1.1 Define the terms: seed propagation and vegetative
propagation.
1.2 Compare two characteristics of plants produced from seed as
compared to those produced by vegetative methods.
1.3 State the relative benefits and limitations of seed
propagation and vegetative propagation.
2.Propagation by seed (1)
2.1 Define the terms: physical and physiological dormancy.
2.2 Describe one method of overcoming a named physical and a
named physiological dormancy.
2.3 State the conditions for successful germination of viable
seed.
2.4 Describe the seed harvesting and collection of a range of
different plants.
2.5 Describe the effects of storage on seed.
3. Plant propagation - definitions
Meaning of propagation human-mediated production of plants; as
opposed to reproduction which is the plants natural processes
without human intervention.
Seed propagation producing plants in a human controlled manner
from seeds
Vegetative propagation - producing plants in a human controlled
manner from parts of a plant.
4. Seed propagation advantages/disadvantages Guarantee only
applies to vegetable seeds. Guaranteed germination rates and
disease free Slower to maturity than vegetatively propagated
plants. Storage most seed can easily be stored for some time Seeds
for single colour of some flower varieties may not be available.
Choice a huge range of seed available Takes time and space to grow
from seed to plants ready to plant out. Large volumes of seed cheap
way to produce new plants Open pollinated plants may not come true
from seed The ability to breed new varieties Disadvantage Advantage
5. Varieties normally propagated by seed
Tender perennial Heliotropium aborescens(Cherry Pie plant)
usually grown as an annual
Hardy perennial Liatris spicata(Gay Feather)
6. Vegetative propagation advantages/disadvantages Smaller
volumes in general but NB -tissue culture. Ability to adapt plant
to environment using rootstock choice e.g.Malus Gradual loss of
juvenility unless care of parent plants is very skilled. Speed to
maturity is much quicker. Time each plant has to be individually
propagated. The only way to reproduce sterile varieties such
asVitis viniferaThompsons Seedless Cost requires skilled labour and
aftercare. Uniformity each will be exactly the same. Little chance
of a new variety arising.Monocultures are susceptible to disease.
True to type each is a clone of the parent.Only way for some
varieties e.g. variegation. Disadvantages Advantages 7. Varieties
normally propagated vegetatively
Wisteria sinensis perennial climber; desirable flower form and
colour not reliable from seed.Long juvenility.
PetuniaSurfina ( P. hybridaxP. pendula ) will not reproduce
from seed; PBR applies.
Mallus domesticaBramleys Seedling all apple varieties are
produced vegetatively by grafting.This enables reproduction of the
variety characteristics and also the control of the size of the
eventual tree by choice of rootstock.
8. Seed dormancy
Physical dormancy thick or impervious seed coat prevents water
from entering the seed.
Physiological dormancy an inherent characteristic of the embryo
that prevents germination.For example, the requirement for
chilling.
9. Breaking physical dormancy
Scarification deliberate controlled damage to the seed coat to
allow water to enter.For example, nicking the seeds ofLathyrus
odoratuswith a sharp knife.
Another method for small seed soaking in very hot water.
Also used commercially soaking in sulphuric acid to carbonise
the seed coat.High risk of damage tothe embryo if not properly
done.Used forDaphne sp.
Stratification deliberate and controlled exposure of moistened
seed to required period of chilling (or warm and then
chilling)
Process breaks down chemicals that retard germination such as
ethylene and also stimulates embryo development.
11. Conditions for germination
These are the limiting factors for respiration
Water required for imbibition.Seeds that dry out after
imbibition may die, or enter a deep dormancy (double
dormancy).
Temperature the ideal varies between species.Lycopersicon
esculentum(Tomato) requires soil temperatures of 15 C.Lactuca
sativa(Lettuce) seed will become dormant at temperatures over
25C.
Oxygen required for respiration
Food provided by the endosperm or cotyledons.If seeds are
planted too deep or are only marginally viable they may use up
their food supply before the shoot breaks the surface.
Light may trigger or prevent germination dependent on
species.Not all species are light sensitive.
Time required for imbibition, breaking of dormancy etc.
12. Seed harvesting and storage
Why?Free seed; keep your favourites even if they fall out of
fashion; share seed with friends or neighbours.
Harvesting mature seed, dry (not after rain), clean to avoid
rotting in storage or after sowing.
Storage controlling respiration.Three types of seed orthodox,
intermediate, recalcitrant.
13. Effects of storage on seed
Viability if respiration is not controlled then the percentage
of seeds that will germinate is reduced.
Vitality if respiration is not controlled then seeds may use up
food required for strong germination.
Dormancy some seeds may become dormant if stored. The seeds
ofBaptisia australis(Wild Indigo) develop seed coat dormancy when
the seed coat dries.
14. Learning outcomes
1.Plant propagation introduction
1.1 Define the terms: seed propagation and vegetative
propagation.
1.2 Compare two characteristics of plants produced from seed as
compared to those produced by vegetative methods.
1.3 State the relative benefits and limitations of seed
propagation and vegetative propagation.
2.Propagation by seed (1)
2.1 Define the terms: physical and physiological dormancy.
2.2 Describe one method of overcoming a named physical and a
named physiological dormancy.
2.3 State the conditions for successful germination of viable
seed.
2.4 Describe the seed harvesting and collection of a range of
different plants.
![52 HANBURYANA 2 UBEY - RHS · Photographic slide [WSY0046433] in the RHS Herbarium (WSY). Chrysanthemum ‘My Patricia’ Certificate of Preliminary Commendation as a flowering plant](https://img.pdfslide.net/doc/110x75/5c6a43bd09d3f2310b8c598b/52-hanburyana-2-ubey-rhs-photographic-slide-wsy0046433-in-the-rhs-herbarium.jpg)
