| 单词 | abscission | ||||||
| 释义 | abscissionabscissionab·scis·sionA0025100 (ăb-sĭzh′ən)abscission(æbˈsɪʒən; -ˈsɪʃ-)ab•scis•sion(æbˈsɪʒ ən, -ˈsɪʃ-)n.
abscissionAbscissionThe process whereby a plant sheds one of its parts. Leaves, flowers, seeds, and fruits are parts commonly abscised. Almost any plant part, from very small buds and bracts to branches several inches in diameter, may be abscised by some species. However, other species, including many annual plants, may show little abscission, especially of leaves. Abscission may be of value to the plant in several ways. It can be a process of self-pruning, removing injured, diseased, or senescent parts. It permits the dispersal of seeds and other reproductive structures. It facilitates the recycling of mineral nutrients to the soil. It functions to maintain homeostasis in the plant, keeping in balance leaves and roots, and vegetative and reproductive parts. In most plants the process of abscission is restricted to an abscission zone at the base of an organ (see illustration); here separation is brought about by the disintegration of the walls of a special layer of cells, the separation layer. The portion of the abscission zone which remains on the plant commonly develops into a corky protective layer that becomes continuous with the cork of the stem.  Auxin applied experimentally to the distal (organ) side of an abscission zone retards abscission, while auxin applied to the proximal (stem) side accelerates abscission. The gibberellins are growth hormones which influence abscission. When applied to young fruits or to leaves, they tend to promote growth, delay maturation, and thereby indirectly prevent or delay abscission. Abscisic acid has the ability to promote abscission and senescence and to retard growth. Small amounts of ethylene have profound effects on the growth of plants and can distort and reduce growth and promote senescence and abscission. abscission[ab′sizh·ən]abscissionab·scis·sion(ab-si'shŭn), Avoid the mispronunciation ab-si'zhŭn.abscission(ăb-sĭzh′ən)abscissionAn antiquated term for cutting; in modern medicine it has been replaced by the term excision, see there.ab·scis·sion(ab-sish'ŭn)abscissionThe act of cutting off. abscissionthe process by which plant organs are shed. This process occurs in the stalks of unfertilized flowers, in ripe fruits and in the base of the petiole of deciduous leaves in autumn, or in diseased leaves at any time. It is due to the formation of an abscission layer of thin-walled cells in the stalk base which rupture under strain produced by e.g. wind. A layer of cork forms beneath the abscission layer to seal the plant surface. Abscission is controlled by plant hormones present: a low concentration of AUXIN, high amounts of ETHYLENE, and (in some plants) a high concentration of ABSCISIC ACID all stimulate production of the abscission layer.ab·scis·sion(ab-sĭ'zhŭn)abscission
Synonyms for abscission
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abscission - shedding of flowers and leaves and fruit following formation of scar tissue in a plant
abscission - the act of cutting something off