Role Of Seeds In Propogation Flashcards
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.
State the benefits to a 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
Describe the structure of a seed -Phaseolus vulgaris
Tests Cotyledon Hilum Plumule Epicotyl Hypocotyl Radicle Micropyle
Testa facts
Seed coat
For protection
Tough
May need damaging before germination - nicking, soaking, soil particles etc.
Cotyledon
Seed leaf
Provides store of food for germinating seed
One seed leaf - monocot
Two seed leaves - dicot
Hilum
Scar from where attached to ovary
Plumule
Part of seed that forms first shoot
Epicotyl
Connects cotyledon to plumule
Hypocotyl
Connects cotyledon to radicle
Radicle
Forms first root
Micropyle
Small hole in testa where pollen tube entered ovule.
Can be where water enters for germination
Horticultural benefits of propagation 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 as guaranteed sources are available.
Limitations for propagation by seed
Some plants may not produce viable seed Lack of uniformity Difficult germination Some seeds don't store easily Time to maturity
Plant examples of usually propagated from seed
Daucus carota Phaseolus vulgaris Solanum lycopersicon Lobelia erinus Nigella damascena Lolium perenne
Main horticultural uses of seed
Vegetables
Lawns
Annual decorative plants
Bedding plants
What is a viable seed?
Has the potential for germination when conditions are right.
Contains living embryo
Requirements for seed germination
Moisture Oxygen Temperature Light/dark Dormancy broken
What is seed dormancy
When viable seed fails to germinate even when all germination conditions have been met.
Describe changes in germinating seed
Takes in water Respiration rate increases Breakdown of food store Rapid cell division Splitting of seed coat/testa Emergence of radicle
Example of epigeal germination
Cotyledon emerges above ground
Phaseolus vulgaris French bean
Example of hypogeal germination
Cotyledons stay below the ground
Vicia faba
What is meant by orthodox seed
Dry
Age slowly
Viable for many years possibly 100s
What is meant by recalcitrant seed
Moist/fleshy Intolerant of drying out E.g. Quercus roba Aesculus hippocastanum Can't be kept for long
Preparation and storage of Phaseolus vulgaris and nigella damascena
Collect ripe seed (when seed pods are brown)
Choose ones that are pest and disease free and true to type
Store pods and capsules in a warm place until they split
Clean the seed so is free from dust and debris (sieve)
Place in paper bag to be kept dry and cool. Lidded plastic box with silica gel in fridge.
Label and date
Seed needing cool dry storage
Daucus carota Phaseolus vulgaris Lobelia erinus Nigella damascena Lolium perenne
Examples of seeds needing short term moist storage
Quercus robur
Aesculus hippocastanum
Preparation of seed from fleshy fruit (Solanum lycopersicum)
Select fruit that is ripe, pest and disease free and true to type.
Cut in half and scoop out seeds into clean container
Wash the seeds to remove pulp that surrounds them
Strain seeds to remove pulp
Place seeds on piece of appear in warm area for 2-3 days until completely dry
Place seeds in paper bags 1-5 degrees
Label and date
