Nepal Engineering Council Registration Exam Protected Cultivation & Greenhouse Engineering: practice questions

1 · Greenhouse types and orientation · easy

Which greenhouse type joins many spans along shared gutters so that a large floor area is covered with less outside wall per square metre of floor?

1. Ridge-and-furrow, gutter-connected multi-span house
2. Lean-to house built against an existing farm wall
3. Uneven-span house built across a hillside slope
4. Free-standing Quonset hoop house with one arch

2 · Greenhouse types and orientation · medium

Which description fits a Venlo-type glasshouse?

1. Multi-span glasshouse with narrow roof spans, light glazing bars and alternating hinged roof vents
2. Single-span hoop house with roll-up side curtains and no roof vents, covered with film
3. Net house of knitted shade cloth on timber poles, with no film and no ventilation openings
4. Lean-to glasshouse built against a thick north wall of earth, covered every night by a rolled insulating blanket

3 · Glazing and cladding materials · easy

On a clear night, why does a glasshouse lose less heat by radiation than a house covered with a single layer of plain polyethylene?

1. Glass reflects all incoming visible light back to the crop at night, while polyethylene absorbs it and re-emits it outward
2. Glass conducts heat far worse than polyethylene, so the U-value of single glass is near zero
3. Glass is nearly opaque to long-wave thermal radiation, while plain polyethylene transmits much of it
4. Glass blocks ultraviolet light from the stars, which is the main cause of night cooling

4 · Greenhouse heating · easy

An unvented gas heater in a closed greenhouse causes flower drop and leaf curling, and workers complain of headaches. Which combustion products explain both effects?

1. Ethylene harming the crop and carbon monoxide harming the workers
2. Oxygen harming the crop and nitrogen harming the workers inside
3. Water vapour harming the crop and argon harming the workers inside
4. Carbon dioxide harming the crop and ozone harming the workers inside

5 · Greenhouse heating · easy

Root-zone (floor or bench) heating is especially suited to

1. propagation and pot plants, where warming the medium speeds rooting
2. melting snow on the roof, where heat must reach the outer cover
3. cooling the house in summer, where cold water runs in the pipes
4. drying harvested fruit, where hot air must be blown over the crop

6 · Shading · medium

How does the air temperature in a shade-net house compare with that in a film-covered polyhouse on a hot, sunny day?

1. The net house stays close to outside air temperature, while the polyhouse runs well above it
2. The net house runs well above outside air temperature, while the polyhouse stays below it
3. Both stay below outside air temperature, because the covers block all of the sunlight
4. Both run at the same air temperature, because shade nets and plastic films transmit exactly the same heat

7 · Shading · easy

Floating row covers of light spunbonded non-woven polypropylene are laid directly on a crop mainly to

1. block all light so that weeds die, in the same way as black polyethylene mulch
2. hold a carbon dioxide-rich atmosphere around the crop so that it is enriched during the day without burners
3. give a few degrees of frost protection and exclude insects while passing light, air and water
4. carry the full weight of snow, replacing a greenhouse in regions with heavy winters

8 · Shading · medium

Low tunnels of thin transparent film over hoops are used in cold winters to raise crops such as cucurbits ahead of the field season. How are they managed as days warm?

1. They are sealed tighter each week with soil on the edges, because warming spring days call for more heat retention
2. They are sprayed with black paint inside, so that the crop is shaded and kept dormant
3. Holes are cut or the edges raised for ventilation, and the tunnels are removed when outside temperatures allow
4. They are filled with fog from a high-pressure line, so that the crop stays humid

9 · Hydroponics and aeroponics · easy

In the nutrient film technique (NFT), the roots of the crop

1. hang in a closed chamber and are sprayed with a fine mist at short intervals
2. sit in rafts floating on a deep tank of aerated solution that rarely moves
3. lie in shallow sloping channels with a thin film of solution flowing past them
4. grow in slabs of rockwool fed by drippers, with the drain run to waste

10 · Micro-irrigation and fertigation in greenhouses · easy

How is fruit set in greenhouse tomatoes usually ensured, since there is no wind to shake the flowers?

1. By spraying the flowers with water at noon to wash pollen onto stigmas
2. By removing all leaves so that light reaches the flowers and opens them
3. By planting male tomato plants between the rows as a pollen source
4. By bumblebee colonies in the house or by vibrating the flower trusses