Unit 5 Lesson 3

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Unit 5Lesson 3

• Understanding Temperature Effects on Plant growth

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Extreme Sport
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Extreme Sport
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Extreme Sport
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Extreme Sport
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Extreme Sport
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Extreme Sport
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Freeze Damage

• Freezing can cause physical damage to the plant
  cells.
• Freeze damage occurs when the cell walls of
  plants break as the contents of the cells freeze.
  
• Hardier plants are better able to withstand low
  temperatures than
• less hardy plants.
• Freeze damage is very important to the orchard
  industries in agriculture.
• This is especially worrisome with a heavy frost
  around the time when fruit trees are in flower.
• Flowers can be lost from freezing, and hence an
  entire crop can be lost.
• To prevent serious damage to crops, growers may
  choose to spray their crops with water as this
  offers some protection to the flowers, leaves,
  and stems.
• A continuous application of water prevents the
  temperature of the plant tissues from dropping
  below 32 degrees F.

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Freeze Damage

• Landscape plants are also susceptible to freeze
  damage.
• If soil temperatures drop too low, roots can be
  killed and the plants will die.
• Landscape plants often have stems, buds, flowers
  and leaves that are marginally hardy to a frost.
  
• Heavy layers of mulch are often used to help
  protect delicate landscape plants from damage.
• Most agricultural crops are herbaceous annual
  plants and are more easily damaged by cold
  temperatures.
• Concern for freeze damage is greatest usually
  during planting season
• before plants are well established
• before harvest.
• To assess frost damage, one must be patient!
• It often takes several days to survey the damage
  and the ability of a crop to recover from the
  frost.

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Freeze Damage
Frost Damage on Corn
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Heat Damage

• The effects of heat damage may not be as evident
  as that of cold
• however it can be as detrimental to crop
  production causing a loss of
• Yields
• aesthetic appeal of crops
• Heat damage is worst when it is not only hot, but
  also dry.
• Plants have some ability to cool themselves by
  transpiration through their stomata.
• As this water evaporates, it has a cooling
  effect.
• Stomata close if the plant roots cannot supply
  water quickly enough to replace water lost from
  transpiration.
• This helps the plant to conserve water.
• Further water loss causes wilting
• a drooping condition and a lack of firmness in
  the plant tissues.
• Wilting will result in a loss of turgidity,
• or water pressure in the plant cells.
• Severe heat conditions can cause plant tissues to
  dry up and die.

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Heat Damage

• Excess heat usually causes scorch symptoms on
  leaf tips and interveinal areas.
• Portions of leaves shaded by other leaves, or
  leaves on the shady side of the plant, may be
  undamaged.
• Frequently, heat damage will occur uniformly
  over all plants in an affected area