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Striga
''Striga'', commonly known as witchweed, is a genus of parasitic plants that occur naturally in parts of Africa, Asia, and Australia. It is currently classified in the family Orobanchaceae, although older classifications place it in the Scrophulariaceae. Some species are serious pathogens of cereal crops, with the greatest effects being in savanna agriculture in Africa. It also causes considerable crop losses in other regions, including other tropical and subtropical crops in its native range and in the Americas. The generic name derives from Latin wikt:striga#Latin, ''strī̆ga'', "witch". Witchweeds are characterized by bright-green stems and leaves and small, brightly colored and attractive flowers.Sand, Paul, Robert Eplee, and Randy Westbrooks. ''Witchweed Research and Control in the United States''. Champaign, IL: Weed Science Society of America, 1990. They are obligate parasite, obligate hemiparasites of roots and require a living host for germination and initial developmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Striga Hermonthica
''Striga hermonthica'', commonly known as purple witchweed or giant witchweed, is a hemiparasitic plant that belongs to the family Orobanchaceae. It is devastating to major crops such as sorghum (''Sorghum bicolor'') and rice (''Oryza sativa''). In sub-Saharan Africa, apart from sorghum and rice, it also infests maize (''Zea mays''), pearl millet (''Pennisetum glaucum''), and sugar cane (''Saccharum officinarum''). ''Striga hermonthica'' has undergone horizontal gene transfer from ''Sorghum'' to its nuclear genome. The ''S. hermonthica'' gene, ''ShContig9483'', is most like a ''Sorghum bicolor'' gene, and additionally shows significant but lesser similarity to a gene from ''Oryza sativa''. It shows no similarity to any known eudicot gene. Host and symptoms Purple witchweed infects a variety of grasses and legumes in sub-saharan Africa, including rice, maize, millet, sugarcane, and cowpea. The symptoms mimic that of drought or nutrient-deficiency symptoms. Chlorosis, wilt, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Striga Asiatica
''Striga asiatica'', the Asiatic witchweed or the red witchweed, is a hemiparasitic plant in the family Orobanchaceae. It is native to Asia and sub-Saharan Africa, but has been introduced into other parts of the world including Australia and the United States. Asiatic witchweed is a serious agricultural pest, as it parasitises important crop species, including corn, rice, sorghum, and sugar cane, often causing substantial yield reductions. While it is native to Africa and Asia, it is invasive in farmlands of Kenya, Tanzania and Uganda. In the US, this witchweed was discovered in the Carolinas in 1956. It is considered an invasive agricultural pest, and a vigorous eradication campaign has reduced the affected area by 99% rom to about Biological control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strigolactone
Strigolactones are a group of chemical compounds produced by roots of plants. Due to their mechanism of action, these molecules have been classified as plant hormones or phytohormones. So far, strigolactones have been identified to be responsible for three different physiological processes: First, they promote the germination of parasitic organisms that grow in the host plant's roots, such as Striga asiatica, ''Striga'' ''lutea'' and other plants of the genus ''Striga''. Second, strigolactones are fundamental for the recognition of the plant by symbiotic Fungus, fungi, especially arbuscular mycorrhizal fungi, because they establish a mutualistic association with these plants, and provide phosphate and other soil nutrients. Third, strigolactones have been identified as branching inhibition hormones in plants; when present, these compounds prevent excess bud growing in stem terminals, stopping the branching mechanism in plants. Strigolactones comprise a diverse group, but they all h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitic Plant
A parasitic plant is a plant that derives some or all of its nutritional requirements from another living plant. They make up about 1% of angiosperms and are found in almost every biome. All Parasite, parasitic plants develop a specialized organ called the haustorium, which penetrates the host plant, connecting them to the host vasculature—either the xylem, phloem, or both. For example, plants like ''Striga'' or ''Rhinanthus'' connect only to the xylem, via xylem bridges (xylem-feeding). Alternately, plants like ''Cuscuta'' and some members of ''Orobanche'' connect to both the xylem and phloem of the host. This provides them with the ability to extract resources from the host. These resources can include water, nitrogen, carbon and/or sugars. Parasitic plants are classified depending on the location where the parasitic plant latches onto the host (root or stem), the amount of nutrients it requires, and their photosynthetic capability. Some parasitic plants can locate their host ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orobanchaceae
Orobanchaceae, the broomrapes, is a family (biology), family of mostly parasitic plants of the order (biology), order Lamiales, with about 90 genus, genera and more than 2000 species. Many of these genera (e.g., ''Pedicularis'', ''Rhinanthus'', ''Striga'') were formerly included in the family Scrophulariaceae ''sensu lato''. With its new circumscription, Orobanchaceae forms a distinct, monophyletic family. From a phylogenetic perspective, it is defined as the largest crown clade containing ''Orobanche major'' and relatives, but neither ''Paulownia tomentosa'' nor ''Phryma leptostachya'' nor ''Mazus japonicus''. The Orobanchaceae are annual plant, annual herbaceous plant, herbs or perennial plant, perennial herbs or shrubs, and most (all except ''Lindenbergia'', ''Rehmannia'' and ''Triaenophora'') are parasitic plant, parasitic on the roots of other plants—either holoparasitic or hemiparasitic (fully or partly parasitic). The holoparasitic species lack chlorophyll and therefore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scrophulariaceae
The Scrophulariaceae are a family of flowering plants, commonly known as the figwort family. The plants are annual and perennial herbs, as well as shrubs. Flowers have bilateral (zygomorphic) or rarely radial (actinomorphic) symmetry. The Scrophulariaceae have a cosmopolitan distribution, with the majority found in temperate areas, including tropical mountains. The family name is based on the name of the included genus ''Scrophularia'' L. Taxonomy In the past, it was treated as including about 275 genera and over 5,000 species, but its circumscription has been radically altered since numerous molecular phylogenies have shown the traditional broad circumscription to be grossly polyphyletic. Many genera have recently been transferred to other families within the Lamiales, notably Plantaginaceae and Orobanchaceae, but also several new families. - on linhere/ref> Several families of the Lamiales have had their circumscriptions enlarged to accommodate genera transferred from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sorghum
''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain is used as food by humans, while the plant is used for animal feed and ethanol production. Sorghum originated in Africa, and is widely cultivated in tropical and subtropical regions. Sorghum is the world's fifth-most important cereal crop after rice, wheat, maize, and barley. Sorghum is typically an annual, but some cultivars are perennial. It grows in clumps that may reach over high. The grain is small, in diameter. Sweet sorghums are cultivars grown for forage, syrup production, and ethanol. They are taller than those grown for grain. Description Sorghum is a large stout grass that grows up to tall. It has large bushy flowerheads or panicles that provide an edible starchy grain with up to 3,000 seeds in each flowerhead. It grows ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoperiod
Photoperiod is the change of day length around the seasons. The rotation of the earth around its axis produces 24 hour changes in light (day) and dark (night) cycles on earth. The length of the light and dark in each phase varies across the seasons due to the tilt of the earth around its axis. The photoperiod defines the length of the light, for example a summer day the length of light could be 16 hours while the dark is 8 hours, whereas a winter day the length of day could be 8 hours, whereas the dark is 16 hours. Importantly, the seasons are different in the northern hemisphere than the southern hemisphere. Photoperiodism is the physiological reaction of organisms to the length of light or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overwintering
Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal activity or even survival difficult or near impossible. In some cases "winter" is characterized not necessarily by cold but by dry conditions; passing through such periods could likewise be called overwintering. Hibernation and migration are the two major ways in which overwintering is accomplished. Animals may also go into a state of reduced physiological activity known as torpor. Overwintering occurs in several classes of lifeform. Insects In entomology, overwintering is how an insect passes the winter season. Many insects overwinter as adults, pupae, or eggs. This can be done inside buildings, under tree bark, or beneath fallen leaves or other plant matter on the ground, among other places. All such overwintering sites shield the insect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
