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Plant Needs:

Above the

Ground

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Living Above the Ground Plants live in two environments - above & below

ground.

The entire plant is subject to conditions above the soil line.

Sudden environmental changes are likely to happen above

the soil.

What environmental factors do plants deal with

above the soil?

Temperature

Light

Humidity

Diseases

Insects

Particles or gasses in the air

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Temperature What temperature extremes do plants live in?

Plants may live in areas that are above freezing for only a

short time of the year.

Some plants live in very harsh desert conditions.

Garden Plants prefer different temperatures.

Cool weather: cabbage, lettuce, & kale.

Hot weather: corn, beans, tomatoes.

How does temperature affect growth?

Generally, growth rate increases as thetemperature gets closer to 90F.

As long as sufficient H2O is available.

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Light How does light affect plant growth?

No green plant can exist without it.

Plants may receive too much light.

Light may affect flowering & dormancy.

What is photoperiodism? The response of the plant to length of day/night.

Mums and Christmas Cactus: bloom in short day.

Lettuce and Radish: bloom in long day.

What other reactions to light can you think of?

Phototropism - moving toward light

Look through a garden catalogue What kind of

light requirements do different plants have?

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Humidity

Humidity is the measure of H2O in the air.

Why do you think humidity affects plants?

Dry air causes plants to loose water rapidly.

Eventually results in wilt.

Permanent wilt eventually results in death.

Plants prefer 40-80% relative humidity

Conditions which are too humid may cause

fungus diseases to spread.

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Diseases and Insects What damaging insects can you think of?

What plant diseases can you think of?

Any time diseases or insects infest plants, plants fail

to produce to their full capacity.

Leaf damage = less food for plant

Stem damage = stops supply of nutrients & water

Root damage = robs plants of nutrient supply

What are some methods used to control these

problems?

Insecticides, Fungicides, other sprays, crop rotation,

resistant crop varieties.

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Gases and Air Particles

What gases are essential to plants?

CO2 - production of energy during photosynthesis

O2 - production of energy during respiration (night)

CO2 increases production - up to 50%

Some particles may damage plants:

Sulfur dioxide, carbon monoxide

both will reduce production.

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Plant Needs:

Above the

Ground

2001 AgriTeach.comTM (12901ms)