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Autotoxicity
Autotoxicity, meaning self-toxicity, is a biological phenomenon whereby a species inhibits growth or reproduction of other members of its same species through the production of chemicals released into the environment. Like allelopathy, it is a type of Competition (biology)#Interference, interference competition but it is technically different: autotoxicity contributes to intraspecific competition, whereas allelopathic effects refer to interspecific competition. Furthermore, autotoxic effects are always inhibitory, whereas allelopathic effects are not necessarily inhibitory–they may stimulate other organisms. This mechanism will result in reduced exploitative competition between members of the same species and may contribute to natural thinning in established communities. Inhibition of the growth of young plants will increase the availability of nutrients to older, established plants. In cultivation, autotoxicity can make it difficult or impossible to grow the same species after ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfalfa
Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as well as a green manure and cover crop. The name alfalfa is used in North America. The name lucerne is the more commonly used name in the United Kingdom, South Africa, Australia, and New Zealand. The plant superficially resembles clover (a cousin in the same family), especially while young, when trifoliate leaves comprising round leaflets predominate. Later in maturity, leaflets are elongated. It has clusters of small purple flowers followed by fruits spiralled in 2 to 3 turns containing 10–20 seeds. Alfalfa is native to warmer temperate climates. It has been cultivated as livestock fodder since at least the era of the ancient Greeks and Romans. Etymology The word ''alfalfa'' is a Spanish modification of the Arabic word ''al-faṣfaṠ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allelopathy
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see black walnut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Competition (biology)
Competition is an interaction between organisms or species in which both require a resource that is in limited supply (such as food, water, or territory). Competition lowers the fitness of both organisms involved since the presence of one of the organisms always reduces the amount of the resource available to the other. In the study of community ecology, competition within and between members of a species is an important biological interaction. Competition is one of many interacting biotic and abiotic factors that affect community structure, species diversity, and population dynamics (shifts in a population over time). There are three major mechanisms of competition: interference, exploitation, and apparent competition (in order from most direct to least direct). Interference and exploitation competition can be classed as "real" forms of competition, while apparent competition is not, as organisms do not share a resource, but instead share a predator. Competition among membe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intraspecific Competition
Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce. By contrast, interspecific competition occurs when members of different species compete for a shared resource. Members of the same species have rather similar requirements for resources, whereas different species have a smaller contested resource overlap, resulting in intraspecific competition generally being a stronger force than interspecific competition. Individuals can compete for food, water, space, light, mates, or any other resource which is required for survival or reproduction. The resource must be limited for competition to occur; if every member of the species can obtain a sufficient amount of every resource then individuals do not compete and the population grows exponentially. Prolonged exponential growth is rare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interspecific Competition
Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. Competition between members of the same species is called intraspecific competition. If a tree species in a dense forest grows taller than surrounding tree species, it is able to absorb more of the incoming sunlight. However, less sunlight is then available for the trees that are shaded by the taller tree, thus interspecific competition. Leopards and lions can also be in interspecific competition, since both species feed on the same prey, and can be negatively impacted by the presence of the other because they will have less food. Competition is only one of many interacting biotic and abiotic factors that affect community structure. Moreover, competition is not always a straightforward, direct, interaction. Interspecific competition m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cunninghamia
''Cunninghamia'' is a genus of one or two living species of evergreen coniferous trees in the cypress family Cupressaceae. They are native to China, northern Vietnam and Laos, and perhaps also Cambodia. They may reach in height. In vernacular use, it is most often known as ''Cunninghamia'', but is also sometimes called "China-fir" (though it is not a fir). The genus name ''Cunninghamia'' honours Dr. James Cunningham, a British doctor who introduced this species into cultivation in 1702 and botanist Allan Cunningham. A female cone Cluster of male cones Description The general shape of the tree is conical with tiered, horizontal branches that are often somewhat pendulous toward the tips. ''Cunninghamia'' bears softly spined, leathery, stiff, green to blue-green needle-like leaves that spiral around the stem with an upward arch; they are 2–7 cm long and 3–5 mm broad at the base, and bear two white or greenish-white stomatal bands underneath and sometimes al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juncus Effusus
''Juncus effusus'', with the common names common rush or soft rush, is a perennial herbaceous flowering plant species in the rush family Juncaceae. In North America, the common name soft rush also refers to '' Juncus interior''. Distribution ''Juncus effusus'' is nearly cosmopolitan, considered native in Europe, Asia, Africa, North America, and South America. It has naturalized in Australia, Madagascar, and various oceanic islands. It is found growing in wet areas, such as wetlands, riparian areas, and marshes. In the United Kingdom it is found in purple moor-grass and rush pastures and fen-meadow plant associations. Description ''Juncus effusus'' grows in large clumps about tall at the water's edge along streams and ditches, but can be invasive anywhere with moist soil. It is commonly found growing in humus-rich areas like marshes, ditches, fens, and beaver dams. The stems are smooth cylinders with light pith filling. The yellowish inflorescence appears to emerg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lolium Rigidum
''Lolium rigidum'' is a species of annual grass. Common names by which it is known include annual ryegrass, a name also given to Italian ryegrass (''Lolium multiflorum''), rigid ryegrass, stiff darnel, Swiss ryegrass and Wimmera ryegrass. It is a native of southern Europe, northern Africa, the Middle East and the Indian subcontinent and is grown as a forage crop, particularly in Australia, where it is also a serious and economically damaging crop weed. Description ''Lolium rigidum'' is an annual grass that grows in open tussocks. It has fibrous roots and can grow up to a metre tall. The plant form is usually erect but may be prostrate. The stems are often geniculate (with a knee-like bend) and are purplish at the base. The leaves are long, and wide; the upper surface is glossy dark green, flat and hairless with longitudinal veins, and the underside is shiny and smooth. The young leaves are rolled when in bud, the auricles are small and the ligule is white and translucent, wide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medicarpin
Medicarpin is a pterocarpan, a derivative of isoflavonoids. Natural occurrences Medicarpin is found in ''Medicago truncatula'' and ''Swartzia madagascariensis''. It can also be found in ''Maackia amurensis'' cell cultures. The root nodule formation by ''Sinorhizobium meliloti ''Ensifer meliloti'' (formerly ''Rhizobium meliloti'' and ''Sinorhizobium meliloti'') are an aerobic, Gram-negative, and diazotrophic species of bacteria. ''S. meliloti'' are motile and possess a cluster of peritrichous flagella. ''S. meliloti'' ...'' is apparently dependent on the flavonoids pathway. Metabolism Pterocarpin synthase has 3 substrates : medicarpin, NADP+ and H2O, and 3 products : vestitone, NADPH and H+. References Pterocarpans {{aromatic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crop Rotation
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant pests and weeds. Growing the same crop in the same place for many years in a row, known as monocropping, gradually depletes the soil of certain nutrients and selects for a highly competitive pest and weed community. Without balancing nutrient use and diversifying pest and weed communities, the productivity of monocultures is highly dependent on external inputs. Conversely, a well-designed crop rotation can reduce the need for synthetic fertilizers and herbicides by better using ecosystem services from a diverse set of crops. Additionally, crop rotations can improve soil structure and organic matter, which reduces erosion and increases farm system resilience. History Agriculturalists have long recognized that suitable rotations — such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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