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

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 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.

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

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?