1.11.2 Trying to Control Climate in Plant Production
Agriculture, broadly speaking, is the activity in which the farmer attempts to
integrate agroecological factors and production inputs for optimum crop production. Greenhouses are one of the examples of modern agriculture that has emerged
with the perspective of growing any plant in any place at any time by providing
suitable environmental conditions inside them. This technology allows to optimize
crop production in areas or periods of the year not appropriate for open field
cultivation (Scarascia Mugnozza 1995). The greenhouse surface area nearly
doubled from 1980 (150,000 ha) to 1995 (280,000 ha) (Zhang 2003). It is stated
that the production per cultivate unit area of a greenhouse is higher than that in the
field. For example, the production per cultivated unit area of a greenhouse tomato
crop ([50 kg/m
2 ) is 10 times superior to that of a field crop.
Greenhouses are spaces covered with transparent materials, large enough to let
plants grow under a partial of fully controlled environment. Through the manipulation of actions like heating, ventilation, and CO 2 enrichment the environment
inside the greenhouse is different from the outside. Their presence will be considered a very common element of agricultural activities in the near future because
they enable to grow crops by overcoming adverse weather conditions. Due to the
adequate environmental conditions for plant growth and development, greenhouse
protected agriculture could face the challenge to increase food production considering the growth of global population. Greenhouses are presented as a good
alternative to tap water use and to protect crops from sudden temperature changes
and adverse conditions such as wind, rain, pests, animals, and pollution. Inside
them are created artificial microclimate conditions that allow cultivation in any
season and create optimal levels of solar radiation, temperature, humidity of air
and soil (Pawlowski et al. 2009), thereby producing higher yielding crops in open
field cultivation (Mózner et al. 2012).
Despite their geographic location, greenhouse climate control systems consist
of fundamental control components that can provide a greater or lesser amount
of climate control, and subsequent plant growth and productivity depending on
their design and complexity. As mentioned by Kittas et al. (2012), an accurate
greenhouse climate control becomes more important at the end of the twentieth
century, when the interest in topics on food, safety, and environmental pollution
encouraged extensive research in the development of protected agriculture.
Temperature is the most significant variable of the greenhouse climate that
needs to be controlled and it is usually controlled. A vast range of plants grown in
greenhouses are warm-season species (Moretti et al. 2010). They are commonly
adapted to average temperatures in the range 17–27 °C, with lower and upper
temperature limits of 10 and 35 °C, for this reason in order to maintain adequate
temperature inside the greenhouse, both heating or cooling systems are required.
The second important variable to be controlled in the greenhouse climate is
humidity. It is commonly expressed in terms of relative humidity. Relative
humidity within the range 60–90 % is suitable for plant growth. Values below
1 Strategies for Sustainable Plant Food Production
29
Agriculture, broadly speaking, is the activity in which the farmer attempts to
integrate agroecological factors and production inputs for optimum crop production. Greenhouses are one of the examples of modern agriculture that has emerged
with the perspective of growing any plant in any place at any time by providing
suitable environmental conditions inside them. This technology allows to optimize
crop production in areas or periods of the year not appropriate for open field
cultivation (Scarascia Mugnozza 1995). The greenhouse surface area nearly
doubled from 1980 (150,000 ha) to 1995 (280,000 ha) (Zhang 2003). It is stated
that the production per cultivate unit area of a greenhouse is higher than that in the
field. For example, the production per cultivated unit area of a greenhouse tomato
crop ([50 kg/m
2 ) is 10 times superior to that of a field crop.
Greenhouses are spaces covered with transparent materials, large enough to let
plants grow under a partial of fully controlled environment. Through the manipulation of actions like heating, ventilation, and CO 2 enrichment the environment
inside the greenhouse is different from the outside. Their presence will be considered a very common element of agricultural activities in the near future because
they enable to grow crops by overcoming adverse weather conditions. Due to the
adequate environmental conditions for plant growth and development, greenhouse
protected agriculture could face the challenge to increase food production considering the growth of global population. Greenhouses are presented as a good
alternative to tap water use and to protect crops from sudden temperature changes
and adverse conditions such as wind, rain, pests, animals, and pollution. Inside
them are created artificial microclimate conditions that allow cultivation in any
season and create optimal levels of solar radiation, temperature, humidity of air
and soil (Pawlowski et al. 2009), thereby producing higher yielding crops in open
field cultivation (Mózner et al. 2012).
Despite their geographic location, greenhouse climate control systems consist
of fundamental control components that can provide a greater or lesser amount
of climate control, and subsequent plant growth and productivity depending on
their design and complexity. As mentioned by Kittas et al. (2012), an accurate
greenhouse climate control becomes more important at the end of the twentieth
century, when the interest in topics on food, safety, and environmental pollution
encouraged extensive research in the development of protected agriculture.
Temperature is the most significant variable of the greenhouse climate that
needs to be controlled and it is usually controlled. A vast range of plants grown in
greenhouses are warm-season species (Moretti et al. 2010). They are commonly
adapted to average temperatures in the range 17–27 °C, with lower and upper
temperature limits of 10 and 35 °C, for this reason in order to maintain adequate
temperature inside the greenhouse, both heating or cooling systems are required.
The second important variable to be controlled in the greenhouse climate is
humidity. It is commonly expressed in terms of relative humidity. Relative
humidity within the range 60–90 % is suitable for plant growth. Values below
1 Strategies for Sustainable Plant Food Production
29