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 …

Climate Interactions Drive Tree Physiology And Growth In A Northeastern Forest Ecotone, Alexandra M. Barry

Electronic Theses and Dissertations

Climate change is a threat to global forest ecosystems. In the northeastern United States, forest trees are facing rising temperatures and increasingly inconsistent moisture regimes. In addition to long-term changes in climate conditions, there is concern about the potential for more frequent and intense climate extremes, which can have severe and rapid negative effects on tree physiology and growth. Further, climate extremes may co-occur to produce a greater magnitude of effect than the sum of their parts, with a prominent example being hot droughts, which are increasing in occurrence and severity. The impact of these and other extreme climate interactions …

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 …

Pearl Millet Response To Drought: A Review, Nikee Shrestha, Hao Hu, Kumar Shrestha, Andrew N. Doust

Department of Agronomy and Horticulture: Faculty Publications

The C4 grass pearl millet is one of the most drought tolerant cereals and is primarily grown in marginal areas where annual rainfall is low and intermittent. It was domesticated in sub-Saharan Africa, and several studies have found that it uses a combination of morphological and physiological traits to successfully resist drought. This review explores the short term and long-term responses of pearl millet that enables it to either tolerate, avoid, escape, or recover from drought stress. The response to short term drought reveals fine tuning of osmotic adjustment, stomatal conductance, and ROS scavenging ability, along with ABA and ethylene …

Pearl Millet Response To Drought: A Review, Nikee Shrestha, Hao Hu, Kumar Shrestha, Andrew N. Doust

Department of Agronomy and Horticulture: Faculty Publications

The C4 grass pearl millet is one of the most drought tolerant cereals and is primarily grown in marginal areas where annual rainfall is low and intermittent. It was domesticated in sub-Saharan Africa, and several studies have found that it uses a combination of morphological and physiological traits to successfully resist drought. This review explores the short term and long-term responses of pearl millet that enables it to either tolerate, avoid, escape, or recover from drought stress. The response to short term drought reveals fine tuning of osmotic adjustment, stomatal conductance, and ROS scavenging ability, along with ABA and ethylene …

Effect Of Water Stress On Weed Germination, Growth Characteristics, And Seed Production: A Global Meta-Analysis, Mandeep Singh, Resham Thapa, Meetpal Singh Kukal, Suat Irmak, Steven Mirsky, Amit J. Jhala

Department of Agronomy and Horticulture: Faculty Publications

Weeds compete with crops for soil moisture, along with other resources, which can impact the germination, growth, and seed production of weeds; however, this impact has not been systematically recorded and synthesized across diverse studies. To address this knowledge gap, a global meta-analysis was conducted using 1,196 paired observations from 86 published articles assessing the effect of water stress on weed germination, growth characteristics, and seed production. These studies were conducted and published during 1970 through 2020 across four continents (Asia, Australia, Europe, and North America). Imposed water stress was expressed as solution osmotic potential (ψsolution), soil water potential (ψsoil), …

Elucidating The Cellular Physiology Of Glyphosate Resistance In Palmer Amaranth (Amaranthus Palmeri) Using Integrated Omics Approaches, Pawanjit Kaur Sandhu

All Theses

The evolution of resistance to herbicides in weeds poses a major threat to agricultural production systems. To date, herbicide resistance has been reported against 21 modes of action in 266 weed species across 71 countries. More than 50 weed species have developed resistance against glyphosate, the most widely used herbicide worldwide. Although several mechanisms of glyphosate resistance have been discovered, our understanding of alterations in the cellular physiology of glyphosate-resistant weed biotypes, and the induction of the resistance mechanisms remains limited. This knowledge is critical to developing sustainable weed management practices and for a comprehensive understanding of plant stress adaptations. …

Genetic And Environmental Regulation Of Plant Growth, Kirk J-M Mackinnon

Doctoral Dissertations

Field grown crops are continually exposed to a variety of external stimuli that influence plant responses. Light, temperature, and water availability interact to affect many economically important traits including growth rate, size, and lifespan. My research is focused on the intersection of genetic and environmental factors influencing plant growth. Specifically, I am interested in elucidating the regulation of rhythmic genes in response to photo- and thermocycles and identifying novel candidate genes associated with growth and drought traits. Understanding the gene regulatory networks that mediate time-of-day signaling is vital to identifying candidate genes across the pan-genome associated with traits of interest.

Inactivation Of The Entire Arabidopsis Group Ii Gh3s Confers Tolerance To Salinity And Water Deficit, Rubén Casanova-Sáez, Eduardo Mateo-Bonmatí, Jan Šimura, Aleš Pěnčík, Ondřej Novák, Paul Staswick, Karin Ljung

Department of Agronomy and Horticulture: Faculty Publications

Indole-3-acetic acid (IAA) controls a plethora of developmental processes. Thus, regulation of its concentration is of great relevance for plant performance. Cellular IAA concentration depends on its transport, biosynthesis and the various pathways for IAA inactivation, including oxidation and conjugation.

Group II members of the GRETCHEN HAGEN 3 (GH3) gene family code for acyl acid amido synthetases catalysing the conjugation of IAA to amino acids. However, the high degree of functional redundancy among them has hampered thorough analysis of their roles in plant development.

In this work, we generated an Arabidopsis gh3.1,2,3,4,5,6,9,17 (gh3oct) mutant to knock out the group II …

Poor Acclimation To Experimental Field Drought In Subalpine Forest Tree Seedlings, Alex Goke, Patrick H. Martin

Biological Sciences: Faculty Scholarship

The ability of tree species to acclimate and tolerate projected increases in drought frequency and intensity has fundamental implications for future forest dynamics with climate change. Inquiries to date on the drought tolerance capacities of tree species, however, have focused almost exclusively on mature trees with scant in situ work on seedlings, despite the central role that regeneration dynamics play in forest responses to changing conditions. We subjected naturally established seedlings of co-dominant subalpine conifer species (Abies lasiocarpa and Picea engelmannii) in the southern Rocky Mountains to 2 years of in situ summer precipitation exclusion, simulating summer drought …

Characterization Of Salt And Drought Tolerance In Sunflower (Helianthus Annuus L.), Sevgi Saylak

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Consequent to the increasing world population, food sources are needed to be increased to meet the nutritional needs. However, due to natural processes and agricultural activities, the most destructive environmental factors that limit crop production, soil salinity, and drought-exposed areas are growing. As one of the major oilseed crops, sunflower (Helianthus annuus L.), is considered to be moderately tolerant to salt and drought. Although it can grow in arid to semi-arid regions, increasing salinity and drought might adversely affect sunflower production. This study aimed to investigate several sunflower germplasms' morphological responses to salt and drought stresses. For this purpose, …

Effect Of Hydrogen Peroxide On Physiological Quality And Germination Of Aged Pumpkin Seeds Under Drought Stress Condition [Research Note], Hossein Reza Rouhi, Mohammad Hasan Vafaei, Maryam Saman, Ali Abbasi Surki

The Philippine Agricultural Scientist

The physiological quality of seeds decreases during their storage under unfavourable conditions. These deteriorated seeds exhibit a poorer performance, especially under stress conditions. A factorial experiment was conducted to investigate the effects of H₂O₂ on the germination of aged pumpkin seeds under drought stress. Hydroprimed seeds and also the seeds pre-treated with 100, 200, and 400 μM H₂O₂ were exposed to drought (0, -0.2, -0.4, and -0.6 MPa applied using PEG). Under drought conditions, seeds primed with H₂O₂ showed improved germination percentages and rates, higher vigour index, greater plumule and radicle …

Leaf Traits And Performance Vary With Plant Age And Water Availability In Artemisia Californica, Jennifer L. Funk, Julie E. Larson, Gregory Vose

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background and aims
Leaf functional traits are strongly tied to growth strategies and ecological processes across species, but few efforts have linked intraspecific trait variation to performance across ontogenetic and environmental gradients. Plants are believed to shift towards more resource-conservative traits in stressful environments and as they age. However, uncertainty in how intraspecific trait variation aligns with plant age and performance in the context of environmental variation may limit our ability to use traits to infer ecological processes at larger scales.

Methods
We measured leaf physiological and morphological traits, canopy volume, and flowering effort for Artemisia californica (California sagebrush), a …

Landscape Performance Of Buck Roses Under Minimal-Input Conditions In North-Central Texas, Derald A. Harp, Gaye Hammond, David C. Zlesak, Greg Church, Mark Chamblee, Steve George

Faculty Publications

Griffith Buck (Iowa State University) bred roses (Rosa sp.) to survive long, cold winters and hot, humid summers yet still retain their foliage without fungicides. Unfortunately, there is little known about the performance of Buck roses in the southern United States. Thirty-eight Buck rose cultivars were evaluated for flowering, disease resistance, drought tolerance, and overall landscape performance in alkaline soils with no fertilizer, no pesticides, and only limited irrigation. Flowering occurred on a bimodal basis, with the highest per plant mean bloom number (16.3 blooms) and bloom coverage (9.7%) in April, and a second flowering in the fall, with …

Microrna156: A Short Rna With A Major Role In Abiotic Stress Tolerance In Alfalfa, Biruk Ayenew Feyissa

Electronic Thesis and Dissertation Repository

The highly conserved plant microRNA156, miR156, affects various aspects of plant development and stress response by silencing SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. Our understanding of the role of miR156 and its mode of action in alfalfa’s (Medicago sativa L.) response to drought and flooding is still elusive, and thus this study was aimed at filling this gap in knowledge. Physiological parameters, metabolite and transcriptional analyses showed an interplay between miR156/SPL13 and WD40-1/DFR to mitigate drought stress. Low to moderate levels of miR156 overexpression suppressed SPL13 and increased WD40-1 to fine-tune the DIHYDROFLAVONOL-4-REDUCTASE (DFR) level for …

Ecological Strategies Begin At Germination: Traits, Plasticity, And Survival In The First Four Days Of Plant Life, Julie E. Larson, Brian L. Anacker, Sara Wanous, Jennifer L. Funk

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

1. We commonly use trait variation to characterize plant function within and among species and understand how vegetation responds to the environment. Seedling emergence is an especially vulnerable window affecting population and community dynamics, yet trait‐based frameworks often bypass this earliest stage of plant life. Here we assess whether traits vary in ecologically‐meaningful ways when seedlings are just days old. How do shared evolutionary history and environmental conditions shape trait expression, and can traits explain which seedlings endure drought?.
2. We measured seedling traits in the first four days of life for 16 annual plant species under two water treatments, exploring trait …

Drought In Temperate Mesic Regions Leads To Micro-Density Anomalies In White Pine, Elise Miller

CSB/SJU Distinguished Thesis

Wood density and wood volume determine the amount of carbon fixed by trees; however, while we are beginning to understand normal seasonal variation in wood density, anomalies are common, and their drivers are poorly understood. In conifers, wood density normally increases continuously throughout the season, but intra-annual fluctuations in wood density can occur and have been linked to climatic events. The causes of these fluctuations in density at the micro-scale (hereafter micro-density anomalies) are still debated.

Mesic regions are experiencing more droughts, but micro-density anomalies are rarely studied in these ecosystems. This study examined micro-density anomaly distribution within the boles …

Subalpine Forest Tree Seedling Response To Drought, Alex Goke

Electronic Theses and Dissertations

Knowledge of tree species’ ability to tolerate drought is necessary to anticipate future forest dynamics with climate change, especially at the seedling stage given their role in shaping forest structure. We used precipitation reduction shelters to mimic drought for subalpine conifer seedlings (A. lasiocarpa and P. engelmannii) in the Rocky Mountains and compared survivorship and morphological and physiological responses to assess relative degrees of drought tolerance. We detected no significant investment in morphological tolerance traits (e.g. root biomass, leaf:stem area ratio) but substantial reductions in net photosynthesis. While shading partially ameliorated drought effects when precipitation reduction was moderate, …

Leaf Angle Extractor: A High-Throughput Image Processing Framework For Leaf Angle Measurements In Maize And Sorghum, Sunil Kumar Kenchanmane Raju, Miles Adkins, Alex Enersen, Daniel Santana De Carvalho, Anthony J. Studer, Baskar Ganapathysubramanian, Patrick S. Schnable, James C. Schnable

Center for Plant Science Innovation: Faculty and Staff Publications

PREMISE: Maize yields have significantly increased over the past half-century owing to advances in breeding and agronomic practices. Plants have been grown in increasingly higher densities due to changes in plant architecture resulting in plants with more upright leaves, which allows more efficient light interception for photosynthesis. Natural variation for leaf angle has been identified in maize and sorghum using multiple mapping populations. However, conventional phenotyping techniques for leaf angle are low throughput and labor intensive, and therefore hinder a mechanistic understanding of how the leaf angle of individual leaves changes over time in response to the environment.

METHODS …

Leveraging Genome-Enabled Growth Models To Study Shoot Growth Responses To Water Deficit In Rice, Malachy T. Campbell, Alexandre Grondin, Harkamal Walia, Gota Morota

Department of Agronomy and Horticulture: Faculty Publications

lucidating genotype-by-environment interactions and partitioning its contribution to phenotypic variation remains a challenge for plant scientists. We propose a framework that utilizes genome-wide markers to model genotype-specific shoot growth trajectories as a function of time and soil water availability. A rice diversity panel was phenotyped daily for 21 d using an automated, high-throughput image-based, phenotyping platform that enabled estimation of daily shoot biomass and soil water content. Using these data, we modeled shoot growth as a function of time and soil water content, and were able to determine the time point where an inflection in the growth trajectory occurred. We …

The Lateral Root Density Gene Regulates Root Growth During Water Stress In Wheat, Dante F. Placido, Jaspreet Sandhu, Shirley Sato, Natalya Nersesian, Truyen Quach, Thomas Clemente, Paul Staswick, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Drought stress is the major limiting factor in agriculture. Wheat, which is the most widely grown crop in the world, is predominantly cultivated in drought-prone rainfed environments. Since roots play a critical role in water uptake, root response to water limitations is an important component for enhancing wheat adaptation. In an effort to discover novel genetic sources for improving wheat adaptation, we characterized a wheat translocation line with a chromosomal segment from Agropyron elongatum, a wild relative of wheat, which unlike common wheat maintains root growth under limited-water conditions. By exploring the root transcriptome data, we found that reduced …

The Lateral Root Density Gene Regulates Root Growth During Water Stress In Wheat, Dante F. Placido, Jaspreet Sandhu, Shirley Sato, Natalya Nersesian, Truyen Quach, Thomas E. Clemente, Paul E. Staswick, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Drought stress is the major limiting factor in agriculture. Wheat, which is the most widely grown crop in the world, is predominantly cultivated in drought-prone rainfed environments. Since roots play a critical role in water uptake, root response to water limitations is an important component for enhancing wheat adaptation. In an effort to discover novel genetic sources for improving wheat adaptation, we characterized a wheat translocation line with a chromosomal segment from Agropyron elongatum, a wild relative of wheat, which unlike common wheat maintains root growth under limited-water conditions. By exploring the root transcriptome data, we found that reduced …