Why%20is%20light%20important? - PowerPoint PPT Presentation

About This Presentation
Title:

Why%20is%20light%20important?

Description:

... intensity suddenly changes Light intensity -Refers to brightness -Often the limiting factor for growing or maintaining plants ... for an interior ... – PowerPoint PPT presentation

Number of Views:343
Avg rating:3.0/5.0
Slides: 29
Provided by: Bryce93
Learn more at: https://www.uvm.edu
Category:

less

Transcript and Presenter's Notes

Title: Why%20is%20light%20important?


1
Why is light important?
  • 1.) Photosynthesis
  • 6CO2 12H2O (chl light) C6H12O6 6O2
    6H2O
  • 2.) Needed for chlorophyll

    production
  • 3.) Photomorphogenesis - development of certain
    plant parts, esp. flower initiation and
    development, seed germ...

2
Why is light important?
  • 4.) Anthocyanin production
  • 5.) Light is energy! Some is converted to heat
    when it strikes a plant surface
  • 6.) Light influences translocation in the plant
  • 7.) Light can affect abscission (dropping of
    plant parts) when intensity suddenly changes

3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
Light intensity
  • -Refers to brightness
  • -Often the limiting factor for growing or
    maintaining plants indoors

7
Light measurement
  • Light can be measured
  • in many ways!
  • - Light meter (photoelectric cell)
  • Footcandle the unit of illumination equivalent
    to that produced by a standard candle at a
    distance of 1 foot
  • Lux the unit of illumination equivalent to that
    produced by a standard candle at a distance of 1
    meter

8
  • Conversion
  • 1 fc 11.1 lux
  • These units measure only visible light (what the
    eye can see!)
  • For scientific reporting of light quantity, you
    might hear the following terms
  • candela
  • lumen
  • photon flux
  • quanta
  • joules

9
(No Transcript)
10
Sources of light for an interior
  • 1.) Natural (sunlight)
  • 2.) Artificial (bulbs and tubes)
  • 3.) Combination of the above

11
Sunlight
  • Factors affecting light penetration into a room
  • 1.) Windows
  • -type (glass/plastic/glazing)
  • -reflection
  • -barriers (overhangs, screens, curtains, shades,
    buildings and plants outside, dirt, etc...)
  • -orientation (N, S, E, W)

12
Sunlight
  • 2.) Latitude
  • (distance away from the equator)

24
22
20
Burlington
18
16
Atlanta
14
12
Equator
10
8
6
4
2
J F M A M J J A S O N D
J (calendar year)
13
Sunlight
  • 3.) Geographic region
  • -annual cloud cover
  • -atmospheric pollution
  • -humidity
  • -elevation

14
Artificial light
  • Supplemental to sunlight
  • -extend hours of light
  • -increase intensity of light
  • Sole source
  • -role room lighting
  • plant lighting
  • combination

15
Artificial light
  • Considerations not necessary with sunlight
  • spectral emission range of colors produced by
    the light
  • Light Quality!!!

Ultra- violet
Gamma rays
Infrared
Radio
X-rays
Visible Light (nanometers)
y e l l o w
v i o l e t
i n d e g o
o r a n g e
b l u e
g r e e n
r e d
380 430 470 500 560 600 650
760
16
Photosynthetically Active Radiation (PAR)
  • Range
  • 400 - 700 nanometers
  • Based on length of each wavelength of light
  • Chlorophyll and associated pigments utilize light
    energy primarily in the blue (430 nm) and red
    (670 nm)

17
Choosing artificial lights
  • Sources
  • Incandescent bulb
  • Pros
  • -small
  • -no special fixtures
  • -dramatic
  • -range of wattages available
  • Cons
  • -light is concentrated
  • -7 of energy usable light
  • -90 of energy heat!
  • -short life (750 hrs.)
  • -high in red/orange low blue

18
  • Fluorescent tubes
  • (cool-white, warm-white, daylight)
  • Pros
  • -diffuse light, new fixtures avail.
  • -efficient! (7x incandescent!)
  • -22 of energy usable light
  • -cool! 36 of energy heat
  • -last 8,000 - 9,000 hrs
  • (15x longer than incandescent!)
  • Cons
  • -work best if 70 - 90oF
  • - traditional fixtures bulky
  • -low far-red emission
  • -contain mercury
  • -emit ultraviolet light

19
Cool white
Warm white
20
Daylight fluorescent vs. Incandescent bulb
100 90 80 70 60 50 40 30 20 10 0
Fluorescent
Relative energy
Incandescent
400 500 600 700
(nanometers)
21
Sodium vapor lamps (HID lighting) Pros -25-3
5 of energy visible light Cons -yell
ow/orange/red spectral emission only! -large
ballast (requires special lighting fixtures)
22
(No Transcript)
23
  • What happens when light contacts a leaf?

Reflected
Absorbed
Transmitted
24
Ways to increase artificial light
  • Added white reflectors to fluorescent fixtures
  • Paint surrounding walls white
  • Regularly clean tubes to remove dust
  • Regularly clean plants to remove dust
  • Change tubes regularly
  • Keep plants centered under fluorescent tubes

25
(No Transcript)
26
Natural vs. Artificiallight intensities
  • Noon sun during summer can measure 10,000 fc
  • Cloudy winter day 500-2,000 fc
  • Inside rarely exceeds 1,300 fc
  • typical office 20-30 fc
  • typical living room
  • day 10-1,000 fc
  • night 5-10 fc

27
Minimum light required for plant maintainance???
  • 100 fc

28
-Light quantity-
  • Total light per day footcandles of light x
    hours of light/day
  • Example
  • 100 fc x 16 hrs of light/day
  • 1,600 fc hours/day
  • Sometimes, extending the daylength can
    compensate for a lower light intensity...
Write a Comment
User Comments (0)
About PowerShow.com