Components of Sun’s Energy that Support Plant Growth:
How does the sun's rays affect plant growth? Understanding the sun's differing components and their effects is key to knowing how to best support your plant's needs.
Sun’s energy is composed of:
PAR: Photosynthetically Active Radiation
Roughly equivalent to visible light spectrum 400-700nm
Colors below play the greatest role in plant growth
Blue Light 400- 495nm
Green Light: 495 –570nm
Red Light: 600-700nm
Far Red: 700- 800: Not as directly involved in photosynthesis but is a key component in other parts of plant development. Difficult for the eye to see, appears to be a deep red
Heat/Temperature
UV (A and B; key for flavonoid production)
UVA 315-400 nm;
Stem length and leaf breadth
Increases flavor and develops anti-oxidants
Helps cell wall strengthen to provide protection
Too much reduces efficiency of photosynthesis
UVB: 280-315nm
Starts production of flavonoids and anthocyanins
Too much can cause various stress responses
Other Aspects of the Sun’s influence on plant growth:
Daily Light Integral:
Amount of PAR light received by a plant in 24 hours
Measured in Photons of PAR per square meter per day (mol/m2/day)
Different plants need different DLI for optimal photosynthesis
Photosynthetic Photon Light Density
Amount of PAR received by plant at a given time
Location of sun in the sky- indicates to plants the length of the day
Important to plants sensitive to specific photo-periods, which influences flowering
Part 3: We will discuss how shade can directly impact your plants' growth.