Science of Plant growth

Question 1

What components are needed for photosynthesis?

Answer 1

Carbon dioxide, light and water = Glucose + Oxygen

Also nutrients to a lower degree.

Question 2

What are the 3 main limiting factors affecting photosynthesis?

Answer 2

Light
Temperature
Carbon Dioxide

Question 3

How can a grower maximise light intensity?

Answer 3

Positioning a greenhouse with the ridge East to West to maximise winter light.
Large panes of glass and metal frame rather than thicker wooden structure.
Use artificial lighting in the winter.

Question 4

What are the perfect conditions we are aiming for growing under cover?

Answer 4

Higher temperature
Maximum light.
Adequate Co2
Enough water.
Humidity control
Ventilation to cool and reduce risk of fungal disease.

Question 5

What is the optimum temperature range for most plants for photosynthesis?

Answer 5

20- 30 degrees.

Question 6

What is transpiration?

Answer 6

The evaporation of water through the leaves of the plant. The plant draws water up through it’s roots, and then it’s taken and distributed up the plant through transpirational pull. It evaporates through the stomatas on the leaves.

Question 7

If the atmosphere is humid what happens to transpiration?

Answer 7

It slows

Question 8

If the atmosphere is dry (or windy) what happens to transpiration?

Answer 8

It speeds up.

Question 9

How can we maximise photosynthesis in protected environment?

Answer 9

Large panes of glass and metal frame rather than thick wooden frame.
Heating the whole structure, or a heated bench for propagation.
Supplementary lighting in winter.
Shade in summer
Ventilation and air movement to decrease temperature in summer.
Humidification and Dehumidification systems
Co2 generator
Damping down
East West axis for maximum light penetration
Thin glass - 3mm is the optimum for light penetration.

Question 10

Describe hardening off technique

Answer 10

Plants raised under cover need to acclimatise to outdoor conditions.
Gradual process, can take 2-3 weeks depending on the plant and the time of year.
Plants could be moved from a heated green house to an unheated greenhouse for a week, or to a cold frame with the lid on. Then the lid can gradually be raised during the day.

Question 11

What examples of structures can be used for hardening off?

Answer 11

Greenhouse
Cold frame.
Glass cloche
Horticultural fleece

Question 12

6 Examples of protected environments?

Answer 12

Greenhouse
Alpine house
Conservatory
Cold Frame
Polytunnels
Cloches