Plant Pathology Commons^™

Measuring Summer Dormancy Of Perennial Grasses In Contrasting Environments, Mark R. Norton, Richard A. Culvenor, Florence Volaire

IGC Proceedings (1977-2023)

The summer dormancy trait has been shown to confer enhanced levels of survival to temperate perennial forage species over long periods of intense summer drought (Volaire and Norton 2006) and is therefore valuable in plant improvement. Normally found in species endemic to drier Mediterranean climates it is recommended that the trait be measured in the field under typical Mediterranean hot, dry summer conditions (Norton et al. 2008). However, this trait has potential utility in regions with summers that can receive substantial rainfall, but still experience extended periods of intense moisture deficit. Therefore, it is important to determine whether summer …

Generation Of Transgenic Tall Fescue Plants With Enhanced Abiotic Stress Tolerance, I. Alam, Y. G. Kim, K. H. Kim, N. Y. Ahn, B. H. Lee

IGC Proceedings (1977-2023)

Environmental stresses, such as drought, salinity and temperature extremes significantly decrease the yield of forage crops. Therefore, traits associated with abiotic stress-tolerance are of prime importance for their improvement. Biotechnological approaches have the potential to accelerate and complement conventional breeding by extending the range of gene sources for valuable traits, thus offering new opportunities for forage improvement. Transgenic technology appears as an efficient biotechnological tool of molecular breeding for improving forage quality and yield as well as tolerance to various environmental stresses. Occurrence of high level of reactive oxygen species (ROS) is a common phenomenon in abiotic stress-challenged plants. Plants …

Physiological Response Of 14 Lotus Tenuis Genotypes Subjected To Drought Conditions, Luis Inostroza, Hernán Acuña

IGC Proceedings (1977-2023)

Lotus tenuis L. is a perennial forage species of European origin. It is found in Chile in a wide range of environments between the Valparaíso (32°S) and Bíobío Regions (38°S), with a strong presence in areas with clay and volcanic soils of medium texture with problems of moisture retention. The Instituto de Investigaciones Agropecuarias (INIA) perennial forage legume breeding program has focused on developing drought-tolerant cultivars of the species. A population of 100 individuals was selected in previous studies, and all individuals were agronomically and physiologically characterized under field and greenhouse conditions. Results led to the selection of a sub-population …

Scenario Analysis: Risk And Return Of Aluminium Tolerant Lucerne, Claire D. Lewis, J. L. Jacobs, K. F. Smith, G. Spangenberg, B. Malcolm

IGC Proceedings (1977-2023)

Lucerne (Medicago sativa) yield is limited by aluminium stress associated with acid soils (Campbell et al. 1988; Scott et al. 2008). With the aid of transgenic technologies, the development of aluminium tolerant (Al Tol) lucerne is proposed. Modelled scenario analysis was conducted to explore the potential net benefits of Al Tol lucerne as part of a grazing system for a sheep production system in the high rainfall zone of south west Victoria.

Germplasm Evaluation And Frost Tolerance Improvement Of Setaria Sphacelata In Uruguay, Rafael Reyno, Javier Do Canto, Daniel Real

IGC Proceedings (1977-2023)

Setaria sphacelata (Schumach.) Stapf & C.E. Hubb is a highly productive warm-season grass that has been eva-luated in Uruguay since the 1970s (Mas 2007). It is one of the most productive and promising subtropical grasses for the Uruguayan climatic conditions. Some of the most re-markable attributes of interest are its palatability, ease to establish from seed, highly persistent, adapted to a wide range of soils, and some frost tolerance. Cultivars ‘Narok’ and ‘Kazungula’ were the only materials evaluated and no genetic improvement was conducted in Uruguay. These cultivars present some limitations, such as low seed yields and quality, and susceptibility …

Effects Of Organic Acids On Alleviation Of Aluminum Toxicity In Alfalfa, Yuan An, Peng Zhou

IGC Proceedings (1977-2023)

On a global scale, acidic soils cover an estimated 37.8 million km² of the earth's surface, and up to 50% of the world’s potentially arable soils are acidic. Aluminum (Al) is highly abundant in acid soil conditions. At low (< 5.5) pH, a toxic form of aluminum, Al³⁺, is solubilized from aluminosilicate clay minerals into soil solutions. High concentrations of Al_³⁺ in soil solutions caused seriously damage to plants by enhancing lipid per-oxidation, limiting root elongation and nutrient uptake, as well as decreasing plant growth (Kochian et al. 2005). Al toxicity represents one of the most important constraints for agricultural production in areas …

Performance Of Some Forages Species (Festuca Arundinacea L., Chloris Gayana Var. Katambora, Lotus Corniculatus L. And Medicago Sativa L.) In Saline Soil, Süleyman Temel, Uğur Şimşek, Bilal Keskin, İbrahim H. Yılmaz

IGC Proceedings (1977-2023)

Salinity is a soil degradation process which reduces plant diversity and agricultural productivity, decreases fertility and devalues the land in regions with arid and semi-arid climate. This process inhibits water and nutrient intake of plants from soil due to changeable nitrogen percentage and/or the intensity of soluble salt concentration. When the fact that agricultural lands are limited around the world and that the need for nutrition increases incrementally is taken into consideration, it is obvious that available lands should be used more effectively. Hence, it is quite crucial to reclaim saline soil and utilize it more economically (Woods 1996).

Salt Secretion Is Essential For Xero-Halophyte Reaumuria Soongorica Responding To Osmotic Stress, Ai-Ke Bao, Hang-Yu Zhou, Suomin Wang

IGC Proceedings (1977-2023)

Reaumuria soongorica, a xero-halophyte semi-shrub belonging to Tamaricaceae with excellent adaptability to adverse arid and salinity environments of northwest China, serves important ecological roles in the improvement of saline-alkali soil and dune stabilisation, and also is an attractive fodder shrub in desert steppe (Ma et al. 2011). Previous studies demonstrated that secreting salt via salt glands is an important strategy for R. soongorica adapting to high salinity environments (Zhou et al. 2012). However, very little is known about the role of salt secretion in the plant’s responses to drought. Therefore, in the present work, R. soongorica seedlings …

Assessment Of Summer Drought Tolerance And Persistence Of Some Grass Cultivars In Algerian Semi Arid Conditions, Mohamed Mefti, Hamena Bouzerzour, Abderrezak Chebouti, Aissa Abdelguerfi

IGC Proceedings (1977-2023)

Stress-tolerant forage resources are increasingly needed for the environmental and economic sustainability of extensive Mediterranean livestock systems. Perennial forages belonging to two species: Festuca arundinacea Schreb. (tall fescue) and Dactylis glomerata L. (cocksfoot) can be a valuable alternative to annuals, if they can survive across successive summer droughts. Poor persistence of sown perennial pasture grasses is a problem in regions of the World with Mediterranean climates where the most stressful, life threatening season is a summer characterised by long and often severe droughts with high temperatures. The objective of this study is to compare 14 grass cultivars in an Algerian …

Summer Dormancy And Survival Of Tall Fescue In Relation To Endophyte Presence, J. L. Thomas, Charles P. West, D. P. Malinowski

IGC Proceedings (1977-2023)

True summer dormancy in temperate perennial grasses is the ability to survive summer stresses by ceasing growth and senescing vegetative tissues independently of water supply, as opposed to summer-active grasses, which respond to rains by continuing growth, but senesce during droughts (Volaire and Norton 2006). Summer dormancy is a common drought-escape mechanism for Mediterranean-origin perennial grasses, but is also being considered as a potentially useful trait in semiarid to humid zones whose climates are not strictly Mediterranean, but where temperate grass survival is threatened by summer heat and water deficits (Malinowski et al. 2005). Moreover, summer dormancy may provide …

Screening Of Ssr Primers And Evaluation Of Salt Tolerance In 20 Sweet Sorghum Varieties For Silage, Qiuwen Zhan, Chunfei Shu, Xiaoliang Li, Min Zhan, Jieqin Li, Ping Lin

IGC Proceedings (1977-2023)

Sweet sorghum belongs to the genus Sorghum in the family Gramineae. It is a variant of common grain sorghum, with characteristics of resistance to drought, flood, barren soil and soil salinity and alkalinity (Zhan et al. 2008). Since the stem of sweet sorghum is rich in sugar, it is usually harvested as silage fodder in grasslands. Often arable land used for forage production is salt-affected. Chinnusamy et al. (2005) have screened and identified a large range of different varieties for salinity tolerance, but there are no published reports of studies screening SSR primers and evaluating the salt tolerance in …

Plantain (Plantago Lanceolata) Outperforms Chicory (Cichorium Intybus) Under Moisture Stress In Glasshouse, Lydia M. Cave, Peter D. Kemp, Paul R. Kenyon, Stephen T. Morris

IGC Proceedings (1977-2023)

Forage chicory (Cichorium intybus) and plantain (Plantago lanceolata) are now widely used throughout the world as high feed quality perennial herbage (Sanderson et al. 2003; Labreveux et al. 2006; Li et al. 2010; Golding et al. 2011; Hutton et al. 2011). Both are taprooted plants and are thus likely to confer a degree of drought tolerance through accessing water deeper in the soil profile (Kemp et al. 2010). Nie et al. (2008) reported chicory can tolerate moisture stress to a greater degree than plantain. However, overall little is known …

Adaptive Responses Of Brachiaria Grasses To Hypoxia Stress, Juan A. Cardoso, Juan Jiménez, Joisse Rincón, Idupulapati M. Rao

IGC Proceedings (1977-2023)

It is likely that oxygen shortage in waterlogged soils is the most limiting factor for plant growth, restricting root aerobic respiration and ATP production (Vartapetian and Jackson 1997). When oxygen becomes limiting for oxidative phosphorylation, plant cells depend on alternative metabolic pathways to produce ATP (Rocha et al. 2010). The induction of fermentative metabolism is considered of adaptive value to maintain ATP production under oxygen-limited conditions. Ethanol is the main end product of fermentation metabolism in plants. Alcohol dehydrogenase (ADH) is a key enzyme in ethanolic fermentation. Roots can sustain aerobic respiration under oxygen deficiency if aerenchyma is present. …

The Effects Of Seed-Applied Fluopyram On Root Penetration And Development Of Meloidogyne Incognita On Cotton And Soybean, Tracy Hawk

Graduate Theses and Dissertations

Plant-parasitic nematodes are major pests of cotton and soybean in Arkansas, and across the Southern United States. These nematodes cause more than $3 billion worth of crop losses each year, in part due to lack of available control tactics, such as nematicides. Fluopyram has recently been registered as a seed-treatment nematicide in agronomic crops. The toxicity of fluopyram against Meloidogyne incognita infection has been reported, however, information on root protection provided by fluopyram against Meloidogyne incognita is lacking. The first objective of this research was to evaluate the effect seed-applied fluopyram had on nematode development, root galling, and reproduction on …

Use Of Aerial Imagery And Novel Experimental Design To Determine The Distribution Of Foliar Diseases On Soybean And Improve Efficiency Of Product Testing, Mckayla Patterson

Graduate Theses and Dissertations

Soybeans are grown on approximately 1.3 million ha in Arkansas generating an estimated $1.7 billion annually. Foliar diseases on soybean can result in economic losses. Growers spend significant time and money on disease scouting via crop consultants and often (subsequent) fungicide applications. Fungicide trials are often arranged in small plots designs. In these scenarios, spatial variability of foliar disease is minimized. While it is advantageous to minimize variance outside of treatment differences, another limitation with many small plot trials is ample disease pressure or having only lower severity. Within a commercial production field, soil types and disease severities vary. Logically, …

Understanding How The Effectors Hopd1 And Hopg1 From The Bacterial Pathogen Pseudomonas Syringae Pv. Tomato Dc3000 Target The Arabidopsis Thaliana Protein Atnhr2b To Cause Disease In Plants, Catalina Maria Rodriguez Puerto

Graduate Theses and Dissertations

The pathogenicity of Pseudomonas syringae is associated with the type III secretion system (T3SS), a complex of proteins assembled in the inner and outer bacterial membranes that traverses the plant cell wall to deliver bacterial proteins into the cytoplasm of plant cells. The effector proteins translocated into the plant cells are called Hops (Hypersensitive response and pathogenicity outer proteins). Bacterial effectors target plant immune proteins to suppress defense responses and enhance bacterial parasitism. The Arabidopsis thaliana nonhost resistance 2B (AtNHR2B), a recently identified immune protein, is degraded after inoculation with the adapted pathogen of Arabidopsis, P. syringae pv tomato DC3000 …

Mitigating Herbicide Impacts To Soybean, Grant Lawson Priess

Graduate Theses and Dissertations

The rapidity in evolution of herbicide-resistant weeds and the resulting cost to U.S. farmers demonstrate the need to responsibly steward the limited number of herbicides available in agricultural systems. To reduce weed emergence and likewise added selection pressures placed on herbicides, early-season crop canopy formation has been promoted. However, impacts to soybean following a potentially injurious herbicide application have not been thoroughly evaluated. Therefore, field experiments were conducted to determine whether: 1) soybean injury from metribuzin or flumioxazin delayed canopy formation or changed the incidence of pathogen colonization; 2) residual herbicides applied preplant reduced the potential for soybean injury and …

Phenotypic Study Of Anthracnose Resistance In Black Walnut And Building A Mapping Population, Sadie D. Land

Graduate Theses/Dissertations

Black walnut anthracnose, caused by Gnomonia leptostyla, is the most widespread and destructive disease affecting black walnut trees (Juglans nigra). Breeding cultivars for a higher resistance to anthracnose is a natural and efficient strategy for improving the health and production quality of black walnut trees. The two goals of this study were to reveal that the ‘Sparrow’ cultivar of black walnut contains a significantly higher resistance to anthracnose than the ‘Football’ cultivar when separated from environmental factors, and to expand the ‘Football’ × ‘Sparrow’ F1 mapping population to evaluate how the trait of resistance is inherited in the progeny. A …

Methods To Evaluate Ruminant Animal Production Responses, Jose Manuel Diaz Gomez

Graduate Theses and Dissertations

In experiment 1, 80 steers (197.0 kg initial body weight; BW for fall, 116.9 kg for spring), were stocked at 2.45 and 4.1 calves/ha in fall and spring, respectively in 16 tall fescue pastures [fall ergovaline (EV) = 1,475 ppb and spring EV = 1,173 ppb] under 2 treatments, mineral (MIN) (n = 8) and cumulative management (CM) (n = 8). Forage allowance did not differ (P = 0.76) between CM and MIN during fall but differed during spring (P ≤ 0.05, 2.55 vs. 3.22 kg DM/kg BW, for MIN and CM, respectively). For fall, average daily gain (ADG) resulted …

Evaluation Of Pheromone Mating Disruption For California Red Scale Control In Commercial California Citrus, Joel Timothy Leonard

Master's Theses

California red scale (CRS), Aonidella aurantii, is an increasingly injurious insect pest for the California citrus industry due to insecticide resistance, changing weather patterns, and shifting trade regulations. The presence of the insect on fruit, damages the rind of the fruit and high populations can cause dieback of branches as well as lower yields. Pheromone mating disruption of CRS has the potential to alleviate population control concerns and reduce insecticide use. The efficacy of the pheromone mating disruption technique for pest management of CRS was determined using the products CheckMate® CRS and Semios CRS Plus. CheckMate® CRS was evaluated …

Nematode Populations As Affected By Residue And Water Management In A Long-Term Wheat-Soybean Double Crop In Eastern Arkansas, Lucia Emperatriz Escalante Ortiz

Graduate Theses and Dissertations

Soybeans (Glycine max) are one of the major row crops in the United States, particularly in Arkansas. Soybean cyst nematode (SCN, Heterodera glycines) and southern root-knot nematode (RKN, Meloidogyne incognita) are two of the most damaging pests that cause major economic losses in soybeans. Little is known concerning the effects of common and alternative agronomic practices on nematodes in fields with nematode population densities below threshold levels. Therefore, the objective of this study was to evaluate the effects of the combination of tillage (conventional tillage and no-tillage), irrigation (irrigated and non-irrigated), wheat (Triticum aestivum) residue burning (burned and no burned), …

Evaluation Of Topramezone For Use In Rice (Oryza Sativa L.) Production, Matthew Moore

Graduate Theses and Dissertations

The rapid development of resistant weeds, particularly to postemergence-applied herbicides, is a growing concern to rice producers worldwide. Barnyardgrass, one of the most problematic weeds in rice cropping systems, alone has been found to be resistant to four herbicide sites of action (SOA) in certain populations, leaving growers no options for control. This unsettling fact has led to research on other SOAs that have not previously been used in US rice. One SOA that has garnered interest is the 4-hydroxyphenylpyruvate dioxygenase (HPPD)- inhibiting herbicides. The only HPPD-inhibitor that will soon be labeled for use in US rice is benzobicyclon. The …

Genetic Resistance To The Downy Mildew Pathogen And Mapping The Rpf Resistance Loci In Spinach, Gehendra Bhattarai

Graduate Theses and Dissertations

Spinach (Spinacia oleracea) is an important cool-season leafy vegetable crop in the United States (US). Downy mildew, caused by the obligate oomycete Peronospora effusa, is the most economically important disease of spinach. A total of 17 races of P. effusa have been reported on spinach, and many of these races (>10) have emerged in the last three decades. The new races of the pathogen are continually overcoming the genetic resistances used in the newly released cultivars.

A detached leaf inoculation assay was evaluated, standardized, and validated as a new method to differentiate resistant and susceptible spinach genotypes. Disease response …

Lucerne For Acid Soils: A Field Evaluation Of Early Generation Aluminium Tolerant Genotypes, Richard C. Hayes, Guangdi Li, Shoba Venkatanagappa, Alan W. Humphries, Ross Ballard

IGC Proceedings (1977-2023)

The development of lucerne germplasm tolerant of acidic soil conditions has long been a research objective of international significance. Many initiatives have previously failed to produce genotypes with adequate improvement in tolerance to be deemed economically viable and as a consequence, still no cultivar of lucerne exists that has improved adaptation to acidic soils. An Australian research program spanning the previous decade sought to redress this issue by developing lucerne genotypes with significantly enhanced tolerance to aluminium (Al) toxicity. Using recurrent selection in hydroponic solution culture, populations selected comprised individuals which displayed enhanced seedling root growth following a pulse of …

Dissecting Drought-Response Strategies Of Perennial Ryegrass (Lolium Perenne L.), Jean-Hugues B. Hatier, Lulu He, Marty J. Faville, Micheal J. Hickey, Chris S. Jones, Mohamed Z. Z. Jahufer, Cory Matthew

IGC Proceedings (1977-2023)

Periodic drought is a severe constraint on the profitability and sustainability of pastoral production. As a result of climate change, drought events are anticipated to increase in frequency and intensity even in regions where annual precipitation is unchanged, as well as where it is reduced.

Many studies have been carried out on drought resistance of forage species (Holloway-Phillips and Brodribb 2011). However, for most experiments, it is unclear which mechanism(s) are responsible for variation in plant performance under moisture stress, whether drought response mechanisms were triggered, or whether differences in performance were simply the result of intrinsic plant vigour. The …

The Effect Of Salinity Stress On Seed Germination Of Agropyron Elongatum, Ghasem Ali Dianati Tilaki, Arezu Alizadeh, Behnam Naserian Khiabani

IGC Proceedings (1977-2023)

Successful seedling establishment depends on the frequen-cy and the amount of precipitation as well as on the ability of the seed species to germinate and grow while soil mois-ture and osmotic potentials decrease. Germination and seedling characteristics are the most valuable criteria for selecting salt tolerance in plants. Salinity stress can reduce seed germination through osmotic effects (Jamil et al. 2006). Agropyron is a perennial grass genus with 19 dif-ferent species reported. This genus has wide adaptation and can be grown in different climates.

The objective of this study was to evaluate the impact of salinity stress on the germination …

Messina (Melilotus Siculus)–A New Pasture Legume For Saltland, Amanda L. Bonython, Andrew D. Craig, Ross A. Ballard, Nigel Charman, Philip G. H. Nichols, Clinton Revell, Natasha L. Teakle

IGC Proceedings (1977-2023)

Messina (Melilotus siculus ((Turra) Vitman ex B.D. Jacks)) is a new annual pasture legume for saltland in temperate Australia and regions of the world that experience Mediterranean climates. Messina has greater tolerance to the combined stresses of salinity and water-logging than existing commercial pasture legumes. Coupled with desirable agronomic traits these characteristics give messina the capacity to rehabilitate saltland and increase productivity on land where existing legumes fail. This paper reviews the agronomic perform-ance of messina in relation to top soil salinity levels.

Agronomic Traits In Tall Fescue Populations Under Irrigated And Rain-Fed Conditions, M. Anowarul Islam, Malay C. Saha

IGC Proceedings (1977-2023)

Grasslands and native rangelands are the predominant land-use all over the world. Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] is a cool-season perennial grass widely grown throughout the temperate regions of the world and an important component of the grasslands. Drought can have serious consequences on performance of agriculture, soil and plant health, and economics. Developing drought tolerant plants that can maintain productivity during drought, will have great environmental and economic benefits to farmers. A tall fescue population was developed by crossing a drought tolerant genotype to a susceptible genotype. The population was evaluated for different morphological and yield traits …

Mechanisms Of Stress Tolerance In Xerophyte Zygophyllum Xanthoxylum And Their Application In Genetic Improvement Of Legume Forages, Suomin Wang, Aike Bao, Qing Ma, Lijun Yue, Jinlin Zhang, Guoqiang Wu, Jiejun Xi, Yanwen Wang

IGC Proceedings (1977-2023)

Xerophytes, naturally growing in desert areas, have evolved multiple protective mechanisms to survive and grow well in harsh environments. Zygophyllum xanthoxylum, a succulent xerophyte with excellent adaptability to adverse arid environments and a fodder shrub with high palatability and nutrient value, colonizes arid areas in China and Mongolia. In this study, we found that Z. xanthoxylum grew better responding to salt condition with a typical feature for halophytes and became more tolerant to drought in the presence of moderate salinity (50 mM NaCl); 50 mM NaCl alleviated deleterious impacts of drought on the growth of Z. xanthoxylum by improving …

Advances In Improving Tolerance To Waterlogging In Brachiaria Grasses, Juan A. Cardoso, Juan Jiménez, Joisse Rincón, Edward Guevara, Rein Van Der Hoek, Andy Jarvis, Michael Peters, John Miles, Miguel Ayarza, Socorro Cajas, Alvaro Rincón, Henry Mateus, Jaime Quiceno, Wilson Barragán, Carlos Lascano, Pedro Argel, Martin Mena, Luis Hertentains, Idupulapati M. Rao

IGC Proceedings (1977-2023)

Poor drainage is found on about 11.3% of agricultural land in Latin America where physiography promotes flooding, high groundwater tables, or stagnant surface water (waterlogging). Waterlogging drastically reduces oxygen diffusion into the soil causing hypoxia which is the main limitation that reduces root aerobic respiration and the absorption of minerals and water. Under waterlogging conditions plants can adapt with traits and mechanisms that improve root aeration such as production of aerenchyma and development of adventitious roots. During the rainy season Brachiaria pastures are exposed to waterlogging conditions that can severely limit pasture productivity and hence animal production. The main objective …