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Articles 31 - 60 of 10533
Full-Text Articles in Entire DC Network
Integrated Grazing Of Goats With Sheep Or Cattle On Continuously Grazed Pasture, A M. Nicol, A.J F. Russel, I A. Wright
Integrated Grazing Of Goats With Sheep Or Cattle On Continuously Grazed Pasture, A M. Nicol, A.J F. Russel, I A. Wright
IGC Proceedings (1993-2023)
Oroups of ewes (10) and their twin lambs were grazed on sown ryegrass• white clover (Lolium perenne L.-Trifollum repens L.) pastures maintained at a sward surface height of 4 or 8 cm and a further group grazed with yearling goats (in a proportion of 1/3 ewe plus lamb live weight) also at fi cm. A second concurrent experiment consisted of 3 similar treatments using young cattle with sward surface heights of 8 and 12 cm. Results over the 140-day grazing period showed that allhough the diet selected by sheep and cattle grazed with goats contained more green grass …
Herbage And Animal Production From Tall Fescue- And Ryegrass-Based Pastures In A Summer-Dry Environment, D E. Hume, R.J M. Hay, T B. Lyons
Herbage And Animal Production From Tall Fescue- And Ryegrass-Based Pastures In A Summer-Dry Environment, D E. Hume, R.J M. Hay, T B. Lyons
IGC Proceedings (1993-2023)
Herbage production and animal performance were measured over 3 years In Hawkes Bay, a summer-dry region of New Z'.ealand. Tall rescue (Festuca arundinacea) (3 cultivars, all endophyte free) was compared with high endophyte perennial ryegrass (Lolium perenne). All pastures were sown with white clover (Trifolium repens). Herbage production and composition were determined for all seasons while cattle were monitored for live-weight gains from spring through to autumn. Tall fescue pastures produced 27% more total dry matter/ year than the ryegrass pasture, primarily in autumn. In summerautumn, ryegrass pastures had up to 76% dead matter …
Pasture Production Of Annual, Hybrid And Perennial Ryegrasses In Cool And Warm Temperature Climates, D E. Hume, M J. Hickey
Pasture Production Of Annual, Hybrid And Perennial Ryegrasses In Cool And Warm Temperature Climates, D E. Hume, M J. Hickey
IGC Proceedings (1993-2023)
Pasture production and persistence of 8 ryegrass species-cultivars were evaluated under 2 grazing frequencies (infrequent and frequent) in a cool temperate climate (Southland) and a warm temperate climate (Manawatu) in New Zealand. All pastures were sown with white clover (Trifolirim repe11s) and rotationally grazed with sheep for 3 years. The 8 ryegrass lines were divided botanically into cultivars of annual ryegrass (Lo/ium muftljlorum), hybrid ryegrass (L. boucl1eanu111) (most of the parentage derived from L. multiflorum) and perennial ryegrass (L. pere,me). Infrequent grazing resulted in higher yields and particularly higher ryegrass yields, but lower ryegrass tiller numbers at the cool site. …
Influence Of Sward Height On The Mechanics Of Grazing And Intake Rate By Racehorses, T P. Hughes, J R. Gallagher
Influence Of Sward Height On The Mechanics Of Grazing And Intake Rate By Racehorses, T P. Hughes, J R. Gallagher
IGC Proceedings (1993-2023)
Indoor studies were conducted with harvested turfs to evaluate the effect of sward height on the mechanics of grazing and Intake rate of racehorses. Bile weight increased from 0.64 g DM at the lowest sward height of 13.1 cm to 1.29 g DM at the highest sward height, 29,2 cm. Bite rate declined from 57.9 bites/min at the lowest sward height to 37.4 bites/min at the highest. This decline in bite rate as sward height Increased reflected increasing depth of bite, bite volume and bile weight. Intake rate did not increase with increasing sward height, It was concluded that this …
Changes In Pasture Composition In Semi-Arid Environments Due To Soil Fertility, P C. Kerridge, J G. Mcivor
Changes In Pasture Composition In Semi-Arid Environments Due To Soil Fertility, P C. Kerridge, J G. Mcivor
IGC Proceedings (1993-2023)
The changes in the yield and botanical composition after the sowing of grass and legume species into cleared native woodland in 2 longterm grazing trials are presented and discussed. Soil fertility, rainfall and method of establishment all affected pasture composition. Increasing the soil fertility through phosphate application was necessary for sustained production of sown grass and also improved legume performance.
Nitrogen Recovery Of Coastal Bermudagrass As Influenced By Sulphur Fertilization, J M. Phillips, W E. Sabbe
Nitrogen Recovery Of Coastal Bermudagrass As Influenced By Sulphur Fertilization, J M. Phillips, W E. Sabbe
IGC Proceedings (1993-2023)
Research was conducted during 2 growing seasons to determine N and S fertiliser recovery of Coastal bermudagrnss (Cynodon dactylon (L.) Pers.) on ft $-deficient Rilla silt loam (fine-silty, mixed, thcrmic Typic Hnpludalf) soil in the Gulf Coastal Plain of the south-eastern USA, S wns applied as gypsum or wettable S at the annual Initiation of fornge growth at 100 kg S/ha, N wu applied as ammonium nitrute (NH4NO3),_ urea, and 32% urea-ammonium nitrate (UAN) solution at rates of 0, 224, and 448 kg N/ha in 4 split applications. N sources did not significantly influence Nor S recovery. However, both …
Climate Change: Adapting Tropical And Subtropical Grasslands, G M. Mckeon, S M. Howden, N.O J. Abel, J M. King
Climate Change: Adapting Tropical And Subtropical Grasslands, G M. Mckeon, S M. Howden, N.O J. Abel, J M. King
IGC Proceedings (1993-2023)
Climate change as a result of increasing greenhouse gas concentrations or lhe repetition of historical climale variability will affect the management and production of tropical and subtropical grasslands that support about half the world's domestic herbivores. Previous studies of the regional impact of climate change and climate variability on intensive agriculture have shown lhat such evaluation should include the known and expected abilities of managers and governments to respond by reducing the negative impacts and taking advantage of positive opportunities, A high priority for grassland scientists is the development of similar evaluation capabilities for grassland systems, which are more complex …
Evaluating The Effects Of Climate Changes On Grasslands, Robert G. Woodmansee, William E. Riebsame
Evaluating The Effects Of Climate Changes On Grasslands, Robert G. Woodmansee, William E. Riebsame
IGC Proceedings (1993-2023)
Determining the effects of climate change on cold region grasslands requires the integration of knowledge from the biological, physical and social sciences. That integration is dependent on new methods, technologies and facilitation techniques ! that allow evaluation and management of complexity rather than focusing on simplification. Specifically, grassland response can be defined as the interaction of 10 basic sectors: (I) wenther and climate (Including chemical factors}, (2) winter, (3) soil properties, (4) assemblages of organisms, (5) energy, (6) economic viability, (7) individual human behavior, (8) cultural and community viability, (9) organisational penalty, and (10) political, legal, policy, and regulatory Influences. …
Greenhouse Gas Exchanges With Temperate Grassland Systems, S C. Jarvis, D J. Hatch, G J. Dollard
Greenhouse Gas Exchanges With Temperate Grassland Systems, S C. Jarvis, D J. Hatch, G J. Dollard
IGC Proceedings (1993-2023)
Preliminary studies are described which examine the fluxes of two important greenhouse gases from grassland systems, In the first, effects of different slurry application methods to a peat soil on the emission of N2O were examined. All methods resulted in a significant release of N20 at rates which varied with treatment, time and environmental conditions. The greatest rates of denitrification occurred with acidified slurry under wet conditions: this however, produced the lowest proportion of losses as N2O, In the second study, changes in CH4 concentration above a grazed sward were measured and indicated a definite positive flux from the system …
Methane Production By New Zealand Ruminants, K Betteridge, M J. Ulyatt, J Knapp, R L. Baldwin
Methane Production By New Zealand Ruminants, K Betteridge, M J. Ulyatt, J Knapp, R L. Baldwin
IGC Proceedings (1993-2023)
Methane production by ruminants in New Zealand was estimated using a ma1hema1ical model of rumen digestion interfaced with census livestock numbers. New Zealand was divided into 4 climatic regions with each classified into improved, unimproved and tussock grasslands, and livestock were allocated to each class at appropriate stocking rates. Models of changing livestock numbers within n year were developed for each animal and land class. Food dry matter intake for each class of livestock was calculated from estimates of feed requirements and diet quality. Total methane production was estimated to be 1.50 Tg per year: 58.4% sheep, 20.7%, beef cattle, …
Vertical And Diurnal Profiles Of Atmospheric Carbon Dioxide Concentrations In Manawatu, New Zealand, C C. Bell
Vertical And Diurnal Profiles Of Atmospheric Carbon Dioxide Concentrations In Manawatu, New Zealand, C C. Bell
IGC Proceedings (1993-2023)
Carbon dioxide concentrations were monitored at 2 heights above pasture, at Flock House, New Zealand using an infrared gas analyzer attached to a multiport sampler, Characteristic profiles for a calm day and a windy day are presented. At low wind speeds there was a marked diurnal cycle in CO2 concentration with a maximum difference of 336 ppm between day and night concentrations. An elevated CO2 concentration· was evident for some hours after sunrise. At higher wind speeds the CO2 cycle was less marked, with only a 20 ppm difference between day and night levels. At times, plants are exposed to …
Nitrous Oxide Emissions From Grassland In Manawatu, New Zealand, R A. Carran, J P. Evans
Nitrous Oxide Emissions From Grassland In Manawatu, New Zealand, R A. Carran, J P. Evans
IGC Proceedings (1993-2023)
Nitrous oxide (Np) is a minor component of the atmosphere which acts as a potent greenhouse gas and also causes ozone depletion. Soil bacteria are the most important agents of N2O production, but both the New Zealand and the international data on N2O emission rates from soils are very poor at present. In order to help define the possible range of emission ranges from pasture soils· we selected sites with characteristics that would make then "high" or "low" emitters of N2O. The "high" emission site was a fine-textured, fertile but poorly drained flood plain soil. The "low" emission site was …
Changing Stocking Rates And Burning Management To Reduce Greenhouse Gas Emissions From Southern Queensland Grasslands, S M. Howden, G M. Mckeon, J C. Scanlan, J O. Carter, D H. White
Changing Stocking Rates And Burning Management To Reduce Greenhouse Gas Emissions From Southern Queensland Grasslands, S M. Howden, G M. Mckeon, J C. Scanlan, J O. Carter, D H. White
IGC Proceedings (1993-2023)
GRASSMAN, an agricultural decision-support model, has been modified to include sources, sinks and storages of greenhouse gases. The modified model was used to investigate the effects of changes in stocking rate and burning management on greenhouse gas emissions of southern Queensland grasslands. These grasslands are significant net emitters of greenhouse gases in their natural state, resulting in large differences between net and anthropogenic (man-made) emissions and hence, to different conclusions regarding emission reduction strategies. At moderate stocking rates, anthropogenic emissions could be reduced by about 20% with little loss of productivity. However, similar reductions in net emissions require larger management …
Development Of Plants Resistant To Insect Pests Using Gene Manipulation, D.W R. White, D R. Biggs, M T. Mcmanus, C R. Voisey, J T. Christeller, A H. Broadwell, E.P J. Burgess, C N. Chilcott, P J. Wigley, P G. Mcgregor
Development Of Plants Resistant To Insect Pests Using Gene Manipulation, D.W R. White, D R. Biggs, M T. Mcmanus, C R. Voisey, J T. Christeller, A H. Broadwell, E.P J. Burgess, C N. Chilcott, P J. Wigley, P G. Mcgregor
IGC Proceedings (1993-2023)
Damage to pasture plants caused by insect pests reduces the supply of feed for grassland animal production. In addition, the use of chemical insecticides for the control of pasture pests is undesirable for reasons of high cost and possible damage to the environment. One way to overcome these limitations is 10 utilize a recent development. in plant molecular biology which has seen the incorporation of cloned genes that confer insect _pest resistance into crop plants. To date, the most widely used genes for this purpose are those coding for insecticidal proteins from the bacterium Bacillus thuringiensis, and for inhibitors …
Genetically Engineer Protection Against Viruses And Fungi, John Fitchen, Roger N. Beachy
Genetically Engineer Protection Against Viruses And Fungi, John Fitchen, Roger N. Beachy
IGC Proceedings (1993-2023)
The first examples of plant genetic engineering for disease resistance were for the control of virus diseases. Plants that were transformed with a gene to express the coat protein of tobacco mosaic virus (TMV) were shown to have increased resistance to infection by TMV. This approach, referred to as coat protein-mediated resistance (CP-MR), has been applied to give protection against at least 35 different viruses, belonging to 12 virus groups in at least 13 plant species. Field trials of some of these examples have demonstrated that CP-MR can effectively protect plants under field conditions. Other viral genes have also been …
Bermudagrass Allelochemistry And Influence On Spodoptera Frugiperda Herbivory, S Quisenberry, M Mohamed
Bermudagrass Allelochemistry And Influence On Spodoptera Frugiperda Herbivory, S Quisenberry, M Mohamed
IGC Proceedings (1993-2023)
Cultivated area of bermudagrass (Cynodon dactylon L. Pers.), in the USA are under stress from a complex of insect and secondary fungal pests which has resulted in a loss in crop production. The fall armyworm (Spodoptera frugiperda (J.E. Smith)) is the major insect herbivore of bermudagrass in the south-eastern USA. Bermudagrass breeding programmes over the last decade have yielded germplasm with potential insect-resistant traits. Thus, a programme was initiated to define bermudagrass allelochemislry with respect to insect herbivory. Pall armyworm is variably responsive to bermudagrass cultivars, the basis being causally related to a differential concentration of the phagostimulant 6, …
Purification And Characterization Of A Proteinase Inhibitor From Lolium Perenne L., Mohammed Tasneem, C A. Cornford, M T. Mcmanus, D W.R White
Purification And Characterization Of A Proteinase Inhibitor From Lolium Perenne L., Mohammed Tasneem, C A. Cornford, M T. Mcmanus, D W.R White
IGC Proceedings (1993-2023)
A proteinase inhibitor from dry seeds of Lolium perenne L. cv. Grasslands Ruanui has been partially purified and characterised. Standard protein separalion techniques have been used to enrich the presence of lhe inhibitor in seed extracts by 37-fold. Using synthetic substrates the inhibitor can retard the activity of bovine chymotrypsin, but not bovine trypsin. Gel filtration column chromatography indicates that the native protein has a molecular weight of c. 20 KDa.
Hypervariable Mini-Chromosomes Of Colletotrichum Gloeosporidoides Infecting The Pasture Legume Genus Stylosanthes, John M. Manners, Andrew Masel, John A.G Irwin
Hypervariable Mini-Chromosomes Of Colletotrichum Gloeosporidoides Infecting The Pasture Legume Genus Stylosanthes, John M. Manners, Andrew Masel, John A.G Irwin
IGC Proceedings (1993-2023)
Coiletotrichum gloeosporioides causes anthracnose disease of the tropical pasture legumes Stylosanthes, Two pathotypes and multiple physiological races are present in Australia. The mechanisms producing genetic variation in this pathogen are not understood. Electrophoretic karyotyping has revealed considerable variation in the size and number of a group of small chromosomes (0.2-1.2 Mb in size) both between and within types. Molecular analysis of a selected mini-chromosome using chromosome-specific DNA probes suggests that it has originated by horizontal transfer from a genetically distinct strain. This mini-chromosome is unique to race 3 within the Type B pathogen and may determine race specificity. A functional …
Coat Protein-Mediated Protection Against White Clover Mosaic Virus And Potato Virus X In Tobacco, D L. Beck, C J. Van Dolleweerd, B Dudas, D R.W White, R.L S. Forster
Coat Protein-Mediated Protection Against White Clover Mosaic Virus And Potato Virus X In Tobacco, D L. Beck, C J. Van Dolleweerd, B Dudas, D R.W White, R.L S. Forster
IGC Proceedings (1993-2023)
The coat protein genes of the potexviruses white clover mosaic virus (WClMY) or potato virus X (PVX) were introduced into Nicotiana benthamiana plants by gene transfer. Transgenic plants expressing the coal protein gene of WCIMY or PYX were highly resistant to infection when challenge-inoculated with the virus from which the coat protein gene was obtained (homologous challenge). Similar resistance was obtained when homologous viral RNA was used as inoculum, The transgenic plants were also protected against infection with the heterologous virus, but only at low inoculum concentrations. The level of protection in PYX transgenic plants was directly correlated with the …
Transformation Of White Clover With A Gene Encoding A Lepidopteran-Active- Endotoxin From Bacillus Thuringiensis Var. Berliner 1715, C R. Voisey, D.W R. White, P G. Mcgregor, B L. Barker
Transformation Of White Clover With A Gene Encoding A Lepidopteran-Active- Endotoxin From Bacillus Thuringiensis Var. Berliner 1715, C R. Voisey, D.W R. White, P G. Mcgregor, B L. Barker
IGC Proceedings (1993-2023)
During sporulation, Bacillus thuringiensis var. berliner 1715 produces insecticidal proteins (6-endotoxins) that are lethal specifically to Lepidopternn insects. Agrobacterium tumefaciens-mediated T-DNA transfer has been used to introduce a cry/A(b) li-endotoxin gene (the 812 gene) from this B. thuringiensis strain into a genotype of white clover (WR8). The aim is to protect white clover (Trifolium repens L.) from damage caused by Lepidopteran insects, including the pasture pests porina (Wiseana spp.) and sod-web worms (Crombidae), White clover plants were transformed with a binary vector (pGSH 163) containing the bidirectional mannopine synthase promoter which directs simultaneous expression of both …
Prediction Of Grassland Plant Responses To Global Change, B D. Campbell, J P. Grime
Prediction Of Grassland Plant Responses To Global Change, B D. Campbell, J P. Grime
IGC Proceedings (1993-2023)
Global change is challenging the predictive power of biology. Increasingly, biologists are being asked to draw together existing knowledge and new experimental data, in order to provide predictions of the effects of global change at regional, national and global scales. In this paper we examine how well global change effects on grassland plants can be predicted, and what avenues might be used in future to improve predictive capabilities. Broad predictions of the direction of change in grassland vegetation can be made quite simply and from a limited set of data. Predictions of the rate and magnitude of change are more …
Climate Change And Grasslands: Ecosystem-Level Responses To Elevated Carbon Dioxide, Clenton E. Owensby
Climate Change And Grasslands: Ecosystem-Level Responses To Elevated Carbon Dioxide, Clenton E. Owensby
IGC Proceedings (1993-2023)
Elevated CO2 is the major greenhouse gas associated with global climate change. The impact of increasing atmospheric CO2 on grassland ecosystems has been studied little. Studies with single plants or populations in controlled environments have provided knowledge of the mechanisms involved in plant response to elevated CO21 but without ecosystem-level studies over an extended period, we will be unable to make any valid predictions. Primary production of grassland ecosystems under elevated CO2 will likely increase, with the greatest increase coming with C3-dominated plant communities, or plant communities that are .subjected to frequent drought stress. Increased nitrogen-use efficiency and reduced nitrogen …
Variation In The Response Of Pasture Plants To Carbon Dioxide, B D. Campbell, W A. Laing, P.C D. Newton
Variation In The Response Of Pasture Plants To Carbon Dioxide, B D. Campbell, W A. Laing, P.C D. Newton
IGC Proceedings (1993-2023)
The percentage increases in growth resulting from a doubling of atmospheric CO2 concentration were measured for 37 common pasture plants under strictly controlled conditions of temperature, nutrient supply and irradiance. A wide range of variation in potential response lo CO2 was detected in the day/night temperature range 12n°c to 28/ 23°C. C4 species responded litlle to elevated CO2 The mean ± standard deviation of the distribution of c3 species responses ranged from l±21% at 1m•c to 90±40% at 28/23°C. These responses varied with the stage of plant development. The response by Lolium perenne cv. Grasslands Nui was of intermediate size …
Will Subtropical Grasses Keep Spreading Through New Zealand?, B D. Campbell, R.J M. Hay
Will Subtropical Grasses Keep Spreading Through New Zealand?, B D. Campbell, R.J M. Hay
IGC Proceedings (1993-2023)
n this paper we briefly examine the effects that rising temperature and atmospheric CO2 concentrations may have on the spread of subtropical grasses in New Zealand. Data are presented from controlled-environment experiments measuring the growth and competitive suppression of white clover by a variety of local temperate and subtropical grasses at CO2 concentrations of 3S0 ppm and 700 ppm. These data support the prediction that some subtropical grasses may decline in aggressiveness relative to temperate species in New Zealand in the future as atmospheric CO2 levels rise. Some of the factors likely to modify the expression of temperature and CO2 …
Effect Of Carbon Dioxide Concentration On The Competitive Ability Of Clover: Measurements Of Growth And Rubisco, W A. Laing, D H. Greer, B D. Campbell
Effect Of Carbon Dioxide Concentration On The Competitive Ability Of Clover: Measurements Of Growth And Rubisco, W A. Laing, D H. Greer, B D. Campbell
IGC Proceedings (1993-2023)
White clover (Trifolium repens cv. Grasslands Huia) was grown in competition with one of 10 established grass species or else grown alone. Plants were grown at either 350 or 700 ppm CO2, at 28/23°C and 700 µmol/m1/sec photon flux density. Plant growth and extractable ribulose bisphosphate carboxylase (rubisCO) were measured. Grass growth responded less to CO2 than clover. In the absence of grass competition, clover growth Increased 30% under 700 ppm CO2 compared with 350 ppm, but the response varied from 0% to 100% • when grass competition was present. Increased CO2 reduced extractable rubisCO activity (expressed on a …
Response Of Natural Turves Of Pasture To Elevated Carbon Dioxide In A Controlled Environment, P.C D. Newton, H Clark, C C. Bell, E M. Glasgow
Response Of Natural Turves Of Pasture To Elevated Carbon Dioxide In A Controlled Environment, P.C D. Newton, H Clark, C C. Bell, E M. Glasgow
IGC Proceedings (1993-2023)
Large natural turves from a ryegrass-white clover (Lolium pernne, trifolium repens) pasture were exposed to increasing day/nighl temperatures at 350 and 700 µVI CO2 over a 7•month period. Growth rate al the highest temperature (22/16°C day/night) was IS% higher at the elevated CO2 level; at lower temperatures the response to CO2 was reduced or even negative (-6% at 10/4°C). The growth rate of ryegrass was much lower at elevated CO2 while that of white clover and other grasses was increased. These results are compared with previous studies using synthetic communities, and the limited response to CO2 is noted …
Implications Of A Doubling In Ambient Carbon Dioxide Levels Of Herbage Quality In Perennial Ryegrass And White Clover, H Clark, C C. Bell, P.C D. Newton, B D. Campbell
Implications Of A Doubling In Ambient Carbon Dioxide Levels Of Herbage Quality In Perennial Ryegrass And White Clover, H Clark, C C. Bell, P.C D. Newton, B D. Campbell
IGC Proceedings (1993-2023)
Digestibility (DMD) and crude protein (CP) percentage in leaf and stem of 4 cultivars each of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) grown at 3 day/night temperatures (12f7, 18/ 13, 28/23°C) and 2 CO2 concentrations (35 0 or 700 ppm) was estimated using near infrared reflectance spectroscopy (N[RS). Differences between cultivars in DMD and CP were small and non-significant. Higher temperatures reduced DMD andCP in both species. DMD was unaffected by CO2 concentration in either species. The higher concentration of CO2 reduced leaf and stem CP by 14.6 and 10% respectively in white clover …
Long-Term Exposure To Global Changes In Grassland Ecosystems: Whole-Season And Temporal Trends In Changing Productivity In Response To Increased Carbon Dioxide Level And Air Temperature, I Nijs, H Teughels, I Impens, T Behaeghe
Long-Term Exposure To Global Changes In Grassland Ecosystems: Whole-Season And Temporal Trends In Changing Productivity In Response To Increased Carbon Dioxide Level And Air Temperature, I Nijs, H Teughels, I Impens, T Behaeghe
IGC Proceedings (1993-2023)
Six commercial grass cultivars were exposed to elevated CO2 level (±700 ppm), increased air temperature (+4°C) or a combination of both during an entire growing season, using a "field tracking system" for continuous simulation of outside field temperatures (or ambient 44C), inside sunlit greenhouse units. On a whole-season basis, elevated CO2 positively affected above-ground productivity, with a range of 11-30%, depending on species, although early-season stimulation was smaller than late spring CO2 gain. Effects of increased temperature were positive in spring, but decreased towards summer and became negative for almost all species, yielding a "no effect" seasonal balance. Almost no …
Effect Of Elevated Carbon Dioxide On The Performance Of Nine Coexisting Grassland Species, J Watson, J D. Graves
Effect Of Elevated Carbon Dioxide On The Performance Of Nine Coexisting Grassland Species, J Watson, J D. Graves
IGC Proceedings (1993-2023)
Microcosms were constructed to represent a neutral grassland community under traditional agricultural management. During a season of fumigation at ambient and 600 µmot/mot CO2, plant performance was recorded. An increase of biomass for the whole community resulted at elevated CO2, but the response of individual species differed, There are indications that competitive interactions may change within a community due to the effects of CO2 enrichment; this may eventually result in a change in species composition.
Effects Of Different Grass Species On Nitrogen Fixation By White Clover Under Conditions Of Elevated Carbon Dioxide And Temperature, J R. Crush, B D. Campbell
Effects Of Different Grass Species On Nitrogen Fixation By White Clover Under Conditions Of Elevated Carbon Dioxide And Temperature, J R. Crush, B D. Campbell
IGC Proceedings (1993-2023)
Growing clover in binary mixtures reduced clover shoot dry matter (DM) and nitrogenase activity compared with clover in monoculture. Nitrogenase activity/g clover shoot OM increased in the mixtures to a similar extent with 5 different companion grass species. Elevated atmospheric 002 increased nitrogenase activity/g clover OM in the mixtures but specific nitrogenase activity was not changed with increased temperature. Using nitrogenase activity/unit grass OM as a competitive index showed that elevated CO2 reduced competitive stress on white clover. Two tropical grasses (Pennisetum clandestinum and Paspalum dilatatum) were less competitive to white clover at 18/13°C than 3 temperate species …