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Nurse Crop
Nurse crops are a subtype of nurse plants, facilitating the growth of other species of plants. The term is used primarily in agriculture, but also in forestry. Cover crops are a type of nurse crop. Agriculture In agriculture, a nurse crop is an annual crop used to assist in establishment of a perennial crop. The widest use of nurse crops is in the establishment of legumaceous plants such as alfalfa, clover, and trefoil. Occasionally, nurse crops are used for establishment of perennial grasses. Nurse crops reduce the incidence of weeds, prevent erosion, and prevent excessive sunlight from reaching tender seedlings. Often, the nurse crop can be harvested for grain, straw, hay, or pasture. Oats are the most common nurse crop, though other annual grains are also used. Nurse cropping of tall or dense-canopied plants can protect more vulnerable species through shading or by providing a wind break. However, if ill-maintained, nurse crops can block sunlight from reaching seedli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nurse Plants
Nurse plants are plants that serve the ecological role of helping seedlings establish themselves and protecting young plants from harsh conditions. This effect is particularly well studied among plant communities in xeric environments. Effects Overstory trees and shrubs have a facilitative effect on the establishment of understory plants. This effect is also seen in some interactions between herbaceous plant species. Nurse plants are important in xeric environments because they provide shaded microhabitats for the survival of several other plant species, buffering temperature extremes and reducing moisture loss. For example, in the Sonoran Desert, nurse plants canopies provide reduced summer daytime temperatures, soil surface temperatures, and direct sunlight, higher soil fertility, protection from the wind and browsing animals, reduced evapotranspiration rates in the nursed species, elevated nighttime temperatures, and post-fire resprouting in some species... This means that nurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pest (organism)
A pest is any animal or plant harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environment for their own purposes and are intolerant of other creatures occupying the same space when their activities impact adversely on human objectives. Thus, an elephant is unobjectionable in its natural habitat but a pest when it tramples crops. Some animals are disliked because they bite or sting; snakes, wasps, ants, bed bugs, fleas and ticks belong in this category. Others enter the home; these include houseflies, which land on and contaminate food, beetles, which tunnel into the woodwork, and other animals that scuttle about on the floor at night, like cockroaches, which are often associated with unsanitary conditions. Agricultural and horticultural crops are attacked by a wide variety of pests, the most important being insects, mit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crops
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponics. Crops may include macroscopic fungus (e.g. mushrooms) and marine macroalga (e.g. seaweed), some of which are grown in aquaculture. Most crops are harvested as food for humans or fodder for livestock. Some crops are gathered from the wild often in a form of intensive gathering (e.g. ginseng, yohimbe, and eucommia). Important non-food crops include horticulture, floriculture and industrial crops. Horticulture crops include plants used for other crops (e.g. fruit trees). Floriculture crops include bedding plants, houseplants, flowering garden and pot plants, cut cultivated greens, and cut flowers. Industrial crops are produced for clothing (fiber crops e.g. cotton), biofuel (energy crops, algae fuel), or medicine (medicinal plan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agriculture
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. The history of agriculture began thousands of years ago. After gathering wild grains beginning at least 105,000 years ago, nascent farmers began to plant them around 11,500 years ago. Sheep, goats, pigs and cattle were domesticated over 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. Industrial agriculture based on large-scale monoculture in the twentieth century came to dominate agricultural output, though about 2 billion people still depended on subsistence agriculture. The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials (such as rubber). Food classes include cereals (grains), vegetables, fruits, cooking oils, meat, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Cropping
In agriculture, multiple cropping or multicropping is the practice of growing two or more crops in the same piece of land during one year, instead of just one crop. When multiple crops are grown simultaneously, this is also known as intercropping. This cropping system helps farmers to double their crop productivity and their income. But, the selection of two or more crops for practicing multicropping mainly depends on the mutual benefit of the selected crops. Threshing can be difficult in multiple cropping systems where crops are harvested together. It can take the form of double-cropping, in which a second crop is planted after the first has been harvested. In the Garhwal Himalaya of India, a practice called barahnaja involves sowing 12 or more crops on the same plot, including various types of beans, grains, and millets, and harvesting them at different times. Benefits of multiple cropping Adopting the practice of multiple cropping on a large scale can help in reducing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Companion Planting
Companion planting in gardening and agriculture is the planting of different crops in proximity for any of a number of different reasons, including pest control, pollination, providing habitat for beneficial insects, maximizing use of space, and to otherwise increase crop productivity. Companion planting is a form of polyculture. Companion planting is used by farmers and gardeners in both industrialized and developing countries for many reasons. Many of the modern principles of companion planting were present many centuries ago in forest gardens in Asia, and thousands of years ago in Mesoamerica. History In China, mosquito ferns (''Azolla'' spp.) have been used for at least a thousand years as companion plants for rice crops. They host a cyanobacterium (''Anabaena azollae'') that fixes nitrogen from the atmosphere, and they block light from plants that would compete with the rice. Companion planting was practiced in various forms by the indigenous peoples of the Americas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Understory
In forestry and ecology, understory (American English), or understorey (Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the forest canopy without penetrating it to any great extent, but above the forest floor. Only a small percentage of light penetrates the canopy so understory vegetation is generally shade-tolerant. The understory typically consists of trees stunted through lack of light, other small trees with low light requirements, saplings, shrubs, vines and undergrowth. Small trees such as holly and dogwood are understory specialists. In temperate deciduous forests, many understory plants start into growth earlier in the year than the canopy trees, to make use of the greater availability of light at that particular time of year. A gap in the canopy caused by the death of a tree stimulates the potential emergent trees into competitive growth as they grow upwards to fill the gap. These trees tend to have straight tru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shade Tolerance
In ecology, shade tolerance is a plant's ability to tolerate low light levels. The term is also used in horticulture and landscaping, although in this context its use is sometimes imprecise, especially in labeling of plants for sale in commercial nurseries. Shade tolerance is a complex, multi-faceted property of plants. Different plant species exhibit different adaptations to shade, and a particular plant can exhibit varying degrees of shade tolerance, or even of requirement for light, depending on its history or stage of development. Basic concepts Except for some parasitic plants, all land plants need sunlight to survive. However, in general, more sunlight does not always make it easier for plants to survive. In direct sunlight, plants face desiccation and exposure to UV rays, and must expend energy producing pigments to block UV light, and waxy coatings to prevent water loss. Plants adapted to shade have the ability to use far-red light (about 730 nm) more effectively ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aspen
Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (China, south of ''P. tremula'') *''Populus davidiana'' – Korean aspen (Eastern Asia) *''Populus grandidentata'' – Bigtooth aspen (eastern North America, south of ''P. tremuloides'') *''Populus sieboldii'' – Japanese aspen (Japan) *''Populus tremula'' – Eurasian aspen (northern Europe and Asia) *'' Populus tremuloides'' – Quaking aspen or trembling aspen (northern and western North America) Habitat and longevity The trembling of the leaves of the trembling aspen Aspen trees are all native to cold regions with cool summers, in the north of the northern hemisphere, extending south at high-altitude areas such as mountains or high plains. They are all medium-sized deciduous trees reaching tall. In North America, the aspen is referred ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shade (shadow)
Shade is the blocking of sunlight (in particular direct sunshine) by any object, and also the shadow created by that object. Shade also consists of the colors grey, black, white, etc. It may refer to blocking of sunlight by a roof, a tree, an umbrella, a window shade or blind, curtains, or other objects. As a resource In temperate and tropical zones (most places on Earth), shade is an important issue in providing cooling and shelter from harmful heat and ultraviolet emitted by the Sun. Plants Green plants produce shade by absorbing sunlight to invest as energy in photosynthesis to produce sugar. They also actively transpire, producing an additional cooling effect. In gardening terms, there are various types of shade: *Full sun – more than five hours of direct sun per day. *Part shade – two to five hours of direct sun, or all-day ' (sunlight shining through open trees). *Full shade – less than two hours of direct sun per day... Under a dense forest canopy, light in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Insulation
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials. Heat flow is an inevitable consequence of contact between objects of different temperature. Thermal insulation provides a region of insulation in which thermal conduction is reduced, creating a thermal break or thermal barrier, or thermal radiation is reflected rather than absorbed by the lower-temperature body. The insulating capability of a material is measured as the inverse of thermal conductivity (k). Low thermal conductivity is equivalent to high insulating capability ( resistance value). In thermal engineering, other important properties of insulating materials are product density (ρ) and specific heat capacity (c). Definition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frost
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) to ice (a solid) as the water vapor reaches the freezing point. In temperate climates, it most commonly appears on surfaces near the ground as fragile white crystals; in cold climates, it occurs in a greater variety of forms. The propagation of crystal formation occurs by the process of nucleation. The ice crystals of frost form as the result of fractal process development. The depth of frost crystals varies depending on the amount of time they have been accumulating, and the concentration of the water vapor (humidity). Frost crystals may be invisible (black), clear (translucent), or white; if a mass of frost crystals scatters light in all directions, the coating of frost appears white. Types of frost include crystalline frost ( h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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