Green house technology

1. PLANT RESPONSE TO GREEN
HOUSE ENVIRONMENT
&
INSTRUMENTS TO CONTROL
GREENHOUSE

2. Constituent of greenhouse environment and its
effect on crop growth
 Light
 Temperature
 Air composition
 Humidity
 CO2 Conc.

3.  Light is one of the key factors
in plant growth development.
 Three properties of this
climatic factor that affect plant
growth and development are
Light quality, Light intensity,
and Daylength or photoperiod.
 Light quality refers to the
specific wavelengths of light;
 Light intensity is the degree of
brightness that a plant receives
 Daylength is the duration of
the day with respect to the
night period.
Light:

4. Factors of lightning system that affects the plant
growth:
Amount of light and duration
Distribution of light in greenhouse
Cost of lighting system (initial + operating)

5. Temperature:
Temperature means the relative hotness and coldness of
an object and can be expressed in terms of °C, °F or K.
In Greenhouse, temperature at which plant can grow
depends upon factors like
1)Available radiant energy
2)Water availability
3)Carbon dioxide concentration
4)Previous history of the plant
5)Stage of growth, age and particular plant structure
6)Nutrition of crop, fertilizer application and water quality

6. Air composition:
Plant contain carbon of about 40% of the total dry matter , which is
more in quantity then other plant nutrient. Plants get this carbon
from carbon dioxide (CO2) present in the air.
 They use ambient CO2 by process of photosynthesis. It
is a natural process of manufacturing food in plants
for their growth in presence of sunlight or artificial
light.
 The rate of CO2 uptakes by the leaves is an easy method
to quantify the rate of photosynthesis.

7. Humidity:
 Humidity is expressed as the amount of moisture present in a
unit mass or volume of air.
 Relative humidity is the ratio of amount of water vapour
present in air to amount of water vapour required to saturate it.
 Oftentimes, high level of humidity results in yield loss of crop.
 Under normal conditions, about 60-70 per cent of relative
humidity should be maintained in greenhouses for better
growth.
 High humidity level inside greenhouse is one of the main
cause of most plant diseases especially fungal diseases
occurring in plants.

8. Climatic Factors Influencing Plant Growth
Sl.No
.
Climatic Factors Important Activities Desirable level in a
green house
1 Radiation/Light
Intensity
Photosynthesis,
Photoperiodsis, Photo
morphogenesis
25,000-50000 lux
2 Temperature Cell Division, Elongation,
Transpiration etc.
18-25oC (Air)
20-25oC (Soil)
3 Relative Humidity Quality of Plant 60%
4 CO2 Photosynthesis 350-1000 ppm
5 Air movement/Wind
/movement
Influence temp, RH & CO2
conc.
Inflow:Outflow-1:1

9.  Measurement of environmental conditions accurately is a
basic key technique to understand the crop performance
in greenhouse.
 Technology development of instrumentation (sensing,
recording, and controlling) has contributed to expanding
what we can do in controlled environment agriculture.
Portable instruments to control the greenhouse

10.  Measured with a common
Thermometer.
 Indicates the temperature of the
exposed sensor tip, or bulb,
which has reached equilibrium
with the surrounding
environment.
 Sensor tip must not be exposed
to radiant energy as this will
increase the sensor tip
temperature.
 Digital thermometers are
becoming more common.
1. TEMPERATURE
Maximum - Minimum
thermometer

11.  An infrared thermometer
measures surface temperature.
 Infrared thermometers look like
hand-held hair dryers with a
small, circular sensing element
that is aimed at a surface.
 It detects the wavelength of
thermal energy emitted from that
surface, which is displayed as a
radiant temperature.
2. SURFACE TEMPERATURE
Infrared
thermometer

12.  The traditional way to
measure relative humidity is
a two-step process:
1) obtain wet bulb and dry
bulb temperatures,
2) convert it to relative
humidity using a
psychrometric chart.
3. HUMIDITY
Compact sling
psychrometer

13. Digital Thermo Hygrometer
 Relative humidity can be
measured directly by
using hygrometer .
 More accurate
hygrometers (with an
accuracy of ±1 percent)
are preferred but are more
expensive.
Digital Thermo
Hygrometer

14.  measured with an
anemometer.
4. AIR SPEED

15.  A set of air speed streamers
may be used to detect air speed
at various greenhouse
locations.
 Threads of string or ribbons of
plastic tape can be “calibrated”
to a specific size so that they
blow horizontally at a
particular airflow of interest.
Air speed
streamers

16.  The carbon dioxide concentration is
commonly expressed in units of parts per
million (ppm)
 The so-called ambient carbon dioxide
concentration is around 350 to 400 ppm.
 Growers usually enrich the greenhouse
environment to a level of around 1,000
ppm.
6. GASES
Portable
CO2 monitor
 Plants use carbon dioxide [CO2] to grow and develop in a process
called photosynthesis in which they convert carbon dioxide and
water into necessary building blocks.

17. 7. LIGHT LEVEL
 Quantum sensors measure light
wavelengths from 400 to 700 nm,
which approximate the
photosynthetic response of plants.
 Many visible light meters offer
display of light readings in both fc
and lux.
Quantum
sensors
 Visible light is similar in range of wavelength to PAR
with more visible light meters available at less cost than
quantum meters.

18.  A pyranometer measures solar irradiance that includes
ultraviolet, visible, and infrared wavelengths
(approximately 280 to 2,800 nm).
Photometric meter
 Place the sensor near the top of
the plant canopy to determine
light level.