Earth Sciences Commons^™

Implications For Grasslands Of The Response To Climate Change By The World Food System, Martin Parry, Cynthia Rosenzweig

IGC Proceedings (1977-2023)

A recent and preliminary assessment of the sensitivity of the world food trade to climate change has indicated the following: Assuming {unrealistically} no adjustments in inputs, global food grains production in 2060 is estimated to be reduced by l-7% from the level that would be expected under a future without climate change. Food prices, including feedstock prices, are estimated lo be increased as a consequence, The implications of lhese changes for grassland production systems are considered. Two broad types of adjustmenls in inputs can be envisaged: firstly, on-farm responses of crop type and management and, secondly, national and international policy …

Defining Gcte Modelling Needs For Pastures And Rangelands, Bruce Campbell, Mark Stafford Smith

IGC Proceedings (1977-2023)

A short workshop was held at the Climate Change session of the XVII International Grassland Congress (JGC - New Zealand, February 1993) under the auspices of the Internntional Geosphere-B iosphere Programme (IGBP) Global Change and Terrestrial Ecosystem (GCTE) core project. The workshop was chaired by the Head of IGBP-GCTE, Dr Brian Walker, and was attended by 50 people. This report outlines discussions from the workshop and is supplemented with material from the GCTE Operational Plan and some other sources, and comments from other researchers unable to attend the workshop. Draft workplans for modelling pastures and rangelands under GCTE have been …

Genetics Of Fibre Degradation In The Rumen, Particularly In Relation To Anaerobic Fungi, And Its Modification By Recombinant Dna Technology, C G. Orpin, G Xue

IGC Proceedings (1977-2023)

A number of rumen bacteria, fungi and protozoa are involved in fibre digestion in the rumen. Recombinant DNA technology bas allowed the isolation and characterisation of key genes coding for several enzymes involved in fibre degradation. The main species that have been examined are the bacteria Ruminococcus spp., Fibrobacter succinogenes and the anaerobic fungus Neocallimastix patriciarum. Genes coding for endo--1,4-glucanases and xylanase are common amongst all these organisms, but we will concentrate on recent advances in the genetics of plant fibre digestion by N. patriciarum, which contains genes coding for relatively high level activity exo- 1,4-glucanase which may …

Molecular Basis Of Legume-Rhizobium Interactions: Potentials For Improving Symbiotic Nitrogen Fixation, Adam Kondorosi, Michael Schultze, Beate Hoffmann, Csaba Koncz, Laszlo Bogre, Michele Cren, Ilona Dusha, Denes Dudits, Eva Kondorosi

IGC Proceedings (1977-2023)

The establishment of nit.rogen-fixing symbiosis between rhizobia and their plant hosls requires multiple interactions between the two pnrtners, which involves transmission of signal molecules activating gene sets controlling nodule development. Plant roots exude specific Oavonoids which can induce the expression of the nodulation (nod) genes in the appropriate bacterium partner, in conjunction with the constitutively produced activator protein NodD. Additional positive and negative regulatory factors further modulate nod gene expression and this fine tuning of 110d gene expression is required for optimal nodulation of the hosts. Some of these factors mediate the effects of some soil factors, such as (he …

Effects Of Vesicular-Arbuscular Mycorrhiza Inoculation, Nitrogen And Phosphorus On The Growth Of Seedlings Of Sesbania Sesban, E Akeampong, T Mamo

IGC Proceedings (1977-2023)

In the first of two pot experiments, growth of seedlings of Sesbania sesban in response to rates of P (0, 40, 120, 160 and 200 kg/ha) and of N (0 11nd 100 kg/ha) was examined. In a second trial the effect of inoculation with vesicular-arbuscular mycorrhiza (Glomus macrocarpus) and 2 levels (0 and 40 kg/hn) each of triple superphosphnte (TSP) and Egyptian rock phosphate (ERP) were studied. Response to P was linear to 80 kg/ha. Application of N improved the response of seedlings to P through enhanced P and N uptake. Application of N increased plant weight by …

Isolation Of A Multi-Functional Cellulase Cdna (Cele) From The Rumen Fungus Neocallimastix Patriciarum, Gang Ping Xue, K S. Gobius, C G. Orpin

IGC Proceedings (1977-2023)

A cellulase cDNA, ce/E, was isolated from a cellulose-induced cDNA library of the rumen fungus Neocallimastix patriciarum by screening for hydrolysis of carboxymethyl cellulose. In addition to its ability to hydrolyse carboxymethyl cellulose, ce/E enzyme was also able to degrade microcrystalline cellulose, methylumbelliferyl cellobioside, p-nitrophenyl cellobioside, lichenan and xylan. These data suggest that ce/E encodes a multi-functional cellulase.

Cellobiohydrolase (Cbh) From Neocallimastix Patriciarum: A Membrane Associated Complex?, J H. Alyward, Gang Ping Xue, G D. Simpson, C G. Orpin

IGC Proceedings (1977-2023)

Three cellobiohydrolases were highly puriried from the rumen fungus Neocallimastix patriciarun. Two of these enzymes were liberated from insoluble material by extraction with the non-ionic detergent Triton X-114, requiring the presence of detergent or dissociating agent throughout their purification. The native cellobiohydrolase is probably membrane associated.

Effect Of Nitrogen Application On Symbiotic Nitrogen Fixation Of White Clover Ecotypes Collected In North-Eastern Japan, K Sugawara, A Nishiwaki, Y Yashima

IGC Proceedings (1977-2023)

Escaped plants of white clover which could not be identified by variety were collected and were grown in pots filled with a perlite contained nutrient solution in a growlh chamber. On 16 of the collecled plants, the change of the nitrogenase activity by treatments with or without nitrogen (20 ppm N, NaNO3) was measured by gas chromatogrnphy and the variation of peroxidase isozyme was analysed by means of slab acrylamide gel electrophoresis. The studied plants of white clover (Trifolium repens L.) were classified into 5 types by the response pattern of nitrogenase to N applied. Six bands showing peroxidase …

Symbiotic Characterization Of Azide-Resistant Mutants Of Rhizobium Leguminosarum By Trifolii, Shashi Bhushan Sharma, K Sakadevan, R Corner

IGC Proceedings (1977-2023)

Azide-resistant mutants of Rhizobium legumnosarum bv, trifolii strain NZPS61 were isolated. Mutations conferring azide resistance appeared at a frequency of 1.6x t0·7 on minimal media containing 25 µglml sodium azide. Two classes of mutants were observed with respect to the nitrogen source in the growth media. Mutants in the first class showed azide resistance in the presence of both nitrate and ammonia whereas the mutants in the second class showed azide resistance only in the presence of nitrate. Eleven azide-resistant mutants were characterised for their symbiotic ability with white clover. All the mutants were similar to their parent strain NZPS61 …

Intake Of South African Mutton Merino Ewes On Wheat Stubble Grazing, T S. Brand, J M. Van Heerden, F Franck

IGC Proceedings (1977-2023)

Wheat stubble was grazed continuously for 154 days during the summer (December-April) by reproducing and dry ewes (n-8) at 2 stocking rates ( 1 or 2 ewes/ha), Samples were collected for chemical analysis from oesophageally fistulated (OF) sheep. Intake was determined using controlled chromium-release devices. The mean CP, ADF and NDF contents and iii vitro OM digestibility of samples were respectively 16.1:t0.4%; 40.7:t0.8%, 59.0:tl.1% and 48.5±0.7% t 1 ewe/ha and 10.8±1.1%; 53.9±1.1%, 72.1±0.9% and 48.8:t0.7% at 2 ewes/ha. The mean CP intake of dry ewes was 202±7 g/day (I ewe/ha) and 113:t6 g/day (2 ewes/ha), while the CP intake of …

Earthworms In Pastoral Soils Of Northland, New Zealand, P W. Woods, A.R J. Christie, J N. Couchman

IGC Proceedings (1977-2023)

Earthworm populations were surveyed in 4S pastures in Northland, New Zealand. Both sheep and beef, and dairying properties were sampled during late winter. European liumbricid earthworm species encountered were Aporrectodea caliginosa, A. trapezoides, A. rosea, A. longa, Lumbricus rubellus, L. terrestris, L. castaneus and Octolasion cyaneum. Amynthas diffringens, a megascolecid of Asian origin, was also found. Three native megascolecid species were found under developed pasture. Shallow burrowing species such as Lumbricus rubellus and A. caliginosa were the most frequently encountered species, being present on 91% and 89% of sites, respectively. A. caliginosa was the main contributor to earthworm biomass. …

First Results On Growth Rates Of The Endophytic Fungi Acremonium And Epichloe On Solid And Liquid Media, P Dapprich, A Klose, V H. Paul

IGC Proceedings (1977-2023)

Growth rates of the ·grass endophytes Acrenonium lolii Latch, Christensen and Samuels, A. coenoplrialiim Morgan-Jones lind Garns and Epichloe typhina' (Fries) Tulasne were measured on different solid media under various conditions and in liquid medium. A. coenophiallum and E. ryphina developed best vegetative growth at 25°C in the dark ori;pofato-dextrose-ilgar (PDA) and on minimal­medium (MM), respectively. A: lo/ii grew best at 2coenophialum and E. typhina produced 1.48 g and 6 g FW, respectively. Within 3 days the conductivit)'. reached constant values.· Osmolarity decreased with the increase of biomass. pH rose in cultures of A. lolii and E. typhina …

Discovery Of Gynaephora Ruoergensis Nuclear Polyhedrosis Virus (Grnpv) And Its Use As A Baculovirus Pesticide In Qinghai-Tibet Plateau, Liu Shigui, Yang Zhirong, Wu Tieqiao, Zeng Ying, Cheng Shuqiu

IGC Proceedings (1977-2023)

A new pathogenic virus agent was isolated from the grassland caterpillar Gynaephora rnoergensis, an important pest of grassland in north-western Sichuan. Identification was based on morphological properties, biological characteristics and biochemical studies. It belongs to Subgroup A of the Baculoviridae, and has been named Gynaephora rnoergensis nuclear polyhedrosis virus (GrNPV). A viral pesticide was prepared using GrNPV. It has a killing efficiency of mote than 84.3% to grassland caterpillars, and has been applied for biological control of the pest to 2.3 million ha of grassland in north we��tern Sichuan grassland and the Qinghai-Tibet,plateau.

Infection By Bdellovibrio Bacteriovirus Of Leguminous Forage Rhizobia, Xu Heng, Liu Shigui

IGC Proceedings (1977-2023)

Two bdellovibrio bacteriovirus infecting rhizobia of leguminous forage were isolated from Sichuan-Tibet plateau grassland. The culture characteristics, host range and other biological properties of two bdellovibrio bacterioviruses were researched. Research indicated that the two bdellovibrio bacterioviruses had a wide host range and a strong lyslng ability with Rhlwbium melilotl, R. trlfolll and R, astragalll. 8dellovibrio bacterioviruses affected nodu lation of leguminous forages in grassland, and are one of the main biological factors that lower the yield of leguminous forages.

Studies On The Mutagenicity Of Gynaephora Ruoergensis Nuclear Polyhedrosis Virus (Grnpv), A New Biological Pesticide, Liu Shigui, Wu Yong, Zeng Ying, Wu Tieqiao, Yang Zhirong

IGC Proceedings (1977-2023)

To test pathogenicity and mutagenicity of Gynaepllora ruoergensis nuclear polyhedrosis virus (GrNPV), a new biological pesticide, acute and subacute infection tests were carried out in 366 vertebrates (16 species). Results indicated that GrNPV has no toxicity to vertebrates. No mutagenicity to Salmonela. typhimium . was found using the Ames.test. Four tests using cytogenelic methods, sister chromosome exchange (SCB), chromosome aberration test, a micro-nuclear test of mouse eosinophH cells, and lethal effect tests, indicated no mutagenictic effects to vertebrates.

Survey For Natural Enemies Of Leafy Spurge Of Rangeland In Northern China, Wang Jian Feng

IGC Proceedings (1977-2023)

Leafy spurge (Euphorbia esula L,) is a serious. toxic weed in the real Plains region of lhe USA and Canada where it is toxic to s9me; classes of livestock and displaces more desirable forage plants. Leafy spurge is also spreading widely in Inner Mongolia rangeland, but it does limited damage. Biological weed control scientists from China, USA and Canada have co-operated in a survey for natural enemies of leafy spurge.in Innc Mongolia rangeland where there is an abundant diverse assemblage of insects and pathogens , including: Aphthona , chln ch ichi, Apthona s.eriata, Oberea prob . erythrocephala, Chamaespecia sp. …

A Method For The Greenhouse Evaluation Of Subterranean Clover Breeding Lines For Phytophthora Clandestina Root Rot, S P. Flett, P A. Taylor, V Wakley

IGC Proceedings (1977-2023)

Subterranean clover root rot, caused by Phytophthora clandestina, is a serious disease in both irrigated and dryland pastoral regions of Australia. An Intensive program of screening cultivars and genetic lines of subterranean clover from the National Subterranean Clover Improvement Program (NSCIP) for resistance to root rot caused by Phytophthora clandestina is described, Subterranean clover (Trifolium subterraneum L.) lines, divided into screening runs, were infected with isolates of P. clandestina in a cooled greenhouse and each run required 11 weeks for complete evaluation, Each line was rated for root rot resistance ogainst a standard resistant cv. Larisa and a …

Tooth Type And Position In A Hypothetical Pectinodon..., Keith Snyder, Jonathon Campos, Neal Doran, Charity Simmons

Achieve

In 1856, Leidy rst identied Troodontidae as a taxonomic unit. It was not until 1945 that C.M. Sternberg assigned it to a family status. There has been much debate on taxonomic naming in this family, but in 1987, Currie conated all previous names into a single species, Troodon formosus. On the basis of isolated teeth, Carpenter (1982) suggested a second species, Pectinodon bakkeri from the Lance Formations. With limited specimens (24), Longrich (2008) proposed tooth positioning for the 4 tooth types he dened. This was especially challenging since no cranial or post-cranial skeletal structures have yet been identied.

Over the …

Monthly Changes In Plant Biomass, Net Primary Productivity And Transfer Dynamics Of A Tropical Grazing Land Ecosystem In Southern India, K.S T.K Karuniachamy, K Paliwal

IGC Proceedings (1977-2023)

Monthly changes in plant biomass, net primary productivity and transfer dynamics of tropical grazing land of western Ghats region, southern India, are presented. The annual above- ground net production was 9.03 g/m2/day and the below-ground net production was 2.56 g/m2/day. Total annual net primary production was estimated at 4232 g/m2/day. Of the total input of 11.59 g/m2/day into the system, about 77.9% was channelled to above-ground and 22.1% to below­ground, The rate of litter disappearance was 0.55 g/m2/day and l.14 g/ m2/day for below-ground disappearance. The total output was 1.69 g/ m2/day which was 14.6% of the total input. Thus, …

Photosynthesis And Water Relations Of Two Savanna Grasses As Influenced By Shade And Water Stress, M J. Trlica, J I. Kinyamario

IGC Proceedings (1977-2023)

Net CO2 assimilation and plant water relations of the African savanna grasses Panicum maximum Jacq. and Tliemeda triandra Porrsk. were measured under controlled conditions. We hypothesised that 1; triandra would be better adapted to higher light and temperature conditions and could withstand greater moisture stress than could P. maximum, as T. tria11dra is commonly found in open areas, whereas P. maximum dominates in the shade of trees. Plants of both species were transplanted into a common soil in large pots and placed under shade (approximately 150 µrnoVm1/s photon flux density (PFD)) or high light (approximately 1200 µmoVm1/s PFD) conditions, with …

Grazing Management Effects On Diverse White Clover Cultivars, G E. Brink, G A. Pederson

IGC Proceedings (1977-2023)

Tall fescue (Festuca arundinacea Schreb.) was oversewn with Grasslands Huia, Louisiana S-1, and Regal white clover (Trifolimn repens L.) and stocked the following year continuously or rotationally with cattle to detennine cultivar response to grazing method. When precipitation was 59% above normal, mean leaf area, forage and stolon dry weight, and stolon growing point density in June and August were unaffected by grazing method. These parameters were reduced under continuous stocking when precipitation was 32% below normal. Cultivar ranking for mean leaf area and petiole length was the same as that for leaf size: Grasslands Huin

Determination Of Nitrogen Sources (Mineral, Atmospheric Or Endogenous) Used By Lucerne During Regrowth, K Tae Hwan, A Ourry, G Lemaire, J Boucaud

IGC Proceedings (1977-2023)

Although for forage legumes such as Medicago saliva, ii is established that nitrogenase activity is very low during the 2 fust weeks of regrowth, there are no data on the amount d nitrogen in regrowin g shoots derived from N1 fixation. In order to ascertain the orisin of N used for regrowth of lucerne, several experiments were unde,taken usin g 15N labellin g to distinguish between endogenous, mineral and atmospheric N recovered' in regrowing shoots of nodulated or non-nodulated lucerne. Calculation of N fluxes from ISN data showed that both N uptake from the medium and N2 fixation strongly decreased …

Effect Of A Legume (Arachis Pintoi) On The Regrowth And Mineral Nutrition Of Associated Pangola Grass (Digitaria Decumbens), P Cruz, H Sinoquet, O Sobesky

IGC Proceedings (1977-2023)

The effect of a companion legume (Arachis pintoi) on the growth and nitrogen nutrition of an associated grass (Di'gitaria decumbems) was studied during 2 regrowth periods. Digitaria growth was expressed as a function of the cumulative absorded PAR (photosynthetically active radiation) i.e., by using the radiation-use efficiency concept. For this purpose, PAR intercepted by both the pure and mixed swards was estimated by using a radiative transfer model. Nitrogen nutrition status of Digitaria was characterised by the relation between N uptake and dry matter production. Results show a close agreement between N nutrition level and radiation-use efficiency of the grass. …

Varietal Differences In Brassica Fodder As Affected By Nitrogen Topdressing And Seeding Date, S H. Moon, H Hirota

IGC Proceedings (1977-2023)

Two experiments were carried out both in spring and fall with cultivars of rape (Brassica napus spp.) and C.O. (B. campestris x B. oleracea). Both cullivars showed lillle increase in plant length in spring sowing with nitrogen topdressing, but the increments were higher in earlier topdressing (T l) and later topdressing (T2) than in control in autumn sowing, although the difference was not significant. There was no difference in the number of leaves throughout the growing stages between the N topdressing treatments in spring and autumn sowing. Leaf area was greater in Tl and T2 than in control in early …

Reserve Mobilization During Regrowth After Cutting Of Forage Species: Quantification And Physiological Mechanisms In Ryegrass And Lucerne, A Ourry, J Bigot, T Kim, J Boucaud, J Salette

IGC Proceedings (1977-2023)

Time course of remobilisation of reserves was studied during the regrowth of Loli11m perem1e and Medicago sativa by 15N labelling, carbohydrate analyses and by measuring time course of several enzymes activities. When photosynthesis decreased during early regrowth, and consequently reduced availability of carbon skeletons within the plant, both nitrogen (N) uptake (lolium perene) and N2 fixatlon (Medicago saliva) decreased. Nilrogenase, as well as nitrate reductase activities, decreased. Reduction of external N assimilation was compensated for by intensive mobilization of endogenous N in roots of lucerne and in stubble of ryegrass. In the same manner, some of …

Effect Of Temperature On Nitrogen Fixation Rates In Seven Clover Cultivars, J R. Crush, B D. Campbell, J R. Caradus

IGC Proceedings (1977-2023)

Seven white clover (Trifolium repens L) cultivars were grown in growth rooms at S different temperatures between S and 2S°C. Plant growth and nitrogenase activity (acetylene reduction) were measured. There were significant effects of temperature on total plant ay matter (DM) accumulation and nitrogenase activity. Temperature x cultivar interactions were significant for DM accumulation, nitrogenase activity per pot and nitrogenase activity/g DM. There was a strong correlation between DM increment/°C rise in temperature over the range 10-20°C, and nitrogenase activity/g DM. Three cultivars had maximum nitrogenase activity/g plant DM at 200C and 4 cultivars peaked at 15° C. These differences …

Physiological Characteristics Of Nitrate Uptake By Different Catch Crop Species, P Laine, A Ourry, J Boucaud, J Salette

IGC Proceedings (1977-2023)

The pollution of aquifers by nitrate is aggravated by farming practices that leave the ground bare during winter. Establishment of catch crops during this time could be suitable farming strategy to decrease nitrate loss from the soil. Only a few studies are available on the physiology of nitrate uptake by these species. Experiments were conducted on Lolium perenne, Secale cereale, Trifolium incarnatum, Trifolirim alexendrnum, Phacelia tanacetifolia, Brassica rapa, Brassica napus, Sinapsis alba and Raphanus sativus grown in hydroponic conditions, in order to investigate the physiological basis of the NO3- uptake system when plants are grown with optimum ocniditons of light, …

Relationships Between Growth And Carbon Isotope Discrimination For Some Pasture Species, J Virgona

IGC Proceedings (1977-2023)

Carbon isotope discrimination (A) by plants can be directly related to plant water-use efficiency (W, total plant dry matter, OM, per water transpired) and used in selection to achieve greater W. As \V (and A) is a complex characteristic, there maybe inherent relationships between it and plant productivity. A range of pasture cultivars (of temperate grasses and legumes) were grown in pots (lo c. 50 days) and \V, A and total dry mailer measured. Among cultivars the relationship between W and A was negative and significant as was the relationship between A and total OM accumulation. A further experiment showed …

Acquisition And Allocation Of Phosphorus In A Population Of White Clover Plants In A Rotationally Grazed Pasture, M.J M. Hay, D F. Chapman

IGC Proceedings (1977-2023)

This paper quantifies the processes of acquisition, allocation and retranslocation of phosphorus (P) within a white clover (Trifolium repens L.) population in a mixed grass-clover pasture during a regrowth period in early winter (13 May-8 July 1991). The work described is part of a broader study examining seasonal variation in these processes. The data allows an analysis of the changing P economy of plants and of whole populations. White clover plants were grouped by !heir hierarchy of branching. Within plants, stolons were grouped by order of branching, dissected into leaf, stolon and root, oven-dried, weighed and analysed for P …

Defoliation Of Young Branch And Parent Stolons Of White Clover In Rotationally Grazed Pastures, M.J M. Hay, M Kim, R W. Mclean, A Gonzalez-Rodriguez

IGC Proceedings (1977-2023)

This study was undertaken to examine the relative severity of defoliation of young branches (those comprising <4 nodes) and parent stolons of white clover (Trifolium repens L.) in rotationally grazed pastures stocked al either 2.5, 5.0 or 7.5 bulls/ha. On 7 occasions over a year, the defoliation of expanded leaves of parenl and branch stolons was assessed using tagged stolons. Petiole length of leaves ,vas measured before grazing. Leaves of young branch stolons (43% of the total number of leaves defoliated) were less severely defoliated than leaves of parent stolons (64%). Defoliation of branch stolon leaves was relatively greater at the higher stocking rates which had lower residual …