Transcript Requirements for Good Plant Growth

AHS Agriculture
 What
are the basic needs of
plants and various factors
that make up their
environment?
 What
factors have the
greatest impact on plants?
 Factors
that have greatest
effect on plants are:
 Water, nutrition, medium,
temperature, light,
humidity, insects and
diseases
 70-90%
of fresh weight &
major component of green
plants.
 Medium for biochemical
rxns
 Transports nutrients &
manufactured food
 Allows
sunlight to penetrate
leaves & green stems to
reach chlorophyll & power
production of food
 Vapor cools plant
 Stress
plants
 More susceptible to disease
& insect attacks
 Slow process of
photosynthesis
 16
elements from soil of
fertilizer
 Nitrogen, phosphorus &
potassium needed most
often
 Growth
greatly influenced
by heat
 Plants unable to maintain
cells at uniform temp.
 Heat
reproduction parts
when ready for fertilization
 Cool leaves by transpiration
(not constant temp)
 Roots less affected – soil
 Select
plants adapted to
area
 Some plants require # of
days at cold temp to flower
(impatiens)

 Growth
increases as temp
increases up to 86*F
 Above 86*,slows or stops
 90*-100* severely damage
 Reduced
growth
 Can result in death of
plants
 Cold-hardy plants can die if
sudden drop in temp also
 More
light= grow & flower
better
 Too much direct light=
damage to shade plants
 Spring
longer days=
growing & flowering
 Fall shorter days =
perennials, shrubs & trees
hardening off & preparing
for dormancy & cold temps
 Why
is soil important?
 Soil
or soil substitute plants
are grown in
 Casualty
of American
agricultural revolution- loss
of native soil fungi
 Allow plants to grow w/
less water, fewer added
nutrients, & fewer
pesticides
 Can
now control plant
diseases through use of
compost & mulch
 Also improves drainage
 Sand,
silt, clay, organic
matter, living organisms &
pore spaces that hold water
& air
 Classified on % of sand, silt
& clay
 Sand
larger then silt, clay
smallest
 Clay important to hold
water & nutrients for plant
topsoil – layer plowed/tilled,
contains most organic matter
• Subsoil- oxygen available,
roots expand here
• Soil bedrock/lower subsoilroots expand until rock, hard
clay or water prevents
•
 50%
solid material
(minerals, organic material)
 50% pore space
 Amount of moisture held
depends on soil type
 Silt
& clay make up less
then 20% of material
 Drain well
 Little capacity to hold
moisture & plant food
 At
least 30% clay
 Heavy soil
 Poor drainage & aeration
capabilities
 Holds fertilizer, plant food
& water well
 Most
desirable
 Mixture of equal parts of
sand, silt & clay
 Answer
the questions using
the texture triangle to
determine the type of soil
 What
are the varieties of
medium?
 Drainage
& aeration- add
organic matter to soil
(aggregation)
 Lime & gypsum (calcium
sulfate)
 Raising beds
 Ditches
 Moisture
retention- organic
matter
 Peat moss- 15x its weight
 Animal manure, green
manure, peat moss,
sawdust- good organic
matter
 Yellow
or pale leaves =
nitrogen deficiency
 Purple under leaf=
phosphorus deficiency
 Nematodes
 Insects
 Crop
– tiny animals
rotation & compost to
control
 Chemicals as last resort
 Mix
uniform
 Sterile
 Lighter in weight
 Good moisture retention &
drainage
 Blown
over bc light
 Minor plant food elements
missing (iron, sulfur, zinc &
calcium)
 From mixes to soilhesitate to extend roots
 Perlite-
gray-white material
of volcanic origin. To
improve aeration
 Peat
Moss- partially
decomposed vegetation
preserved under water
 High moisture-holding
capacity, 1% nitrogen, low
in phosphorus & potassium
Sphagnum moss- dehydrated
remains of acid bog plants in
shredded form for seeds
• Sterile, lightweight, controls
disease well, excellent waterholding capacity
• acid
•
 Vermiculite-
light,
expanded material with
neutral pH
 High moisture-holding
capacity
 Limestone-
calcium
carbonate (CaCO3) raise pH
 Tree Bark- pine or oak trees
 Slow-release fertilizersplant food gradually made
available
 May
contain 2 or more of
above ingredients
 Different plants have
different requirements
 May
 How
can we ensure proper
fertilization?
 Most
important plant food
element
 Plant food must be
dissolvable in water
 Major
elements
 Secondary nutrients
 Minor nutrients
 Show
% of or lbs per
hundred weight of 3 major
elements in large #’s on
bag or container
 5-10-5
 5%
nitrogen
 10% phosphorus
 5% potassium
 Other 80% filler material to
help spread plant food
evenly
 Most
noticeable effect on
plants
 Encourages vegetative
growth
 Dark green leaves
 Soft, tender growth, good
quality for crops, better
tasting
 Too
much:
 Lowers resistance to
disease
 Weaken stem
 Lower quality of fruits
 Delay maturity/damage to
plants
 Lost
by leaching (washing
out)
 Not held by soil particles
 Legumes (beans, peas)
manufacture own nitrogen
 Held
tightly by soil
 Encourages plant cell
division
 Flowers & seeds
 Hastens maturity, offsetting
quick growth from nitrogen
 Encourages
root growth
 Makes potassium more
easily available
 Increases resistance to
disease
 Improves quality of grain,
root & fruit crops
 Can
dry out roots by pulling
water from roots
 Insufficient- purple
coloring, reduced fruit,
flower & seed production,
plant disease, poor quality
fruits
 Increases
resistance to
disease
 Encourages strong, healthy
roots
 Essential for starch formation
 Development of chlorophyll
 Encourages use of carbon
dioxide
 Deficiency
as yellowing on
edge of leaves
 Affects
soil acidity
 Availability of plant food
elements
 Pg.
45 pH scale
 Best growth 5.6-7
 Sulfur,
iron sulfate or
aluminum sulfate used
 Flushing with low salt
irrigation also works
 Lime
to raise pH
 Can also release
phosphorus when too acid
 Decreases aluminum & iron
 Activates soil organisms &
encourages release of plant
food
 Do
not lime blueberries,
azaleas, & rhododendron
 May cause iron deficiency if
pH above 6
D
 What
does a plant need
aboveground to survive?
 Temperature
 Light
 Humidity
 Plant
Diseases
 Insects
 Gases/Particles
 One
of strongest affects
 Some grow in cooler temps
 Some prefer hot temps
 Near & below freezing stops
plant growth
 86* good temp, above plant
growth slows
 Must
be present to produce
food
 Too much can destroy plant
 Some plants only bloom
when days shorter
(chrysanthemum)

Photoperiodism – response to different
periods of day & night in terms of growth
 Grow
towards light
 Flavanoids- natural sun
blockers in leaves
 Enzymes to repair leaf
damage from UV lgiht
 Most
not affected
 40-80% humidity best
 High humidity will spread
fungus
 Relative
humidity- amount of
moisture in air as compared
with the % of moisture that
the air could hold at same
temp if completely saturated
 Reduces
production
 Stem injury may girdle
(circle) or clog up a stem &
kill plant
 Prevent- varieties resistant to
diseases and/or insects, crop
rotation or chemical sprays
 Carbon
Dioxide (CO2) vital
 Some add to greenhouse
 Damage: sulfur dioxide (coal
furnaces) Carbon monoxide
(cars)
 Consider fumes
 Plant
Heat-Zone Map (AHS)
 Plant Hardiness Zone Map
(USDA)
 Using both, #’s set up to
indicate where plants grow
best
 First
2= cold hardiness 1stcoldest zone, 2nd- least cold
zone
 Second set= heat tolerance &
st
requirement. 1 - hottest
zone, 2nd- lowest heat zone
 EX:
Cornus florida, East Coast
dogwood (5-8, 8-3)
 Other
factors will affect plant
growth also
 Carbon