R2104 - Understanding Plant Propagation Flashcards
1.1 What is a seed?
A seed is the product of sexual reproduction Formed from ovules as a result of fertilisation. Method by which plants reproduce.
1.1 What are the benefits to the plant of sexual reproduction?
Adaptation – survival of the fittest; strongest plants will thrive
Variety – mixing of characteristics gives chance of new and better plants
Survival – can survive harsh conditions as a seed
Volume
Phaseolus vulgaris - Common bean
1.1 Describe the internal external structure of a dicotyledonous seed.
Phaseolus vulgaris (Common bean)
Embryo - consists of a radicle, plumule, hypocotyl, epicotyl, cotyledon
Testa - (seed coat) waterproof and airtight. May contain germination inhibitors which enable the seed to stay dormant over winter.
Cotyledon - (seed leaves) food store for the embryo (1 monocot, 2 dicot)
Radicle - develops into first root to take up water and nutrients
Plumule - develops into the shoot system, (bearing leaves for photosynthesising and flowers for seed and fruit production)
Hypocotyl - region between the cotyledon and radicle (connects cotyledon to radicle)
Epicotyl - short length of stem between cotyledon and plumule (connects cotyledon to plumule)
Micropyle - weakness in the test where water uptake occurs triggering germination
Hilum - scar on Testa where seed was attached to the fruit
1.1 What are the benefits of propagating plants from seed?
- Produces variation from which new cultivars can be developed
- Only method for some species
- Can get large numbers from one plant
- Easily stored
- Can avoid virus transmission
1.1 What are the limitations of propagating from seed?
- Some plants may not produce viable seed
- Lack of uniformity
- Difficult germination
- Some seeds don’t store easily
- Time to maturity
1.1 State examplesof plants that are usually propagated from seed.
- Daucus carota (carrot)
- Phaseolus vulgaris (green/French bean)
- Solanum lycopersicon (tomato)
- Lobelia erinus
- Nigella damascena
- Lolium perenne (lawn ryegrass)
1.1 State the main horticultural uses of seed.
- production of vegetables
- annuals
- bedding plants
- making lawns
- green manure crops
- wild flower meadows and prairies
1.2 What is meant by ‘seed viability’?
Seeds which contain a living embryo and will germinate when conditions are right.
1.2 List the requirements for seeed germination.
- moisture
- temperature
- oxygen
- light/dark
1.2 State the meaning of seed ‘dormancy’.
When viable seed fails to germinate even when all germination requirements are met.
1.2 Describe the changes that take place in a
germinating seed.
- First the seed takes in water setting off a series of chemical reactions
- Respiration rate rises
- Food store breaks down
- Rapid cell division
- Testa (seed coat) splits
- Radicle emerges
1.2 What is epigeal germination?
In epigeal germination the hypocotyl extends and the cotyledons come out of the ground.
Phaseolus vulgaris (common bean) is an example of a plant that has epigeal germination.
1.2 What is hypogeal
germination?
Hypogeal germination the epicotyl extends and the cotyledons stay in the ground.
Vicia faba (broad bean) is an example of a plant that has hypogeal germination.
Common/French bean
1.3 Describe the preparation and storage of Phaseolus vulgaris.
harvesting - at the dry stage before first frost
drying - if bad weather threatens, uproot plants and hang upside down somewhere warm until pods are completely dry
separation - large seed taken from dry pods by hand, let seeds dry completely
cleaning - remove chaff and debris
packaging - Lidded airtight container with silica gel
storage conditions - Cool/fridge
Love-in-a-mist
1.3 Describe the preparation and storage of Nigella damascena.
harvesting - seeds are ripe and ready when the pod turns brown and papery
drying - allow seed heads to dry upside down in a paper bag
separation - shake pods and seeds will collect at the bottom of the bag
cleaning - remove chaff, insects and other debris
packaging - ensure seeds are completely dry, store in paper bag, envelope, airtight container
storage conditions - cool dry place
1.3 What are orthodox seeds? Name some examples.
Orthodox seeds require cool, dry storage. Humidity can be lowered in the air by using dehydrating agents like silica gel. Cool temperatures minimise respiration and therefore deterioration.
- Daucus carota
- Phaseolus vulgaris
- Lobelia erinus
- Nigella damascena
- Lolium perenne
1.3 What are recalcitrant seeds? Name some examples.
Recalcitrant seeds require cool moist storage. The seed contain high levels of moisture or oils and
need to be kept moist and cool until sowing, as drying out can kill the seed.
- Quercus robur (Oak)
- Aesculus hippocastanum (Horse Chesnut)
- Mangifera indica (Mango)
1.3 State the effect that storage factors have
on the ability of seed to germinate.
Temperature: Warmer conditions will cause seed viability to lost more quickly. Cool temperatures minimise respiration and therefore deterioration.
Moisture/Humidity levels: Moisture and heat speed up loss of viability.
Storage time: Some seeds can be stored longer that others before they lose viability.
1.3 Describe preparation and storage of Solanum lycopericum (tomato) fruits for seed storage.
- Harvesting collect healthy, free from damage, ripe fruit
- Maceration gently mash the using an implement like a table fork
- Separation seeds should now be visible, and can be teased out to separate them from the pulp
- Cleaning seed should be thoroughly washed under running water in a sieve, this removes any germination inhibitors that may be in the pulp
- Drying seed should then placed on a non-absorbent surface to dry thoroughly before storing
2.1 Describe the method of sowing; pricking out; potting off; aftercare: for fine seed,** Begonia semperflorens**
Bergonia semperflorens
Use a seed compost which has 50% grit/perlite or vermiculite to improve drainage. Ensure compost has no large lumps and firm. Water with an upturned rose.
Mix seed with fine sand, this makes it easier to distribute evenly and see where you have sown.
Firm the seed into the surface of the compost. Label and date.
Can cover with clear plastic and put in a warm place away from direct sunlight.
When seedlings are large enough to be handled, prick out and potted off into prepared individual containers or plug trays.
Once pricked out and **potted off **, seedlings will need particular attention to watering and being kept out of direct sunlight or heat for a few days. As they grow, it will be possible to give them more light.
If seedlings have been in a protected environment up to now they need to be acclimatised to conditions outside before planting out.
2.1 Describe the method of sowing; pricking out; potting off; aftercare: for medium seed, Lactuca sativa (lettuce)
** Lactuca sativa (lettuce)**
Use multi purpose (crumble or sieve lumpy) or seed compost. Use a clean pot or tray. Firm the compost before sowing.
Sow seeds thinly over compost. Firm the seed into the surface of the compost.
Cover the seed to twice its depth with compost or vermiculite, gently firm and water carefully with upturned rose. Label and date.
Can cover with clear plastic and put in a warm place away from direct sunlight.
When seedlings are large enough to be handled, prick out and potted off into prepared individual containers or plug trays.
Once pricked out and **potted off **, seedlings will need particular attention to watering and being kept out of direct sunlight or heat for a few days. As they grow, it will be possible to give them more light.
If seedlings have been in a protected environment up to now they need to be acclimatised to conditions outside before planting out.
2.1 Describe the method of sowing; pricking out; potting off; aftercare: for large seed, Cucurbita pepo (melon)
Cucurbita pepo (melon)
Best sown in individual containers, or plug trays with large cell sizes. New or thoroughly cleaned.
Use multi purpose (crumble or sieve lumpy) or seed compost.
Seed can be sown individually but sowing 2 or 3 to every container means you can thin out the weakest seedlings.
Cover with compost to a depth roughly equivalent to the size of the seed. Water carefully with an upturned fine rose. Label with name and date planted. Can cover with clear plastic and put in a warm place away from direct sunlight.
Do not allow compost to dry out
When seedlings emerge remove lid or bag and allow maximum light without direct sunlight
Prick out strongest seedlings with a dibber, lift gently by leaves, pot off to a larger pot with more space (ready made hole in compost), gently firm and water in.
Seedlings will need particular attention to watering and being kept out of direct sunlight or heat for a few days. As they grow, it will be possible to give them more light.
Then can be potted on to a larger container or planted out, when acclimatised and if the conditions are correct.
2.1 List important things to remember when pricking out.
- never hold seedlings by the stem, as if you crush this you will kill the seedling; hold or pull them by their leaves,
- try to break up the interlocked root mass of young seedlings
as carefully as possible by gently teasing them apart at the
roots, - pricking out when small reduces damage, and seedlings are
less likely to have interlocked roots.
2.1 Describe methods of avoiding pest and disease problems when sowing seeds.
Hygiene is most important.
seedlings are very vulnerable to a range of fungal diseases including ‘Damping off’
All tools, containers, composts
and water used should be as clean as possible and ideally sterile.
Containers and tools can be sterilised
in a suitable disinfectant or by using water at near boiling point.
The growing environment, such as propagators, should also be clean.
Sow seeds at correct density, over crowding spreads disease quickly and makes pricking out harder.
Water with clean tap water
2.2 Describe the ground preperation of an outdoor site for seed sowing.
- Break up the soil surface into lumps with a fork or spade - remove any weeds - Add organic matter such as well rotted farmyard manure
- Break up the lumps into smaller lumps, the tilth; this can be done by hand with a fork or with a rotovator. Ideally, the tilth should have the consistency of coarse breadcrumbs.
- Level with a rake. Stones and other debris can now be collected and removed.
- Ideally the soil should be left for some time to partially consolidate
- Water ground and allow to drain before sowing
2.2 Name 5 different ways of seed sowing, with a named plant example for each.
Broadcast - lolium perenne (grass)
Drills - Daucus carota (carrot)
Station - in groups of 3 or 4 pastinaca sativa (parsnips)
Trench - pisum sativum (peas)
Individual - Phaseolus vulgaris (beans)
2.2 What is broadcast sewing?
Broadcast sowing - the aim is the even distribution of seed over an area
e.g lawns and wildflower seed
Prepare ground
Choose a non windy day as seed will blow away
Can be tricky to get an even distribution, one way is to mix the seed with sand
Divide it into two equal batches then with the first batch walk backwards and forwards in parallel lines one way scattering seed
Then walk at right angles sowing with the second batch
Sowing thickly has no advantage unless you have a severe bird problem
Gently rake the soil surface to cover the seed, if the conditions are dry water regularly to keep the soil moist and encourage the seed to germinate.
2.2 What is drill sowing?
Drill sowing - sowing in shallow trenches with a V profile
Prepare the soil
Make a shallow trench with a V profile
Filling the drill with water and letting it drain before sowing is a good way of ensuring seedlings have enough water for the first few weeks at least.
Sow the seed into it, and then gently rake the soil from the side into the drill.
The aim is to get the seed at the right
depth as directed by the packet.
Gently firm with the back of a rake.
4.2 Describe how and when to propagate by leaf lamina
cuttings. Name example.
Sansevieria trifasciata (snake plant)
When - spring/summer
Leaf lamina cutting (The flat and expanded portion of the leaf in its entirety is known as the lamina)
Sansevieria: Select a full-grown leaf and cut in half along the midrib (central leaf vein), which should be discarded. Using a seed tray make a shallow trench and insert the leaf, cut side down and firm in.
Water and allow to drain. Place in a
propagator or a clear plastic bag in a light place out of direct sunlight.
Leaf cuttings from tropical plants must be kept in high humidity at about 20°C (68°F).
When plantlets form, remove covers and allow them to grow on until large enough to pot up individually.
4.2 Describe how and when to propagate by leaf petiole
cuttings. Name example.
Saintpaulia spp. (african violet), Peperomia
When: spring/summer
Select young leaves.
Cut the leaves with the leaf stalk (petiole) intact from the parent plant.
Insert into compost with the leaf petiole pointing downwards. The leaf base should be just touching the compost surface. Firm in.
Leaf lamina cutting (The flat and expanded portion of the leaf in its entirety is known as the lamina)
Sansevieria: Select a full-grown leaf and cut in half along the midrib (central leaf vein), which should be discarded. Using a seed tray make a shallow trench and insert the leaf, cut side down and firm in.
Water and allow to drain. Place in a
propagator or a clear plastic bag in a light place out of direct sunlight.
Leaf cuttings from tropical plants must be kept in high humidity at about 20°C (68°F).
When plantlets form, remove covers and allow them to grow on until large enough to pot up individually.
4.2 Describe how and when to propagate by leaf bud
cuttings. Name examples.
Camellia spp., Clematis spp.
When: spring /summer
Leaf bud cuttings are a form of stem cutting. They are comprised of a leaf, a bud in its leaf axil, and a very short piece of stem.
The leaf provides food to support the cutting whilst it establishes roots, the bud provides the starting point of the new stem system and the lower piece of stem is where the first roots form.
Select a new stem with an undamaged leaf and a viable bud in its axil, later in the season.
Make an angled cut just above the bud. Make a straight cut 2 - 3cm at the bottom.
Roll or trim a large leaf. Dip cutting in rooting hormone.
Plant in pot with bud level with compost surface. Firm well and water in.
4.2 Describe how and when to propagate by root cuttings. Name examples.
Papaver orientale, Primula
denticulate.
When: late autumn or winter
thick sections of root near to the crown are selected and cut into
3-5cm lengths.
Cut the top square and the
lower part cut on a diagonal to easily identify top and bottom.
Important not to plant upside down as this prevents establishment. The cuttings are
Inserted vertically into compost.
Lightly water and place in a cold frame. Shoots should appear from the top of the roots in the spring.
thinner rooted species such as Phlox, are placed horizontally on compost and then covered with a thin layer of compost.
