IJERD – International Journal of Environmental and Rural Development (2018) 9-1

Research articleerd

The Low-Cost Controlled Temperature Greenhouse
Investigation for Marigold Seedlings in Global Warming
Situation
ANCHASA PRAMUANJAROENKIJ*
Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakon Nakhon
Province Campus, Sakon Nakhon, Thailand
Email: anchasa.p@ku.th

AMARIN TONGKRATOKE
Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakon Nakhon
Province Campus, Sakon Nakhon, Thailand

SIRILUK PHANKHOKSOONG
Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakon Nakhon
Province Campus, Sakon Nakhon, Thailand
Received 27 December 2017

Accepted 18 May 2018(*Corresponding Author)

Abstract Global warming situation has affected many life in the world; especially its
effects on agricultural industry. Greenhouse was one of many tools which was brought tohelp farmers in growing many plants and flowers in uncontrollable environments for longtime. This work was aimed to build a low-cost controlled temperature greenhouse prototype.
The greenhouse prototype was studied for temperature distributions inside the prototype tosow marigold seedlings. A water evaporative cooling system was chosen to remove heatfrom the greenhouse, a low-cost temperature control set was fabricated to help controlling
air flow and temperature inside the greenhouse. A cooling pad system was chosen as theevaporative cooling system in this work. The greenhouse frame was built locally as a lengthof 2.1 m., a width of 1.8 m. and a height of 3.1 m. and was covered with clear UV reducing
plastic. The cooling pad system consisted of 25-watts ventilating fans with a length of 30cm, a width of 30 cm, a height of 16 cm and one 60-watt water pump. The low-cost
temperature control set was connected with the cooling pad system to turn on and off thefan of the system automatically and to remove the humid air out of the greenhouse. Six
different seedling materials; pure peat moss, pure bagasse, bagasse mixed with soil at 1:1
and at 1:0.5 by weight, bagasse mixed with soil and rice-straw biochar at 1:1:0.5 and at
1:0.5:0.5 by weight, were also investigated in the greenhouse. The experimental results
showed that using one cooling pad could reduce inside temperature with an averagetemperature different of 2.5 Celsius while using three cooling pads could reduce insidetemperature with an average temperature different of 5 Celsius. The air circulation system
also affected the temperature distribution inside the greenhouse and could control thetemperature inside the prototype. The seedling material which was prepared from bagasse
mixed with soil; at a mixing ratio of 1:0.5 by weight, allowed marigold seedling to grow themost in the same experiment period.
Keywords geenhouse, marigold seedling, cooling pad, evaporative cooling system,
heat transfer

INTRODUCTION
Global warming situations affect life on the world such as human, animals and plants. Many plants
are able to grow in certain ranges of temperatures. High ambient temperatures have affected on
annual plants which can grow from seeds and last for a year. Many researches paid attentions on
adjusting temperatures to suit seedlings and growing of plants. One of many tools to controlⒸ ISERD

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suitable temperatures for seedlings and growing of plants was a greenhouse; where sunlight can gothrough a structure of the greenhouse, humidity and temperature inside the greenhouse can beadjusted by heating, ventilation and air conditioning systems.
Marigold is one of many flowers in Thailand which is used in many occasions such ascelebrating for our beloved King Rama 9, worshipping in Buddhist traditions, etc. Varied ambient
temperatures also affect seedling and growing rates of marigold because Marigold growing in
Thailand prefers surrounding temperatures between 14.5 to 28.6 Celsius (Wongput 2001), quite
low temperatures compared with global-warming ambient temperatures in Thailand. Taylor et al.
(2013) grew 14-day-old marigold (Tagetes erecta L. 'Inca Gold') seedlings on a greenhouse bench
to document the occurrence of nitrification in Pine tree substrate (PTS) and to determine if
nitrification and density of nitrifying microorganisms were affected by substrate storage time andlime and peat amendments. Bridgen (2015) proposed UV-C light treatments as a plant growth
regulator in seedlings of annual plants such as African marigold and French marigold. He claimed
that the use of UV-C irradiation as the novel low-cost technique could provide tremendous benefits
for the environment by reducing pesticide applications to plants. Randall and Lopez (2015) alsostudied and compared seedlings; vinca, impatiens, geranium, petunia, and French marigold, grownunder low greenhouse ambient light (AL) to those grown under supplemental lighting (SL) or solesource photosynthetic lighting (SSL) with a similar photosynthetic daily light integral (DLI). They
found that height of marigold was 7% to 19% shorter, for seedlings grown under SSL comparedwith those under AL and SL. Pramuanjaroenkij et al. (2015) studied fluid flow in Red Oak
hydroponics systems to create 4 prototypes of the hydroponics systems inside a greenhouse for ahousehold application with initial conditions as low investment cost and easy installation. Olbergand Lopez (2016) found that all plants were delayed when grown outdoors compared with in thehigh tunnel, and all marigolds grown outdoors died in April of the Midwestern United States whenoutdoor air temperatures dropped below −4 °C, growers must be aware of the risk of crop loss due
to extreme temperatures and plan for delays when growing annual bedding plant crops outdoors.
Pramuanjaroenkij et al. (2017) studied the turbulent flow of the nutrient solution which affected thegrowth of Red Oaks in four hydroponic systems inside a greenhouse; the greenhouse was proved tohelp adjusting the temperatures inside the greenhouse. Owen et al. (2017) revealed that the overall
trends indicated in most cases as the percent PWC increases, pH increases and electricalconductivity (EC) decreases while plant shoot growth was often as large in fresh PWC-grownplants compared to aged.
OBJECTIVE
This work was aimed to build a low-cost controlled temperature greenhouse prototype to control
temperatures to sow marigold seedlings. The greenhouse prototype was constructed locally andexperimentally investigated for temperature distributions inside the prototype to sow marigold
seedlings. We also investigated suitable marigold for six different seedling materials in thegreenhouse with high humidity air because of evaporated water from the cooling pad system.
METHODOLOGY(1)A greenhouse structure was designed and locally built. (2) A clear UV reducing plastic sheet
was cut and covered the greenhouse structure. (3) Temperatures of the greenhouse and environment
were measured by an infrared temperature measurement camera to find natural temperature
distributions. (4) A temperature control set was fabricated by connecting a thermocouple, atemperature controller and a relay. The relay was used to switch on and off two ventilating fan; one
fan was equipped on the top part of the greenhouse to reject the heat and moisture to theenvironment and another fan was installed opposite to a cooling pad set. (5) Two sets of coolingpads were installed and compared. The first set contained one cooling pad and another set
contained three cooling pads. (6) Twenty-three marigold seeds were put into six different seedlingmaterials mixing ratios by weight: pure peat moss, pure bagasse, bagasse mixed with soil at of 1:1Ⓒ ISERD

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and 1:0.5 by weight, bagasse mixed with soil and rice-straw biochar at mixing ratios of 1:1:0.5 and
1:0.5:0.5 by weight. And (7) Three seedling investigations were studied in three consecutive
periods (14 days per period) to conclude the current study. Germination rates of marigold seedlings
from these materials were obtained and compared while temperatures inside and outside thegreenhouse were measure 3 times a day; 9am, 12.45pm and 7pm.
RESULTS AND DISCUSSION
A greenhouse was locally built as a length of 2.1 m., a width of 1.8 m. and a height of 3.1 m. andwas covered with clear UV reducing plastic. The self-built greenhouse was placed in theenvironment, the temperatures of the greenhouse and environment were measured by an infrared
temperature measurement camera to find natural temperature distributions. At the beginning, one
cooling pad set was installed and the first temperature distribution was observed as shown in Fig. 1that high temperature humid air was accumulated on the top of the greenhouse and opposite of thecooling pad. The temperature control set (Fig. 2) was linked with both fans inside the greenhouseand the thermocouple was positioned in the middle of the greenhouse to measure insidetemperatures; if the measured temperatures were higher than our set value or 25 Celsius, both fanswere switched on and off when the measured temperatures were lower than the set value. To reduce
temperatures inside the greenhouse, one cooling pad and three cooling pads were connected withthe cooling system and compared, we found that the more pads the lower temperatures, as well as,
the higher humidity. High humidity could cause fungi to grow inside the greenhouse; as we avoided
too high humidity, three pad were kept as the maximum number. Six different seedling materials
were prepared and 23 marigold seeds were put into six seedling materials; 15 holes for eachmaterial. Three experiments were carried on consequently, 14 days for each experiment. During
each experiment, temperatures and humidity of humid air both outside and inside the greenhousewere measured three times a day; minimum and maximum different temperatures and relative
humidity percentage of humid air both outside and inside the greenhouse were detailed in Table 1
according to measuring times during three months in 2017. We noticed that the highest temperatureand humidity were in April 2017, the middle month in Summer of Thailand.

Fig. 1 The greenhouse and temperature distributions

Fig. 2 The temperature control setⒸ ISERD

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Table 1 Minimum and maximum different temperatures (Celsius) and relative humidity
percentage (%RH) of humid air both outside and inside the greenhouse
9 am
1sttest

2nd
test

3rd
test

'Tmin
1.4°C
on
Mar.
11th
2.4°C
on
Mar.
29th
0.5°C
on
May
13th'Tmax
8.3°C
on
Mar.
18th
8.8°Con
Apr.
4th
8.4°C
on
May
6th

7 pm

12.45 pm'%RHmin'%RHmax

1 on
Mar.
17th

14 on
Mar. 12th0 on
Mar.
31th

48 on
Apr. 6th4 onMay
12th28 on
May 2nd'Tmin
1.1°C
on
Mar.
19th
2.0°C
on
Mar.
29th
2.1°C
on
May
7th'Tmax
7.9°C
on
Mar.
16th
9.9°C
on
Apr.
5th
7.4°C
on
May
5th'%RHmin'%RHmax

1 on
Mar.
20th

19 on
Mar.
13th

7 on
Apr. 4th

56 on
Apr. 5th

1 onMay
13th24 on
May 6th'Tmin
1°C
on
Mar.
12th
1.6°C
on
Mar.
29th
3.3°C
on
Mayrd th3 ,4'Tmax
4.9°C
on
Mar.
22nd
5.8°C
on
Apr.
9th5.3°ConMay
2nd'%RHmin'%RHmax

1 on
Mar.
12th22 onMar.
23th5 onMar.
31th60 on
Apr. 9th3 on
May 6th42 on
Apr. 30thFigures 3, 4 and 5 showed average outside and inside temperatures of the greenhouse in March,
April and May, respectively. We found that the average inside temperature of the greenhouse in themorning (9am) in May was the lowest inside temperature among temperatures in threeexperimental periods, the inside temperatures varied from 23 to 35 Celsius, the lowest and highest
average different temperatures between outside and inside greenhouse was about 1.4 Celsius and8.3 Celsius, respectively. The average inside temperature of the greenhouse at noon (12.40pm) inMarch was the highest inside temperature among temperatures in three experimental periods, theinside temperatures varied from 29 to 38 Celsius, the lowest and highest average different
temperatures between outside and inside greenhouse was about 1.1 Celsius and 7.9 Celsius,
respectively.

Fig. 3 The outside and inside temperature of the greenhouse in March
We noted that our greenhouse, which was cooled by evaporative refrigeration, contained highrelative humidity. Seedling materials, which was suitable inside this specific greenhouse, must
function well in the high humidity atmosphere. Among three different experimental periods, thefirst set of seedlings in any seedling materials, which were placed inside the greenhouse, could
germinate out of their seedling materials in the same day on the fourth day of marigolds planting.
The highest amount of seedlings germinated out from the bagasse mixed with soil at mixing ratiosof 1:0.5 by weight. The bagasse mixed with soil at mixing ratios of 1:0.5 by weight showed its
potential in growing marigold seedlings inside the greenhouse while the marigold seedlings indifferent seedling materials, which were placed outside the greenhouse, were damaged by pest
animals and less seedlings could germinate out of the materials than those of the materials inside
the greenhouse. Therefore, the bagasse mixed with soil at mixing ratios of 1:0.5 by weightgreenhouse could be applied as the seedling material which suited to the high humidity atmosphereoccurred by the evaporative refrigeration. Another greenhouse utilization found in this study was thegreenhouse could protect seedlings, plants and their seedling materials from pest animal damages.
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We summarized costs of the greenhouse structure, plastic cover, simple temperature control
set and three cooling pad set including a water circulating pump, and we found the cost of ourgreenhouse at $4 per square meter. From our survey, the estimating cost of the greenhouse building
in US was $55.56 per square meter (HomeAdvisor, Inc. 2017) or $19.45 per square meter as weestimated Thai construction cost at 65% lower than the American construction cost (Neal andRawlinson 2014). The cost of the current greenhouse installed with the cooling pad andtemperature control sets or $4 per square meter was lower than the estimated greenhouse cost or$19.45 per square meter about 79%.

Fig. 4 The outside and inside temperature of the greenhouse in April

Fig. 5 The outside and inside temperature of the greenhouse in May
CONCLUSION
This study was aimed to study and develop a closed controlled greenhouse. Evaporative coolingsystem was chosen as the greenhouse cooling system. The evaporative cooling system consisted ofcooling pads (where water was circulated and received heat from the greenhouse), water pumps(which were used to circulate the water) and ventilation fans (one fan was placed near the cooling
pad to draft inside air to pass the cooling pads and another fan was placed at the top of thegreenhouse roof to release hot air out of the greenhouse). The temperature control set could control
operation of the evaporative cooling system and the system could reduce inside greenhousetemperatures down with an average temperature difference (between inside and outside greenhousetemperatures) of 5 Celsius. There were six different seedling materials which were investigated, 23
marigold seeds were put into these six different seedling materials in each experiment period; 15
seedling holes for each material. Six different seedling materials were prepared from 1) peat moss,
2) bagasse mixed with soil at mixing ratios of 1:1 by weight, 3) bagasse mixed with soil at mixing
ratios of 1:0.5 by weight, 4) bagasse mixed with soil and rice-straw biochar at mixing ratios of
1:1:0.5 by weight, 5) bagasse mixed with soil and rice-straw biochar at mixing ratios of 1:0.5:0.5
by weight and 6) only bagasse. The air circulation system also affected the temperature distribution
inside the greenhouse and could control the temperature inside the greenhouse. The seedlingⒸ ISERD

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material which was prepared from bagasse mixed with soil; at a mixing ratio of 1:0.5 by weight,allowed marigold seedling to grow the most in the same experiment period. Marigold seedlinggerminated the first set in every seedling material at the same day (the fourth day of the plantingperiods). The greenhouse could also protect the Marigold sprouts from pest animals because thesprouts grown outside the greenhouse were damaged by pest animals. The bagasse mixed with soil;
at a mixing ratio of 1:0.5 by weight as the marigold seedling material revealed its function andpotential in the high humidity atmosphere because the evaporative cooling system, which appliedcooling pads, generated a lot of water vapor causing high humidity atmosphere. The construction
cost of the current designed greenhouse was $4 per square meter which was an affordable cost forfarmers, the current greenhouse with the temperature control set was suitable as a household
greenhouse, simple in design and construction as well as easy to maintenance and develop tosustain the greenhouse application in the rural area.
ACKNOWLEDGEMENTS
We would like to thank all students who participated in this value work; Taradon Panochit, Piphon
Kieochaum, Anirut Klangbunrueang, Kitisak Pathumwan, Ratchaneekorn Ponsukkhua, Nattaporn
Phanwong. This work was financially supported by Faculty of Science and Engineering, Researchgroup titled Thermo-Fluid, Material Chemistry and Technology and Kasetsart University Researchand Development Institute of Kasetsart University.
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