1. 1
Low Cost Detachable Roof
Greenhouse for Round the Year
Cultivation of Tomato/Capsicum
2. 2
Low cost detachable roof greenhouse for
round the year cultivation of tomato/capsicum
1. Introduction
The productivity and quality of tomato/capsicum is influenced by the
genetic characteristics of the cultivar, environment and agronomical
management. Under open field cultivation, we can best manage
agronomical management and there is no control on environment around
the plant. The environment management involves management of light,
temperature, relative humidity and carbon dioxide. The main purpose
of environment management is to create a favorable environment for
the sustained growth of plant so as to realize its maximum potential in
yield and quality. The favorable environment for cultivation of tomato/
capsicum can be provided by greenhouse, insect net proof house
and shade net structure depending upon season of cultivation. The
greenhouse can be used successfully for round the year cultivation of
tomato and capsicum by providing desirable environmental condition.
But the major challenge is cost of construction of greenhouse and
its running cost. The greenhouse can be of various types based on
cost of construction i.e. high cost, medium cost and low cost. Based
on the types of greenhouse, its environment can be fully or partially
controlled. Keeping this in view, a low cost detachable roof greenhouse
was designed so that it can be used successfully for round the year
cultivation of tomato and capsicum.
2. Open field environmental conditions and desired
environmental conditions
The environment conditions (temperature, light intensity and relative
humidity) available in open field conditions during January to December
varies considerable and based on environment conditions it can be
divided into three blocks i.e. winter season (November-February),
summer season (March-June) and rainy season (July-October). The
normal environment conditions during these three seasons are given
in Table 1. It is clear from the Table 1 that minimum temperature
during winter is very low in comparison to summer and rainy season.
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The maximum temperature and light intensity during summer season
is on higher side in comparison winter and rainy season. The suitable
environment conditions for cultivation of tomato/capsicum are given in
Table 2. The environment condition required for cultivation of tomato
and capsicum are similar in nature. Though environment condition
required for cultivation varies with various growths stage of cultivation
and also during day & night temperature. The conditions in given in
Table 2 are broad average range of environment required for cultivation
of tomato/capsicum.
Table 1: Environmental conditions in open field condition
Cultivation time Environmental conditions in open field
Temperature (0
C) Light intensity
(Klux)
Relative
humidity (%)
Winter season
(November-February)
0-26.6 30-55 51.8-85.5
Summer season (March
- June)
7.5-39.5 28-68 69.9-85.3
Rainy season (July-
October)
10.4-37.5 34-59 71.5-84.9
Table 2: Desired environmental conditions for cultivation of
tomato/capsicum
Vegetable Desired environmental conditions
Temperature (0
C) Light intensity
(Klux)
Relative humidity
(%)
Tomato 10-28 40-60 55-60
Capsicum 12-25 40-60 65-70
The suitability of environmental conditions for cultivation of tomato/
capsicum in various protected structure [low cost natural ventilated
polyhouse, low cost insect net proof house (40 mesh) and low cost
shade net house (green, 50%) is given in Table 3 and environmental
challenges in these structures is given in Table 4.
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2. Ployhouse
A polyhouse is a framed structure covered with a transparent material
in which crops or nursery is grown under controlled or partially
controlled conditions. The purpose of polyhouse is provide and
maintain suitable environment (temperature, light, humidity and carbon
dioxide concentration) for crop production with high productivity and
quality. Solar radiation passes through glazing material and enters into
the polyhouse but the thermal radiation emitted by the objects within
the polyhouse cannot pass through the glazing. This results in trapping
of radiation within the polyhouse and subsequent temperature rise and
the effect is known as greenhouse effect.
2.1 Environment conditions inside the polyhouse
The poyhouse can be utilized round the year if all the environment
parameters are suitable for the intended purpose. Due to
greenhouse effect the temperature inside the polyhouse is always
higher than open field and it is very much beneficial during
winter season (November-February) but major problem arises
during summer season (March-June) as clear from Table 3. The
maximum temperature inside the polyhouse will be always higher
by 5-100C in comparison to open field conditions during summer
season. The temperature is not only challenge in polyhouse but
higher light intensity is also a problem during summer season as
clear from Table 4. So to utilize the polyhouse during summer
time, there is need to reduce the temperature and light intensity
both during summer to make it suitable for cultivation.
2.2 Cooling options during summer
There are various options are available for cooling the polyhouse
during summer like ventilation (natural and forced), shading/
reflection screen, evaporation cooling system (fan-pad, fog/mist
and roof cooling). In those areas where summers are not severe
and maximum ambient temperature remains less than 330C,
ventilation and shading techniques can work well. In the extreme
environmental locations, where ambient temperatures in summer
generally exceeds 330C, evaporative cooling is the most efficient
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means of greenhouse cooling, which can lower the inside air
temperature below the ambient air. But the option available for
low cost polyhouse system is natural ventilation and shading/
reflection screen but the temperature inside the polyhouse cannot
be reduced or maintained upto open field temperature using these
options. Apart from high temperature during summer high light
intensity is also challenge, which needs to be reduced to make
the environment suitable for cultivation. The natural ventilation
and shading/reflection screen used for reducing the temperature
also reduce the light intensity below required level of cultivation
because light passes through cladding material (UV stabilized
film) and shading/reflection screen.
3. Low cost detachable roof polyhouse
The main objective of this design was to reduce both the maximum
temperature and maximum light intensity during summer, so that a single
structure can be used for round the year cultivation of tomato/capsicum.
The environmental conditions in low cost detachable roof polyhouse
is given in Table 5, it is clear from table that summer temperature and
light intensity is reduced in comparison to open field condition as given
in Table 1. The materials required and cost of construction of low cost
detachable roof polyhouse is given in Table 6.
Conceptual framework of the design
The major point considered in design aspects were
i. The specification of structure is same as normal polyhouse but the
major point was selection of cladding material.
ii. The whole structure (except roof) was covered with insect net
proof material (40 mesh) but the roof was covered with UV stabi-
lized film (200 micron), so the developed structure will be act as
greenhouse(November-February), rain shelter (June-october) and
shade net (March-May).
iii. The fixing of plastic film was done with profile and gripper sys-
tem, so that it can be easily removed during summer (March-
May) and replaced with shade net material (green, 50%) without
damage the plastic film.
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iv. The same plastic will be again fixed to structure for June-Febru-
ary.
v. The developed structure is provided with double door system
to protect it from insect while entering - exiting the developed
structure.
vi. Use coal tar for protection of construction material i.e., bamboo
from termite.
Table 5: Environmental conditions in low cost detachable roof
polyhouse
Cultivation time Environmental conditions
T (0
C) L I (Klux) RH (%)
Winter season (November-Feb-
ruary)
6-30 15-33 37-55
Summer season (March-June) 15-35 14-30 25-50
Rainy season (July-October) 23-31 20-32 52-66
Table 6: Materials required and cost of construction of GH
S.
N.
Materials Quantity Rate per unit Total amount
(Rs.)
1. Bamboo 56 Rs. 100/piece 5600
2. UV stabilized plastic film
(200 micron)
65.4 m2
Rs.45/ m2
2943
3. Shade net (Green, 50%) 65.4 m2
Rs.33/ m2
2158
4 Insect net proof (40 mesh) 97 m2
Rs.38/ m2
3686
5. Profile & gripper 18 piece Rs.100/piece 1800
6. Wire 18 kg Rs.80/ kg 1440
7. Labour charge 10 man
day
Rs. 187.06 per
man day
1871
8. Others (coaltar, waste
plastic etc.)
- 500 500
Construction cost/m2
- Rs. 278/- 19998
8. 8
Advantages of detachable roof greenhouse
• It can be efficiently utilized for cultivation of tomato/capsicum
round the year (January-December).
• The developed structure work as greenhouse (November-February),
shade net (March-June) and rain shelter (July-October).
• There is no problem of sunburn of tomato and capsicum during
summer (March-June).
• The cost of construction of polyhouse is low and it can be
constructed locally.
• The quality of produce is better than open field due to favorable
environment condition.
• The marketable productivity (kg/m2
) and water productivity is
much high than open field condition.
• The temperature inside the greenhouse is more than 5-100
C in
comparison to open field condition, which is very favorable during
winter time.
• It also protect from damages due to hail, strong winds, heavy rain,
insect etc.
For further information please contact :
Dr. Pramod Rai, Junior Scientist cum Assistant Professor/D. K. Rusia,
Head, AICRP on PET, Directorate of Research
Birsa Agricultural University, Kanke, Ranchi 834006 (Jharkhand)
Mobile No.: 8986644713, E mail: pramod_kgp@yahoo.co.uk
