Plant Pathology Commons^™

Multi-Strata Silvipastoral Systems For Increasing Productivity And Conservation Of Natural Resources In Central America, Muhammad Ibrahim, Andrea Schlonvoigt, Juan Carlos Camargo, M. Souza

IGC Proceedings (1977-2023)

Conversion of primary forest to pasture is widespread in Central and Latin America and the progressive removal of trees has resulted in environmental degradation and a decline in productivity, simultaneously threatening rural livelihoods and regional biodiversity. Recently there has been keen interest to develop silvipastoral systems for sustainable animal production. Traditional silvipastoral systems are characterised with a diversity of woody perennials that plays an important role in supplying feed to animals in the dry season, production of timber, shade for animals, and in the conservation of natural resources. Improved novel woody perennials such as Morus alba (mulberry) and Trichanthera gigantea …

Transgenesis And Genomics In Molecular Breeding Of Forage Plants, G. Spangenberg, R. Kalla, A. Lidgett, T. Sawbridge, E. K. Ong, U. John

IGC Proceedings (1977-2023)

Forage plant breeding has been largely based on phenotypic selection following sexual recombination of natural genetic variation found between and within ecotypes. Advances in plant genetic manipulation over the last 15 years have provided convincing evidence that these powerful technologies can complement and enhance plant breeding programs. Significant progress in the establishment of the methodologies required for the molecular breeding of forage plants has been made. Examples of current products and approaches for the application of these methodologies to forage grass and legume improvement are outlined. Large-scale genomic analysis of many organisms is under way with human, arabidopsis and rice …

Opportunities In Molecular Biology: Enhancement Of The Nutritional Value Of Forages, K. R. Hancock, M. J. Ulyatt

IGC Proceedings (1977-2023)

Pasture plants, while producing a cost-effective source of feed for grazing ruminants, can frequently be less than optimal in meeting the animals’ nutrient requirements. Over the past half century, there has been a major effort to improve the quantity and nutritional quality of pasture plants using conventional plant breeding. Although considerable progress has been made in improving the quality and agronomic characteristics of our major pasture plants by this means, breeding can only be applied to plants capable of sexual crosses. This poses severe limitations both in terms of speed of progress and in the number of genes available for …

The Role Of Endophytic Fungi In Brachiaria, A Tropical Forage Grass, S. Kelemu, J. F. White, Idupulapati M. Rao

IGC Proceedings (1977-2023)

In temperate zones, endophytic fungi are widely used as biological protection agents for forage and turf grasses. They form nonpathogenic and intercellular associations with grasses and sedges, completing their entire life cycle within the plants’ aerial parts. Our surveys and studies confirmed that various endophytic fungi, including Acremonium spp., also inhabit native savanna grasses and introduced tropical forage grasses. We are now determining the potentially symbiotic relationships between these fungi and C₄ tropical forages, specifically between the endophyte A. implicatum and Brachiaria grasses. We treated half of a group of genetically identical clones of Brachiaria with fungicide to generate …

Advances In Endophyte Research. Progress And Priorities In Temperate Areas, L. R. Fletcher, H. S. Easton

IGC Proceedings (1977-2023)

Fungal endophytes infect a large number of temperate grass species, genera and tribes (Leuchtmann and Clay, 1997). The majority of these systemic endophytes fall into the genus Epichloe or the closely related Neotyphodium genus.

The asexual Neotyphodium endophytes are asymptomatic, never emerge from between the host grass cells, and are only transmitted vertically, via seed of the host plant. They are believed to have derived from the Epichloe endophytes, (Bacon and White, 2000; Schardl and Wilkinson, 2000) which do emerge from their intercellular habitat and form stromata around the emerging seedhead of their host. This is manifested as the choke …

Advances In Rhizobial Research – Progress Priorities In Temperate Areas, Angela Sessitsch

IGC Proceedings (1977-2023)

Rhizobia are well known for their capacity to establish a symbiosis with legumes. During this symbiosis the bacteria inhabit root nodules where they reduce atmospheric nitrogen and make it available to the plant. Biological nitrogen fixation (BNF) is an important source of nitrogen and the various legume crops and pasture species often fix as much as 200-300 kg nitrogen per hectare (Peoples et al., 1995). Globally, symbiotic nitrogen fixation has been estimated to amount to at least 70 million metric tons of nitrogen per year (Brockwell et al., 1995). Furthermore, in many cases nitrogen fertilizers are not efficiently used by …

The Legume – Rhizobia Symbiosis. Does It Vary For The Tropics Relative To The Mediterranean Basin?, J. G. Howieson, A. Mcinnes

IGC Proceedings (1977-2023)

Symbiotic N fixation from legumes is one of the most important biological processes on the planet. It currently provides the majority of the N requirement in agriculture, yet will have to double if cereal crop production is to meet world demand by 2020 (Kennedy and Cocking 1997). To effectively harness the value of biological N fixation from legumes we need to more fully understand G² x E; where G refers to the genotypes of both the legume (G_l) and its microsymbiont (rhizobia; G_r), and E refers to the edaphic environment in which the symbiosis is …

Advances In Forage Legumes: Shrub Legumes, M. H. Shelton

IGC Proceedings (1977-2023)

Forage tree legumes benefit agriculture through their multi-purpose contributions to livestock feeding, to productivity of farming systems, and to protection of the environment.

Of the several hundred forage tree legume species regarded as having potential for forage only c. twenty are in common use. These are listed together with their agroecological range and tolerance of adverse environments including acid soils, cool temperatures, low rainfall, poor drainage and high salinity. The value of many species to ruminants is limited due to low nutritive value arising from low protein availability and low acceptability caused principally by high condensed tannin content. Only 10 …

Alfalfa, J. H. Bouton

IGC Proceedings (1977-2023)

Cultivated alfalfa or lucerne (Medicago sativa spp. sativa) is the most important forage legume in the world with approximately 32 million hectares cultivated mainly in the temperate regions of both the northern and southern hemispheres. Intensive research has been conducted on the management and physiology of the crop and a major seed industry has developed world wide. Since insect and disease pests are numerous in alfalfa, development of cultivars with the proper fall dormancy and a broad genetic base for pest resistance has been pursued in order to provide increased adaptation, persistence, and yield. There has been a …

Carbon And Nitrogen Isotopic Discrimination In Alfalfa For High Yield And Quality Forage, W. S. Oliveira, P. P. A. Oliveira, M. Corsi, S. M. Tsai

IGC Proceedings (1977-2023)

Biological nitrogen fixation and assimilation of CO₂ can be indirectly monitored in alfalfa (Medicago sativa L.) through the variation of the stable N and C isotopes in the plant (Δ values). Such measurements result in a simple, non-destructive and reliable method for identification of alfalfa cultivars of high yield and nutritional quality. A program for selection of 12 alfalfa cultivars under field and controlled conditions (lysimeters) included determination of biomass and N accumulation. Under controlled conditions yields ranged from 1.77 to 2.47 ton/ha/month (Pioneer 5312 and WL-605) and N2-fixed varied from 77.43 to 84.01% for total N (Brazilian …

Response Of Roseau Cane (Phragmites Australis) To Two Biotic Stresses: Hyalopterus Pruni And Bipolaris Yamadae, Heather E. Cizek

LSU Master's Theses

Roseau cane (Phragmites australis) is considered an invasive plant because of its ability to replace native plant species. However, in Louisiana it plays an important role protecting coastal infrastructure and being part of the marsh ecosystem in the lower Mississippi River Delta. In recent years, Roseau cane has been affected by a die-off, a problem that has also been reported in some European countries. Possible biotic and abiotic factors that have been associated with the die-off include scale insects, climate change, pollution, salinity levels, and pathogens.

In this research, the individual and combined effect of a foliar disease …

Stolon Growth And Its Morphological Components In White Clover (Trifolium Repens L.) Cultivars, Omar Scheneiter, E. M. Pagano

IGC Proceedings (1977-2023)

A trial was performed to study the seasonal changes in stolon growth and its morphological components in four white clover cultivars, in the north of Buenos Aires Province, in Argentina. Stolons were tagged in four seasonal measurements periods per year, during two consecutive years. Leaf, stolon and flowerheads weights were recorded at regular intervals in each measurement period and total stolon growth was calculated. Differences among cultivars were found in stolon growth and its morphological components in most of the measurement periods. In spring and summer, differences among cultivars in stolon growth were related to flowering quantity and earliness, and …

Dry Matter Production Of Shoots And Root Density Of Two Cultivars Of Lablab Purpureus (L.) Sweet, L. R. De A. Rodrigues, T. J. D. Rodrigues, A. K. B. Ramos, D. G. De Quadros

IGC Proceedings (1977-2023)

This experiment was conducted in green house conditions to evaluate the DM accumulation in the shoots and in the roots of two cultivars of Lablab purpureus (L.) Sweet. A 2x3 factorial (two cultivars and three evaluation dates) was conducted according to a randomized complete block design with four replications, being the cultivars Highworth and Rongai evaluated at 42, 56, and 70 days after seedling emergence (DASE). The results indicated that the cvs. Highworth and Rongai have the same pattern of DM accumulation in the shoots. In the upper layer of the soil (0-0.20 m) it was found 38.83% and 43.64% …

Yellow-Flowered Lucerne (Medicago Falcata L.) - A Potential Forage Legume For The North, T. Mela, H. Ihamäki, M. Matilainen

IGC Proceedings (1977-2023)

The suitability of yellow-flowered lucerne (Medicago falcata L.) for forage production under the northern conditions was studied in a mixture sward with timothy (Phleum pratense L.) in field trials in South Finland for four years from 1995 to 1998. Through the first three winters lucerne stayed unharmed. In June and July lucerne grew vigorously, but in August little. The total seasonal yields were highest in the second and the third year of harvesting, up to 10 t DM ha^-1. In the winter 1997-1998 , winter damages killed 21 to 38 % of lucerne plants, and resulted …

Role Of White Clover In The Improvement Of Economical Efficiency Of Feeds From Grasslands, P. Goliñski

IGC Proceedings (1977-2023)

The aim of the research was to analyse the role played by white clover in the improvement of economical efficiency of feeds obtained from permanent grasslands. The influence of the proportion of white clover in the pasture sward on unit production costs of yield, energy and crude protein and the profit threshold in milk production was analysed taking into account three white clover cultivars, nitrogen fertilisation, irrigation and overdrilling. The investigation procedures employed the author’s own calculation models elaborated in optimisation programs based on production conditions found in dairy farms in the region of Wielkopolska. It was proved that the …

The Use Of Cafeteria Trials For The Selection Of Desmodium Ovalifolium Genotypes, Axel Schmidt, R. Schultze-Kraft, B. L. Maass, C. E. Lascano

IGC Proceedings (1977-2023)

For the selection of tropical legumes which contain anti-nutritive components such as tannins, relative acceptability of genotypes to ruminants is of particular importance, since these plant components may influence selective grazing behaviour and subsequent animal productivity. Plant-animal interactions are not predictable from laboratory analyses. Involving grazing animals through the conduction of relative-acceptability (=cafeteria) trials at early stages of the germplasm selection process might therefore provide a convenient tool to adjust and confirm genotype selection based on laboratory quality analyses data. As part of a multilocational germplasm evaluation project, cafeteria-experiments were conducted at two contrasting environments in Colombia with a core …

Stolon Mass And Classes In White Clover (Trifolium Repens L.) With Two Soil Water Availability Levels, Omar Scheneiter, E. M. Pagano

IGC Proceedings (1977-2023)

Two trials were carried out to study the stolon mass and classes in white clover (Trifolium repens L.) under two soil water availability levels in summer. In each trial, treatments were two white clover cultivars. From December 15^th to February 15^th in 1993/94 and again during the same period the following year, white clover was grown under 30 to 70 % (Forced water uptake) or 85-to100 % (Maximum water uptake) of field capacity. Every two months, throughout two years, total stolon mass, and buried, superficial, and aerial stolons were measured. Differences between cultivars were detected in stolon …

Morphological Description Of Selected Pigeonpea (Cajanus Cajan (L.) Millsp.) Lines, Rodolfo Godoy, F. H. De Souza

IGC Proceedings (1977-2023)

Seventeen pigeonpea pure line accessions selected for desirable forage traits and three commercial cultivars were described according to morphological characters. The following descriptors were used: growth habit, plant height, number of primary and secondary branches, stem color and thickness, leaf shape and hairiness, flower base and second color, pattern of flower streaks, flowering pattern, immature and mature pod color, pod form and hairiness, seed color pattern, base and second seed color, seed eye (region around hilum) color and seed shape and width. Each individual line and cultivar was satisfactorily distinguished from the others by the chosen characters.

Improvement Of Rose Clover Winter Forage Production, Gerald R. Smith, F. M. Rouquette Jr.

IGC Proceedings (1977-2023)

Rose clover (Trifolium hirtum All.) is a winter annual forage legume that has potential for increased use in the U.S. southern region. New cultivars of rose clover are needed with the combination of cold tolerance, winter forage production and full bloom date of late April. Crosses were made between two early flowering cultivars and one late flowering rose clover cultivar. The F₂ and F₃ generations from these crosses were evaluated in northeast Texas for winter growth, cold damage and date of flowering. Fourteen F₃ lines, out of 37 selected F2 parents, showed large increases (>100%) …

Evaluation Of Brachiaria Brizantha Ecotypes Under Grazing In Small Plots, Valéria P. B. Euclides, Cacilda B. Do Valle, Manuel C. M. Macedo, M. P. Oliveira

IGC Proceedings (1977-2023)

An intense search for new cultivars amongst recently collected and introduced ecotypes from Africa is in effect since 1988, at the National Beef Cattle Research Center, of the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle). After agronomic evaluations of a large collection, 21 ecotypes were pre-selected for multilocational trials and from these, eight were elected for evaluation under grazing. The objective of this trial was thus to evaluate the persistence and carrying capacity of these eight new Brachiaria brizantha ecotypes after two years of grazing. The experimental design was a randomized complete block with nine treatments and two replicates. The …