Paper 6/18

Question 1

Air temperature.

Inside a protected environment.

Answer 1

Generally higher than outside.
Easily controlled by ventilation and/or heating.
Very high temperatures are less likely to happen although temperatures below 0 degrees C are possible.

Question 2

Air temperature outside a protected environment.

Answer 2

Variable according to seasons of the year, time of day etc.

Generally it will be lower than inside a protected environment.

Question 3

Air movement within a protected environment.

Answer 3

There is less air movement within a protected environment.
Air movement can be controlled by the use if ventelation.
Convection currents take place as the structure warms up naturally.

Question 4

Effect of high air temperature on plant growth

Answer 4

Higher levels of temperature usually encourage plant growth.
Range of suitable temperatures will depend on plant type.
Excessively high air temperatures wil slow down vital processes within the plant.
Leaf scorch can occur due to temporarily shortage of water in the leaf cells.

Question 5

Effect of low air temperature on plant growth.

Answer 5

Low air temperature will slow plant down processes in the plant eg. Photosynthesis and respiration resulting in reduced plant growth.
Very low temperatures can cause plant cells to freeze, cells subsequently collapse and die.

Question 6

Effect of higher levels of air movement on plant growth.

Answer 6

Amount of water loss from the foliage of the plant by transpiration will affect the amount of water and nutrients taken up by the plant.
Excessive air movement can cause physical damage to the plant.

Question 7

Effect of lower levels of air movement on plant growth.

Answer 7

Reduced rate of transpiration which will affect the amount of nutrients taken up by the plant and increase level of humidity around the plant.

Question 8

Factors that affect the amount of natural light entering a glasshouse.

Answer 8

Design of the protective structure
Orientation of glasshouse.
Cleanliness of cladding material.
Constructional materials.

Question 9

Orientation of structure

Effect

Answer 9

Amount of natural light entering a protective structure depends on the amount of glass presented to the sun.
If the orientation is east/west with the longest side facing the sun the amount of light entering the glass house will be maximised.

Question 10

Design of protective structure.

Effect on natural light entering protected structure.

Answer 10

Most light will pass into structure where light strikes the glass at an angle of 90 degrees. This is known as the angle of incidence.

By designing a mansard shaped structure or raising the eaves as high as possible natural light entry into green house will be maximised.

Question 11

Shade paint

Answer 11

Applied to the outside of a glasshouse structure in early spring as sun becomes stronger.
Plastic based and sprayed on or painted on using a brush.

Question 12

Shade netting

Answer 12

Eg. Rockolene can be suspended across the base of the eaves of the structure in early spring to avoid leaf scorch on plants. It is removed in Autumn when light levels are reduced.

Question 13

Supplementary lighting

Answer 13

Artificial lighting used to supplement natural light.
Extends growing day in winter and provides additional light when the natural light is insufficient to achieve optimum growth.

Example. Early main season tomato crop may require supplementary lighting between potting and planting in the season when natural light is poor.

Question 14

Polystyrene containers.

Answer 14

Characteristics: very light weight, good insulator of heat and cold.
Benefit - easy to transport as so light weight.

Limitation - non recyclable

Question 15

Plastic containers

Answer 15

Characteristics: impermeable to water, brittle when exposed to light.

Benefit - light weight and impermeable to water
Limitation - becomes brittle with age and when exposed to light.

Question 16

Peat when used in protected environments

Answer 16

Characteristics: acidic, difficult to re-wet once it has dried out.
Benefit - natural material can be reused.
Limitation - difficult to re-wet when dried out.

Question 17

Propagation of Cyclaman persicum.

Answer 17

Cyclamen is a large seed.
Seed has hard seed coat which can be softened by soaking for 12 hour before sowing.
Seeds can be sown in individual modules or seed trays.
Use peat based seed growing media.
Keep moist but not wet.
Germination temperature 21 - 24 degrees C

Question 18

Establishment of Cyclamen persicum.

Answer 18

Once germinated a corn will begin to form.
Pot on in growing media such as John Innes No 1.
Do not bury the form.

Question 19

Cyclamen persicum - plant husbandry.

Answer 19

Temp. 15 - 18 degrees C.
Well ventilated.
Kept moist by use of capillary action.
Avoid overcrowding of plants, leaves should not be touching.
Feed with liquid feed, potassium is particularly important at flowering stage.
Pot on into using John Innes No 3 into 14 1/2 cm pots as required.

Question 20

Damage done by Vine Weevil to Cyclamen persicum

Answer 20

Rounded larvae of vine weevil has brown head and will eat roots of plant.
In warm weather plants will wilt due to lack of roots.
In severe cases all the roots will be eaten and the plant will collapse and die.

Question 21

Damage caused by Sciarid fly on Cylamen persicum.

Answer 21

Larvae of Sciarid fly are long, small and almost transparent.
They tunnel into root system and eat roots until shredded.

Adults can be seen on the surface of the growing media.