propagation, seeds and vegetative

1. RHS Level 2 Certificate
Week 12 – Plant
Propagation
introduction

2. Learning outcomes
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Plant propagation – introduction
Define the terms: ‘seed propagation’ and ‘vegetative propagation’.
Describe the characteristics of plants that can be propagated (a)
from seed (b) vegetatively.
State 5 benefits and 5 limitations of propagating plants (a) from seed
(b) vegetatively
Describe the preparation of fleshy berries for seed storage, under
the following headings: harvesting; maceration; separation; cleaning
and drying.
State Five NAMED examples of seeds requiring cool dry storage
State Two NAMED examples of seeds requiring cool moist storage

3. Plant propagation - definitions
 Meaning
of ‘propagation’ – human-mediated
production of plants; as opposed to
‘reproduction’ which is the plant’s 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
Advantage
Disadvantage
The ability to breed new
varieties
Open pollinated plants may not
come true from seed
Large volumes of seed – cheap
way to produce new plants
Takes time and space to grow
from seed to plants ready to
plant out.
Choice – a huge range of seed
available
Seeds for single colour of some
flower varieties may not be
available.
Storage – most seed can easily
be stored for some time
Slower to maturity than
vegetatively propagated plants.
Guaranteed germination rates
and certified disease free
Guarantee and certification only
applies to vegetable seeds.

5. Varieties normally propagated by seed
 Hardy
Annual – Centaurea cyanus
(Cornflower)
 Half Hardy Annual – Impatiens walleriana
(Busy Lizzie)
 Tender perennial – Heliotropium aborescens
(Cherry Pie plant) usually grown as an
annual
 Hardy perennial – Liatris spicata (Gay
Feather)

6. Vegetative propagation – advantages/disadvantages
Advantages
Disadvantages
True to type – each is a clone of the Little chance of a new variety
parent. Only way for some varieties arising. Monocultures are
e.g. variegation.
susceptible to disease.
Uniformity – each will be exactly the
same.
Cost – requires skilled labour and
aftercare.
The only way to reproduce sterile
varieties such as Vitis vinifera
‘Thompson’s Seedless’
Time – each plant has to be
individually propagated.
Speed to maturity is much quicker.
Gradual loss of juvenility unless
care of parent plants is very skilled.
Ability to adapt plant to environment Smaller volumes in general – but
using rootstock choice e.g. Malus
NB - tissue culture.

7. Varieties normally propagated vegetatively
Wisteria sinensis – perennial climber; desirable
flower form and colour not reliable from seed. Long
juvenility.
 Petunia ‘Surfina’ (P. hybrida x P. pendula) – will not
reproduce from seed; PBR applies.
 Mallus domestica ‘Bramley’s 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.
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8. Conditions for germination
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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.
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.

9. Seed harvesting and storage
 Why?
Free seed; keep your favourites even
if they fall out of fashion; share seed with
friends or neighbours; grow plants that are
not generally available commercially.
 Harvesting – mature seed, dry (not after
rain), clean to avoid rotting in storage or after
sowing.
 Storage – controlling respiration. Two main
types of seed – orthodox and recalcitrant.

10. Seed Harvesting and storage
 Plant
must be healthy, vigorous and true to
type. Must produce fertile, viable seed.
 Aim is to collect ripe seed, clean it and store
it in the correct conditions.
 Orthodox seeds need cool, dry conditions.
How cold depends on the species. Viable
storage time depends on the species.
 Recalcitrant seeds need cool (not cold),
moist conditions – and do not retain viability
for long.

11. 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 of Baptisia
australis (Wild Indigo) develop seed coat
dormancy when the seed coat dries.

12. Learning outcomes
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Plant propagation – introduction
1.1 Define the terms: ‘seed propagation’ and ‘vegetative
propagation’.
1.2 Describe the characteristics of plants that can be
propagated (a) from seed (b) vegetatively.
1.3 State 5 benefits and 5 limitations of propagating
plants (a) from seed (b) vegetatively
1.4 Describe the preparation of fleshy berries for seed
storage, under the following headings: harvesting;
maceration; separation; cleaning and drying.
1.5 State Five NAMED examples of seeds requiring cool
dry storage
1.6 State Two NAMED examples of seeds requiring cool
moist storage