Shannon McNeil AGED 410

Cal Poly, SLO

Requirements

Modified by Georgia Agricultural Education Curriculum Office

July, 2002

Plant Growth Requirements

Temperature

Light

Moisture

CO2

Essential Nutrients

Temperature

Temperature effects many essential plant growth processes including most biochemical reactions in the plant.

•Generally higher temperatures increase the rate of reaction

Temperature

Plants should be selected according to the growth conditions and climate in the area.

Light

Light effects plants based on its intensity, duration and quality.

Quality

•Normal plant growth requires white light or sunlight

Duration

•Photoperiodism: the growth response to the length of dark period.

Light Intensity provides energy for

photosynthesisThe rate of photosynthesis is affected by the availability of water, CO2 and sunlight.

• Phototropism: the tendency for plants to “lean” in the direction of the greatest light intensity.

Plant types:• Short-day: Poinsettia and

Chrysanthemums require special time periods of light to initiate the blooming cycle

• Long-day: Azaleas can be forced to bloom sooner by adding light

• Day-neutral: Dandelions can initiate flowers under any day length

Light

Light We can control light and influence

blooming or vegetative growth by:• Shortening day with blackcloth: covering the

growing plant with an opaque cover to exclude light.

• Lengthening day with artificial light: adding light in the evening hours.

Moisture

Water carries essential nutrients from the roots and acts as a solvent for salts and minerals.

Moves photosynthetic products from the leaves via the phloem.

Water is a chemical reactant in photosynthesis.

Cools the plant.

Moisture Water Quality:

• Excessive salt in the water may cause: Leaf burn Root corrosion Poor seed germination

CO2

Required for photosynthesis Taken in through the stomata Air contains 0.3% co2

CO2 can be added in the greenhouse to increase production• This may be done with the use of gas

burners or the release of CO2 directly from tanks.

Essential Nutrients 16 essential nutrients that are normally

available in the soil Classified by use

Essential Nutrients

Primary nutrients:N, P, K

Secondary nutrients: Ca, S, Mg

Trace: Mn, Fe, Cu, Cl, B, Mo

Carbon, Hydrogen and Oxygen are usually not limited since they are freely available in the atmosphere.

Review

1. What is the importance of temperature, light, moisture and CO2 to plant growth?

2. In terms of plant production, how do we control light?

3. What is phototropism?

4. What are the 16 essential nutrients for plant growth?