Life Sciences Commons^™

The Interaction Between Root Distribution And Pasture Growth During Water Deficit, D J. Barker, N Dymock

IGC Proceedings (1997-2023)

Quantification of water-limited pasture growth is of interest in agriculture since it allows prediction of impaired animal production during drought, and is the basis for scheduling irrigation. Experimental work on two dairy pastures 25 km south-west of Palmerston North, New Zealand found 50% of root mass was in the top 2.3 cm of soil. Soil moisture was, similarly, not uniformly distributed down the soil profile and dried most rapidly in the top 20†cm of soil. Leaf appearance rate was more strongly correlated with water status nearer the soil surface (r = 0.52 & 0.63 for 0-5 & 10-15 cm depth, …

Response To Drought Of White Clover Lines Selected For Different Stolon Morphologies, H D. Karsten, J R. Caradus, D R. Woodfield

IGC Proceedings (1997-2023)

White clover (Trifolium repens L.) lines were selected from within large and small-leaved cultivars of Grasslands Kopu and Grasslands Tahora, respectively, for long or short internodes, and for high or low branching frequency from plants grown in sun and shade (50% full sunlight). Lines were compared for drought tolerance in a perennial ryegrass (Lolium perenne L.) sward in boxes. Prior to imposing drought branching frequency selections did not differ in branching frequency, although the low branching frequency selection had a higher percentage of rooted nodes. After an imposed drought treatment sun-selected lines grew better than shade-selected lines relative …

Variation In Grazing Sward Chicory Content After Periods Of Low Rainfall, Kevin Dolan, C. Hearn, D. Hennessy, R. Henriques, M. B. Lynch, Michael O’Donovan

IGC Proceedings (1997-2023)

Multispecies (MS) swards can reduce chemical nitrogen (N) fertiliser requirement due to the legume components of the sward mixtures, and have the potential to increase drought tolerance, particularly where chicory (CH, Chicorium intybus L.) is included in the sward mixture. A grazed plot experiment was established to investigate the persistency of forage herb species in MS swards under typical Irish grazing conditions. The swards contained three plant functional groups: grass, legume and herb; four sward types were established which included sward mixtures of the following species: perennial ryegrass (PRG, Lolium perenne L.) white clover (WC, Trifolium repens L.), red clover …

Irrigation Effects On Forage Dry Matter Yield And Nutritive Value Of Alfalfa, Rudra Baral, Doohong Min

IGC Proceedings (1997-2023)

Alfalfa (Medicago sativa L.) is among the top four field crops in United States (U.S.) in terms of acreage harvested and economic value. Several studies have documented that alfalfa requires high amount of water compared to other major field crops. However, more than 65% alfalfa in the U.S. is grown under rainfed condition where severe to moderate drought condition has been pronounced during alfalfa growing season. The magnitude of yield loss due to water-limited conditions is still unknown. In this context, the objective of our study is to evaluate the forage dry matter yield and forage nutritive value of …

Beyond The Boom: Integrated Approaches To Managing Weeds And Brush, M. L. Treadwell, D. Burson

IGC Proceedings (1997-2023)

William Bray stated in his 1904 report, The Timber of the Edwards Plateau of Texas, "This struggle of the timberlands to capture the grasslands is an old warfare....it spreads like infection.” This trend is true today and especially pronounced in the Great Plains, where only 1/4 of the Great Plains’ original grasslands remains intact. Species like honey mesquite, honey locust, black locust, sumac, dogwood, post oak, winged elm, Siberian elm, salt cedar, huisache, Eastern redcedar, Ashe and redberry juniper, pricklypear, sericea lespedeza, and many other species represent alarming rates of spread and rapid establishment throughout Great Plains grasslands. Although, these …

Effect Of Timing And Intensity Of Drought On Perennial Ryegrass Seed Yield, R. J. Martin, R. N. Gillespie, S. Maley

IGC Proceedings (1997-2023)

Perennial ryegrass seed worth about $50 million is produced annually in Canterbury, New Zealand (Rowarth 1998). Ryegrass seed production in New Zealand is often affected by drought, reducing both seed number and seed size (Rolston et al., 1994). Irrigation management recommendations are not currently available for farmers growing ryegrass seed crops. To quantify the effect of water stress on perennial ryegrass seed yield, we carried out an experiment in a rainshelter where rainfall was excluded from experimental plots otherwise exposed to normal weather (Martin et al., 1990).

Forage Monitoring Technology To Improve Risk Management Decision Making By Herders In The Gobi Region Of Mongolia, Jay Angerer, J. W. Stuth, D. Tsogoo, G. Tolleson, Dennis Sheehy, U. Gombosuren, Sean Granville-Ross

IGC Proceedings (1997-2023)

In the period from 1999 to 2002, Mongolia experienced a series of droughts and severe winters that lowered livestock numbers by approximately 30% countrywide. In the Gobi region, livestock mortality reached 50% with many households losing entire herds (Siurua & Swift 2002). In March 2004, a program was initiated by the United States Agency for International Development (USAID) through the Global Livestock Collaborative Research and Support Program (GLCRSP). The goal of this program is to develop forage monitoring technologies that provide early warning of drought and winter disaster to improve livestock herder decision making in the Gobi region. The program …

Dynamics Of Long-Term Carbon Sequestration On Rangelands In The Western Usa, G. E. Schuman, L. J. Ingram, P. D. Stahl, G. F. Vance

IGC Proceedings (1997-2023)

Rangelands in the USA occupy 161 million hectares of land. Worldwide, rangelands occupy about half of the land area and account for more than 1/3 of the world's terrestrial carbon (C) reserves. Because of their large land area, rangelands have the potential to sequester a significant amount of additional atmospheric C. Schuman et al. (2001) estimate that rangelands and marginal croplands restored to grasslands in the USA can sequester 64 million metric tonnes C/ha/yr if properly managed. The objective of this research was to evaluate the long-term effects of grazing on soil C storage in a northern mixed-grass prairie (NMP).

Long-Term (9-Year) Response Of Two Semiarid Grasslands To Prescribed Fire In The Southwestern Usa, R. L. Pendleton, B. K. Pendleton, C. S. White

IGC Proceedings (1997-2023)

Historically, arid grasslands of SW USA experienced fire return intervals of 5-10 years. During the last 100 years, however, fire has been a rare event. Recent expansion of woody plants in arid grasslands has prompted managers to re-introduce fire as a tool to reduce abundance of woody plants and maintain perennial grass cover. The use of fire in desert grasslands poses unique challenges, however, due to extreme variability in rainfall patterns. Our research examines vegetation response to repeat fire in 2 desert grassland ecotones near Albuquerque, New Mexico (35.05^o N 106.60^o W).

Endophyte Effects On Antioxidants And Membrane Leakage In Tall Fescue During Drought, C. P. West, R. D. Carson, C. A. Guerber, B. De Los Reyes

IGC Proceedings (1997-2023)

Tall fescue [Festuca arundinacea (Schreb.)=Lolium arundinaceum (Schreb.) S.J. Darbyshire] infected (E+) by its fungal endophyte [(Neotyphodium coenphialum Morgan-Jones & Gams.) Glenn, Bacon & Hanlin] often shows greater persistence during summer drought than endophyte-free (E-) plants (Malinowski et al., 2005). Survival of the apical meristem and growing zone of vegetative tillers likely involves biochemical adaptations whose benefits to the host are enhanced by endophyte presence. Antioxidant enzymes may scavenge free radicals during heat and drought, and thereby reduce membrane damage. Their roles in endophyte-mediated drought tolerance in tall fescue have not been tested. Our objective was to …

Spring Forage Stash Module To Prevent Forage Crisis On Uruguayan Livestock Systems: An Evaluation Based On Model Simulations, M. Pereira Machín, F. Dieguez Cameroni

IGC Proceedings (1997-2023)

In Uruguay, rangeland cattle production systems support national economy by beef exportation chain and economic inputs to the country. Soil hydric stress episodes results to forage crisis on grassland-based production systems, having high impact on its trajectory and leaving sequels at several farm levels mainly on rearing cattle systems in drought sensitive regions of the country. In that context, the proposal is to create a spring forage stash module, with a simple management rules as a mechanism to build stability to farms and to buffering drought impact. The concept is to differ spring forage (season with low variation coefficient on …

Species Richness Increased Yield Stability In Intensively Managed Grasslands Subjected To Experimental Drought, J. A. Finn, M. Suter, E. Haughey, D. Hofer, A. Lüscher

IGC Proceedings (1997-2023)

Climate change is expected to cause an increase in the frequency and intensity of drought events. Over two years we investigated the effects of experimentally imposed drought on intensively managed grassland communities (5 m x 6 m plots) of varying richness (1, 2 and 4 species), and comprising four species (Lolium perenne L., Cichorium intybus L., Trifolium repens L., Trifolium pratense L.). In each year a summer drought period of nine weeks with complete exclusion of precipitation was simulated, inducing severe drought stress at Reckenholz (Zürich, Switzerland), and extreme drought stress at Wexford (Ireland). Mean yield and plot-to-plot variance …

Elevated Co2 And Extreme Climatic Events Modify Nitrogen Content And Ruminal Protein Digestion Of Temperate Grassland, V. Niderkorn, C. Picon-Cochard

IGC Proceedings (1997-2023)

This study was aimed at analyzing changes in nitrogen (N) content and in vitro protein rumen digestion of an upland grassland exposed to climate changes in controlled conditions. Monoliths of grassland were inserted in 12 macrocosms in which climatic conditions for the 2050s were simulated (i.e., +2.3°C and 33 mm less precipitation compared to the current climatic conditions). Six of them were subjected to ambient CO₂ (390 ppm) while the other six were subjected to elevated CO₂ (520 ppm). After four months, an extreme climatic event (ECE) consisting of four weeks of reducted precipitation (-50%) followed by two …

Climate Change Threats To Semi-Arid Transhumance Grazing Systems: Proposals For Adaptation In Cabo Verde, J. F. Castro, S. Tavares, M. Castro

IGC Proceedings (1997-2023)

Global warming has changed the rainfall regime in the Sahelian region, endangering and widespread poverty and chronic famines in Cape Verde, where rural communities' well-being and food security depend on rainy agriculture. Local responses to rainfall new patterns and scarcity have been livestock reduction with significant revenue losses. Together with dry mist occurrences, these environmental constraints demand to define priority actions to adapt and mitigate climate change's direct impacts. According to fifty household inquiries, this work explains the transhumant grazing practices on a semi-arid plateau in Tarrafal (Santiago, Cabo Verde), prospecting adaptation alternatives for sustainability. We related grazing patterns and …

Interactive Effects Of Drought And Fire On Co-Existing Woody And Herbaceous Communities In A Temperate Mesic Grassland, R. Keen, J. Nippert, E. Tooley, K. O’Keefe, S. Bachle, M. Sandwick

IGC Proceedings (1997-2023)

Increased drought and woody encroachment are likely to have substantial and interactive effects on grassland carbon and water cycling in the future. However, we currently lack necessary information to accurately predict grassland responses to drought-by-fire interactions in areas experiencing woody encroachment. A more thorough understanding of these interactive effects on grass-shrub physiology would improve the effectiveness of demographic vegetation models and refine predictions of future changes in grassland ecosystem function. To this end, we constructed passive rainout shelters over mature Cornus drummondii shrubs and co-existing grasses in two fire treatments (1-year and 4-year burn frequency) at the Konza Prairie Biological …

Forage Quality And The Environment, C. E. Lascano, A. Schmidt, R. Barahona

IGC Proceedings (1997-2023)

The influence of environmental factors on forage quality of temperate and tropical grasses has been reviewed by several authors, who summarized how light, temperature, drought and soil nutrients influence chemical composition, and digestibility of forages grown in contrasting areas of the world. The effects of season of the year on forage growth, grazing behavior and animal performance have also been the subject of numerous papers and reviews. However, there are few recent reviews that summarize how changes in climatic and edaphic factors influence forage quality of legumes with variable levels of condensed tannins (CT), which are important secondary compounds in …

The Effect Of Water Deficits During Flowering And Seed Production On Cultivars Of Subterranean Clover And Annual Medic, E. C. Wolfe, W. J. Collins, R. C. Rossiter, W. R. Stern

IGC Proceedings (1997-2023)

In improved pastures in inland southern Australia, the persistence and growth of annual pasture legumes depends in part on their ability to produce and conserve abundant seed for regeneration and production. For near-maximum seed production in spring, adequate soil water is needed for at least 70 days in subterranean clover (Trifolium subterraneum) and medic (Medicago) species. Water deficits during spring are a common occurrence, and they appear to be increasing in frequency. The effect of relatively short periods of water deficit during reproductive development has received some attention but the findings conflict. The present experiment was …

Effect Of Drought Stress On Fibre Digestibility Of Corn For Silage, G. Ferreira, C. L. Teets, A. M. Kingori, J. O. Ondiek

IGC Proceedings (1997-2023)

Limited information exists about the impact of drought stress on corn silage digestibility. The objective of this study was to determine the effect of irrigation on in situ NDF digestibility of corn tissues grown under controlled conditions in a greenhouse. Five commercial corn hybrids were planted in pots and grown in a greenhouse. Pots were subjected to an abundant or restricted irrigation regime. Leaf blades and stem internodes were collected from the upper and bottom portion of each hybrid. Tissue samples were incubated in the rumen of 3 rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 …

Strategies For Assessing Grassland Degradation With Biogeochemical Models, S. Rolinski, S. B. Wirth, C. Müller, B. Tietjen

IGC Proceedings (1997-2023)

Marginal grasslands provide the basis for livestock rearing and rural livelihoods globally, but are subject to permanent degradation from mismanagement and climate change. Global biogeochemical models are so far not able to represent degradation tipping points in marginal grasslands because plant growth is dependent only on bio-climatic conditions and nutrient availability. Due to their central role for sustaining livelihoods, this lack of representation in such models needs to be addressed. We present an idea on processes and interactions to be considered and on the actual implementation of necessary changes. The model for which we exemplarily develop implementation strategies, LPJmL, accounts …

Hydraulic Responses Of Shrubs And Grasses To Fire Frequency And Drought In A Tallgrass Prairie Experiencing Bush Encroachment, K. O’Keefe, R. Keen, E. Tooley, S. Bachle, J. B. Nippert, K. Mcculloh

IGC Proceedings (1997-2023)

The increase in abundance and density of woody plants in herbaceous ecosystems (i.e. bush encroachment) is occurring globally and is driven by reduced fire frequency, climate change, and the utilization of deeper, more reliable soil water by woody plants. Thus, a comprehensive understanding of the physiological processes through which woody and herbaceous plants use water will provide greater insight into the mechanisms of bush encroachment, as well as the trajectory of encroachment in a changing climate. Our objective was to assess how experimental changes in water availability and fire frequency impact belowground water-use traits in Cornus drummondii, the primary …

Climate Variability In The Woodbush Granite Grasslands Of South Africa: Effects On Grassland Diversity, M. Muller, F. Siebert, A. Linstädter, D. I. Thompson, S. J. Siebert

IGC Proceedings (1997-2023)

South African old-growth grasslands are hyper-diverse ecosystems which evolved under naturally occurring rainfall variability. It is predicted that future precipitation patterns will become more variable, which could lead to increased frequencies of extreme and prolonged drought events. This study aimed to investigate the effects of climate variability on plant diversity of the fragmented pristine, mistbelt grasslands of the Woodbush Granite Grasslands (WGG) at Haenertsburg, South Africa. It has been reported that species composition has changed substantially in this area, as disturbance-tolerant species enter these systems or existing competitor species become more dominant. A Temporal Beta-diversity Index (TBI) was used to …

Adaptation Of Forage Species To Drought, D. J. Barker, J. R. Caradus

IGC Proceedings (1997-2023)

Variability in rainfall is the single greatest cause of variation in forage production for a given site. Current climate scenarios predict future annual rainfall to decrease at some geographic regions. The intensity of future rainfall is also predicted to increase at other regions, with the expectation of greater variability in soil moisture. The adaptation of forage species to drought is an issue that is likely to remain with us into the future.

Precise definitions are critical to water relations work, and imprecise use of terms has complicated comparisons of some studies on plant response to drought. Drought is a purely …

Defoliation And Water Deficit: Their Influence On Pasture Growth And Water Use Of White Clover, F. H. Santiñaque

IGC Proceedings (1997-2023)

With the objective of understanding the physiological basis of defoliation and water use relationships of white clover (Trifolium repens L.) pastures during water deficits, an experiment in controlled conditions was carried out. Outdoors nine liters pots were filled with a loam-clay soil with a water content at field capacity (FC), of 35%(w/w), at a bulk density of 1.1 g/cm³. Pre-germinated and inoculated clover seeds were transplanted, and the number of plants was adjusted to permit the development of full plant cover. The level of P in the soil did not limit plant establishment or growth. The …

The Grassbank Concept: Potential Applications In China?, Wenjun Li, Lynn Huntsinger, Sally K. Fairfax

IGC Proceedings (1997-2023)

No abstract provided.

Amino Acid And Protein Incorporation In Water‐Stressed Perennial Ryegrass, W. J. Jung, B. R. Lee, L. S. Li, Y. L. Jin, T. H. Kim

IGC Proceedings (1997-2023)

No abstract provided.

Microbial Community Of The Rhizosphere Of Ceanothus Velutinus Improves The Plant's Growth And Development Under Greenhouse Conditions, Jyothsna Ganesh

Student Research Symposium

Climatic change-induced environmental stresses affect crop production. Drought is such a stress which affect crop production and landscaping adversely. Native plants are great for low water use landscaping and can adapt to the natural environment. USU Center for Water-Efficient Landscaping has released a list of native plants that can be used for this purpose. This study focuses on a native plant Ceanothus velutinus (snowbrush) which is an evergreen plant native to western North America. It thrives well in harsh conditions and can act as ornamental plant in low water use landscaping but is difficult to propagate under landscape conditions. Here, …

Identification, Evaluation And Molecular Characterization Of Stylosanthes Seabrana--A Potential And Nutritious Range Legume Having Wider Applicability In India, A. Chandra, R. K. Bhatt, A. B. Majumdar, S. Kumar, D. Nagaich, K. Kumar

IGC Proceedings (1997-2023)

No abstract provided.

Carbon Isotope Discrimination, Selection Response, And Forage Production Of Tall Fescue In Contrasting Environments, R. C. Johnson, Andrew A. Hopkins, M. A. Evans

IGC Proceedings (1997-2023)

No abstract provided.

Metabolic Response Of Lolium Perenne To Drought Stress, Heike Hahn, J. Kopka, Oliver Fiehn, B. Scott

IGC Proceedings (1997-2023)

No abstract provided.

A Record Of Vapour Pressure Deficit Preserved In Wood And Soil Across Biomes, Adrian Broz, Gregory J. Retallack, Toby M. Maxwell, Lucas C.R. Silva

Biology Faculty Publications and Presentations

The drying power of air, or vapour pressure deficit (VPD), is an important measurement of potential plant stress and productivity. Estimates of VPD values of the past are integral for understanding the link between rising modern atmospheric carbon dioxide (pCO₂) and global water balance. A geological record of VPD is needed for paleoclimate studies of past greenhouse spikes which attempt to constrain future climate, but at present there are few quantitative atmospheric moisture proxies that can be applied to fossil material. Here we show that VPD leaves a permanent record in the slope (S) of least-squares …