plant anatomy and physiology just the concepts. environmental factors on plant growth
TRANSCRIPT
Plant Anatomy
and PhysiologyJust the Concepts
Environmental
FactorsOn Plant Growth
Obje
ctiv
es
Describe the functions of water
in plant growth; Explain plant responses to a
shortage or excess of water;
Describe efficient use of water in
plant production; Describe the effects of
temperature on plant growth;
Describe plant responses to
temperature extremes;
Explain the qualities of light that
affect plant growth, including
color, intensity, and duration;
and Explain plant responses to light.
Functio
ns o
f
Wate
rWater covers three-fourths
of the earth’s surface and it
is available for plants in
most areas of the world.
It is a major component of
plants and animals.
Humans are about 70 percent
water and cacti are about 90
percent water
Funct
ions
of
Wate
r
Water Plays an important
role in all plant functions
Needed for turgor – gives
a plant rigidity and shape
Provides internal pressure
to help roots push through
soil Aides in cell division and
growth Used in photosynthesis Release oxygen Use hydrogen to
manufacture carbohydrates
Functio
ns o
f
Wate
r Water Plays an important role in
all plant functions
Transport nutrients and energy
through the plant
Movement of materials through plants
is called Translocation
Transpiration is the process of
evaporating water from the
stomates to pull in new water
through the roots
This process helps stabilize the
temperature of the plant
Resp
onse
to
Short
age a
nd E
xcess
Shortage Transpiration continues
even though water is
not absorbed Wilting occurs due to
loss of turgor Color changes
Resp
onse
to
Shorta
ge a
nd E
xcess
Excess
Root hairs die due to
saturated soil (no
oxygen)
Can no longer absorb
water and nutrients
Usi
ng W
ate
r Effi
cientl
y
What determines the
frequency and the amount of irrigation water that we use? The plant is the factor
Type of soil is next Irrigation is artificial
application of water to
a crop
Usin
g W
ate
r
Effi
ciently
Who is the least
efficient Irrigator?
Why
The home owner
Usi
ng W
ate
r Effi
cientl
y What is the goal of efficient water use? There can be several Greater production
Conservation of water
Conservation of soil
Usin
g W
ate
r
Effi
ciently
Greater Production
Got to have water to make a
good crop.
Conservation of Water
Why?
How?
Conservation of Soil
What does this have to do with
using water efficiently?
Tem
pera
ture
Temperature is one factor that contributes
to plant growth Metabolism: all of the
chemical reactions in a
plant Photosynthesis,
respiration Temperature affects the
speed of metabolism
Tem
pera
ture
Most plants show optimum growth
when night temps are 10˚ -15˚ cooler
than day temps
Photosynthesis occurs mostly during the
day
Cool temperatures slow down respiration
Photosynthesis > Respiration = growth
Most plants will stop photosynthesis at
temps above 86˚
At that time they begin using stored
reserves.
Tem
pera
ture
The daily change in temp. is a thermoperiod When thermoperiod influences plant functions they are called thermoperiodic Begin to flower when the
days get shorter and the
temps are cooler
Tem
pera
ture
Some plants are cool season
crops
Wheat, barley, rye, spinach,
lettuce
They grow best in cooler
weather and are tolerant to
frost
They begin to flower when the
temps get warmer and the
days are longer
Tem
pera
ture
Warm season crops grow best in warmer
temps Cotton, Corn, Soybeans,
Sorghum Tomatoes will absolutely
not flower in cool temps
Tem
pera
ture
Plants like tulips or
winter wheat require
Vernalization
Period of cold
temperatures, often
below freezing, in order
for physiological
processes to occur
Tem
pera
ture
Some seeds will remain
dormant until it has been
subjected to a period of cold
temperatures This is called stratification If a plant is hardy it can
withstand cold weather
There are categories of
hardiness Plants are usually classified
into hardiness categories by
the zone of the country where
they grow best
Light
Light Quality
Color or wavelengths
Wave length range is placed
on the electromagnetic
spectrum
Visible light is a very small
portion of the spectrum
It is what drives
photosynthesis
Light
Red and blue are the
most effective for plant growth Why? Readily absorbed by
chlorophyllGreen is the least effective Why? It gets reflected
Light
What type of lights are best for
plants?
Fluorescent or incandescent
Fluorescent
Blue wave lengths
Cool
Incandescent
Red wave lengths
Hot
Light
Light Quantity Intensity of light More intense at high altitudes
and near the equator The greater the intensity the
more food produced through
photosynthesis What will a plant do if it prefers
full sun but is grown in shady
area? It stretches Internodes become longer to
push the plant towards more
sunlight
Light
Light duration is called
Photoperiod
Many plants respond to
changes in day length
They are called photoperiodic
Usually this affects flowering
Long day, short day, day neutral
Light
Long-day Initiate flowering when
nights grow shorterShort-day Initiate flowering when
nights grow longerDay-neutral Don’t respond to
changes in day length