Lighting

Question 1

How light effects plant growth:

Answer 1

1. Light is essential for photosynthesis. Lights that contain a similar spectrum to natural day light can augment or replace natural light.
2. Day length is critical to trigger growth and flowering in some plants (photoperiodism). Day length can be manipulate to cause growth and flowering at times when it wouldn’t naturally occur eg. Chrysanthemum production.

Question 2

Mercury-tungsten lighting

Answer 2

Fit into an ordinary light socket.
Cheap to run.
Satisfactory for seedlings and cuttings.
Can be used indoors for house plants.

Question 3

Metal halide

Answer 3

Produce light in the blue spectrum.
Encourages vegetative growth.
Shortens intermodal spacing, prevents leggy growth.

Question 4

Sodium.

Answer 4

Highly efficient.
Cover the red spectrum.
Good at encouraging flowering growth in later stages of development.

Question 5

LED

Answer 5

Specialist lamps are available which are tailored for requirements of plant producers.
Reduced electricity consumption.
Better coverage of light spectrum.
Low heat output enabling lights to be positioned close to the plants.