Plant Processes and Factors That Affect Them

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Plant Processes and Factors That Affect Them

• Original Power Point Created by
• Mr. Morgan

Modified by the GA Agriculture Education
Curriculum Office July 2002
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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

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Why Plants are a Vital Part CO2/O2 Exchange

• The large-scale destruction of plants may lead to
  problems with the air we breathe

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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

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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 --gt C6H12O6 6O2
• Photosynthesis occurs only in the presence of
  light

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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 --gt 6CO2 6H2O energy
• Respiration occurs 24 hours a day

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Plant Growth Requirements
A. Nutrients B. Air C. Water D. Light E. Correct
temperature
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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

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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

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Phototropism

• Phototropism is the development responses of
  plants to the relative direction of the light

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Thermotropism

• Thermotropism is the plant characteristic in
  which a plant will grow towards areas with more
  desirable temperatures

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Places where Plants Get Nutrients for Growth

• Soil
• Air

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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

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Functions of Secondary Nutrients

• Calcium components of cell walls, cell growth
  and division
• Magnesium central part of chlorophyll,
  photosynthesis
• Sulfur amino acids and vitamins

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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

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Effects of CO2 Fertilization on Plant Growth

• Plant growth will increase as carbon dioxide
  increases, as long as carbon dioxide is the
  limiting nutrient

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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