They also performed the diabolical experiment on morning glory seeds, which are larger, have thick seed coats, and are known to survive decades in the soil before germinating.
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Scarification, regardless of type, works by speeding up the natural processes which normally make seed coats permeable to water and air.
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For seeds with hard seed coats such as sunflowers or groundnuts, dehusking or decortication is required. This removal of the seed coats improves productivity and reduces bulk. In addition to decortication, preliminary milling for some oilseeds such as groundnuts is needed. Before the oilseed can be pressed, scorching or heating of the seed may also have to be conducted.
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Springer Science and Business Media, 2012. • Infected seeds exhibiting: cracked seed coats, shriveling, flattening, grey mold, or black spots (pycnidia) on the seed coat.
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Their seed coats form spine-like intrusions into their endosperm. A layer of the outer pollen wall, called the infratectum, has a granular appearance.
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The amount of toxin in māmane varies, and the palila can be seen to avoid certain trees. It is possible that these contain the highest amounts of poison, but how the birds would be able to recognize this is not known. The bitter taste of the seed coats probably does not affect the birds (see below). Nonetheless, the seed coats are not very nutritious, and are thus discarded.
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The presence of separate styles is also a distinguishing feature from Asparagales, where it is rare. Phytomelan is completely absent in Liliales seed coats, unlike Asparagales, which nearly all contain it.
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The seeds of some species became substantially larger and/or their seed coats were less thick compared to the wild plants. For example, the seed coats of domesticated chenopodium is less than 20 microns thick; the wild chenopodium of the same species is 40 to 60 microns thick.Smith (1995), p. 188 Conversely, when Native Americans quit growing these plants, as they did later, their seeds reverted within a few years to the thickness they had been in the wild.
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In the pistillate flowers, ovaries are single or sometimes quadri- or quinticelled. One to three styles and one ovule occur in each cavity. Fruits rarely open at maturity and are most often drupes. Seed coats are very thin or are crust- like.
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Haferkamp, M. R., et al. (1984). Impact of presowing seed treatments, temperature and seed coats of germination of velvet bundleflower. Journal of Range Management 37(2) 185-88. Wildlife such as deer graze it, and birds such as quail eat the seeds.
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Seed coat dormancy involves the mechanical restriction of the seed coat. This, along with a low embryo growth potential, effectively produces seed dormancy. GA releases this dormancy by increasing the embryo growth potential, and/or weakening the seed coat so the radical of the seedling can break through the seed coat. Different types of seed coats can be made up of living or dead cells, and both types can be influenced by hormones; those composed of living cells are acted upon after seed formation, whereas the seed coats composed of dead cells can be influenced by hormones during the formation of the seed coat.
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To other animals, māmane seeds are highly poisonous. House finches die within minutes after eating the seeds. The māmane employs a two-layered biochemical defence system: The seed coats contain some 4% phenolic compounds, which give them a vile taste. They are also somewhat toxic and have a high fibre content.
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Englewood Cliffs, NJ: Prentice-Hall. . pp. 175–177. Some seeds germinate best after a fire. For some seeds, fire cracks hard seed coats, while in others, chemical dormancy is broken in reaction to the presence of smoke. Liquid smoke is often used by gardeners to assist in the germination of these species.
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The pods break into two to five segments and contain pale brown seeds about long. The flowers are insect pollinated and wind pollinated. The seeds have hard seed coats which restrict germination and make osmotic pressure and soil acidity less significant hindrances. High temperatures are the main stimuli that cause the seeds to end dormancy.
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E. lebomboensis is a dioecious species, that is, with separate male and female plants. Male specimens have one, or rarely two, short-stalked yellowish-orange cylindrical cones long and wide. Female specimens have one or rarely two barrel-shaped cones, long and wide, which are yellowish-green in colour. The seed coats are glossy red.
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In Chenopodium literature, the terms outer epiderm, testa, and seed coat are often used interchangeably. The pericarp is often dehiscent, but is non-dehiscent in some varieties. In domesticated varieties, the seed coat may be reduced or absent. Uniform seed assemblages with seed coats less than 20 µm thick are considered to represent domesticated population.
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Rousettus celebensis is a fruit-eating bat; it has big wings which allow it to carry heavy loads and also make it a good seed disperser. Its diet consists of large seeds, an uncommon feature, compared to other frugivorous bats. R. celebensis has a unique digestive system which allows it to digest certain seeds or seed coats or both.
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For example, a seed coat can be extremely thick. According to Evert and Eichhorn, very thick seed coats must undergo a process called scarification, in order to deteriorate the coating. In other cases, seeds must experience stratification. This process exposes the seed to certain environmental conditions, like cold or smoke, to break dormancy and initiate germination.
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Over time the seeds were sown and the ground was cleared of any competitive vegetation. The seeds which germinated quickest (i.e. thinner seed coats) and the plants which grew fastest were the most likely to be tended, harvested, and replanted. Through a process of unconscious selection and, later, conscious selection, the domesticated weeds became more productive.
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One reason this occurs is that lupine seed coats are so tough that only pressure changes due to rapid heating or abrasion are strong enough to allow water to penetrate and start germination. Moreover, fires, feeding by large ungulates, and mowing can improve habitat quality for established lupines by changing soil quality, vegetative structure, and leaf litter depth.
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A spice is generally made from ground seeds of the plant, with the seed coats removed. The small (1 mm) seeds are hard and vary in color from dark brown to black. They are flavorful, although they have almost no aroma. The seeds are commonly used in Indian cuisine, for example in curry, where it is known as rai.
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Seeds are small and lightweight compared to other Annona species. The native ecology of A. hypoglauca is rich whitewater floodplains of Amazonian lowland rain forests. And fish are likely candidates for seed dispersal, as the trees grow in seasonal floodplains and seed coats are excessively hard and pass directly through the digestive systems. Like other Annona spp.
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This seems not to be sufficient to deter predators however as they are also cryptically colored. The palila is apparently impervious to the phenolic aroma (as they eat Cydia caterpillars which would smell and taste like the plant), discarding the seed coats due to their low nutritional value. How the palila deals with the toxins is not known.(Banko et al.
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The hardening of seed coats during ripening often occurs through sclerification, when the secondary cell walls are thickened in the epidermis and below the epidermis. Leguminous seeds are examples of such sclerification. Larger sclereids form columns in the epidermis of pea, bean, and soybean seeds, and bone-shaped osteosclereids occur beneath the epidermis. In the seedcoats of coconuts, sclereids possess numerous bordered pits.
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Fruit: The tulip's fruit is a globose or ellipsoid capsule with a leathery covering and an ellipsoid to globe shape. Each capsule contains numerous flat, disc-shaped seeds in two rows per chamber. These light to dark brown seeds have very thin seed coats and endosperm that does not normally fill the entire seed. Leaves: Tulip stems have few leaves.
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S. punicea seed Flowers appear in late spring and persist until the autumn. In the United States, this species blooms between June and September, in South Africa between November and January. When the carpellous structures dry out, the seeds drop close to the base of the plant. The seed coats are impermeable, which means they can be dispersed by water.
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Seeds of many plants have evolved a variety of defenses to deter predation. Seeds are often contained inside protective structures or fruit pulp that encapsulate seeds until they are ripe. Other physical defenses include spines, hairs, fibrous seed coats and hard endosperm. Seeds, especially in arid areas, may have a mucilaginous seed coat that can glue soil to seed hiding it from granivores.
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A number of different strategies are used by gardeners and horticulturists to break seed dormancy. Scarification allows water and gases to penetrate into the seed; it includes methods to physically break the hard seed coats or soften them by chemicals, such as soaking in hot water or poking holes in the seed with a pin or rubbing them on sandpaper or cracking with a press or hammer. Sometimes fruits are harvested while the seeds are still immature and the seed coat is not fully developed and sown right away before the seed coat become impermeable. Under natural conditions, seed coats are worn down by rodents chewing on the seed, the seeds rubbing against rocks (seeds are moved by the wind or water currents), by undergoing freezing and thawing of surface water, or passing through an animal's digestive tract.
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The harvest of flowers is usually done by hand during three to four months. Seeds and seed pods can be harvested when they turn black four to eight months after planting. After sun drying for two to three days, they are processed by mechanical tools to separate seed coats and embryos. The rhizomes mature to a suitable stage for eating in approximately six to nine months.
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The most common type of scarification is mechanical scarification. In mechanical scarification, the testa is physically opened to allow moisture and air in. Seed coats may be filed with a metal file, rubbed with sandpaper, nicked with a knife, cracked gently with a hammer, or weakened or opened in any other way. Another type of scarification is chemical scarification, which involves the use of one or more chemicals to promote germination.
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Cicer canariense, a perennial species, has a lowered field emergence due to a hard seed coats. However, various methods such as chemical scarification with concentrated sulphuric acid as well as hot water treatment can be used to improve germination. In one particular study, physical dormancy was overcome most effectively by mechanical scarification and sulphur immersion. More studies regarding crop development could introduce this species as a potential food source.
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A variety of over 100 species of vascular plants utilize this dispersal method for their fruit. Many plants have evolved with specific adaptations to maximize the distance that seeds, fruits, or propagules are dispersed in the ocean. For an increased protection against sinking in the water column, seeds have developed hair or slime on their outer seed coats. Seeds with filled with air, cork, or oil are better prepared to float for farther distances.
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Seeds with hard seed coats can be soaked in hot water to break open the impermeable cell layers that prevent water intake. Other methods used to assist in the germination of seeds that have dormancy include prechilling, predrying, daily alternation of temperature, light exposure, potassium nitrate, the use of plant growth regulators, such as gibberellins, cytokinins, ethylene, thiourea, sodium hypochlorite, and others.Hartmann, Hudson Thomas, and Dale E. Kester. 1983. Plant propagation principles and practices.
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Belladonna cultivation, Eli Lilly and Company, 1919 Atropa belladonna is rarely used in gardens, but, when grown, it is usually for its large upright habit and showy berries. Germination of the small seeds is often difficult, due to hard seed coats that cause seed dormancy. Germination takes several weeks under alternating temperature conditions, but can be sped up with the use of gibberellic acid. The seedlings need sterile soil to prevent damping off and resent root disturbance during transplanting.
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The palila, for example, can deal with dozens of times the dose of cytisine that would kill a laboratory mouse. Both seed predators seem to be able to recognize and avoid the most poisonous trees, which would be natural selection in action. Cydia caterpillars are able to break up the toxic compounds. They do not sequester the alkaloids for their own use, but are found to contain about as much phenolic compounds as the seed coats do.
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O.4′-neolignan (of > the β-propenylaryloxy-arylpropane type) and in the seed coats of its fruits > 8.5′-neolignans (carinatone, carinatol) and 8.5′,7.O.4′-neolignans > (dihydrocarinatin, carinatin). Some previous 13C NMR assignments for the > latter four compounds are corrected." The leaves of Virola pavonis contain the chemical compounds DMT and pavonisol, according to Pedro H Ferria and Lauro E.S Barataa; > "Pavonisol, a new C-1/C-2 oxygenated phenylpropanoid, together with the > known eusiderin-E and an 8,4′-oxyneolignan, were isolated from Virola > pavonis leaves.
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Oligomeric proanthocyanidins (OPC) strictly refer to dimer and trimer polymerizations of catechins. OPCs are found in most plants and thus are common in the human diet. Especially the skin, seeds, and seed coats of purple or red pigmented plants contain large amounts of OPCs. They are dense in grape seeds and skin, and therefore in red wine and grape seed extract, cocoa, nuts and all Prunus fruits (most concentrated in the skin), and in the bark of Cinnamomum (cinnamon) and Pinus pinaster (formerly known as Pinus maritima), along with many other pine species.
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Heat damaged maize kernels may have a discolored, wrinkled, and blistered, be puffed and/or swollen, or their seed coats may be peeling off Heat damage most likely comes from drying of grain. It is a subset of damage including broken or cracked kernels but is identified as its own type of damage by the USDA. The elevated temperatures used during the drying process to eliminate moisture can have adverse effects on the kernels themselves. The most common signs of heat damage include breakage/cracks, discoloration, and shrinkage.
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This plant, like many chaparral species, is fire-adapted and requires wildfire or other disturbance to propagate. The beanlike seeds require scarification to break down their tough seed coats before they can germinate. The seeds persist for years in the soil until fire allows them to sprout, with populations of the plant springing up in an area that has been recently swept by wildfire. It is a pioneer species, one of the first to grow in a disturbed area and one that is soon crowded out by plant species that appear later in ecological succession.
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Many of the members of the order are parasitic plants, mostly hemiparasites, able to produce sugars through photosynthesis, but tapping the stems or roots of other plants to obtain water and minerals; some (e.g. Arceuthobium) are obligate parasites, have low concentrations of chlorophyll within their shoots (1/5 to 1/10 of that found in their host's foliage), and derive the majority of their sustenance from their hosts' vascular tissues (water, micro- and macronutrients, and sucrose). Most have seeds without testae (seed coats), which is unusual for flowering plants.
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Abrin is not known to have been weaponised, however, due to its high toxicity and the possibility of being processed into an aerosol, the use of abrin as a biological weapon is possible in principle. Despite this, the rosary pea yields small quantities of abrin, which reduces the risk. Abrin naturally occurs in the seeds of the rosary pea, a plant common to tropical regions that is occasionally employed as an herbal remedy for certain conditions. While the outer shell of the seed protects its contents from the stomachs of most mammals, the seed coats are occasionally punctured to make beaded jewelry.
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Parrots are granivores rather than seed dispersers, and in many cases where they are seen consuming fruit, they are only eating the fruit to get at the seed. As seeds often have poisons that protect them, parrots carefully remove seed coats and other chemically defended fruit parts prior to ingestion. Many species in the Americas, Africa, and Papua New Guinea consume clay, which releases minerals and absorbs toxic compounds from the gut. Chestnut-fronted macaws, yellow-crowned amazons, and dusky-headed parakeets at a clay lick in Ecuador Geographical range and body size predominantly explains diet composition of Neotropical parrots rather than phylogeny.
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Aboriginal Australians have traditionally harvested the seeds of some species, to be ground into flour and eaten as a paste or baked into a cake. The seeds contain as much as 25% more protein than common cereals, and they store well for long periods due to the hard seed coats. In addition to utilizing the edible seed and gum, the people employed the timber for implements, weapons, fuel and musical instruments. A number of species, most notably A. mangium (hickory wattle), A. mearnsii (black wattle) and A. saligna (coojong), are economically important and are widely planted globally for wood products, tannin, firewood and fodder.
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Tylosema esculentum have hard seed coats, which lead to many ecological benefits such as an accumulation of seed banks in soils and a higher percentage of germinating, establishing, and completing a successful life cycle. In order to optimize germination and growth of this perennial legume and increase its importance in the food market, germination behavior of untreated Tylosema esculentum seeds compared to seeds undergoing various dormancy-breaking treatments was investigated. The results indicated that seed germination was greatest when scratching and cracking of the seed coat with sandpaper, also known as mechanical scarification, was applied. Other types of scarification include immersion of seed in water or acid.
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The maturing ovule undergoes marked changes in the integuments, generally a reduction and disorganization but occasionally a thickening. The seed coat forms from the two integuments or outer layers of cells of the ovule, which derive from tissue from the mother plant, the inner integument forms the tegmen and the outer forms the testa. (The seed coats of some monocotyledon plants, such as the grasses, are not distinct structures, but are fused with the fruit wall to form a pericarp.) The testae of both monocots and dicots are often marked with patterns and textured markings, or have wings or tufts of hair. When the seed coat forms from only one layer, it is also called the testa, though not all such testae are homologous from one species to the next.
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In the latter case, the seed coat protects the seed from digestion, while often weakening the seed coat such that the embryo is ready to sprout when it is deposited, along with a bit of fecal matter that acts as fertilizer, far from the parent plant. Microorganisms are often effective in breaking down hard seed coats and are sometimes used by people as a treatment; the seeds are stored in a moist warm sandy medium for several months under nonsterile conditions. Stratification, also called moist-chilling, breaks down physiological dormancy, and involves the addition of moisture to the seeds so they absorb water, and they are then subjected to a period of moist chilling to after-ripen the embryo. Sowing in late summer and fall and allowing to overwinter under cool conditions is an effective way to stratify seeds; some seeds respond more favorably to periods of oscillating temperatures which are a part of the natural environment.
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