Download Horticulture I Obj. 4.0

Plant Processes
4.00: Analyze the process of
growth in horticultural plants
Processes of plant growth
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Photosynthesis
Respiration
Absorption
Transpiration
Translocation
Reproduction
Photosynthesis
• The food and manufacturing process in
green plants that combines carbon
dioxide and water in the presence of
light to make sugar and oxygen.
– Formula:
6CO2+6H2O+672Kcal
Carbon Water
Dioxide
Light
Energy
C6H12O6+6O2
Glucose Oxygen
Sugar
Respiration
• The process through which plant
leaves, stems and roots consume
oxygen and give off carbon dioxide.
• Plants produce much more oxygen
through photosynthesis than they use
through respiration.
Absorption
• The process by which plant roots take in
water and air
Transpiration
• The process by which plants lose water
from leaves and stems through
evaporation
Translocation
• The process by which food and
nutrients are moved within a plant from
one plant part to another
Reproduction
• The plant process that increases plant
numbers
– usually by seeds
Osmosis
• 1. The process by which minerals enter
the plant through cell walls.
• 2. The process by which water enters
the plant through cell walls
Stages of Plant Growth
• Juvenile-when a plant first starts to grow
from a seed
• Reproductive-when a plant produces
flowers, seeds and fruits
• Dormant-when a plant rests or grows
very little, if any
Cell Organelles
• Chloroplast - cells that
contain stacks of
chlorophyll, where
photosynthesis takes
place.
– Chlorophyll - green
pigment responsible for
food production in plants.
– Only located in plant cells
Phases of the asexual cycle
• Vegetative-growth and development of
buds, roots, leaves and stems
– cell elongation-stage when cells enlarge
– differentiation-stage when cells specialize
• Reproductive or flowering-plant
develops flower buds that will develop
into flowers, fruits and seeds
Effects of Light, Moisture,
Temperature and Nutrients on
Plants
Light
• Photoperiodism-response of plants to
different amounts of light regarding their
flowering and reproduction cycles
• Necessary because of photosynthesis
• Not enough light causes long, slender,
spindly stems
• Too much light will cause plants to dry out
faster
• Phototropism is the tendency for plants to
grow toward a light source.
Moisture
• Needed in large amounts because plant
tissues are 90% water and water carries
nutrients
• Not enough water causes wilting and
stunted growth
• Too much water causes small root
systems and drowning which is a result of
air spaces in soil being filled with water
Temperature
• Needs vary depending on type of plants
• Either too high or too low will have
adverse effects
VS
Nutrients
• Essential for optimal plant conditions
• Has little effect on seed germination
Combining growth factors
• Ideal quantities and quality will give
optimum plant growth
• Each has an effect on the other factors
• Unfavorable environmental conditions
for plant growth causes diseases to be
more severe in their damages to plants
Plant Propagation
4.02: Apply different methods
of plant propagation as related
to horticultural plant production
Propagation
• The multiplication of a kind or species.
• Reproduction of a species.
Sexual Propagation
• Propagation from seeds.
• Pollen is transferred from the anther to
the stigma.
• Fertilization occurs and seeds are
produced.
Germination Rates
• Percent of seeds that sprout
– 75 out of 100=75%
• Rate is affected by seed viability,
temperature and moisture.
• Rates vary depending on plant and
quality of seed.
Seeds
• Plant depth depends on the size of
seeds
– larger seeds are planted deeper
– water small seeds from bottom by soaking
Embryo
Seed Coat
Endosperm
Seedlings (small plants)
• Transplant when first true leaves appear
• Reduce humidity and water and make
environment more like outside to
“harden off” plants
Seeds to Seedlings
Advantages of Sexual
Reproduction
• Fast way to get many plants
• Easy to do
• Economical
Disadvantages of Sexual
Reproduction
• Some plants, especially hybrids, do not
reproduce true to parents
• Some plants are difficult to propagate
from seeds
Asexual Reproduction
• Uses growing plant parts other than
seeds
• Types of asexual reproduction:
– cuttings
– layering
– division or separation
– budding
– grafting
– tissue culture
Rooting from Cuttings
• Rooting media should be about 4 inches
deep
• Best time of day is early mornings
because plants have more moisture
• Types of cuttings:
– stem
– leaf
– root
Stem Cuttings
• Using a small piece of stem to
reproduce plants
• using hormones and dipping in
fungicides help speed up rooting
Leaf cuttings
• Using small pieces of leaves to
reproduce new plants
• from herbaceous plants
• vein must be cut
Stem Cuttings-Step 1
Gather all materials needed
Stem Cuttings-Step 2
Cut 3 to 4 inch shoot from
stem tip
Stem Cuttings-Step 3
Remove lower leaves from the
shoot
Stem Cuttings-Step 4
Dip cut surface in rooting
hormone
Stem Cuttings-Step 5
Thoroughly moisten rooting
medium
Stem Cuttings-Step 6
Stick one or more cuttings in
rooting media
Stem Cuttings-Step 7
Cover with plastic wrap or place on
a mist bench in a warm area away
from direct sunlight.
Stem Cuttings-Step 8
Once rooted, cuttings can be
separated carefully and
transplanted
Root Cuttings
• Using small pieces of roots to reproduce
plants
• should be three inches apart in rooting
area
Layering
• Scarring a small area of stem to
produce new plants
– air layering
– trench layering
Trench Layering
Division or Separation
• Cutting or pulling apart plant structures
for reproduction
– bulbs
– corms
– rhizomes
– tubers
– runners
– stolons
– suckers
Bulbs
Rhizome
Grafting
• Joining separate plant parts together so
that they form a union and grow
together to make one plant.
Wedge
Graft
Approach
Graft
Grafting Terms
• Scion-the piece of plant at the top of the
graft
• Rootstock-the piece of the plant at the
root or bottom of the graft
Methods of Grafting
• If the scion and rootstock are the same
size
– wedge
– splice
– whip and tongue
– approach
Methods of Grafting
• If the scion is smaller than the rootstock
– cleft
– side
– notch
– bark inlay
Budding
• A form of grafting when a bud is used
– patch budding
– T-budding
– Chip Budding
Chip
Budding
How to perform T-budding
Step 2
Step 4
Step 1
Step 3
Tissue Culture
• Using a small amount of plant tissue to
grow in a sterile environment
• The most plants in a short time
• True to parent plant
Advantages of Asexual
Production
• Plants mature in a shorter time
• Budding is faster than grafting
• In trench layering, a plant forms at each
node on a covered stem
• Some plants do not produce viable seed
• New plants are the same as the parent
plant
Disadvantages of Asexual
Reproduction
• Some require special equipment and
skills, such as grafting
• Cuttings detach plant parts from water
and nutrient source
• Some plants are patented making
propagation illegal
The Uses of Biotechnology in
Horticulture
What is Biotechnology?
• The use of cells or components (parts)
of cells to produce products or
processes
Methods
• Tissue culture or micropropagation
• Cloning
• Genetic Engineering
Tissue Culture
• Uses terminal shoots or leaf buds in a
sterile or aseptic environment on agar
gel or other nutrient-growing media to
produce thousands of identical plants
Cloning
• Genetically generating offspring from
non-sexual tissue
Genetic Engineering
• Movement of genetic information in the
form of genes from one cell to another
cell to modify or change the genetic
make-up
Benefits of Biotechnology
• Produce many identical plants in a short
time
• Increase disease and insect resistance
• Increase tolerance to heat and cold
• Increase weed tolerance
Benefits of Biotechnology
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Increase tolerance to drought
Improve environment
Increase production
Other genetic changes