About Lesson
Dormancy in Seeds
Dormancy is an inactive state, when growth and development slow or cease, in order to survive adverse environmental conditions
Some seeds can germinate immediately after being shed from the parent plant while others must pass through dormancy period, lasting for weeks, months or even years before the seed can germinate.
Importance of Seed Dormancy
- Provides the seeds with enough time for dispersal.
- Enables the seed to survive adverse environmental conditions.
Causes of Seed Dormancy
- Immaturity of the embryo.
- Presence of chemical inhibitors e.g. abscisic acid.
- Very low concentration of growth enzymes and hormones e.g. gibberellins.
- Hard impermeable seed coat (prevent entry of air and water in some seeds e.g., wattle.
- Freezing of seeds (especially during winter lowers their enzymatic activities)
- Absence of certain light wavelengths e.g. in lettuce plants.
Ways of Breaking Seed Dormancy
- Allow maturity of seeds.
- Increase concentration of hormones e.g. gibberellins.
- Favourable environmental factors e.g. temperature, oxygen and water.
- Exposure to certain light wavelength (this triggers production of hormones like gibberellins)
- Scarificatione. weakening of the testa (for seeds with hard impermeable testa).
Scarification is achieved artificially by boiling, cracking and roasting or naturally by saprophytic bacteria and fungi.
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