Transcript Plant Physiology - Dover High School

Plant Anatomy &
Physiology
Root Anatomy
Warm-up
Grab a plant and take it out of the pot
Answer the following:
-How is the soil being held in place?
- What can you see in the soil and on the
roots?
Use hand lenses or stereoscopic microscopes
to observe roots closely..
-Why are the roots so hairy?
Lesson Essential Question
• Connect the importance of roots to the survival of a plant.
Student Learning
Objectives
•Examine the functions of roots in plants.
•Identify the parts of a root.
•Differentiate the two major types of root
systems.
•Evaluate the health of a root system.
Terms
• root cap
• root hairs
• roots
• secondary roots
• taproot system
• unavailable water
• water-holding capacity
• aeration
• apical meristem
• available water
• epidermis
• fibrous root
system
• napiform root
• primary root
What are the functions of a
plant’s roots?
• A plant’s health is very closely tied to its roots.
• Root health is often closely linked to good soil
aeration, which is the exchange of gases in the
medium.
• A high percentage of pores in soil
provides good aeration.
• When roots are weak or diseased,
the whole plant has difficulties.
What are the functions of a
plant’s roots?
• The roots need to be constantly growing in order to
stay healthy.
• This is one reason that a plant growing in one pot
for a long time tends to become root bound.
What are the functions of a
plant’s roots?
• Soil moisture plays a significant role in helping or
hurting the root systems and involves the following:
• Available water is water that can be absorbed by the
plant roots.
• Unavailable water is a thin film of water that binds so
tightly to the medium’s particles that it cannot be used by
the plants.
• Water-holding capacity refers to the ability of soils to
hold water. Sandy soils have low water-holding capacity,
and clay soils have high water-holding capacity.
What are the functions of a
plant’s roots?
• The roots anchor the plant to the ground and
support the above ground part of the plant.
• The roots store food that has been made through
photosynthesis.
• This food can be used later when a plant needs it to
grow or survive.
What are the parts of a root?
• When a plant seed germinates, the first structure to
emerge from the seed is a root.
• This root becomes the primary root and on some
plants the most important root in the whole root
system.
What are the parts of a root?
• Other roots eventually branch out from the primary
root.
• These are called secondary roots.
• At the tip of the root, there is an area where new
cells develop, which is called the apical meristem.
• The apical meristem is easily damaged and so it has
a root cap over the top to protect it from damage
as it grows through the large and sometimes coarse
soil particles.
What are the parts of a root?
• The surface of the root is covered with a skin of cells
called the epidermis.
• This epidermis is where the water and minerals enter
the root through osmosis and diffusion.
• The larger the surface area of the epidermis, the better
able the plant is to bring in water and minerals.
What are the parts of a root?
• The epidermis cells begin to elongate and grow
hair-like projections.
• These projections, called root hairs, greatly
increase the surface area of the root and allow
much
more water and
minerals to enter
the plant.
What are the two types of root systems?
• Plant root systems are organized in two basic ways;
both have a lot to do with primary and secondary
roots.
• A root system that is composed of one main
primary root and many secondary roots branching
off of the primary root is called a taproot system.
• Many dicot plants have taproot systems.
• A specialized type of taproot is called a napiform root.
• Examples of napiform roots include radishes, beets, and carrots.
What are the two types of root systems?
• A system that has no dominant primary root but is
made of many primary and secondary roots of
similar size is called a fibrous root system.
• Monocot plants typically have fibrous root systems.
What are the two types of root systems?
What does a healthy root system look like?
• A healthy root system is white or nearly white in
color and smells fresh.
• If roots are black, brown, or dark orange and smell
rotten or sour, the root system is having some
problems.
• Although a plant growing outside has a majority of
roots in only the top two feet of soil, a plant in a
pot should have its roots evenly dispersed
throughout the soil in the pot.
What does a healthy root system look like?
• Watering a plant properly is one of the most
important ways to keep the root system healthy.
• Proper watering for most plants involves growing
the plants in pots with proper drainage holes in the
bottom of the pot.
• The pot is soaked with water until it is dripping out
of the drainage holes.
• This encourages roots to grow through the entire
pot.
What does a healthy root system look like?
• The plant’s soil is usually allowed to dry slightly
before watering again.
• If plants have adequate drainage, over-watering of
plants is not a matter of how much water, but of
how often watering occurs.
Activity
• Identify the structures of roots
• Lab worksheet
Exit Ticket
•1. What are the functions of a plant’s roots?
•2. What are the parts of a root?
•3. What are the two types of root systems?
•4. What does a healthy root system look like?
Plant Anatomy &
Physiology
Stem Anatomy
Warm-Up
1. From the branch, what can you tell
about the tree that it was growing
on?
2. How many structures on the stem can
you identify?
Lesson Essential Question
• Interpret the function of a stem and its importance to the
plant.
Student Learning
Objectives
•Describe the functions of a stem.
•Recognize the external structures of a
stem.
•Analyze the internal structures of a stem.
•Distinguish between the different types of
specialized stems.
Terms
• apical meristem
• bud
• bud scale scar
• bud scales
• bulb
• cambium
• corm
• cortex
• heartwood
• internode
• lateral bud
• leaf scar
• lenticels
• node
• phloem
• rhizome
• sapwood
• stolon
• terminal bud
• translocation
• tuber
• vascular
cambium
• xylem
What are the functions of a stem?
• Stems have many
important jobs in a plant.
• Stems are responsible for
the size and shape of a
plant.
• Some stems are made of
wood, and some are
herbaceous or soft.
What are the functions of a stem?
• The following are four functions of stems.
• Stems support the leaves. They hold the leaves in the
most efficient position to collect sunlight.
• Stems move water, minerals, and manufactured food
throughout the whole plant. The movement of materials
through vascular tissues is known as translocation.
What are the functions of a stem?
• Stems that are green in color help produce food
through photosynthesis. While this is not usually the
primary food production, it can be quite important in
plants with no leaves or very small leaves.
• Stems store food that has been manufactured by the
plant.
What are some of the structures on the outside of a stem?
• Many structures on the stem are useful to us in
identifying plants.
• The following are some external structures on a
stem.
• The growing point at the tip of the stem, called the apical
meristem, is contained inside of the bud at the end of the
stem, which is called the terminal bud.
• The apical meristem is the same type of structure that the
tip of the root has and is responsible for growth in the
length of the plant.
What are some of the structures on the outside of a stem?
• The leaf is attached to the stem at the
node.
• The area between leaves is called an
internode.
• At the node, just above where the leaf is
attached, there is always a side bud
called the lateral bud.
• On the outside of both terminal and
lateral buds are small protective
structures called bud scales.
What are some of the structures on the outside of a stem?
• When the leaf falls off of the stem, it leaves behind a
small scar just below the lateral bud.
• This scar is called the leaf scar.
• When the buds sprout each spring, the bud scales fall
off, leaving behind a ring of scars called the bud scale
scar.
• The distance between bud scale scars represents one
year’s growth of the stem.
• Lenticels are small spots on the stem that allow it to
exchange gases with its environment.
What are some of
the structures on
the outside of a
stem?
What are some of the structures inside a stem?
• Inside of the stem, there are tissues used to
transport materials throughout the plant.
• Stem tissues are organized in one of the following
ways.
• The important vascular tissues are either found in
small bundles scattered throughout the stem or
arranged in rings or a ring of vascular bundles,
which are located in the cortex.
What are some of the structures inside a stem?
• The first way, scattered bundles, is found in
monocots.
• The second way, in rings, is found in dicots.
• There are three important types of tissue found
inside of the stem.
What are some of the structures inside a stem?
• The xylem is tissue that conducts the water
and minerals throughout the plant.
• The xylem is made of tube-like cells that
grow together to conduct liquids.
• Xylem tends to be found closer to the
center of the stem.
• It is responsible for growth in girth of the
stem and is generally found between the
xylem and the phloem.
What are some of the structures inside a stem?
• The phloem is tissue that conducts food that is
produced in the leaf to the rest of the plant.
• Phloem cells also form tubes.
• Phloem is generally found toward the outside of
the stem.
What are some of the structures inside a stem?
• Vascular cambium is tissue that is responsible for
the production of new xylem and phloem.
• It is responsible for growth in girth of the stem and
is generally found between the xylem and the
phloem.
What are some of the structures inside a stem?
• The darker wood to the center of the tree is called the
heartwood.
• The xylem cells of the heartwood have filled with gums,
resins, pigments, and tannins.
• They provide strength and no longer function in conducting
materials.
• The
lighter wood circling the
heartwood is called the sapwood.
―The younger sapwood actively conducts water and
dissolved minerals.
What are some of the structures inside a stem?
• The age of a tree can be determined by counting
annual growth rings.
• During rapid growth, the cells of the
wood are thin walled and
large in diameter.
• As growth slows during mid-to-late
summer, the wood cells produced by the
cambium become smaller and have
thicker walls.
• Each ring is the growth during one
growing season.
What are some different kinds of specialized stems?
• We generally expect stems to be upright and above
ground.
• Some stems are modified to store food or to help
the plant reproduce.
• Some stems grow beneath the soil instead of above
it.
• The following are some types of specialized stems.
What are some different kinds of specialized stems?
• A bulb is a very short flattened stem that has
several fleshy leaves attached to it.
• Bulbs tend to be found beneath the soil. An
onion is a bulb.
• A corm is a spherical structure, much like a
bulb. The entire structure, however, is stem
as opposed to stem and leaves. A gladiolus is
a corm.
What are some different kinds of specialized stems?
• A rhizome is a thick underground
stem that lies horizontally. Hostas
and Mother-in-law’s Tongue are
rhizomes.
• A stolon is a horizontal stem that
lies above the ground. Stolons are
sometimes called runners and tend
to be involved with the spreading
of the plant. Strawberries spread
by stolon.
What are some different kinds of specialized stems?
• A tuber is a rhizome with a tip that is
swollen with stored food. Irish potatoes are
tubers.
What are some
different kinds of
specialized
stems?
Exit Ticket
•1. What are the functions of a stem?
•2. What are some of the structures on the outside
of a stem?
•3. What are some of the structures inside a stem?
•4. What are some different kinds of specialized
stems?
Plant Anatomy &
Physiology
Leaf Anatomy
Interest Approach
Bring several different plants with different leaves into
class. Ask students to compare and contrast them. Use
student responses to form a list of how the leaves are
the same and how they are different. Begin to build on
the list. Do the similarities on the list have something to
do with photosynthesis? (Similarities may be that leaves
are green or have a large flat surface.) What words are
used to describe the differences? Can we choose better
terms?
Student Learning
Objectives
•Describe the main parts of a leaf.
•Compare common vein patterns found in
leaves.
•Examine how a leaf is organized.
Student Learning
Objectives
•Distinguish some major types of leaves.
•Differentiate major leaf arrangements.
Terms
• alternate
• compound leaf
• cuticle
• dichotomous venation
• epidermis
• guard cells
• leaf blade
• leaflet
Terms
• midrib
• netted veins
• opposite
• palisade mesophyll
• palmately compound
• palmately netted
• parallel veins
• petiole
Terms
• pinnately compound
• pinnately netted
• simple leaf
• spongy mesophyll
• stomata
• subopposite
• whorled
What are the main parts
of a leaf?
• Leaves are the primary food-producing organs of the
plant.
• They are designed to efficiently collect light and use
that light energy to produce food.
• The main sun-collecting structure on the leaf is a
large broad flat surface called the leaf blade.
What are the main parts
of a leaf?
• The blade is held away from the stem and supported
by a leaf stem called the petiole.
• The petiole is not exactly like a stem, but it does have
xylem and phloem so it can transport water and
sugar.
What are the main parts
of a leaf?
• Many leaves are organized with one main vein
running down the middle of the blade.
• This vein is called the midrib.
• All of the veins, the petiole, and the midrib help
position the blade in a way that it is facing the light
source.
What are
the main
parts
of a leaf?
What are some vein patterns
found in leaves?
• Veins of flowering plants are found in several patterns.
• Most of these patterns can be categorized into two
groups.
• Monocots have leaves with parallel veins.
• While the veins may not be parallel in a strict mathematical sense, none of
the veins on the leaf cross.
• It may look like they are fused together at the top or bottom of the blade.
• Corn and grass plants are good examples of monocot leaves.
What are some vein patterns
found in leaves?
• Dicots have veins that connect and branch from each
other.
• Veins in a branching pattern are called netted veins.
• Some leaves with netted veins have several smaller veins
branching out of a dominant midrib, which is a condition
known as pinnately netted.
What are some vein patterns
found in leaves?
• Other leaves have several dominant veins branching out
from the petiole.
• This condition is known as palmately netted.
• A few plants have a spreading vein pattern called
dichotomous venation; a gingko leaf is an example.
How is a leaf organized?
• A leaf is organized to collect sunlight and turn it,
through photosynthesis, into food.
• The leaf blade has many layers of tissue to allow
this to happen.
• On top of the leaf is a waxy non-cellular layer
called the cuticle.
• The cuticle is on the leaf to prevent water from
escaping.
How is a leaf organized?
• The next layer on the leaf is also there for
protection.
• The epidermis is the skinlike layer of cells
found on both the top and the bottom surface
of the leaf.
• The epidermis may be one or many layers
thick.
How is a leaf organized?
• Directly beneath the upper epidermis is a
layer of cells that are standing on end and
packed very tightly.
• These standing cells are responsible for most of the
photosynthesis in the leaf and are called the
palisade mesophyll.
How is a leaf organized?
• Located under the palisade mesophyll are
loosely packed cells called the spongy
mesophyll.
• The spongy mesophyll forms air spaces that hold
raw materials to be used and products of
photosynthesis.
How is a leaf organized?
• The lower epidermis has holes in it for gas exchange.
• The holes, stomata, can open and close.
• The opening and closing is controlled by the guard
cells, which surround each stoma.
What are some of the
major types of leaves?
• Many different types of leaves exist.
• Some leaves have adapted to hot, dry climates by storing water or
being smaller.
• Some leaves have very large blades to collect the maximum light
in a shady location.
What are some of the
major types of leaves?
• In some leaves, the blade is broken into several sections.
• A leaf that has only one blade on its petiole is called a simple leaf.
Most plants have simple leaves.
What are some of the
major types of leaves?
• In some leaves, the blade is divided into three or more
sections.
• A leaf with multiple blades, called leaflets, is said to be a
compound leaf.
What are some of the
major types of leaves?
• There are many different kinds of compound leaves.
• A palmately compound leaf has all its leaflets attached to a
common point.
• A pinnately compound leaf has multiple leaflets attached
along a rachis or axis.
What are the major leaf arrangements?
• The arrangement of leaves on a stem varies
from one genus to another.
• Leaves are arranged along stems in one of four
major ways.
• When leaves and buds are arranged directly across
from each other on a stem they are said to be
opposite.
What are the major leaf arrangements?
• Leaves and buds that are spaced along a stem in
an alternating fashion are termed alternate.
What are the major leaf arrangements?
•A third arrangement is
subopposite, which refers to a
condition where leaves and
buds are not spaced far
enough apart to be called
alternate nor perfectly
opposite.
What are the major leaf arrangements?
• When three or more leaves and buds are
attached at a node, the arrangement is called
whorled.
Review/Summary
•What are the main parts of a leaf?
•What are some vein patterns found in
leaves?
•How is a leaf organized?
Review/Summary
•What are some of the major types of
leaves?
•What are the major leaf arrangements?
Plant Anatomy &
Physiology
Flower Anatomy
Interest Approach
Begin a discussion on sexual reproduction. Ask what
students know about sexual reproduction in animals.
Although the initial responses may be slow, given time,
most students will be able to tell you about animal
reproduction.
Interest Approach
Now, switch to plant sexual reproduction. What do
students know? Are there girl and boy plants? (Yes,
sometimes.) Do plants “have sex”? (Yes.) Do plants have
sperm and eggs? (Yes.) Do plants have genitalia? (Yes,
although we call them “flowers.”) If students are having
fun with this last concept, you may comment
on the wearing of flowers to a dance or having a vase of
flowers on a dinner table.
Student Learning
Objectives
•Describe the parts of a flower.
•Explain the purpose of a flower.
•List some different types of flowers.
•Describe the difference between monocot and
dicot flowers.
Terms
• anther
• calyx
• complete flower
• corolla
• fertilization
• filament
• imperfect flower
• incomplete flower
Terms
• ovary
• perfect flower
• petals
• pistil
• pistillate
• pollen
• pollination
Terms
• sepals
• stamen
• staminate
• stigma
• style
What are the parts of a flower?
• Flowers are the most obvious part of most plants.
• They are made of many intricate and important
parts.
• Most flowers contain both male and female parts.
What are the parts of a flower?
• The male part of the flower is
called the stamen, which is
made of the stalk-like filament
that holds up the sack-like
anther.
• The anther contains pollen, the
grain released by flowers, which
contains the sperm.
• Flowers that only have male
parts are called staminate.
What are the parts of a flower?
• The female part of the flower is called
the pistil.
• It consists of a sticky tissue at its end
called the stigma, which is receptive to
pollen.
• Below the stigma is a rodshaped
middle part called the style and a
swollen base containing eggs called the
ovary.
• Flowers that only have female parts are
called pistillate.
What are the parts of a flower?
What are the parts of a flower?
• Flowers also often have
parts that are neither male
nor female; these are the
petals, usually colorful
leaf-like structures that
often attract animals and
insects.
• When all of the petals are
fused together, we call
them a corolla.
What are the parts of a flower?
• Beneath the petals are more leaf-like structures,
called sepals, which are often green. The sepals
support the petals and protect the flower before it
opens.
• When all of the sepals are fused together, we call
them a calyx.
What is the purpose of a flower?
• The purpose of a flower is for a plant to be able to
reproduce sexually.
• The process of sexual reproduction in plants follows.
• The first step in sexual reproduction is for the stamen to
release its pollen.
• The pollen is carried by animal, wind, gravity, or many other
methods to the stigma of another flower.
What is the purpose of a flower?
• When the pollen from one
flower lands on the stigma of
a compatible flower, we call it
pollination.
• Flowers are adapted to
pollinate each other in an
astounding number of
different ways using an
equally amazing number of
methods, called vectors, to
help them.
What is the purpose of a flower?
• Once the pollen reaches the stigma,
it starts to go down into the style,
depositing sperm in the ovary.
• When the sperm combines with the
eggs in the ovary, we call it
fertilization.
• After the eggs have been fertilized,
the ovary and surrounding tissue
start to enlarge to become a fruit and
the fertilized eggs become seeds.
What are some different
types of flowers?
• Flowers come in many shapes, sizes, and colors. Not
all of them have all of the structures mentioned
previously.
• A flower that has both male and female parts is called a
perfect flower.
• A flower that is missing either male or female parts is called
imperfect flower.
What are some different
types of flowers?
• If a flower has sepals, petals, pistils, and stamens, we call it
a complete flower.
• If a flower is missing one of those, we say it is an
incomplete flower.
• Imperfect flowers are always incomplete. Incomplete flowers may
or may not be imperfect.
How is a monocot flower different from a dicot
flower?
• A good way to tell the difference between a monocot
and a dicot is to look closely at the flowers.
• Monocots have flowers with flower parts in multiples of
three.
• Dicots have flowers with flower parts in multiples of four or
five.
Review/Summary
•What are the parts of a flower?
•What is the purpose of a flower?
•What are some different types of flowers?
•How is a monocot flower different from a
dicot flower?
Plant Anatomy &
Physiology
Light, Temperature, Air and water effects on plant growth
Interest Approach
Students love to set up experiments. This is your chance
to allow them to set up their own. Allow the class to
have 10–15 plants. This can be done in groups or as an
entire class. Tell the students they need to study the
effects of light, temperature, air, and water on plants.
For example, you might use four plants and put one in a
bright window, one on the teacher’s desk, one in a
greenhouse or under a bright light, and one in a dark
closet in order to study the effects of light.
Interest Approach
Allow students to be creative. Within a week you will
start to see some serious differences. Students can
check and measure the progress of the plants at the
beginning of each class as a gathering and interest
activity. You may ask students to draw conclusions from
their data. This can take the form of a discussion,
paper, or an oral presentation.
Student Learning
Objectives
•Examine the effect of light on plants.
•Describe a plant’s temperature needs.
Student Learning
Objectives
•Explain how the quality of air affects plants.
•Determine a plant’s water needs.
Terms
• day neutral plant (dnp)
• DIF
• electromagnetic spectrum
• foot candle
• hardiness
• humidity
• long day plant (ldp)
• photoperiod
Terms
• photoreceptor
• phytochrome
• plant heat-zone map
• plant hardiness zone map
• short day plant (sdp)
• soluble salts
• thermoperiod
• vernalization
• wilting
How does light affect plants?
• The sun emits a wide range of radiation.
• The light we see is called visible light.
• It is a small segment of all the radiant energy given
off by the sun.
• Visible light is what drives photosynthesis.
• Some other types of radiation are X-rays, gamma
rays, ultraviolet rays, microwaves, and radio waves.
How does light affect plants?
• The wavelengths of the different rays are measured
in nanometers.
• Based on their wavelengths, the rays have been
placed on an electromagnetic spectrum.
How does light affect plants?
• Sunlight contains a complete blend of visible colors
including red, orange, yellow, green, blue, and violet.
• Plants need mostly the colors blue and red to
activate the chlorophyll.
• Other pigments collect other colors of light and pass
that energy to the chlorophyll to make more sugar.
How does light affect plants?
• Different colors of light solicit different plant
responses.
• Red light promotes seed germination, seedling growth,
and stem elongation.
• Red wavelengths also influence flowering and anthocyanin (pigments in
blue, red and purple flowers) formation.
How does light affect plants?
• Blue light reduces stem length, increases branching,
and promotes stem strength.
• Blue light improves leaf and flower color, too.
• Far-red light triggers a shade avoidance response in
plants when levels of blue or red light are low.
• Stems stretch and become weak while leaves become thinner and wider.
• Far-red light also plays a key role in breaking seed dormancy and in
photoperiod responses.
How does light affect plants?
• Light intensity can have an impact on crops.
• Intensity of light depends largely on the angle of the
sun, clouds, and dust in the atmosphere.
• Light intensity is greater in the summer months
when the sun is higher in the sky.
How does light affect plants?
• Light intensity is measured in foot candles.
• A foot candle is the amount of light distributed by a single candle one foot
away.
• A sunny, summer day provides about 10,000 foot candles of light.
• The high light intensity elevates the rate of photosynthesis; as a result, the
plant is able to produce more food.
How does light affect plants?
• Plants receiving the optimum level of light will be
compact and have good leaf color.
• Symptoms of lower than optimum light levels include a slower growth rate,
thin leaves, small flowers, dull leaf and flower color, and etiolation or
stretching.
• Extended periods of cloud cover can slow crop growth and ultimately
reduce yields.
How does light affect plants?
• Some plants are responsive to the length of time
they are exposed to light.
• These plants have a photoreceptor or light-sensitive
pigment that absorbs light.
• Phytochrome is a type of photoreceptor within plants
that detects day lengths.
• The length of the days or the length of the light period is known to
influence different phases of plant growth, such as flowering.
How does light affect plants?
• Other phases are seed germination, enlargement of leaves, and
development of buds.
• A plant’s response to light duration is called photoperiod.
How does light affect plants?
• Plants can generally be separated into three groups
based on the photoperiod response.
• Short day plants (SDP) are plants that begin to flower when
the nights are more than 12 hours long.
• Long day plants (LDP) begin to flower when the nights are
under 12 hours long.
• Day neutral plants (DNP) are plants with a flowering
response that is unaffected by the photoperiod.
What temperatures are best for plants?
• Plants have adapted to a wide range of
temperatures.
• Some plants thrive within the Arctic Circle and others
can survive in the blazing sun of a desert.
• Plants tend to adapt for higher temperatures with
smaller leaves in lighter colors with thicker cuticles.
What temperatures are best for plants?
• Plants adapt to low temperatures by growing lower
to the ground with short life cycles and parabolic
dish-shaped flowers to collect light and heat.
• Although plants can survive
higher and lower extremes,
plants do not really grow at
temperatures below 32 degrees
Fahrenheit or above 100
degrees Fahrenheit.
What temperatures are best for plants?
• A plant’s ability to withstand low temperatures is
called its hardiness.
• A plant that is very hardy can survive in a cold
climate.
• Hardiness is measured using the USDA plant
hardiness-zone map.
What temperatures are best for plants?
• Each area of the country is assigned a zone number
(1 to 10).
• A plant proven to withstand zones 1–4 will survive
the cold temperature extremes in zone 5, but a plant
rated for zone 6–11 would likely die.
• Hardiness zones are derived from the average
coldest temperatures for the year.
What temperatures are best for plants?
• Heat also plays a role in the performance of plant
species.
• Some plants are more sensitive to heat than others.
• The plant heat-zone map has been developed by the
American Horticultural Society to help identify areas in
which landscape plants can flourish.
• The map shows 12 zones.
What temperatures are best for plants?
• Each zone reflects a rating of summer heat based on the
average number of days above 86F.
• Eighty-six degrees is a temperature at which plants are
unable to process water fast enough to maintain normal
functions.
• Plants also experience damage to cellular proteins at
temperatures above 86F.
What
temperatures are
best for plants?
What temperatures are best for plants?
• The inability of a plant to absorb enough water to
replace water lost through transpiration can be a
problem in hot weather.
• Plants that lose water faster than it can be replaced
become flaccid, a condition known as wilting.
• The guard cells also wilt, causing the stomata to close.
• Without an exchange of gases, photosynthesis shuts
down.
What temperatures are best for plants?
• Thermoperiod is a term used to describe a
temperature requirement that produces a plant
response.
• Poinsettias and holiday cactus are examples of
thermoperiodic plants.
• A period of cool temperatures along with short days
causes them to initiate flowering.
What temperatures are best for plants?
• For some floriculture crops, a period of cold
temperature is required for flowering.
• This physiological process is known as vernalization.
• Bulb crops like tulips, narcissus, and Easter lilies must
undergo vernalization.
• A common practice is to expose bulbs to freezing or
near freezing temperatures for a number of weeks to
satisfy the plant’s cold requirement
What temperatures are best for plants?
• Greenhouse growers use temperature to control the
height of plants.
• They do this by managing the difference between
daytime and nighttime temperatures.
• The mathematical difference between the day
temperature and the night temperature is called DIF.
• DIF can be positive, negative, or zero.
What temperatures are best for plants?
• A positive DIF results when the day temperature is
higher than the night temperature.
• Positive DIF causes a plant to lengthen its stems.
• A negative DIF occurs when the day temperature is
cooler than the night temperature.
• Plants grown under negative DIF conditions have
limited stem elongation.
• Zero DIF is a result of identical day and night
temperatures.
How does the quality of air
affect plants?
• Air contains carbon dioxide and oxygen, both of
which are necessary for plant growth.
• Oxygen is necessary for cellular respiration to occur in
a normal manner.
• Oxygen is picked up mainly by the roots of the plant.
How does the quality of air
affect plants?
• Carbon dioxide is used for photosynthesis in very high
amounts.
• Carbon dioxide usually enters the plant through the leaves via the
stomata.
• In greenhouses, we often try to boost the level of carbon dioxide to speed
up photosynthesis.
How does the quality of air
affect plants?
• Humidity, which is water vapor in the air, affects
plant growth.
• The growth rate of plants increases under
conditions of high humidity.
• Lush, tropical forests exist, in part, because of
frequent rain and high humidity.
How does the quality of air
affect plants?
• High humidity reduces water stress of a plant so
photosynthesis can function smoothly.
• If the humidity is low, the dryness of the air can put
stress on the plant.
• This is especially true if soil moisture is inadequate
and wilting occurs.
• One drawback of excessive humidity is the increase
of leaf and flower diseases.
How does the quality of air
affect plants?
• Air pollution can be damaging to plants.
• Dust in the air can reduce light intensity, slowing
photosynthesis.
• Chemical pollutants, such as sulfur dioxide and
ozone, can actually kill plant cells or the entire
plant.
How do plants get water?
• Plants receive most water through the root system.
• In some situations, plants can soak up water
through stems or take in water through leaves.
• Watering is the most important cultural practice in
horticulture.
• Life processes of plants depend on water.
• Photosynthesis and respiration require water.
How do plants get water?
• Roots are able to absorb minerals only if the minerals
are dissolved in water.
• Water is the carrier of materials through the xylem
and phloem.
• Water also comprises a large percentage of the plant
cells, tissues, and organs.
How do plants get water?
• Water must be given to plants when
needed to avoid damage to the root
system.
• Timing is critical. Frequent
applications of water can keep a
growing medium too wet.
• The result may be damaged plant
roots caused by the lack of good air
exchange.
How do plants get water?
• Plants in containers should be grown in pots with
drainage holes so the water can drain and allow
oxygen into the root zone.
• Allowing soils to become too dry between waterings
may also cause root death and lower the quality of
the crop.
How do plants get water?
• A good rule is to water plants thoroughly when they
need water and wait until they need water before
watering again.
How do plants get water?
• Water with a favorable pH range of 5.8 to 6.2 is best
for most plant growth.
• If the water supply has a pH outside that range, the
pH can be adjusted.
• A second consideration in determining water quality
involves soluble salts.
• Soluble salts are dissolved minerals.
• Water with high levels of soluble salts is detrimental
to plant growth.
• Soluble salts damage roots.
Review/Summary
•How does light affect plants?
•What temperatures are best for plants?
•How does the quality of
air affect plants?
•How do plants get
water?
Plant Anatomy &
Physiology
Supplying nutrients
Horticulture Science
Lesson 22
Supplying Nutrients to Floriculture Crops
Interest Approach
Lay out several examples of fertilizers. Pick a flowering
plant and ask the students to find the correct fertilizer
for that particular plant. Ask them why they chose that
fertilizer. Repeat this activity with a houseplant and a
vegetable plant. Then ask the students to describe how
they would use the fertilizer (e.g., mix with water, apply
to the soil, spray on the leaves). Finally, ask the
students to describe what is in the fertilizer that helps
plants grow.
Student Learning
Objectives
•Discuss plant nutrition.
•Describe pH and how it is modified.
Student Learning
Objectives
•Describe the components of a fertilizer.
•Explain the methods of applying fertilizers to
horticultural crops.
Terms
• chlorosis
• complete fertilizer
• fertilizer
• fertilizer analysis
• fertilizer injector systems
• incomplete fertilizer
• limestone
• macronutrient
• micronutrient
Terms
• nutrient deficiency
• parts per million (ppm)
• plant nutrition
• primary macronutrients
• secondary macronutrients
• slow release fertilizer
• soil pH
• soil test
• sulfur
• water-soluble fertilizer
What is plant nutrition?
• Plants need nutrients for healthy growth and
development.
• Plant nutrition involves the absorption of nutrients
for plant growth and is dependent on 16 essential
elements, often referred to as nutrients.
What is plant nutrition?
• Three of the 16 elements comprise 89 percent of a
plant’s tissue by dry weight: oxygen (O), hydrogen (H),
and carbon (C).
• They are considered to be non-fertilizer nutrients.
• The plant acquires these three elements through
natural processes from air and water.
What is plant nutrition?
Six essential elements in addition to oxygen, hydrogen,
and carbon are required in greater quantity than the
others; they are called macronutrients.
• The macronutrients are nitrogen (N), phosphorus (P),
potassium (K), calcium (Ca), magnesium (Mg), and
sulfur (S).
• 1. Nitrogen, phosphorus, and potassium are considered
primary macronutrients because they are used in complete
fertilizers.
• Nitrogen promotes green leafy growth.
• Phosphorus encourages flowering and root growth.
• Potassium provides disease resistance.
What is plant nutrition?
• 2. Calcium, magnesium, and sulfur are said to be secondary
macronutrients because plants need them in moderate amounts.
• These secondary macronutrients may or may not be used in complete
fertilizers.
What is plant nutrition?
• The other seven essential elements, called micronutrients, are
needed in small quantities.
• These are sometimes called trace elements. They are boron (B),
copper (Cu), chlorine (Cl), iron (Fe), manganese (Mn),
molybdenum (Mo), sodium (Na), and zinc (Zn).
• Six of these (boron, copper, iron, manganese, molybdenum,
sodium, and zinc) are supplied to plants as fertilizers.
• Chlorine is not added to fertilizers since plants obtain sufficient
quantities of chlorine from the medium or from water.
What is plant nutrition?
A little phrase can be used to help memorize the 16
essential elements for plant growth.
• It is “C. B. Hopkins Café Mighty Good Closed Monday See You
Zen.”
• It represents the following: Carbon (C), Boron (B),
Hydrogen (Hopkins), Oxygen (HOpkins), Phosphorus
(HoPkins), Potassium (HopKins), Nitrogen (HopkiNs),
Sulfur (HopkinS), Calcium (Café), Iron (café), Magnesium
(Mighty good), Chlorine (Closed), Manganese (Monday),
Molybdenum (Morning), Copper (See you = Cu), Zinc
(Zen).
What is plant nutrition?
• Other elements play important roles in plant growth
and development.
• For instance, silicon (Si) improves plant strength and
disease resistance.
• Nickel (Ni) is another element considered important
for plant growth.
What is plant nutrition?
• Plants receive most of the nutrients they need from
the growing media.
• In order to maintain healthy plants, a grower must
provide the right type and amount of nutrients to the
media so the plants can absorb the nutrients and
grow.
• 1. A soil test can be performed to determine which nutrients
are present and which nutrients are deficient or lacking.
• 2. When nutrients are deficient in the soil, the plant growth
is adversely affected.
What is plant nutrition?
• It is common for plant leaves to show symptoms of a
nutrient deficiency by turning colors.
• When nitrogen is deficient in the soil, a
plant’s older leaves turn yellow.
• Abnormal yellowing of plant leaves is a
condition called chlorosis.
• A plant will show purpling in the
stem or leaf when phosphorus is
deficient.
What is pH and how is it modified?
• Many times, the nutrients needed for plant growth
are present in the soil, but the plants do not have
access to the nutrients.
• Nutrient availability is influenced by the pH of the soil.
• Soil pH measures the amount of acidity or alkalinity
and is based on the amount of hydrogen ions present
in the soil.
What is pH and how is it modified?
• Soil pH can range from 1 to 14.
• A pH reading of 7 is neutral.
• Substances that have pH readings
below 7 are acidic.
• Substances with pH readings
above 7 are alkaline or basic.
What is pH and how is it modified?
• Plants have specific pH ranges that are ideal for
maximum plant growth.
• Most plants grow best at a pH of 5.5 to 7 because the
most nutrients are available for the plant to absorb in
that range.
• Some important horticultural plants (azaleas) do
better in a medium that has a more acidic pH.
What is pH and how is it modified?
• A soil test can be performed to determine the pH of
the soil, and amendments can be added to modify the
pH.
• Limestone is commonly added to growing medium in
order to raise the pH.
• Sulfur or sulfur compounds can be added to the
media to lower the pH.
What are the components of a fertilizer?
• A fertilizer is any material added to growing medium
that provides nutrients for plants.
• Fertilizers vary in the components they contain, the
way they are applied, and the function they serve.
What are the components of a fertilizer?
• When choosing a fertilizer, one should always look for the
fertilizer analysis on the bag or box.
• The fertilizer analysis states the percentage of primary
nutrients (nitrogen, phosphate, and potash) present in the
fertilizer.
• The analysis is written as three numbers (i.e., 15-10-26), which
represent the percent of nitrogen, phosphorus, and potash
present in the fertilizer.
• They are always listed in that order.
What are the components of a fertilizer?
• Fertilizer analysis
What are the components of a fertilizer?
• If a fertilizer contains all three primary nutrients, it is
called a complete fertilizer.
• If a fertilizer is lacking any of the three primary
nutrients, it is an incomplete fertilizer.
• The fertilizer analysis does not equal 100%.
• The rest of the fertilizer composition consists of filler
materials (necessary for the fertilizer to be applied) and
possibly some micronutrients.
How are fertilizers applied to horticultural crops?
• Different plants have different nutrient requirements;
some are heavy feeders and others are light feeders.
How are fertilizers applied to horticultural crops?
Plants have different nutrient requirements based on the
stage of growth.
• The first stage is when the plant is a young seedling or cutting.
• In the second stage, vegetative or leafy growth is encouraged.
How are fertilizers applied to horticultural crops?
• This is followed by the flower bud initiation stage, the flower bud
development stage, and the flowering stages.
• Each stage calls for different rates of fertilizers.
• In the vegetative stage, plants use more nitrogen, whereas the flowering
stage requires less nitrogen and more phosphorus.
How are fertilizers applied to horticultural crops?
• Fertilizers are typically applied as water-soluble fertilizer
or as slow-release fertilizers.
1. Water-soluble fertilizers dissolve completely in water
and stay in solution.
• The concentrations of the water-soluble fertilizers are also
easily adjusted.
• The fertilizer concentrate is then mixed with the water in exact
proportions before irrigating plants.
How are fertilizers applied to horticultural crops?
• Fertilizer injector systems are standard equipment in
today’s greenhouses.
• With fertilizer injector systems, growers can provide
exact levels of water-soluble fertilizers to a crop.
How are fertilizers applied to horticultural crops?
2. Slow-release fertilizers continually discharge a small
amount of nutrients into the growing media over a
period of time.
• They are available in two forms.
• One form consists of a water-soluble fertilizer held within a
plastic resin or sulfur coating and is designed to allow a small
amount of fertilizer to be slowly released; they have the
appearance of little round beads and are sometimes mistaken
as insect eggs by the uninformed.
How are fertilizers applied to horticultural crops?
• The other type of slow-release fertilizer comes in a granular form.
• This type releases no more than one percent of the fertilizer in a 24-hour
period.
How are fertilizers applied to horticultural crops?
• There are a number of advantages to using fertilizer
injectors.
• The greenhouse plants are provided with constant liquid
feeding, which is especially important with soilless media
that have a low cation-exchange capacity.
• The plants are fertilized when they are watered, thus
reducing labor.
How are fertilizers applied to horticultural crops?
• All the plants of a particular crop receive the same levels
of nutrients, which assists in producing a uniform crop.
• In addition, adjustments to the level of nutrients in
solution can be made easily.
How are fertilizers applied to horticultural crops?
• Nutrients in solution are measured in parts per million
or PPM.
• Fertilizer rates can be taken from tables in reference
books or to instructions with their injector system, or
growers can calculate the amount of fertilizer needed to
reach a desired PPM.
• In either case, it is beneficial for a grower to understand
how to calculate parts per million (PPM) of fertilizer
nutrients.
How are fertilizers applied to horticultural crops?
1. An example problem might call for 200 PPM nitrogen.
• The chosen fertilizer is calcium nitrate with an analysis of
15-0-0.
• A rule of thumb in calculating PPM is that 1 ounce of
anything in 100 gallons H2O equals 75 PPM.
How are fertilizers applied to horticultural crops?
• Problem: Wanted, 200 PPM N 15-0-0 Calcium Nitrate
• Multiply the percent of the nutrient in the given fertilizer by 75.
• .15 N × 75 = 11.63 PPM N (if 1 oz added to 100 gallons) 200 divided by 11.63
= 17.2 oz of fertilizer needed in 100 gallons to get 200 PPM.
How are fertilizers applied to horticultural crops?
• If the injector system delivers 1:100 (one gallon
concentrate mixed with 99 gallons water for a total of
100 gallons), 17.2 ounces of fertilizer is needed for each
gallon of concentrate.
• If the tank holds 30 gallons of concentrate, 516 ounces
(32.25 pounds) of fertilizer is needed to deliver 200 PPM.
Review/Summary
•What is plant nutrition?
•What is pH and how is it modified?
Review/Summary
•What are the components of a fertilizer?
•How are fertilizers applied to horticultural
crops?
Plant Anatomy &
Physiology
Plant Breeding
Interest Approach
• Ask the students to tell you what they have heard
about genetically modified organisms (GMO). Make
a list of these items on the board. Discuss these
items briefly. Ask the students to make a copy of
the list. Tell them that you will take another look at
the items on this list after you have completed the
unit. At that time, ask what the students know
about GMOs. What items changed?
Objectives
• 1 Define plant breeding, and examine the history of plant
domestication and improvement.
• 2 Define the selection process.
• 3 Define hybrid, and describe the three basic types of hybrids.
• 4 Compare and contrast the four classes of commercial seed.
• 5 Discuss the advantages of genetic engineering as compared to
conventional plant-breeding techniques.
Terms
•
•
•
•
•
•
•
breeder seed
certified seed
double cross
foundation seed
genetic engineering
genotype
hybrid vigor
Terms
•
•
•
•
•
•
•
hybridization
mass selection
pedigree selection
phenotype
plant breeding
pure line selection
registered seed
Terms
•
•
•
•
•
•
selection
single cross
three-way cross
top cross
totipotent
transgenic plants
What is plant breeding, and what is
the history of plant domestication
and improvement?
• I. Plant breeding is the systematic
process of improving plants using
scientific methods. A variety of
methods are used to pollinate
certain plants and to prevent the
unwanted pollination of other
plants.
What is plant breeding, and what is
the history of plant domestication
and
improvement?
A. The goals of plant breeding vary according to the
type of plant improvement desired. Plant breeding
may be used to accomplish a variety of goals.
1. Gain disease resistance
2. Gain insect resistance
3. Improve environmental adaptation
4. Improve productivity
5. Make a species more suited to cultural practices
6. Obtain a more desirable product from plants
What is plant breeding, and what is
the history of plant domestication
and improvement?
B. The genotype is the genetic makeup of a
plant. Plant breeders are continually looking
for new plant genotypes that will produce
desired results. The outward or physical
appearance of a plant is the plant’s phenotype.
Changes in plant genotype will most often
result in a change in the plant’s phenotype. In
their work to develop new plants, plant
breeders often develop new plant cultivars,
which are cultivated plants that have specific
and distinguishable characteristics. Another
important attribute of a cultivar is that plants
within a cultivar will retain the characteristics
of that group when reproduced.
What is the selection process?
• II. One of the most common methods used
in plant breeding is selection, which is the
process of selecting plants for breeding
based on particular characteristics.
Selection leads to the dominance of certain
genetic traits, such as yield and quality of
the crop, drought tolerance, and resistance
to disease, pests, and herbicides.
What is the selection process?
• A. Selection for the purpose of plant breeding started with
the domestication of plants by early man. However, selection
has occurred without human influence. Natural selection is a
process essential to evolution. With an increased knowledge
of agriculture, humans introduced crop species to
geographical areas outside the natural range of the plant
species.
What is the selection process?
• 1. The key to selection is the availability of variability within
species. The best performing plants are chosen, and the rest of the
population is discarded or rejected. The offspring of the selected
plants are grown, and the best performing offspring are chosen for
the desired feature. This process is repeated over and over. In time,
a uniform crop with the desired characteristics is produced.
What is the selection process?
• 2. Plant selection is carried out by three common methods.
• a. Selection for uniform plants is known as pure-line selection. A
variety developed by this method is more uniform than a variety
developed by mass selection because all of the plants in such a
variety have the same genotype. Instead of adding the seed from
selected plants together, they are kept apart and used to perform
offspring tests.
What is the selection process?
• b. The simplest and oldest method, known as mass selection,
involves the selection of individual plants based on phenotypic
performance. The bulk seed produced is used for the next
generation. For hundreds of years, mass selection resulted in the
improvement of corn. However, improvement of yields slowed. The
problem was in the lack of control over the pollen parent. In effect,
the selection is limited only to the female parent plants.
What is the selection process?
• c. The selection from a well-documented
list of parentage is commonly known as
pedigree selection. Parental lines are
crossed. Each generation of selected
populations that follow is subjected to
selection until genetic uniformity is
reached. Records are kept of the origin of
the selected individuals or lines.
What is a hybrid, and what are the
three basic types of hybrids?
• III. Hybridization is the process of breeding distinctly
different species or varieties to achieve a hybrid. The goal of
this procedure is to gain a superior characteristic in the
offspring. Often hybrid plants exhibit a trait known as hybrid
vigor, which is a condition where the offspring may have
greater yield, height, disease resistance, or other traits than
either of the parents.
What is a hybrid, and what are the
three basic types of hybrids?
• A. Hybridization may be a double cross, a three-way cross, a single
cross, or a top cross.
• 1. A double cross is defined as the first generation of a cross
between two Foundation single crosses.
• 2. A three-way cross is the first generation of a cross between a
Foundation single cross as one parent and an inbred line or a
Foundation backcross as the other parent.
What is a hybrid, and what are the
three basic types of hybrids?
• 3. A single cross is the first generation of a cross between
two inbred lines: an inbred line and a Foundation backcross
or of two Foundation backcross.
• 4. A top cross is the first generation of a cross between an
inbred line and an open-pollinated variety or the first
generation of a cross between a single cross and an openpollinated variety.
What are the four classes of
commercial seed?
• IV. There are four recognized classes of commercial seed.
• A. Breeder seed is seed directly controlled by the originating
or sponsoring plant-breeding organization.
• B. Foundation seed is the progeny of Breeder or Foundation
seed handled to maintain specific genetic purity and identity.
What are the four classes of
commercial seed?
• C. Registered seed is the progeny of Breeder
or Foundation seed handled to maintain
satisfactory genetic purity and identity.
• D. Certified seed is the progeny of Breeder,
Foundation, or Registered seed handled to
maintain satisfactory genetic purity and
identity.
What are the advantages of genetic engineering as compared to
conventional plant-breeding techniques?
 V. Genetic engineering is the direct manipulation of
an organism’s genes. Also, known as recombinant
technologies, genetic engineering may involve
removing, modifying, or adding genes. This process
permits scientists to select and move fairly specific
sections of genetic material from one living
organism to another. The organisms do not have to
be related, so there are an increased number of
genes available for plant breeding.
WHAT ARE THE ADVANTAGES OF GENETIC ENGINEERING AS
COMPARED TO CONVENTIONAL PLANT-BREEDING
TECHNIQUES?
• A. The plants into which genes from another organism have
been incorporated are called transgenic plants. To
genetically modify an entire plant, the initial transfer of
genetic information occurs at the single-cell level. The
process is aided by the plant’s ability to grow from a singlecell, meaning the plant is totipotent.
What are the advantages of genetic engineering as compared to
conventional plant-breeding techniques?
• B. There are advantages to genetic engineering: yields
improve, money is saved because damage to the crop is
lessened, and the need for applying pesticides may be
reduced. Desired results can be obtained much more quickly
than with traditional breeding methods. There is also greater
control over which characteristics will be expressed in the
offspring.
What are the advantages of genetic engineering as compared to
conventional plant-breeding techniques?
C. Researchers have targeted a number of areas
for improved performance of agronomic crops.
They are developing plants that will be resistant
to diseases, herbicides, insects, and viruses. Work
is being done to engineer plants that will be
tolerant of cold, drought, and salty soils. The
nutritional properties of foods may be improved
through genetic engineering. Storage properties
may be improved to reduce losses to spoilage
before the food can be sold. Also, the appearance
of fruits and vegetables may be enhanced,
resulting in increased consumer appeal.
REVIEW
• 1. What is plant breeding, and what is the history of plant
domestication and improvement?
• 2. What is the selection process?
• 3. What is a hybrid, and what are the three basic types of
hybrids?
• 4. What are the four classes of commercial seed?
• 5. What are the advantages of genetic engineering as
compared to conventional plant-breeding techniques?