Light Measurements
Light can be measured as either ______ or ______.
Fill in the blanks
waves or particles
What is the DLI (calculated to one decimal place), for a 14 hour photoperiod with light intensity of 375 umol?
18.9 DLI
If you add more energy (in Watts) to the growzone than you remove, would you expect that grow space to increase or decrease in temperature?
What does VPD stand for?
200 Bonus: What units do we measure VPD in?
Vapor pressure deficit
200 Bonus: kPa
Describe the visual symptoms of an iron deficiency.
Chlorosis of new growth with uniform coloration and steady transition.
What unit do we measure particles of light in?
micromoles
What is the DLI (calculated to one decimal place), for a 20 hour photoperiod with light intensity of 165 umol?
11.9 DLI
What is Heat Emission?
Process by which the plant radiates infrared radiation to a cooler object until both objects hit equilibrium
True or False: VPD is a measurement of the difference between the current amount of water vapor in the air, and the maximum amount of water vapor that air at that temperature could hold.
True
This element is the most numerous of the mineral nutrients within the plant. It makes up to 20% of the total biomass of a plant by constituting the majority of the building blocks for proteins, nucleic acids, etc. It is important to balance this nutrient with potassium to steer plant growth.
100 Bonus: Name one of compounds of that element that is added to our grow zone.
Nitrogen
100 Bonus: Ammonium, Nitrate, CaNO3, KNO3, NH4NO3, MgNO3
What unit of measurements do we measure light spectra in?
wavelength in nanometers
What is the DLI (calculated to one decimal place), for a 18.5 hour photoperiod with light intensity of 302 umol?
20.1 DLI
What is Conduction?
Conduction is the transfer of thermal energy through direct contact between atoms or molecules, typically in solids, from a region of higher temperature to a region of lower temperature.
When water is added to the surface of leaves, the highest energy molecules escape the liquid water and enter the air column, thus leaving the rest of the water cooler. What is this method of heat transfer called?
Evaporation
Describe what is meant when iron is described as chelated.
200 Bonus points: Name two types of chelated iron that we use in our nutrient mix.
Iron is bonded with an organic molecule to stabilize it and protect it from pH and oxidation changes.
200 Bonus: DPTA, EDHA, EDTA - Prayon doesn't count
What is the small slice of the total electromagnetic spectrum that we measure because it is required for photosynthesis?
100 Bonus: what are the nanometer values for that range?
PAR, or ePAR
PAR 400-700nm
ePAR 380-740nm
What is the DLI (calculated to one decimal place), for a 12 hour photoperiod with light intensity of 557 umol?
24 DLI
What is Convection?
Convection heat transfer is the process of transferring heat between a solid surface and a moving fluid, combining molecular diffusion and bulk fluid motion.
True or False: The vapor capacity of the air doubles with every 20F increase in temperature.
200 Bonus: Would a higher VPD mean that the air can hold less or more moisture?
True: Air at 80F would hold about twice the water vapor that air at 60F would hold.
200 Bonus: A higher VPD means that the air can hold more moisture than it is currently.
This element is key for the formation of chlorophyll, as well as other enzyme functions. It has an antagonistic relationship with calcium since they are very close on the periodic table.
100 Bonus: Name the compound of that element that is added to our grow zone.
Magnesium
100 Bonus: Magnesium sulfate, Magnesium nitrate
What composite number do we use to measure the combined photoperiod length and light intensity?
Day-Light-Interval (DLI)
What is the DLI (calculated to one decimal place), for a 17.6 hour photoperiod with light intensity of 289 umol?
18.3 DLI
What is the difference between Relative humidity and Absolute Humidity?
The Relative Humidity is the relative holding capacity of moisture in the air and is affected by the temperature while the Absolute humidity is the total amount of water (g/kg) in the air.
True or False: For single leaves, the transpiration rate is proportional to the difference between moisture concentration (water vapor pressure) in the leaf’s internal airspace (i.e., stomatal cavities) and the surrounding air.
100 Bonus: Why?
True
100 Bonus: Because moisture moves by diffusion
Name 2 of the 5 nutrients that can have an anatgonistic relationship with iron.
300 Bonus: 100 points each for the remaining 3 nutrients (up to 300 points)
Calcium, Copper, Manganese, Phosphorus, and Zinc