R2104 1 ROLE OF SEEDS IN PROPAGATION Flashcards
Seed definition
Product of sexual reproduction. Contains embryo and food store in the seed coat
Benefits of SEXUAL REPRODUCTION
- Variantion allows plant adaption to the environment
- Enables genetic variation
- More plants can be created to avoid extintion
- Wide dispersal of seeds and plants
Internal and external structure of seed (x 9)
Testa - seed coat, protect embryo
Cotyledon - seed leaf, can be used for starch storage
Radicle - first root
Plumule - first shoot
Epicotyl - section of them between cotyledons and first true leaves
Hypocotyl - section between the root and the cotyledons
Hilum - the point where seeds was attached within ovary
Micropyle - small hole intesta
Embryo - portion of seed that grows into a plant
Benefits of growing from SEED
- Produces variantion from which new cultivars can be developed
- Only method for some species
- May get large numbers from each plant
- Easily stored
- Can avoid virus transmission
Limitations of growing from seed
- Some plants not reproduce viably from seed
- difficult germination
- lack of uniformity
- can be slow to mature
- some seeds do not store easily
Plant examples that are usually propagated by seed
Daucus carota Phaseolus vulgaris Solanum lycopersicum Lobelia erinus Nigella damascena Lolium perenne
Main horticultural uses of seed
- Vegetable and bedding production
- Growing annual plants
- Establishing lawns
Seed viability definition
Seeds contain living embryo and will germinate when condition are right
Requirements for seed germination
- Appropriate moisture levels
- Appropriate temperature
- Oxygen
- Appropropriate light levels
Seed dormancy definition
Viable seeds fail to germinate even when all the germination requirement are met
Stages in a germinating seed
- Taking in water
- Raising respiration rate
- Breaking of food store
- Rapid cell division
- The splitting of the seed coat
- Emergence of radicle
Epigeal germination
When cotyledons rise to the soil evel
Hypogeal germination
When cotyledons stay below the soil level
Preparation and storage: Phaseolus vulgaris: Harvesting
Undamaged ripe pods from true to type plants, free from p&d. Harvest in dry weather when pods turned brown on the plant.
Preparation and storage: Nigella damascena: Harvesting
Harvesting: when seed pods are dry, collect ripe (brown) seedheads within a paper bag underneath. Give the head a shake to collect the seed
Orthodox seeds definition including examples
Seeds that tolerate drying and can be stored for long periods of time
need cool, dry storage
Long store time
Example Daucus carota Phaseolus vulgaris Loberia erinus Nigella damascena Lolium perenne
Recalcitrant seeds definition including examples
Lose viability quickly even with suitable storage conditions
Short storage time
Best sown immediatly following collection
Need cool, moist storage condition
Examples: Quercus robur
Aesculus hippocastanum
Effect that storage factors have on ability for seed to germinate: lenght of time
Cool dry storage extends period of time seeds can be stored as it slows down respiration
Prolonged storage can decrease seed viability
Effect that storage factors have on ability for seed to germinate:
temperature
Depending on seeds, some seeds inhibits or promoted germination by given temperatures
Lower temperatures slows down respiration
Preparation of fleshy fruits for seed storage (Solanum lycopersicum): Harvesting
Harvesting: Quality fruit, that are fully mature (slightly soft), free from p&d, true to type
Collect into a dry bag so it would not dry out
Preparation and storage: Phaseolus vulgaris: Seperation
Carefully seperate undamaged plants from the pods. reject any that are small
Preparation and storage: Phaseolus vulgaris: Cleaning
Does not need washing as dry
Preparation and storage: Phaseolus vulgaris: Drying
Dry seeds on paper for 7-10 days
Preparation and storage: Phaseolus vulgaris: Storage conditions
As an orthodox seed, it should be stored in a cool, dry place
Preparation and storage: Phaseolus vulgaris: Packaging
Labelled dry envelope/paper bag when fully dried in a plastic box containing silica gel (longer tern: place in a refrigirator)
Preparation and storage: Nigella damascena: Seperation
Seperate from capsule, gently crush if does not open
Preparation and storage: Nigella damascena: Cleaning
Dry, no cleaning
Preparation and storage: Nigella damascena: Drying
Place on paper towel to dry in a cool enviroment
Preparation and storage: Nigella damascena: Storage conditions
Keep cool and dry
Preparation and storage: Nigella damascena: Packaging
Paper bag in a sealed container containing silica gel
Refrigirator for longer term
Preparation of fleshy fruits for seed storage (Solanum lycopersicum): Maceration
Maceration: remore fruit stalk and macerate fruit through sieve to remove some of the flesh. Place flesh and seeds in a bucket of water and leave for a few days to ferment
Preparation of fleshy fruits for seed storage (Solanum lycopersicum): Seperation
Seed and flesh can be placed in a large volume of water where the pulp and non-viable seed will float and the viable seed will sink. Remove the viable seed. Discard the rest
Preparation of fleshy fruits for seed storage (Solanum lycopersicum): Cleaning
Wash seed through with sieve then place on a non-stick paper
Preparation of fleshy fruits for seed storage (Solanum lycopersicum): Drying
Drying: place in a dry, warm enviroment to fully dry, remoce any final chaff before storing seed in a labelled paper envelopes
