Transcript Plant Processes and Factors That Affect Them

Plant Processes and Factors
That Affect Them
Original Power Point Created by
Mr. Morgan
Modified by the GA Agriculture Education Curriculum Office
July 2002
Why Plants are a Vital Part of
CO2/O2 Exchange
 Animals
breathe in air, use oxygen, and
exhale carbon dioxide
 Animals need oxygen to survive
 Plants do the opposite- they take carbon
dioxide from the air and give off oxygen
 Through this cycle the correct balance of
oxygen and carbon dioxide is maintained in
the atmosphere
Why Plants are a Vital Part CO2/O2
Exchange
 The
large-scale destruction of plants may
lead to problems with the air we breathe
Why Photosynthesis is Essential to
CO2/O2 Exchange
The broad surface area of the leaf absorbs sunlight
to be used as energy
 Carbon dioxide is taken from the air and the other
nutrients (including water) are taken from the soil
and transported to the leaves in the water through
the xylem
 Chloroplasts participate in a chemical process that
converts their raw materials into usable food for
the plant

Why Photosynthesis is Essential to
CO2/O2 Exchange
The chemical reaction takes carbon dioxide and
water and converts these materials to sugar and
oxygen
 6CO2 + 6H2O --> C6H12O6 + 6O2
- Photosynthesis occurs only in the presence
of light

Respiration Importance in CO2/O2
Exchange
 Respiration
is the reverse of
photosynthesis
 Sugar and oxygen are broken down,
releasing carbon dioxide, water, and
energy
 C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
 Respiration
occurs 24 hours a day
Plant Growth Requirements
A.
B.
C.
D.
E.
Nutrients
Air
Water
Light
Correct temperature
How Light and Temperature affect
Plants
 Light
intensity- growth is greatly reduced at
lower light intensities. Most plants cannot
grow below 100-200 foot candles, about the
level of light in an average room
 The compensation point is the light intensity
at which a plant will maintain itself but not
grow
 Temperatures at night are lower, therefore
the plant goes through respiration
How Light and Temperature affect
Plants
 Light
duration- the length of the day helps
plants distinguish what time of year it is
 Some plants will only flower in the spring
but can be induced to flower in the winter
(in a controlled environment) by
extending the light duration
 Temperatures during the day hours are
higher and encourage plant development
Phototropism
Phototropism is the development
responses of plants to the relative
direction of the light

Thermotropism
 Thermotropism
is the plant characteristic
in which a plant will grow towards areas
with more desirable temperatures
Places where Plants Get Nutrients for
Growth
 Soil
 Air
Functions of Primary Nutrients
Nitrogen: fast growth, synthesis of organic
compounds- including amino acids, proteins,
coenzymes, nucleic acids, and chlorophyll
 Phosphorus: energy storage and transfer
 Potassium: photosynthesis, sugar
translocation, and enzyme activation

Functions of Secondary Nutrients
Calcium: components of cell walls, cell
growth and division
 Magnesium: central part of chlorophyll,
photosynthesis
 Sulfur: amino acids and vitamins

Functions of Micronutrients
Iron: synthesis of chlorophyll
 Boron: regulation of metabolism
 Zinc: protein synthesis
 Manganese: respiration, photosynthesis
 Copper: enzyme activation
 Chlorine: photosynthetic processes
 Sodium: plant-water relations

Effects of CO2 Fertilization on Plant
Growth
 Plant
growth will increase as carbon
dioxide increases, as long as carbon
dioxide is the limiting nutrient
Five Types of Growth Regulators

Auxins: growth promoting hormone


Freshly cut stems are dipped into this
Gibberellins: stimulates growth in plants

Dwarf plants transform into normal sized plants
Kinins (cytokinins): influence in stimulation of cell
division
Dormin: promotes flowering in some short day
plants and promotes dormancy in buds and seeds
Ethylene: uniform ripening, sex conversion
