Download asexual reproduction

PLANT REPRODUCTION
PART 1: ASEXUAL PLANT REPRODUCTION
Reproduction is important for
evolution. Asexual
Reproduction or cloning
produces numerous identical
individuals.
selection to occur.
Definition
Sexual
Reproduction
Asexual
Reproduction
•Involves sex cells and
fertilization
•Does not involve sex cells
and Fertilization
•Only one parent plant
Advantages/
Disadvantages
•Offspring are not
•Offspring have no
genetically identical to one variation
another
•There is variation in the
offspring
•Offspring are genetically
identical to one another
ASEXUAL REPRODUCTION
• Also known as vegetative propagation. Vegetative reproduction is
the multiplication of plants that does not involve the seed cycle. It is
also known as clonal propagation.
• Clones are genetically identical assemblage of individuals produced
from a plant entirely by vegetative means.
• There are several methods of vegetative propagation or asexual
reproduction.
• Rooting cuttings
• Layering; air layering
• Grafting
• Specialized structures
• Tissue culture; micropropagation
BENEFITS OF CLONAL
PROPAGATION...
• Some plants produce few (if any) viable seeds.
• Clonal progeny are highly uniform in all characters.
• Outcrossing plants produce highly variable progeny.
• Plants may have extended juvenile period.
• Cloning allows for combining genotypes in one plant.
• Seeds may have lengthy and complex dormancies.
CUTTING PROPAGATION
• Cutting capable of regenerating roots (or shoots) from
adventitious meristem.
• Cuttings defined by size and location on parent plant:
• Stem tip
• Nodal
• Root
• Leaf
• Cuttings also defined by condition of growth:
• Softwood, semihardwood, hardwood
FRAGMENTATION- PLANT
CUTTINGS
Some plants can grow from cutting them up and replanting them.
Cuttings are small pieces of stem with some leaves
attached, the new plant grows from this.
They can be placed in moist
soil or water (and sometimes
dipped in rooting
powder).
EXAMPLES OF CUTTING PROPAGATION.
Species
Cutting Type
African violet, begonia
leaf cuttings
Many woody shrubs
stem tip cuttings (softwood)
brambles
root cuttings
Willow, poplars
dormant hardwood cuttings
PROPAGATION BY SPECIALIZED
STRUCTURES.
Species
Structure
tulip, onion, Easter lily
bulb
potato, Jerusalem artichoke
tuber
Iris, lily-of-the valley
rhizome
Gladiolus, Crocus
corm
strawberry, Ajuga
runner
Dahlia, sweet potato
tuberous root
TUBERS
Tubers are underground
modified stems that stores food
over the winter and provides a
new plant with food until it can
make its own. Examples: potato,
artichoke, yam, cassava, water
chestnut, arrowroot
TaroJapanese
potato
BULBS
RUNNERS
Runners are side shoots which
grow out from the parent plant.
Buds form at points along the
runner and eventually these
buds form roots and grow into
new plants.
Examples: spider plant
(Anthericum), strawberry
(Fragaria x ananassa)
GRAFTING
A cut stem of one plant (with good flower or fruit
growth) (the graft) is taken and firmly attached to
the rootstock of another plant (which has a strong,
established root system) (the stock). Ex: Roses,
fruit trees.
GRAFTED AND BUDDED PLANTS.
Species
Graft/bud Type
apples
chip, T-bud, cleft
conifers
side veneer
pecans
patch
roses
T-bud (shield)
grapes
modified wedge
LAYERING
Layering involves
inducing roots on an
intact plant . For
example air layering
COMMERCIAL ASPECTS
Artificial propagation has allowed us to adapt and
improve plants for our own use. Some of the
benefits include:
• Quick production of large numbers of genetically
identical plants.
• Specific varieties, desired features or consistent
quality can be produced especially in fruit,
flowers.
MICROPROPAGATION.
“Micropropagation has many synonyms - tissue culture,
mass propagation, in vitro culture, cloning.”
• Micropropagation is rapid, continuous, and efficient.
• Specialized equipment, facilities, and technically trained
personnel are required.
• Steps can be taken to obtain and maintain certified pest-free
plants.
• Cost effective if large numbers of a given clone are produced.
• Widely used for orchids, ferns, many interior foliage plants,
rootstocks, etc.
Sexual reproduction produces
variable offspring, creating
diversity and variation among
populations (shuffling of
genes) and you need variation
for natural selection to occur.