Benefit of Greenhouse Production

Question 1

Define sustainability

Answer 1

Able to be maintained at a certain level/rate conserving an ecological balance by avoiding depletion of natural resources.

Question 2

Name the 3 pillars of sustainability

Answer 2

1) Environmental: ecological integrity maintained and resourced consumed at rate of replenishment
2) Economic: generates enough profit to ensure operations to continue
3) Social: communities and citizens healthy, safe and secure in relation to human rights.

Question 3

Benefits of GH production

Answer 3

1) Potential for improved yields: by reducing plants exposure to harsh climates=higher output
2) Soilless production: improved land efficiency (don’t need acres of great soil), local production can lead to less transportation needed to get produce to people = lower carbon footprint.
3 Potential to provide alt.IMP (integrated pest management)

Question 4

What are the 3 things that impact a pest/disease out break in a GH (Plant Pest Triangle)

Answer 4

*need all three for outbreak to occur, if u can stop/ change course of one it can be avoided.
1) Host/Crop
2) Environment
3) Plant/Pest

Question 5

Provide 2 examples of optimal use of resources

Answer 5

1) Collect and use recirculated run off water and nutrient solutions by using a closed irrigation system
2) Improve structures and equipment, such as using thermal energy curtains to reduce heat loss at night (can reduce energy cost of GH 30-40%)

Question 6

Name 5 of the things you should consider when doing GH production plans.

Answer 6

*5 of any of these
1) Sales and Marketing (need a market to sell the product, needs to be sellable to cover the costs)
2) Greenhouse Design and Facility Planning
3) Labour Planning
4) Maintenance Planning
5) Energy Planning
6) Future Planning
7) Financial Planning

Question 7

6 Aspects that need to work together for successful GH production.

Answer 7

1) Type of production system and plant support.
2) Climate and growing strategies.
3) Structure and equipment (do purchases or arrangements need to be made?).
4) Irrigation systems (know crop requirements to make decision).
5) Substrate selection (strong iteration with water).
6) Environmental control systems (how accurate it is).

Question 8

Define crop physiology

Answer 8

The study of the internal processes responsible for plant growth, development and the production of crop yields.

Question 9

What is ‘Forcing’?

Answer 9

An attempt to grow a crop in a GH to produce a higher yield than normals or to produce a crop outside its normal growing conditions.

Question 10

Explain Photosynthesis

Answer 10

-occurs in the chloroplasts
-the process in which light energy is converted to chemical energy in the form of sugars

Question 11

Explain Respiration

Answer 11

-the opposite of photosynthesis
-occurs in the mitochondrion
-used for the process of growth and development in the plant

Question 12

How does light intensity affect photosynthesis and respiration?

Answer 12

a) as light increases the rate of photosynthesis increases to a point of saturation
b) uses a wavelength of 400-700nm also know as PAR, most effective wave length for photosynthesis

Question 13

What is Light Compensation Point?

Answer 13

lowest intensity needed, below which no growth occurs, indicates need for supplemental lighting

Question 14

Explain Light Saturation Point

Answer 14

Light intensity that will maximize the rate of photosynthesis, indicates need for supplemental light or shading.

Question 15

What does DLI stand for and what is it?

Answer 15

Optimal Daily Light Integral: ideal amount of light radiation in the PAR wavelength.

Question 15

How does temperature affect photosynthesis and respiration?

Answer 15

As temperature increases the rate of photosynthesis increases to a max. but then decreases with further temp increases.

Temperature is also the primary influence on the rates of respiration. As temp increases the rate of respiration also increases.

Question 16

What is a base temperature?

Answer 16

Lowest temp, below which plants can not grow, an indication for supplemental heating.

Question 17

Max. Threshold Temperature?

Answer 17

The highest temp, above which plant is under heat stress and no growth will occur (plant will eventually die).

Question 18

How does Carbon Dioxide Availability affect photosynthesis and respiration?

Answer 18

As the concentration of CO2 increases the rate of photosynthesis increases to a point of saturation. Ambient CO2

Question 19

What is crop Phenology?

Answer 19

The study of changes in the timing of the life cycle events such as germination, seeding development, vegetative stage, reproductive stages.

Question 20

Name three examples of Circadian Rhythms

Answer 20

1)temperatures
2)daylength/ seasonal
3)plant stress

Question 21

What is photoperiodism?

Answer 21

Plant flowering response to length of day/night in a 24 hour cycle.

Question 22

Short day plant vs. long vs. neutral?

Answer 22

Short day: requires shorter day length for flowering
Long day: requires longer day length, such as easter lily
day Neutral: irregardless will flower, typically tomatoes and cucumbers.

Question 23

obligative response vs facultative?

Answer 23

Obligative: A plant that needs the exact correct day length otherwise will not flower.
Facultative: ***

Question 24

Explain Growing Degree Days

Answer 24

a climate measurement of heat accumulation that can be used to predict timing of lifecycles of the plant and will effect the crop production .

Question 25

What is Average Daily Temperature?

Answer 25

The average temperature in a 24 hr period that ultimately controls the plants rate of development (as the temp rises the plant will grow faster).

Question 26

What is diurnal temperate difference response? (DIF)

Answer 26

The plants response to the difference between the day temp and the night temp in a 24 hr period.

-DIF = night temp warmer than day
+DIF = day temp warmer than night
0 DIF = no difference

*sometimes plants grown at a neg. DIF temp to control the size of plants and flowering times

Question 27

What are the three most common greenhouse designs that are covered all year round in Canada?

Answer 27

1) Gothic
2) A Frame
3) Ridge & Furrow

Question 28

Most pop. GH structures used for a 3 season cover?

Answer 28

1) Round Arch (high tunnel)
2) Flatroof

Question 29

What structure best used in extreme snow and wind loads?

Answer 29

Dome (can survive and produce yield even in the Arctic)

Question 30

What is the characteristics of a Venlo roof style?

Answer 30

Mostly in Ridge and Furrow design, vents are on the alternate sides of the roof.

Question 31

Name two venting systems that are only in Ridge and Furrow designs.

Answer 31

Cabrio: Vents are hinged at guttered entire roof opens
Closed/Semi Closed: little to no air vents, air circulated and treated as well as recycled back into the GH.

Question 32

What does glazing provide and control in the GH structure?

Answer 32

-controls amount of light
-heat transmission
-provides strength and physical protection to crop (from hail, wind, rain and sand)

Question 33

Types of glazing materials?

Answer 33

1) Poly films (most common): flexible and impact resistant, however, lower light transmission and prone to attract dust particles, needs UV stabilizers otherwise will break down quickly, 4 yr max warranty!
2) Rigid Plastic Panels (acrylics and Plexiglas): higher impact resistances than glass, easy to cut and light weight, but cost more than poly, shorter life span than glass and light transmission varies with design and thickness.
3) Glass: provides highest PAR transmission, good for winter months, longest lifespan, good insulation value, heavy and needs good support system. It is expensive and needs to be tempered if it break it is more safe.

Question 33

Space Utilization Efficiency

Answer 33

= Production Area / Greenhouse Area x 100%

Question 33

Plant Density Equation

Answer 33

3 of Plants / unit area of production space