BIOL 341 Lecture Notes - Lecture 19: Seed Dormancy, Axillary Bud, Aleurone
17 Mar 2017
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Document Summary
Fruit = pericarp + testa covering the seed. Coleoptile- protects first leaves in the soil. Blocks to germination: extrinsic: unfavourable conditions. Intrinsic: seed dormancy: dispersal (if competing against other conspecifics, waiting for favourable conditions (for flowering plants) Resting (quiescent) vs dormant: quiescence - add water (metabolism, as soon as seed exposed to water, metabolism increases and seed germinates, dormancy, primary - aba e. g. completing maturation, secondary - prolonged exposure to unfavourable conditions. Coat-imposed dormancy: water impermeability, mechanical constraint. Interference with gas exchange: retention of inhibitors (inhibitors that are stopping the seed from germinating, with the help of animal digestion, the seed coat is degraded enough so that water can penetrate the seed and initiate germination. If embryo has not matured enough to germinate. Aba:ga ratio is primary determinant of seed dormancy : ga = gibberellic acid. Dormancy-breaking: ga synthesis (stops dormancy, aba is degraded. Dormancy- inducing: ga degraded, aba synthesis.
