Dormancy And Quiescence

As the days grow shorter in the fall, cells produce sugars and amino acids that lower the point at which cold damage will occur. Protective bud scales develop on buds, and leaves become senescent. As cell metabolism slows down, many plants that are now prepared for winter become dormant. Dormancy may be defined as a period of growth inactivity in seeds, buds, bulbs, and other plant organs even when environmental requirements of temperature, water, or day length are met.

Quiescence is a state in which a seed cannot germinate unless environmental conditions normally required for growth are present. We have already discussed the formation of abscission layers in the fall as plants undergo change from an active condition to either a dormant or a quiescent one. In temperate and cold climates, most plants and their seeds go through a dormant period lasting from a few days to several months, and in each case, the dormancy nearly always has some survival value for the species. Many of the stone fruits (e.g., cherries, peaches, and plums) need at least several weeks of rest at temperatures below 7°C (45°F) before the buds will develop into flowers or new growth, and in some instances, the buds will not develop before the tree has encountered a period of freezing temperatures. This dormancy adapts the plants to the conditions prevailing in the cooler temperate zones of the world. In response to prevailing conditions, seeds of desert plants germinate only after appreciable rain has fallen, and seeds of plants native to vernal pools and other wet areas may germinate only if they are immersed in water.

Depending on the species concerned, the change from dormancy to a state in which germination will occur in seeds is sometimes controlled by a variety of factors referred to as after-ripening. Some plants become sensitive to photoperiods

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Responses

  • Girmay
    What are dormancy and quiescence?
    8 years ago
  • lena
    What are dormancy and quiescence in plants?
    5 years ago

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