Plant Growth and Development

Essential Standard 4.00: Examine factors relating to plant growth and development.

Objective 4.01

• Explain the growth process of plants

Processes of plant growth

• 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

C6H12O6+6O2

Carbon Dioxide

Water Light Energy

Glucose Sugar

Oxygen

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

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

Plant Cells

• Basic unit of growth• A nucleus and a mass of

protoplasm contained within a plasma membrane

Parts of a Plant Cell

• Nucleus– location of plant’s genetic and

hereditary make-up

• Protoplasm– the living matter of the cell

• Plasma Membrane– surrounds protoplasm and allows for

exchange of nutrients and gases into and out of cell

Parts of a Plant Cell

• Cell Wall– rigid and provides support for the cell

and thus the whole plant

Parts of a Plant Cell

• Other Structures– Chloroplasts– Vacuole– Plastids– Mitochondrion

Parts of a Plant Cell

Plant Cells

Plant tissue

• A group of cells with similar origin and function

• Classified according to their origin, structure and physiology

• Structure of permanent tissue– simple-usually one type of cell– complex-several types of cells

Tissue origin and function

• Meristematic-near tip of stems and roots where cell division and enlargement occur

• Vascular cambium-increase growth in diameter of stems

Simple Tissues

• Epidermal-one-cell thick, outer layer, protects and prevents water loss

• Sclerenchyma-have thickened cell walls and contain fibers to give strength and support to plant structures

Other tissues

• Collenchyma-have thick cell walls that strengthen and support plant structures

• Parenchyma-fleshy part of plant that stores water and nutrients

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

Moisture

• Needed in large amounts because plant tissues are mostly 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

Hardiness Zones

Hardiness Zones

• North Carolina– Zones 6 to 8

• Considers minimum temperature extremes– Zone 6

• -10 to 0 degrees F– Zone 7

• 0 to 10 degrees F• Charlotte

– Zone 8• 10 to 20 degrees F

Plant Propagation

Essential Standard 4.00: Examine factors relating to plant growth and development.

Objective 4.02

• Use sexual and asexual methods of propagation.

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

Endosperm

Seed Coat

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– mound layering

Trench Layering

Division or Separation• Cutting or pulling apart plant

structures for reproduction– bulbs– corms– rhizomes– tubers– runners– stolons– suckers

Bulbs

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

• If the scion is smaller than the rootstock– cleft– side– notch– bark inlay

Methods of Grafting

Budding• A form of grafting when a bud is

used– patch budding– T-budding– Chip Budding

Chip Budding

How to perform T-budding

Step 1

Step 2

Step 3

Step 4

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

• Increase tolerance to drought• Improve environment• Increase production• Other genetic changes

Benefits of Biotechnology