Transcript plants that complete their life cycle in 1 growing season Winter

Plant Science
Plant Needs
 Climate factors impact plant growth and adaptation
 Temperature affects the growing season of a plant
Warm season crops cannot tolerate cold temperature and typically
die following the first frost
 Cool season crops cannot tolerate warm weather and typically die
when soil temperatures rise
Precipitation needs of a plant vary by species and determine where
plants can successfully grow
Light or photoperiod refers to the amount of time a plant receives
sunlight each day
Nutrients provide plants with building blocks they need to grow
 Nitrogen, phosphorus, and potassium are considered the most
important nutrients
Greenhouse, irrigation systems, and fertilizers are tools people can
use to adjust or modify these climate factors for plants
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Plant Life Cycles
 Annuals: plants that complete their life cycle in 1 growing
season
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Winter annuals are planted in fall, grow in winter, mature in spring
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Ex. Wheat, oats, rye, collard, clover, snapdragon, pansy
Summer annuals are planted in spring, grow in summer, mature in fall
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Ex. Peanuts, tomatoes, corn, squash, petunia, begonia
 Biennials: plants that live 2 growing seasons
 1st season  seed to maturity (dormancy stage)
 2nd season  reproduction to death
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Ex. Cabbage, beets, carrots
 Perennials: plants that live more than 2 growing seasons
 Deciduous perennials lose their lives during their dormant season
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Ex. Oaks, sweet gums, pecans, crepe myrtle
Evergreen perennials retain foliage year round
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Ex. Pines, furs, hollies, boxwoods
Vegetative Plant Parts
 Leaves
 Vital for processes such as photosynthesis,
respiration, transpiration, and energy/water storage
 Stems
 Provides support for plant, transports water,
minerals, and nutrients, allows for gas exchange,
and can store energy/water
 Roots
 Absorb water and nutrients from soil, anchor the
plant, and can store energy
Leaf Parts
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Blade: large, flat part where most of the photosynthesis occurs.
Margin: edge of the leaf.
Apex: tip of leaf.
Base: part of blade that attaches to petiole (bottom of leaf).
Veins: distribute water throughout the leaf.
 The way they are arranged is known as venation.
Midrib: primary vein in the center of the leaf.
Epidermis: the outer surface of the leaf. It holds all the parts
together and usually has a waxy coating to prevent excessive
water evaporation.
Stomata: tiny holes or openings in the epidermis. Water vapor,
oxygen, and carbon dioxide pass through them.
Petiole: is where the leaf is attached to the stem.
Leaves
 Used to determine if plant is monocot or dicot
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Monocots have parallel leaf venation
Dicots have palmate or pinnate venation
 Classified as simple or compound
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Simple  1 leaf blade per petiole
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Ex. Corn, oak, elm, wheat
Compound  2 or more leaflets per petiole
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Ex. Pecan, rose, locust
 Attached in 3 basic patterns
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Alternate  1 leaf per node on a stem, staggered
Opposite  2 leaves per node on stem
Whorled  3 or more leaves per node on stem
External Stem Parts
 Bud: contains undeveloped plant parts.
 Bud Scale: tiny leaf-like protective coverings over buds during
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dormancy.
Terminal Bud: large bud at end of stem.
Lateral Bud: buds that will become leaves.
Fruit Bud: buds that will become flowers.
Node: point along stem where leaves or other stems attach.
Internode: space between 2 nodes.
Leaf Scar: scar left when a leaf drops from stem.
Lenticel: tiny pores along stem that allow for gas exchange.
Terminal Bud Scale Scar: ring-like scar that can be found back
from the terminal bud, indicates end of growth from prior
growing season.
Bark: outer skin that protects stem from injury and holds it
together.
Internal Stem Parts
 Xylem: tissue that transports water and
minerals from roots to leaves.
 Phloem: tissue that transports food from
leaves to other parts of plant.
 Cortex: primary stem tissue, located between
bark and phloem.
 Cambium: layer where growth occurs.
 Pith: center of stem, stores food and
moisture.
Stems
 Plants are classified into 2 basic stem groups
 Herbaceous  soft, typically have short life cycle
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Ex. bedding plants
Woody  hard, typically have longer life cycle
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Ex. trees and shrubs, perennial ornamentals
 Succulents are plants that can store excess
water in their stem
 Aerial stems grow above ground
 Subterranean stems grow below ground
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Tubers, bulbs, corms, rhizomes
Root Parts
 Primary root: main root that all others grow
off of, first to emerge from the seed.
 Secondary root: branches off of the primary
root.
 Root hairs: small roots along primary and
secondary roots that grow between soil
particles and absorb water and nutrients.
 Root cap: mass of cells that protect root tips
as they grow.
Roots
 2 main kinds of roots
 Taproots  primary root is large and grows down
from stem
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Ex. Pine, carrot, dandelion
Fibrous roots  roots branch at a shallow level and
spread throughout the soil
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Ex. Corn, soybeans, tomatoes
 Adventitious roots grow from stems or leaves
of some climbing plants
Plant Processes
 Photosynthesis
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Allows plants to produce their own food
Carbon dioxide and water are converted to sugar and
energy when light is present and oxygen is produced as a
by-product
 Respiration
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Essentially the opposite of photosynthesis
Sugars are broken down for use and energy and carbon
dioxide are released
 Transpiration
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Evaporation of excess water through plant leaves and
stems
Cools the plant
More abundant during wet conditions
Reproductive Plant Parts
 Seeds
 Formed in ovary of flowers
 2 classifications  monocots and dicots
Monocots have 1 seed leaf or cotyledon
 Dicots have 2 seed leaves or cotyledons
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 Flowers
 Attract pollinators
 Contain reproductive plant parts
 Fruits
 Store and protect seeds
 2 classifications  fleshy (fibrous) and dry (pod or
hull)
Seed Parts
 Seed coat: outer covering that protects embryo
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and holds seed together.
Hilum or Seed scar: place where seed attached
to pod.
Micropyle or Silk Scar: tiny opening near hilum
where sperm entered ovule during fertilization.
Endosperm: food storage compartment.
Cotyledon: first leaves of a plant.
Plumule: undeveloped leaf system.
Epicotyl: undeveloped stem system.
Radicle: undeveloped root system.
Flower Parts
 Sepal: outer part of flower, usually green, found
at base of petals
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Covers and protects bud, supports petals
 Petals: attract insects for fertilization
 Stamen: male reproductive organ, located inside
petals
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Anther  end of stamen, produces pollen
Filament  stalk that supports anther
 Pistil: female reproductive organ, located in
center of flower
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Stigma  outer end with opening, often sticky to collect
pollen
Style  tube-like structure that connects stigma to ovary
Ovary  enlarged base that contains ovules
Flower Classification
 Complete: have all 4 principal parts
 Incomplete: lack at least 1 of the principal
parts
 Perfect: has both stamen and pistil
 Imperfect: lacks either a stamen or pistil
* A complete flower must be perfect, but an
incomplete can be either perfect or imperfect.
Plant Reproduction
 Propagation involves increasing the number of
plants by using natural reproduction
 Sexual propagation involves using seeds and
flowers
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Female sex cell is the egg/ovule which is produced in the
ovary
Male sex cell is the pollen which is produced by the anther
Fertilization occurs creating the seed which has a unique
genetic make-up
 Asexual propagation involves using vegetative
plant parts (no fertilization needed)
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Genetically identical offspring
Seeds are not necessary to produce new offspring
Asexual Propagation
 Cutting (most common – wandering jew)
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Remove short section of the parent plant with buds and place in
growing media
 Budding (fruit and nut trees, roses)
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Removing bud from one plant and placing it on another – must be
compatible
 Layering (shrubs, houseplants)
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Manipulate stems so that new roots grow from stems before they are
removed from parent plant
 Grafting (fruit trees, roses)
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Place section of stem onto the stem of another plant – must be
compatible
 Separation (spider plant)
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Structures are removed from parent plant to grow on their own
 Division (ferns)
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Plant parts are cut into sections that will grow into larger plants
 Tissue Culture (requires specialized lab)
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Removing cells from parent plant to allow for many new plants
Pollination
 Pollination is the transfer of pollen from the
anther (male) to a stigma (female) of a flower of
the same species.
 Pollen is often moved by wind, insects, birds, etc.
 Plants with brightly colors flowers attract insects
and birds.
 Flowers may be cross-pollinated or selfpollinated.
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Cross-pollination is when 2 different plants are involved.
Pollen from the anther of one plant is moved to the stigma
of another plant.
Self-pollination involves flowers of the same plant; it is
moved from one flower to another.
Fertilization
 Fertilization is the union of pollen (sperm)
with the ovule (egg).
 Pollen grains come in contact with the stigma
and are moved through the style to the
ovules. The ovule then develops into a seed.
 Fertilization initiates the growth of fruit and
seed.
 A fertilized ovary forms fruit. Once this fruit
is formed the flower is no longer useful
which is why many of them dry up and fall off
soon after fertilization.
Seed Germination
 Seed germination is the process of events where the
seed embryo moves from dormancy to active growth.
 It starts when the seed begins to absorb water and
swell.
 Primary root and stem structures emerge first.
 Process ends when the cotyledons start manufacturing
food.
 Moisture, oxygen, temperature, humidity, planting
depth, soil type, and sunlight can all impact seed
germination.
 Seeds are tested to determine germination rates
(percent germination). This is important because it
influences the number of seeds that should be planted.
Seed Treatments
 Some woody plants experience dormancy
and must be planted accordingly.
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Seed coat dormancy – some seeds have hard seed
coats that will not allow for moisture absorption.
These seeds must be broken or softened through
scarification without damaging the seed embryos.
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Ex. redbud
Embryo dormancy – some seeds embryos most go
through a chilling process before they will
germinate. This can be addressed by stratification –
placing seeds in a moist soil medium at temperatures
between 32-50° F for a certain period of time.
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Ex. elm
Nutrients
 Essential plant nutrients help with plant
growth and development. Plants will be
susceptible to disease or yield low amounts of
fruit without the right balance of nutrients.
 Additional nutrient needs can be provided by
fertilizers.
Major Plant Nutrients
 Nitrogen (N)
 Most important
 Helps with leaf and stem development, plant resistance, gives plants
dark green color
 Phosphorus (P)
 Helps with root and flower development, improves winter hardiness
 Potassium (K)
 Second most important
 Aids in food transportation, thickens cell walls, disease resistance
 Calcium (Ca)
 Increases pH, influences availability of other nutrients, cell wall
strength
 Magnesium (Mg)
 Essential for photosynthesis and chlorophyll production
 Sulfur (S)
 Lowers pH, root growth, protein formation
Fertilizers
 Any material used to provide plants with needed
nutrients.
 Inorganic fertilizers include commercial
formulations that are often man-made.
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Advantages: fast acting, proven performance, specific
nutrient composition
Disadvantages: expensive, can cause environmental
problems (leaching/run-off), greater burn potential, require
strict government labeling
 Organic fertilizers are found in many forms
include animal manure, cover crops, and
processing plant waste.
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Advantages: slow release, low burn potential, contains
microorganisms, conditions soil
Disadvantages: bulky, difficult to handle, weed seed is likely,
odor, heavy metals may be present
Why do we conduct soil tests?
 To increase yields of plants. By being able to
apply the needed nutrients, plants will
respond favorably and yield higher
quantities.
 To save money. By knowing exactly which
nutrients are in short supply, growers can
apply just the right amount and kind of
nutrients.
 Tests are important to determine how much
of each nutrient is available for plant growth.
What are the methods for determining
nutrient shortages?
 Visual inspection of the plant. This method is
very unpredictable because the plant’s
symptoms could be caused by something else.
 Soil tests. This is probably the most widely
used method. It is especially helpful when
tests are taken before the crop is planted.
 Tissue testing. Very accurate, but not used as
extensively.
Name the nutrient levels of plants that can
be divided into four levels:
 Deficient: The nutrient is clearly deficient; the growth
and productivity of the plant are affected. Growth
response is strong once the missing nutrient is applied.
 Sufficient: Just enough to satisfy plant needs. More
fertilizer will increase yields only slightly.
 High: Nutrient levels are high and yields are maximum.
Additional nutrients would be stored in the plant. This is
called luxury consumption (good when used as forage).
 Toxic: Nutrient levels are too high. Yields may decline.
The kind and amount of fertilizer to use
depend on several major factors.
 The requirements of the crop that will be
grown.
 The nutrients available in the soil.
 Soil pH
What are the types of fertilizers?
 dry fertilizer
 liquid fertilizer
 gas
What do the numbers on a bag of fertilizer
indicate to the user?
 The nutrients that are in the fertilizer
 First number tells the percent nitrogen
 Second number tells the percent phosphorus
(actually it is the percent of anhydride of
phosphoric acid)
 Third number tells the percent potassium
(actually it is the percent potash)
When is fertilizer applied to plants?
 Proper placement means it is close enough
for the roots to get it but not so close that it
damages the roots.
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pre planting applications
planting applications
post planting applications
top dressing
 side dressing
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Handling fertilizer
 Use only the recommended kind and amount
 Apply only where it is needed
 Store fertilizer in dry places where nutrients
won=t be lost.
 Clean equipment after use.
 Wear protective clothing and wash after
handling or using fertilizer.
 Fertilizer is a chemical that can cause
reactions that are dangerous and damaging.
How do you calculate the
percentage/pounds of N-P-K in fertilizer?
 Example: A bag of 20-20-20 contains:
 20% nitrogen or 20 pounds
 20% phosphorus in the form of P2O5 or 20 pounds
 20% potassium in the form of K2O or 20 pounds
 The remaining 40% of the 100-pound bag is
inert material.