Download Seed Coat

What is a Seed?
We will learn more details later to answer this question.
For now:
1. Seed Coat: a surface tissue to
keep seed dry inside
2. Storage Tissue: could be a
separate tissue (endosperm =
inside seed) or part of the embryo
(often cotyledons)
3. Dormant Embryo: a small diploid
plant with minimal metabolism
(“suspended animation”)
Capsella
Seed:
Seed Coat
Endosperm
Embryo
Shoot Apex
Cotyledons dicot
Hypocotyl
Radicle
Root Apex
Micropyle
Seed Germination: Emergence of Radicle through Seed Coat
Seeds lacking dormancy need:
Water Warm Temperature
So if you want to store seeds what are the conditions? Dry Cold
Dormant seeds need more than moisture and warmth:
Dormancy is caused by: Is overcome by:
Thick Seed Coat
Thin Seed Coat
Insufficient Development
Inhibitor: Abscisic Acid
Scarification
Light
or
Dark
Soil Fungus Association
Stratification > Vernalization
6 weeks at 4° C
Inhibitor: Phenolics
nick digest
scrub fire
freeze-thaw cycles
Example:
Kentucky Coffee Tree
Lettuce
Pea
Orchids
Most CT feral plants
20° C
Leaching by Repeated Rain
or
Cacti
Barley Seed
Germination
Fruit + Seed Coat
Endosperm
starch
maltose
sugar
cotyledon
monocot
exocytosis
-amylase
shoot apex
Aleurone Layer
Storage Protein
RNA
Amino Acids
Embryo
DNA
GA
radicle apex
water
imbibition
Lettuce Seed Germination
starch
Seed Coat
shoot apex
cotyledons
dicot
sugar
-amylase
RNA
Embryo
DNA
radicle apex
phytochrome
water
imbibition
photoreversibility red and
660 nm
white light
Pfr
Pr
stimulate
photoactivation
730 nm
germination
dark