Name: Vernalisation- an overview
Uploaded: 2019-07-19
Duration: 7 min 50 s
Description: Vernalisation is the phenomenon of cold exposure that provides some plants with the ability to flower in the best season. Let’s learn about these cold memori...

Question

Define seed dormancy. Write about the causes of dormancy.

Accepted Answer

Seed dormancy is a resting condition with reduced metabolism of the seed under unfavourable conditions of germination. It is a period of delay in action of growth for most of the plants which may be due to external control. However, many perfectly viable seeds fail to germinate even when the conditions are perfectly favourable this is referred to as rust or dormancy. It is under endogenous control.

Dormancy is caused by the following methods:
Mechanically resistant seed coat: Due to the thick seed coat, the growing embryo fails to come out of the seed coat. Example: mustard
Impermeable nature of seed coat: Due to the tough and impermeable nature of the seed coat, water cannot enter through the seed coat. In some seeds, the seed coat is impermeable to oxygen. This also fails germination.

Rudiment embryos: Due to immature embryos, the seeds remain dormant. Such seeds develop into a new individual plant after the embryo is completely developed. Example: orchids
Dormant embryo: Some seeds contain matured embryos, fail to germinate even when the environmental conditions are completely favourable. Such embryos are called dormant embryos. This is purely due to the physiological maturity of the embryo. Example: apple, peach, etc.
Growth inhibitors: Germination of seeds considerable a change in some plants when some chemical compounds are produced called inhibitors. Example: Chemicals like coumarin has the property of inhibiting seed germination.

Define seed dormancy. Write about the causes of dormancy.

Important Questions on Plant Growth and Development

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