Plant Pathology Commons^™

Brachiaria Hybrids: Potential, Forage Use And Seed Yield, Esteban A. Pizarro, Michael D. Hare, Mpenzi Mutimura, Changjun Bai

IGC Proceedings (1977-2023)

A brachiaria breeding program initiated in 1988 at CIAT (Centro Internacional de Agricultura Tropical) combined desirable attributes found in accessions of Brachiaria brizantha and B. decumbens. Three apomictic hybrids have been released (cvs. Mulato, Mulato II and Cayman). Mulato showed agronomic potential but seed yields were low. Trials in Central America demonstrated the superiority of Mulato II, a vigorous grass with very deep and branched roots, giving it excellent drought resistance in the Brazilian Cerrado and Mexico. Mulato II has excellent nutritional value. Following trials in Mexico and Thailand, evaluating 155 new hybrids for 7 years, cv. Cayman was …

Molecular Genetic Variability, Population Structure And Mating System In Tropical Forages, Melissa Garcia, Bianca B. Z. Vigna, Adna C. B. Sousa, Letícia Jungmann, Fernanda W. Cidade, Guilherme Toledo-Silva, Patricia M. Francisco, Lucimara Chiari, Marcelo A. Carvalho, Claudio T. Karia, Fabio G. Faleiro, Rodolfo Godoy, M. Dall’Agnol, Sueli S. Pagliarini, Francisco H. D. Souza, Tatiana T. Souza-Chies, Liana Jank, Rosangela M. S. Resende, Cacilda B. Valle, Maria I. Zucchi, Anete P. Souza

IGC Proceedings (1977-2023)

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyse population structure and genetic diversity, evolution and origin of the genetic variability in the centre of origin, mating systems and genetic resources in EMBRAPA’s germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed …

Leucaena Toxicity: A New Perspective On The Most Widely Used Forage Tree Legume, Michael J. Halliday, Jagadish Padmanabha, Chris S. Mcsweeney, Graham L. Kerven, H. Max Shelton

IGC Proceedings (1977-2023)

The tree legume Leucaena leucocephala (leucaena) is a high quality ruminant feed, vitally important for livestock production in the tropics despite the presence of mimosine in the leaves. This toxic non-protein amino acid has the potential to limit productivity and adversely affect the health of animals. The discovery and subsequent distribution in Australia of the ruminal bacterium Synergistes jonesii as an oral inoculum was shown in the 1980s to overcome these toxic effects. However, recent surveys of the status of toxicity worldwide; improved understanding of the chemistry and mode of action of the toxins; new techniques for molecular sequencing; and …

Global Impacts From Improved Tropical Forages: A Meta-Analysis Revealing Overlooked Benefits And Costs, Evolving Values And New Priorities, Douglas S. White, Michael Peters, Peter Horne

IGC Proceedings (1977-2023)

The wider use and improved performance of planted tropical forages can substantially change social, economic and environmental landscapes. By reviewing impact-related studies published in the past two decades, this paper shows how evolving development priorities have influenced the types of impacts being documented. A meta-analysis was used to examine 98 studies according to: (1) breadth of reported effects, as related to development goals of social equity, economic growth and environmental sustainability; (2) extent of effects, ranging from intermediate to longer-term impacts; and (3) measurement precision (identification, description and quantification). Impacts have been assessed for fewer than half of the documented …

Cellular Causes For Leaf Elongation Reductions Under Salinity In Panicum Coloratum, Leandro Cáceres, Edith Taleisnik

IGC Proceedings (1977-2023)

Soil salinity is a growing constraint to crop and forage production worldwide and has driven the quest for salt-tolerant germplasm. Perennial forage grasses are regarded as choice alternative for the productive use of saline areas as well as for mitigating salinity in these areas (Ridley and Pannell 2005). Panicum coloratum L. is a C4 perennial grass native to tropical Africa, adapted to a wide range of rainfall conditions which makes it attractive as a forage for semiarid areas (Jones 1985). In forage grasses, yield is directly related to leaf area expansion and duration and the purpose of this work was …

Response Of Axonopus Catarinensis And Arachis Pintoi To Shade Conditions, A. N. A. Pachas, E. J. Jacobo, M. C. Goldfarb, S. M. Lacorte

IGC Proceedings (1977-2023)

In the north-east of Argentina, there are more than 100,000 hectares of silvopastoral systems where trees, forages and livestock are combined with the goal to diversify income, reduce financial risk, obtain more profit and enhance environmental benefit (Cubbage et al. 2013). The rapid adoption of this production system by farmers has generated high demand for information on shade tolerant grass and legume forage species.

Axonopus catarinensis is a native grass from Itajai Vally (Brazil) that was introduced to the north-east of Argentina 10 years ago; whereas Arachis pintoi is a sub-tropical legume (also native to Brazil) adapted to acid …

The Growth Response Of Tropical And Sub-Tropical Forage Species To Increasing Salinity, Hayley E. Giles, Christopher J. Lambrides, Scott A. Dalzell, David C. Macfarlane, H. Max Shelton

IGC Proceedings (1977-2023)

There is currently a growing coal seam gas (CSG) industry in Queensland, Australia. The industry requires beneficial-use strategies to consume the significant volumes of water released during CSG extraction. Irrigation of tropical and sub-tropical forage species for beef production is one option, however coal seam (CS) water is of varying quality due to moderate to high salinity and alkalinity. The application of chemically amended CS water over time could potentially increase soil salinity, which is known to reduce plant biomass production. While there were studies of salinity tolerance of many tropical and sub-tropical forage species 30 years ago, there is …

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. …

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), …

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 …

Improved Drought Stress Tolerance Of White Clover Through Hybridisation With Trifolium Uniflorum L., Shirley N. Nichols, Rainer W. Hofmann, Isabelle M. Verry

IGC Proceedings (1977-2023)

The objective of this study was to determine the effect of hybridisation with Trifolium uniflorum L. on drought resistance of Trifolium repens L. (white clover). Shoot dry weight of backcross 1 (BC1) hybrids was reduced less by water stress than for backcross 2 (BC2) hybrids and white clover, as were key morphological traits such as leaf area. Under water stress, important differences for the BC1 generation compared to white clover also included lower senescence, higher stolon density, increased root dry weight, and a higher maximum nodal root diameter. Drought decreased the net photosynthetic rate by up to 48% in BC2 …

Designing Resilient And Sustainable Grasslands For A Drier Future: Adaptive Strategies, Functional Traits And Biotic Interactions, Florence Volaire, Karim Barkaoui, Mark Norton

IGC Proceedings (1977-2023)

In many regions of the world, such as Southern Europe and most Mediterranean areas, the frequency and magnitude of droughts and heat waves are expected to increase under global warming and will challenge the sustainability of both native and sown grasslands. To analyze the adaptive strategies of species, genotypes and cultivars, we aim both: (1) to understand the composition and functioning of natural grasslands; and (2) to propose ideotypes of cultivars and optimal composition for mixtures of species/genotypes under water deficit and high temperatures. This review presents a conceptual framework to analyze adaptive responses of perennial herbaceous species, starting from …