of New Zealand pastures to potential climate warming next century. Temperature affects the length of the growing season with present pasture species extending 200 m higher in altitude for every 1 •c temperature increase. The greater area of New Zealand that becomes frost free allows the spread of subtropical pasture grasses southwards. However, where low rainfall limits pasture production, changes to the rainfall amount have a significant effect. A rainfall change of I 0% changes the …
A Climate Change Perspective On Grasslands,
2024
CSIRO
A Climate Change Perspective On Grasslands, A Barrie Pottock
IGC Proceedings (1977-2023)
Grasslands are the result of interactions between climate, soil, interspecies competition and natural or humnn distucbance. They are vital to human sustenance but vulnerable to human mismanagement and climatic stress.• Thece is now a strong scientific consensus that climate will change during the next century at a rate unprecedented since the end of the last glaciation. Expected climatic changes include not only increasing temperatures, but also changes in total rainfall and its seasonality, and systematic increases in rainfall intensity. Along with the direct effects of increasing carbon dioxide concentrations on plants, and changes in fire frequency, these environmental influences will …
Structure Of White Clover Populations And Plants In Pastures Grazed By Beef Cattle,
2024
AgResearch, NZ
Structure Of White Clover Populations And Plants In Pastures Grazed By Beef Cattle, I Pinxterhuis, D F. Chapman, M.J M. Hay
IGC Proceedings (1977-2023)
Seasonal variation in the structure of white clover (Trifolium repens) populations and the morphology of individual plants was studied in permanent pastures grazed by beef bulls. Three grazing regimes were applied: set stocking with 5.0 bulls/ha and rotational grazing with either, 5.0 or 7 .5 bulls/ha, Management had little effect on the structure of the plants or the stolon branching structure of the population. On average, 45% of the plants were of 2nd order; this value remained relatively constant throughout the year. The proportion of 1st-order plants increased ��nd the proportion of plants of 3rd- and highCl' order …
Effects Of Defoliation Height And Time Of Initital Defoliation On Regrowth Components In A Poa Pratensis- Dominated Sward,
2024
Swedish University of Agricultural Sciences
Effects Of Defoliation Height And Time Of Initital Defoliation On Regrowth Components In A Poa Pratensis- Dominated Sward, B E. Frankow-Lindberg
IGC Proceedings (1977-2023)
Two experiments on swards dominated by Poa pratensis L. were conducted in 2 climatically contrasting (wann/dry and cold/wet) years. There were either 4 or 3 initial defoliation dates in spring and 3 defoliation heights (2, 6 and 10 cm). Regrowths were harvested 4 weeks after the initial defoliation. The swards received a total of 80 kg/ha nitrogen split into 2 dressings. Regrowth characteristics, based on samples cut to ground level, depended on weather conditions. The yield of vegetative shoots was affected most by shoot size, which in turn was determined by initial defoliation date, in the dry year. In the …
Comparative Growth Of Arrowleaf, Crimson, Rose And Subterranean Clovers In East Texas,
2024
Texas Agricultural Experiment Station
Comparative Growth Of Arrowleaf, Crimson, Rose And Subterranean Clovers In East Texas, G W. Evers
IGC Proceedings (1977-2023)
Annual clovers (Trlfolium sp.) differ in maturity and plant growth during the growing season. Undefoliated plots of Yuchi arrowleaf (T. vesiculosum Savi,), Tibbee crimson (T. incarnatum L.), Overton R18 rose (T. hurtim All.), and Mt. Barker subterranean (T. subterneum L.) clovers were sampled biweekly throughout the growing season in east Texas to study shoot and root weight. Species ranking for shoot weight during the first 100 days was crimson > subterranean > arrowleaf > rose. Ranking for root weight was the same except crimson and subterranean clovers had similar root weights for the first 49 days. Shoot weight increased rapidly in spring in …
Tiller Dynamics Of Perennation In Three Herbage Grasses,
2024
Massey University
Tiller Dynamics Of Perennation In Three Herbage Grasses, C Matthew, C K. Black, B M. Butler
IGC Proceedings (1977-2023)
Data on tiller demography of perennation in prairie grass (Bromus wildenowii Kunth), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca anmdinacea Schreb,) are presented. Two pathways of perennation are described: a reproductive pathway in which perennation is by production of daughter tillers from flowering tillers, and a vegetative pathway in which perennation is by tillering from surviving non• flowering tillers. Both pathways normally contribute to perennation. However, there are few quantitative reports in the literature on how the balance between the 2 pathways varies in different species, or under different defoliation managements, The ranking of species for dominance ri …
Effect Of Air Temperature On Plant Reserves And Regrowth Potential In Napiergrass (Pennisteum Purpurem),
2024
Taiwan Livestock Research Institute
Effect Of Air Temperature On Plant Reserves And Regrowth Potential In Napiergrass (Pennisteum Purpurem), Yeong Chyn Wang, Main Lian Lee
IGC Proceedings (1977-2023)
The response of plant reserves to air temperature and the relationship between these reserves and the regrowth potential of napiergrass (Penniseetum purpurem) after defoliation was examined. Two cultivars, A7007 and Taishiuh No. 1, were cut in Wagner pots and established outside. The plants were moved into the growth chamber for 3 weeks of temperature treatment, from 2 weeks before to 1 week after harvest. Pour temperature combinations were examined: 15-15°C (temperature before-after the harvest), 15-35 °C, 35-15°C and 35-35°C. High temperature (35°C) before the harvest benefited plant growth but was associated with lower plant reserves. The stubble stored more reserves …
Persistence Of Phalaris Aquatica L. In Response To Grazing,
2024
CSIRO
Persistence Of Phalaris Aquatica L. In Response To Grazing, R A. Culvenor
IGC Proceedings (1977-2023)
Cultivars of phalaris (Plialaris aquatica L.) bred in Australia for seedling vigour and winter activity are reported to be less persistent in response to heavy_ grazing than the original introduction, cv. Australian. In an experiment comparing the morphological characters of cultivars, Australian was shown to possess a morphology well adapted to grazing. In contrast, the bred cultivars formed more erect pastures with low basal area, more prone to invasion by annual grasses and retaining less leaf area after grazing. In a second experiment, sheep displayed preference during July for grazing the winter-active cultivar Sirosa over cv. Australian, probably because …
Effect Of Management On Leaf Growth And Senescence Of Three Contrasting Grass Species,
2024
Massey University
Effect Of Management On Leaf Growth And Senescence Of Three Contrasting Grass Species, B M. Butler, J Hodgson
IGC Proceedings (1977-2023)
The innuence of continuous grazing management on leaf extension, leaf senescence and tiller density of 3 grass species with contrasting tillering rates, tiller size and growth habit was examined. Perennial ryegrass (Lolium perenne L. cv. Grasslands Nui), tall fescue (Festuca arundinacea Schreb, cv. Grasslands Roa) and Yorkshire fog (Holc,,s la11allls L. cv. Massey Bnsyn) were maintained in as near a steady state as possible at sward heights of 3-10 cm. The balance between leaf extension and senescence, and tiller density resulted in net extension per unit area being generally greatest at sward heights of- 5.5 cm in Yorkshire fog and …
Whole-Stand Carbon Gains And Nitrogen Distribution In Herbaceous Stands,
2024
Utrecht University
Whole-Stand Carbon Gains And Nitrogen Distribution In Herbaceous Stands, M.J A. Werger, T Hirose
IGC Proceedings (1977-2023)
We studied canopy structure and leaf nitrogen distribution in open and dense stands of tall dicot and monocot herbs and compared the results with simulated canopy performance under uniform and optimised leaf nitrogen distributions. Dense stands showed leaf nitrogen distributions that greatly differed from those of uniform distribution but did not completely match optimum distribution. In dense stands this led to strongly enhanced potential whole canopy carbon gains, while in open stands the leaf nitrogen distribution was not very important in this respect. Dense stands of monocots kept more leaf nitrogen in the lower parts of their canopies than is …
Advances In Genetic Transformation Of Plants,
2024
Purdue University
Advances In Genetic Transformation Of Plants, Thomas K. Hodges, Keerti S. Rathore, Jianying Peng
IGC Proceedings (1977-2023)
Many plant species, including both dicots and monocots, can now be genetically engineered with individual genes isolated from any source. Methods for delivery of foreign DNA into plant cells or protoplasts utilise Agrobacterium tumefaciens (and A. gazogenes), microinjection, polyethylene glycol, electroporation and particle guns. Advantages and disadvantages of each system are discussed. At present, all systems involve i11 vitra cell or tissue culture lo some extent, and this is the most difficult and variable aspect of plant genetic engineering. In addition, all systems suffer from random insertions of the foreign DNA into the plant genome. This requires Southern blot screening …
Applications Of Random Amplified Polymorphic Dna (Rapd) Markers In Plant Biology,
2024
New Zealand Institute for Crop and Food Research
Applications Of Random Amplified Polymorphic Dna (Rapd) Markers In Plant Biology, Gail M. Timmerman, John A. Mccalum
IGC Proceedings (1977-2023)
RAPDs are a new class of molecular marker based on PCR amplification of genomic DNA using random sequence primers. Their value for studying plant genomes has been clearly demonstrated in the short lime they have been in use. Uses of RAPD markers include genome mapping, lagging of genes, studying genetic diversity, identifying cultivars and analysing parentage. RAPDs should prove to be as applicable to the study of animal genomes ns they have for plant genomes, It is important that researchers using or planning to use this type of molecular marker be aware of two possible drawbacks of RAPDs. Since RAPDs …
A Strategy For Cloning Apomixis-Associated Cdna Markers From Buffelgrass,
2024
USDA, Agricultural Research Service
A Strategy For Cloning Apomixis-Associated Cdna Markers From Buffelgrass, D L. Gustine, R T. Sherwood, D A. Hulce
IGC Proceedings (1977-2023)
A strategy to select apomixis-associated cDNA sequences was partially tested in buffelgrass (Pennisetum ciliare (L.) Link, = Cenclrrns ciliaris L.). The dominant A gene allele which confers apomixis would likely be expressed as mRNA only in reproductive tissue undergoing megasporogenesis. Sexual lines lack the apomixis allele. Poly A+ mRNA was isolated from meiotic florets of obligately apomictic line Higgins and sexual line B-11-7 and cloned into lwnbda gl23A. cDNA sequences associated with the npomictic phenotype were enriched by subtracting sequences common lo both plants as follows. Insert DNA sequences of sexual and apomictic cDNAs were released with Notl and …
Genetic Transformation Of Dactylis Glomerata By Microprojectile Bombardment,
2024
University of Tennessee, Knoxville
Genetic Transformation Of Dactylis Glomerata By Microprojectile Bombardment, B V. Conger, D D. Songstand, J K. Mcdaniel, J Bond
IGC Proceedings (1977-2023)
Dactylis glomerata L., cv, Embryogen-P, has been previously genetically transformed by direct uptake of DNA by suspension culture-derived protoplasts. The objective of the present experiments was 10 use this genotype to obtain transformation by microprojec1ile bombardment. Bmbryogenic suspension cultures and plated basal leaf segments were bombarded with DNA coated tungsten particles propelled by two different helium pressure discharge apparatuses. The DNA plasmids contained genes for chlorosulfuron resistance, hygromycin resistance and !i-glucuronidase (GUS). Transient expiession for GUS was obtained on both suspension cultures and leaf segments. A stable event for GUS and 16 plants which rooted well on 2.5 mg/I chlorosulfuron …
Somatic Embryogensis And Plant Regeneration From Immature Inflorescences Of Hyparrhenia Hirta (L.) Stapf,
2024
Cukurova University
Somatic Embryogensis And Plant Regeneration From Immature Inflorescences Of Hyparrhenia Hirta (L.) Stapf, R Hatipoglu, A Gland, C U. Hesemann, T Tukel
IGC Proceedings (1977-2023)
The study was conducted to determine an efficient system for in vitro culture and Hyparrhenia hirta, The effects of 2 different auxins (2,4-D and dicamba) at 3 concentrations (4.5 µM, 22,6 µM and 45,2 µM) and 2 ecotypes with different chromosome numbers (2n= 36 and 2n • 54) on callus induction and plantlet regeneration from immature inflorescences of Hyparrhenia hirta were investigated. Inflorescence segments of 5 mm length from greenhouse-grown plants were cultured on a modified Linsmaier and Skoog medium supplemented with 30 g/1 agar, Large differences In frequency of callus induction and callus weight were observed among lhe different …
Somatic Embryogensis And Plant Regeneration From Long-Term Suspension Culture Of Digitaria Decumbens,
2024
Livestock Research Institute
Somatic Embryogensis And Plant Regeneration From Long-Term Suspension Culture Of Digitaria Decumbens, Yu-Kuei Cheng
IGC Proceedings (1977-2023)
The optimum condition for embryogenic callus formation and plant regeneration from immature inflorescences of Digltarla decumbens was MS medium supplemented with O,S mg/I 2,4-D, 2.0 mg/) kinetin and 0,591, NaCl. For long-term subcultures, pieces of embryogenic callus were cultured on MS liquid medium supplemented with 1-2 mg/1 2,4-D, 0.591, NaCl, 5% coconut milk, SOO mg/I casein hydrolase and O.S mg/I 6-benzylaminopurlne, and were subcultured every 4-S days. Bmbryogenic suspension cultures were maintained for more than 1 year. More than 5000 plants may be produced from an explant within 6 months. Bmbryoids from suspension cultures showed a bipolar organisation.
Transformation Of White Clover With A Gene Encoding A White Clover Mosaic Virus Coat Protein,
2024
AgResearch, NZ
Transformation Of White Clover With A Gene Encoding A White Clover Mosaic Virus Coat Protein, Brigitta Dudas, R L.S Forster, C J. Van Dolleweerd, D.W R. White
IGC Proceedings (1977-2023)
Genes encoding the white clover mosaic virus (WClMV) coat protein . have been introduced into white clover (Trifolimn repens L.) using Agrobacterium tumefaciens mediated T-DNA transfer. Integration of the coat protein gene in regenerated callus has been confirmed hy Southern blotting of polymerase chain reaction (PCR) amplification products generated using specific oligonucleotide primers. A polyclonal antibody, raised against purified WCIMV coal protein, recognised a polypeptide of c. 25 kDa after SOS-PAGE and Western blotting. The recogilised polypeptide co-migrates with the purified coat protein. Using ELISA, levels of coat protein accumulation in transgenic callus have been determined. The scope for …
Embryo Rescue And Somatic Hybridisation For The Production Of Interspecific Hybrids In The Genus Medicago,
2024
Instituto di Ricerche sul Miglioramento Genetico delle Plante Foraggere del CNR
Embryo Rescue And Somatic Hybridisation For The Production Of Interspecific Hybrids In The Genus Medicago, S Arcioni, F Damiani, M Piccirilli, F Pupilli
IGC Proceedings (1977-2023)
T• broaden the germplasm sources available for the genetic improvement of alfalfa, new interspecific hybrids between Medlcago saliva L. and other Medicago species (M. coemlea, M. arborea and M. rugosa) hove been obtained. To • overcome lncompalibility barriers existing between alfalfa and the wild species, ovule-embryo culture and somatic hybridisation were used. Viable plants were obt11incd through the utilisation of both techniques Md their hybrid nature was demonstrated by analysis of morphological traits, by cylological investigations and by electrophorelic profiles of esterascs and peroxidases. Hybrids were fertile and In the fulure their backcross to alfalfa should allow the useful tr11i,s …
Use Of Molecular Markers In Alfalfa For Construction Of A Genetic Map And Studying Genetic Rearrangements In Non-Sexually Derived Hybrids,
2024
Instituto di Ricerche sul Miglioramento Genetico delle Plante Foraggere del CNR
Use Of Molecular Markers In Alfalfa For Construction Of A Genetic Map And Studying Genetic Rearrangements In Non-Sexually Derived Hybrids, F Damiani, F Pupilli, M Piccirilli, S Arcioni
IGC Proceedings (1977-2023)
Two genomic libraries have been constructed from Medicago saliva DNA reslfictcd with both Pstl and EcoRT. The libraries have been screened and compared for the presence of highly repeated DNA sequences. Restriction fragment length polymorphism among 3 varieties of M. saliva (Rangelander, Adriana, CADL) and 3 species of the genus Medicago (M. coerulea, M. falcata, M. arborea) has been investigated using a large number of probe-enzyme combinations .. Four-and 6-base cutter restriction enzymes have been used. DNA electrophoresis has been performed with· 2 substrates (agarose and polyacrylamide) in order to detect polymorphism at a higher range of fragment lengths. About …
Use Of Allozyme Genetic Markers To Follow The Establishment Of White Clover Oversown Into Hill Country,
2024
University of Walkato
Use Of Allozyme Genetic Markers To Follow The Establishment Of White Clover Oversown Into Hill Country, K D. Adam, M E. Wedderburn, L A. Greaves
IGC Proceedings (1977-2023)
Allozyme marker loci Gpi-3,4 and Pgm-3,4 were used to monitor establishment of plants of the white clover (Trifolium repens L., cv. Grasslands Huia) oversown into 3 steep, north-facing hill country pastures. Comparisons of genotype frequencies in samples of the unimproved (resident) populations, the oversown populations 18 months after oversowing and Huia, provided information about changes in the genetic composition of the white clover populations after oversowing. In each case, oversowing brought about significant changes in allele frequencies but the estimated proportions of plants of cuhivar Huia were variable at 24.2%, 92.4% and 100%, indicating that establishment rates can vary not …
