Agricultural/Bioengineering Greenhouse and Controlled Environment Agriculture 1 — Questions and Answers
Question 1: The greenhouse effect within a glasshouse structure occurs because:
- Plants absorb all sunlight directly
- Short-wave solar radiation enters and is re-emitted as long-wave infrared radiation that cannot escape through the glazing (Correct answer)
- Ventilation fans trap heat inside
- CO2 enrichment raises internal temperature
Correct answer: Short-wave solar radiation enters and is re-emitted as long-wave infrared radiation that cannot escape through the glazing
Greenhouse glazing transmits short-wave solar radiation inward, which warms interior surfaces and is re-emitted as long-wave infrared radiation that is largely trapped by the covering material.
Question 2: Hydroponic systems grow plants without soil by delivering nutrients dissolved in:
- Pure distilled water only
- A carefully balanced water solution containing essential macro and micronutrients (Correct answer)
- Organic compost tea only
- Rainwater with added sugar
Correct answer: A carefully balanced water solution containing essential macro and micronutrients
Hydroponic systems supply all plant-essential nutrients through a precisely formulated aqueous nutrient solution delivered directly to plant roots.
Question 3: In a nutrient film technique (NFT) hydroponic system, plants are grown in:
- Deep water tanks where roots are fully submerged
- Channels where a thin film of nutrient solution flows continuously over roots (Correct answer)
- Inert growing medium flooded and drained intermittently
- Aeroponics chambers where roots are misted
Correct answer: Channels where a thin film of nutrient solution flows continuously over roots
NFT systems recirculate a shallow, continuous stream of nutrient solution over bare roots in sloped channels, providing both nutrients and oxygen to the root zone.
Question 4: Supplemental LED lighting in greenhouses is used primarily to:
- Provide heat during cold nights
- Extend photoperiod or supplement natural light to increase growth and year-round production (Correct answer)
- Sterilize the growing environment
- Simulate the greenhouse effect
Correct answer: Extend photoperiod or supplement natural light to increase growth and year-round production
Supplemental LED lighting extends daily light integral (DLI) or day length during short winter days, enabling year-round crop production in controlled environment agriculture.
Question 5: Vapor pressure deficit (VPD) is monitored in greenhouses because it affects:
- Soil nutrient availability
- Plant transpiration rate, water uptake, and nutrient delivery to leaves (Correct answer)
- CO2 fixation in photosynthesis directly
- Root respiration rates only
Correct answer: Plant transpiration rate, water uptake, and nutrient delivery to leaves
VPD drives transpiration — too high causes plant stress and wilting, too low promotes disease; controlling VPD optimizes growth and prevents physiological disorders.
Question 6: The primary advantage of vertical farming in controlled environment agriculture is:
- Lower electricity costs compared to field production
- Dramatically higher crop yield per unit of land area through stacked growing layers (Correct answer)
- Elimination of all inputs including water and nutrients
- Greater genetic diversity in crop production
Correct answer: Dramatically higher crop yield per unit of land area through stacked growing layers
Vertical farms stack growing layers to multiply effective growing area, enabling high production density in urban settings regardless of outdoor conditions.
Agricultural/Bioengineering Greenhouse and Controlled Environment Agriculture 1
The greenhouse effect within a glasshouse structure occurs because: