Urban farming

Question 1

What is Photosynthetic Photon Flux
Density (PPFD)?

Answer 1

• ‘Intensity’ of PAR that a plant needs (quality of light)

Question 1

What is Photosynthetically active radiation (PAR)?

Answer 1

Spectral range of electromagnetic radiation that plants use in the process of photosynthesis

Question 2

What is Daily Light Integral
(DLI)?

Answer 2

The ‘amount of light’ that a plant needs
per day (quantity)

Note : IN PFAL (plant factory with artifical lighting), PPFD is usually kept constant unlike natural sunlight, which varies in intensity, duration and spectral composition during the day

Question 3

What is Light compensation point?

Answer 3

light intensity where the rate of photosynthesis is equal to the rate of respiration.

For growth to occur, light provided must be at higher levels than light compensation point so rate of photosynthesis > resp

Question 4

What is light saturation point?

Answer 4

Light intensity where maximum photosynthetic rate is attained. Beyond which, the rate of photosynthesis is no longer affected by increasing light intensity.

Question 5

What is photoperiod?

Answer 5

Flowering response that corresponds to the
number of light hours in a 24-hour period

Question 6

The flowering of day neutral plants growth rate is dependent on day/night length. True or False?

Answer 6

False, flowering is triggered when plants reach a certain age.

Question 7

what are the 3 advantages of chelating cationic nutrients?

Answer 7

• Protect ions from unfavourable chemical reactions.
• Prevent formation of insoluble precipitates.
• Allows uptake via foliar feeding (direct uptake of nutrients by applying on leave of plant)