EnvReg213-page17 - germinate unless exposed to a specific period of cold In a similar fashion many plants will not flower until the plant has been

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Plant Environmental Regulators - 17 Other Environmental Controls of Plant Growth and Development Dormancy Dormancy, as discussed, is a period of low metabolic activity and arrested growth in plants, usually accompanied with low water content in cells. Plants enter dormancy to “wait out” unfavorable environmental conditions, such as cold or drought. It is a common phenomenon in plants. Seeds often experience a period of dormancy prior to germination. Perennials, both herbaceous and woody, have seasonal dormancy. Environmental cues are important in setting and breaking dormancy. Trees and shrubs set dormancy prior to the unfavorable season by altering meristematic activity and forming bud scales on terminal buds to protect the shoot meristems. Changing photoperiod triggers the action of abscisic acid and takes place before other seasonal changes are noted in the trees and shrubs. Environmental Cues to Break Dormancy Vernalization Seeds in areas that have seasonal temperature differences cannot
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Unformatted text preview: germinate unless exposed to a specific period of cold. In a similar fashion, many plants will not flower until the plant has been exposed to cold temperatures. Perennials that have bulbs or corms frequently require a cold period to break dormancy and initiate above ground growth and flowering. This cold requirement to break bud or seed dormancy is called vernalization. Artificially inducing plants to break dormancy by providing the essential treatment is called stratification. Some temperature requirements can be overridden with gibberellins. • Abrasion – Weakening the Seed Coat Some seeds must have the seed coat subject to abrasion prior to germination. Stomach acid often does this, or a period of time in soil, which is harsh on surfaces. The abrasion makes the seed coat weaker and more permeable to water, which is needed for germination....
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This note was uploaded on 01/08/2012 for the course BIO 213 taught by Professor Makina during the Fall '09 term at SUNY Stony Brook.

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