1. Shannon McNeil AGED 410 Cal Poly, SLO
Plant Growth
Requirements
Shannon McNeil
AGED 410
Cal Poly, SLO
Modified by Georgia Agricultural Education Curriculum Office
July, 2002

2. Plant Growth Requirements
Temperature
Light
Moisture
CO2
Essential Nutrients

3. Temperature
Temperature effects many essential plant growth processes including most biochemical reactions in the plant.
Generally higher temperatures increase the rate of reaction

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

5. 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.

6. Light
Intensity provides energy for photosynthesis The 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.

7. Light
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

8. 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.

9. 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.

10. Moisture Water Quality: Excessive salt in the water may cause:
Leaf burn
Root corrosion
Poor seed germination

12. 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.

13. Essential Nutrients
16 essential nutrients that are normally available in the soil
Classified by use

14. 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.

15. 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?