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Heterodera Avenae
''Heterodera avenae'', the cereal cyst nematode or European cyst nematode, is a plant pathogen and an obligate parasite of cereal crops including barley, oats, wheat and rye. Cereal crops infected with this nematode are more susceptible to infection by fungal diseases such as rhizoctonia root rot. Life cycle This microscopic nematode exhibits sexual dimorphism. The female is rounded and white and measures 680 by 930 micrometres. The male is vermiform and transparent and measures 40 by 1300 micrometres. The Egg (biology), eggs are oval and the vermiform larvae moult four times. The second instar larvae are mobile and can travel distances of up to thirty centimetres, looking for and invading roots of suitable host species. Here they develop, growing into sedentary bottle-shaped third instar larvae and rounded fourth instar ones. These then develop into either females or males and mating takes place. The female retains the majority of the several hundred eggs she produces inside her ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wollenweber
Louis r LudwigAugust Wollenweber (5 December 1807 – 25 July 1888) was a German-American German-language journalist and a writer of prose and poetry in Pennsylvania Dutch. Biography Germany As he was orphaned early in life, he was compelled to give up any hope for higher education. He was educated at Speyer for the trade of a printer. Upon the completion of his term of apprenticeship, he traveled through Germany as a journeyman worker, finally settling in Homburg and working for the ''Deutsche Tribüne''. He was compelled to emigrate to the United States, via France and the Netherlands, in consequence of his being one of the agitators of the " Hambacher Volksfest." The journal he was working on was suppressed by the German Diet as well. Pennsylvania After his arrival in Philadelphia, he was first engaged on J. G. Wesselhöft's ''Schnellpost''. He later founded a new German-language paper, ''Der Freimuethige'' (The Free-Thinker), which lasted only for a short time. He subseque ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg (biology)
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches. Most arthropods such as insects, vertebrates (excluding live-bearing mammals), and mollusks lay eggs, although some, such as scorpions, do not. Reptile eggs, bird eggs, and monotreme eggs are laid out of water and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark and was in size. Whale shark eggs typically hatch within the mother. At and up to , the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cereal Diseases
A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food energy worldwide than any other type of crop and are therefore staple crops. They include wheat, rye, oats, and barley. Edible grains from other plant families, such as buckwheat, quinoa and chia, are referred to as pseudocereals. In their unprocessed whole grain form, cereals are a rich source of vitamins, minerals, carbohydrates, fats, oils, and protein. When processed by the removal of the bran and germ the remaining endosperm is mostly carbohydrate. In some developing countries, grain in the form of rice, wheat, millet, or maize constitutes a majority of daily sustenance. In developed countries, cereal consumption is moderate and varied but still substantial, primarily in the form of refined and processed grains. Because of this dietary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterodera
''Heterodera'' is a genus of nematodes in the family Heteroderidae. Members of the genus are obligate parasites and different species attack different crops, often causing great economic damage. The genus is unique among nematode genera because of the ability of the female to transform into a tough, brown, cyst which protects the eggs which have been formed within her body. The name heterodera "refers to the different 'skins' of female and cyst."Tylenchida: Parasites of Plants and Insects, 2nd ed., by Mohammad Rafiq Siddiqi Diversity The following is a list of taxa in the genus ''Heterodera'': * ''Heterodera amygdali'' * '' Heterodera arenaria'' * '' Heterodera aucklandica'' * ''Heterodera avenae'' * '' Heterodera bergeniae'' * ''Heterodera bifenestra'' * '' Heterodera cacti'' * ''Heterodera cajani'' * '' Heterodera canadensis'' * '' Heterodera cardiolata'' * ''Heterodera carotae'' * '' Heterodera ciceri'' * ''Heterodera cruciferae'' * ''Heterodera delvii'' * '' Heterodera elachis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Take-all
Take-all is a plant disease affecting the roots of grass and cereal plants in temperate climates caused by the fungus ''Gaeumannomyces tritici'' (previously known as ''Gaeumannomyces graminis ''var. ''tritici''). All varieties of wheat and barley are susceptible. It is an important disease in winter wheat in Western Europe particularly, and is favoured by conditions of intensive production and monoculture. The disease The pathogen survives in the soil on infected cereal and grass residues. The fungus infects the root tissue of young plants and can spread from plant to plant in the form of hyphae growing through the soil which is why the disease is often seen in patches. The fungus blocks the conductive tissue of the plants and reduces water uptake. Early symptoms of the disease include yellowing and stunting, tillering is reduced and plants mature prematurely and often exhibit bleached seed heads. The affected roots are blackened and the plants are easy to pull from the soil. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyst
A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble); however, the distinguishing aspect of a cyst is that the cells forming the "shell" of such a sac are distinctly abnormal (in both appearance and behaviour) when compared with all surrounding cells for that given location. A cyst may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst may resolve on its own. When a cyst fails to resolve, it may need to be removed surgically, but that would depend upon its type and location. Cancer-related cysts are formed as a defense mechanism for the body following the development of mutations that lead to an uncontrolled cellular division. Once that mutation has occurred, the affected cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After shedding their exoskeleton (moulting), the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars. For most insect species, an ''instar'' is the developmental stage of the larval forms of holometabolous (complete metamorphism) or nymphal forms o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larvae
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The larva's appearance is generally very different from the adult form (''e.g.'' caterpillars and butterflies) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments, but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like polychaetes and barnacles, adults are immobil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerated dim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Nebraska
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, the designation is reserved for colleges that have a graduate school. The word ''university'' is derived from the Latin ''universitas magistrorum et scholarium'', which roughly means "community of teachers and scholars". The first universities were created in Europe by Catholic Church monks. The University of Bologna (''Università di Bologna''), founded in 1088, is the first university in the sense of: *Being a high degree-awarding institute. *Having independence from the ecclesiastic schools, although conducted by both clergy and non-clergy. *Using the word ''universitas'' (which was coined at its foundation). *Issuing secular and non-secular degrees: grammar, rhetoric, logic, theology, canon law, notarial law.Hunt Janin: "The university i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematode
The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broad range of environments. Less formally, they are categorized as Helminths, but are taxonomically classified along with Arthropod, arthropods, Tardigrade, tardigrades and other moulting animalia, animals in the clade Ecdysozoa, and unlike platyhelminthe, flatworms, have tubular digestion, digestive systems with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species described to date vary by author and may change rapidly over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizoctonia
''Rhizoctonia'' is a genus of fungi in the order Cantharellales. Species form thin, effused, corticioid basidiocarps (fruit bodies), but are most frequently found in their sterile, anamorphic state. ''Rhizoctonia'' species are saprotrophic, but some are also facultative plant pathogens, causing commercially important crop diseases. Some are also endomycorrhizal associates of orchids. The genus name was formerly used to accommodate many superficially similar, but unrelated fungi. Taxonomy History Anamorphs ''Rhizoctonia'' was introduced in 1815 by French mycologist Augustin Pyramus de Candolle for anamorphic plant pathogenic fungi that produce both hyphae and sclerotia. The name is derived from Ancient Greek, ῥίζα (''rhiza'', "root") + κτόνος (''ktonos'', "murder"), and de Candolle's original species, ''Rhizoctonia crocorum'' (teleomorph ''Helicobasidium purpureum''), is the causal agent of violet root rot of carrots and other root vegetables. Subsequent authors added ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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