During photosynthesis, light provides the energy required to fix (reduce) which atmospheric gas to form carbohydrates?
N2
O2
CO2
SO3
None of the above
Which is a term that refers to changes in plant growth and development that are controlled or influenced by light but not as a function of photosynthesis?
Thigmotrophic
Photomorphogenic
Skolotrophic
Alphatrophic
None of the above
Which is the term used to describe discrete particles of light with varying energy levels?
Photons
Volts
Mhos
Ohms
None of the above
To what does the term "PAR" refer?
Photon altered radiation
Photosynthetically active radiation
Photosynthetically altered radiation
Photonically absorbed radiation
None of the above
What range of wavelengths is generally used to define "PAR"?
400 - 700 nm
500 - 900 nm
200 - 900 nm
500 - 1000 nm
None of the above
Which term refers to the duration (over a 24 hour period) that a plant perceives light?
Skotoperiod
Nictoperiod
Optiperiod
Photoperiod
None of the above
A plant that becomes reproductive when the night length is less than some critical value is referred to as being what type of plant?
Long-day plant
Short-day plant
Day-neutral plant
Facultative plant
None of the above
A plant that becomes reproductive when the night length exceeds some critical value is referred to as being what type of plant?
Long-day plant
Short-day plant
Day-neutral plant
Facultative plant
None of the above
Why are footcandles not considered an appropriate measure of light with respect to photosynthesis?
The instrument used to measure footcandles are non longer available.
The measurement is expressed as Einsteins/second/square meter.
Devices to measure footcandles mimic the sensitivity of the human eye.
All of the above
None of the above
What are the units of measure for quantum flux density?
watts
moles/m(Square)/second
volts
watts/m(Square)
None of the above
What is the optimal light level (mmole/m(Square)/second) for production of geraniums (Pelargonium x hortorum)?
150 - 250
250 - 450
600 - 900
900 - 1200
None of the above
What is the optimal light level (mmole/m(Square)/second) for most foliage plants?
150 - 250
250 - 450
600 - 900
900 - 1200
None of the above
Which is not a common method used to reduce light levels in a greenhouse?
Latex shading
Polypropylene shade cloth
Aluminum-coated polyester shade cloth
Retractable shade systems
None of the above
Which are common plant responses to suboptimal light levels?
Flower bud abortion
Reduced growth rates
Increased internode lengths
Increased disease incidence
All of the above
Incandescent lamps are typically not used for photosynthetic lighting. This is because, in addition to the relatively low quantum flux density provided by a typical incandescent bulb, a large portion of the energy given off by an incandescent bulb is emitted as what type of radiation?
Infrared
Radio waves
X-rays
Blue visible light
None of the above
Which is (are) a significant difference(s) between "warm white" and "cool white" fluorescent lamps?
Warm whites emit more photons in the blue region of the visible spectrum
Warm whites emit more photons in the red region of the visible spectrum
Cool whites are only available 60-watt bulbs
Cool whites are only available in 100-watt bulbs
None of the above
Which is (are) a significant difference(s) between incandescent lamps and fluorescent lamps?
The type of ballast required
Efficiency rating
Bulb life span
Wavelengths emitted
All of the above
For what does the term "HID" stand with respect to greenhouse lighting?
Heavy industrial lighting
Heavy industrial density
High intensity discharge
High incandescent discharge
None of the above
What is a major reason that low-pressure sodium lamps are not well suited for use in HID lighting in greenhouses?
They emit light in a narrow band at approximately 590 nm
They emit light in a narrow band at approximately 680 nm
They emit light in a narrow band between 400 to 700 nm
They emit light in a narrow band at approximately 730 nm
None of the above
Which is the most common type of bulb used for HID lighting in greenhouses?
Low-pressure sodium
High-pressure sodium
Incandescent
Pressurized incandescent
Warm white fluorescent
When using incandescent bulbs to create a night interruption and an artificial "long day", what is the most common period during the night that the lights are turned on?
5:00 to 7:00PM
4:00 to 10:00PM
10:00PM to 2:00AM
5:00AM to 8:00AM
None of the above
When conducting HID lighting to increase photosynthesis, the lamps are turned on for approximately how long?
3 hours
4 hours
16 hours
24 hours
None of the above
Which type of bulb is most commonly used in greenhouse to conduct a night interruption and produce and artificial long day?
Warm white fluorescent
Cool white fluorescent
Incandescent
Low pressure sodium
None of the above
A shade cloth that blocks out light is often used to create which photoperiodic condition in a greenhouse?
A artificial short day
A artificial long day
A neutral day length
All of the above
None of the above
What is the function of a reflector used on an HID lamp?
Improve the distribution and uniformity of the emitted light
Deflect rain or water that might drip from the ceiling