Most of the following discussion applies to large
commercial greenhouses with the investment to produce on a large
scale, but small greenhouses and the humble cloche count benefit
from the same factors too!
So the
various factors can be
manipulated to increase the rate of photosynthesis and hence increase plant
growth.
Summary so far to help increase crop yields
A greenhouse used is to artificially create the
best environment for growing plants and increase photosynthesis
efficiency.
ventilation - need to keep the
air fresh and ensure the carbon dioxide level doesn't fall below that in
the air outside.
glass (or transparent plastic)
panels - allows the transmission of visible light for photosynthesis
and infrared radiation to be absorbed and raise the temperature.
carbon dioxide supply - can
artificially increase CO2 available to plants to increase
rate of photosynthesis.
water supply - plants need a
constant supply of water, the soil or compost may get to dry for optimum
plant growth and the higher temperatures in a greenhouse increase the
rate of transpiration.
heater - electric to
raise temperature on colder days, preferably from renewable source, if
paraffin, the combustion produces CO2 so that helps increase
the rate of photosynthesis.
artificial lighting - enables
photosynthesis to be continuous 24/7 and independent of the weather, BUT
you need periods of darkness (use a timer) to allow the plant to
transport and store glucose as starch.
humidifier - if the atmosphere
becomes too dry the rate of transpiration increases and plants may droop
from lack of water
blinds - can be used to control the
light if necessary.
thermostat - not sure if this is used
in greenhouses?
Growing crops in greenhouses can
significantly increase the crop yield for a given area.
Greenhouse horticulture
(agricultural growing of flowers, fruit and vegetables) is an intensive
farming method using various technological developments - this
particularly applies to
hydroponics - method of food
production,
ideally farmers-horticulturalists want
optimum yields of crops without excessive leaf or root production.
A greenhouse traps the sunlight energy
raising the internal temperature to make it less of a limiting factor but heating may be required in
winter.
However, the extra costs of
heating, artificial lighting or adding CO2 to the air, must be
off-set by selling an acceptable quality product at a
sustainable market price that the consumer is prepared to pay!
You can increase the temperature and
carbon dioxide levels at the same time by using a paraffin heater - one
of the better uses of a fossil fuel when burned to form carbon dioxide!
In summer it might get too hot so
extra shade and ventilation may be needed to create cooler conditions.
Using artificial light extends the
growing period beyond normal daylight hours - but an extra cost.
You should also note that plants enclosed
in a greenhouse are less susceptible to pests and diseases.
For more see sections on
plant diseases and pest control
Fertilisers may be added to the soil to provide the minerals the
plant need's and absorbed from the soil by the root system.
Greenhouse design/operation and
the photosynthesis light intensity factor
