Optimal Environmental Condition for Moss production in plant factory system

J.E. Park, H. Murase

Department of Applied Life Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka, Japan ZIP299-8531 Phone: +81-72-254-9429, Fax: +81-72-254-9918

E-mail: park@ bics.envi.osaka-u.ac.jp, hmurase@ bics.envi.osaka-u.ac.jp

Abstract: The objective of this study is to propose a method for measuring the light reception of Sunagoke moss during the stirring process in the tank, and the optimal environmental condition for high speed production of moss in commercial plant factory system. The average amount of light reception of Sunagoke moss during cultivation in the tank was measured using integrated solarimeter film. The results shows large difference between the amounts of emitted light and received light. The various environmental composition found in this study can be used to optimize the environmental condition in commercial plant factory system.

Keywords: environmental control, commercial plant production system, Sunagoke moss.

1. INTRODUCTION

Urbanization and industrialization improve our material lives and comfort. However, the surface geometry and characteristics in urban areas have been changed compared to the original natural surfaces (Gal and Unger, 2009) by them. These urbanization and industrialization also induce many problems to human beings, such as global warming, industrial waste, and air pollution (Rizwan et al., 2008). Recently, the climate in the urban area has attracted much public attention as an environmental problem.

Urban Heat Island Phenomenon (UHIP), which is a reflection of the totality of microclimatic changes brought by man-made alterations of the urban surface (Landsberg, 1981), is a recognized environmental problem and many preventing and mitigating measures are being studied in various fields.

Many studies on mitigating UHIP have been studied using relationship between intensity of UHIP and particular meteorological condition. Bio-greening (Ichinose et al., 2006; Irie, 2003; Kagawa et al., 1998; Lin et al., 2008; Narita et al., 2004a; Solecki et al., 2005; Spronken-Smith et al., 2000; Takebayashi and Moriyama, 2007; Wong et al., 2007; Wong and Yu, 2005) can be an effective method for reducing UHIP and cooling loads because plants absorb large amounts of heat for evapotranspiration during the daytime and inhibit temperature increase of the surrounding air.

Recently, building greening, which uses Sunagoke moss greening material (Rhacomitrium japonicum), is attracting attention as a measure to reduce urban heat island phenomenon because this plant has many unique qualities: it is resilient with minimum maintenance, requires no soil growing media, and is slow-growing.

Bryophytes in general have adopted the alternative strategy of desiccation tolerance, photosynthesizing and growing during moist periods and suspending metabolism during

times of drought. They typically take up water and nutrients over the whole surface of the shoots because they don’t have vascular system for transferring water and nutrients. There is no development of root system and cuticle layers. Therefore, they must colonize hard for water uptake by capillary and grow on impermeable surfaces like tree trunks and rock outcrops (Shaw and Goffinet, 2000).

However, one feature of the Sunagoke moss, which is slow-growing, is highly preferred by consumers, but problem goes to the production process by producers. Currently, most of Sunagoke moss for greening materials is produced by open culture, and it takes at least one year or more to produce Sunagoke moss mat for greening materials.

Therefore, culturing moss in a tank to achieve high speed production has been developed. The objective of this production is to fulfill the increasing demand of the Sunagoke moss. In the Sunagoke moss culture, light condition is the most significant factor. In this respect, outside lighting and stirring are performed during the Sunagoke moss culture.

However, the amount of light-reception of the Sunagoke moss is low due to the high density and the low transmittance of light. Furthermore, there is no study related to the amount of light-reception of the Sunagoke moss in tank. Therefore, the study of amount of light-receiving by the Sunagoke moss subjected to lighting environment is highly required.

The objectives of this study were; (1) to measure average amount of light reception of Sunagoke moss during high speed and mass culture in water (hydroculture) using commercial plant production system; and (2) to study optimal light intensity and water temperature for high speed and mass culture in water (hydroculture) of the Sunagoke moss based on practical environmental condition.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

Copyright by theInternational Federation of Automatic Control (IFAC)

621

2. MATERIAL AND METHODS

2.1 Development of calibration curve

Integrated solarimeter film, which is used in the environment to measures the integrated solar radiation （R-3D, Opt Leaf,

Taisei E&L Co., Japan） using the change of color fading with absorption of light by photo-degradation reaction of pigment, is difficult to be implemented (Atsuko and Hideo, 2006; Yamada et al., 2004).

It is highly affected by the temperature and no information has reported color fading by artificial light source.

Therefore, calibration curve of the film for color fading was measured under the metal halide lamp (HL-106A, GS YUASA, Japan) in 15°C of water temperature.

R-3D and Pyranometer（LI-200, LI-COR, Inc., USA）were installed under the artificial light source, and the color fade rate was calculated through Eq. (1) by substituting absorption of light of R-3D which was measured every day using spectrophotometer.

C = Log(D/D0 × 100) (1)

where C is color fading rate, D is absorption of light after exposure and D0 is initial absorption of light before exposure.

Calibration curve was developed using the color fading rate and integrated solar radiation under the artificial light source.

2.2 Measuring average PPFD of the Sunagoke moss in the tank

Average PPFD of Sunagoke moss during stirring in the tank was measured using the columnar model. The model was made from the R-3D and selected based on preliminary experiment. Measurement of average PPFD during stirring in the tank was performed with three conditions. The first was performed without the Sunagoke moss. The second was performed with the Sunagoke moss. Environment of the Sunagoke moss culture is as shown Table 1.

Average amount of light reception in the tank was measured on both condition that with and without the Sunagoke moss in the tank. In order to measure the average amount of light reception in the tank under stirring condition, 10 cylinders (circumferential length is 4 cm and height is 4 cm ), which were made from integrated solarimeter films, were used in each tank (Fig. 1).

Average amount of light reception of on and in the water of with and without Sunagoke moss in the tank were estimated using photosynthetic photon flux density indicator (LI-250A, LI-COR. Co., USA).

Fig. 1. Stirring water tank without Sunagoke moss (upper) and with Sunagoke moss (lower).

Table 1. Experimental conditions

Without Sunagoke

With Sunagoke

Average PPFD on the water ( µmol/m2s ) 233.5 231.1 Before putting the

Sunagoke moss in the tank Average PPFD in the

water ( µmol/m2s ) 119.3 111.8

Average PPFD on the water ( µmol/m2s ) 152.6 After putting the

Sunagoke moss in the tank Average PPFD in the

water ( µmol/m2s ) 0.2

Air flux ( liter/hour ) 100 100

Dry weight of Sunagoke moss ( g ) 0 1400

Density of Sunagoke moss in the tank ( g/L ) 0 2

Water temperature ( °C ) 14.5 ± 1.0 14.5 ± 1.0

Experimental duration ( hours ) 72 72

Number of samples ( n ) 10 10

Integrated value of photosynthetic photon flux density (mol/m2s) was obtained by regression formula of the calibration curve in Eq. (2) as follows:

Ip = 1809.6C2 - 7420.1C + 7601.6 (2)

where Ip is integrated value of photosynthetic photon flux density (mol/m2s).

And then, average photosynthetic photon flux density (µmol/m2s) was calculated using the following an Eq. (3):

Ap = Iv × 1000000 / 3600t (3)

where Ap is average photosynthetic photon flux density (µmol/m2s) and t is exposure time in the experiment (hour).

2.3 Optimal light intensity and water temperature for high speed and mass culture in the water of the Sunagoke moss based on practical environmental condition.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

622

This study was conducted in a growth chamber (MLR-351H, SANYO, Japan) for four weeks to observe optimal light and temperature condition of the high speed and mass culture of the Sunagoke moss in the water.

The environmental condition was referred to the condition that can be provided in commercial purposes (Table 2.).

Table 2. Experimental conditions for cultivating the Sunagoke moss in the water

Environmental condition Set range in the growth chamber

Light intensity ( μmol/m2s ) 50, 100, 200

Water temperature ( ºC ) 15, 20, 25, 30

Photoperiod ( h ) D:N = 12:12

Relative humidity ( % ) 70

Light source Fluorescent light

Table 3. Characteristics of the Sunagoke moss sampleswhich were used in this study

Water temperature 15 oC 20 oC 25 oC 30 oC

Light intensity

(μmol/m2s) 50 100 200 50 100 200 50 100 200 50 100 200

0.0010 2 2 2 2 2 2 2 2 2 2 2 2

0.0011 2 2 2 2 2 2 2 2 2 2 2 2

0.0012 2 2 2 2 2 2 2 2 2 2 2 2

0.0014 2 2 2 2 2 2 2 2 2 2 2 2

Number of sample per dry weight ( g )

0.0015 2 2 2 2 2 2 2 2 2 2 2 2

Number of Buds (n) 0 0 0 0 0 0 0 0 0 0 0 0

Average dry weight of every samples were 0.0012 g ± 0.0002 g.

The samples of Sunagoke moss which are used in the experiment were selected based on some criteria i.e. had no-buds with 50% of green parts. The samples then were cut down at the upper and the lower part of so that they have 1cm of length. Number of the Sunagoke moss samples was ten with equal average dry weight per treatment (Table 3).

Number of buds of the moss was measured every week and dry weight was measured before and after experiment.

3. RESULTS AND DISCUSSION

3.1 Development of calibration curve

The first experiment measured the fading curve of the R-3D and integrated amount of solar radiation. A strong correlation was found as shown Fig. 2. It can be concluded that the R-3D

could measure the average PPFD under the artificial light source during the Sunagoke moss culture.

Fig. 2. Color fading line of Opt Leaf under metal halogen light.

3.2 Measuring average PPFD of the Sunagoke moss in the tank

Fig. 3 shows the results of average PPFD with the integrated solarimeter film (R-3D) in the tank during the Sunagoke moss culture. It can be explained that the film was rotated in the tank by stirring, because average PPFD was lower than the average PPFD measured on the water and higher than the average PPFD measured in the water during the first experiment. When the stirring was stop, films settled to the bottom of the tank. Accordingly, it can also be explained that the films were rotated in the tank by physical force of the stirring.

Fig. 3. Measured average amount of light received using the integrated solarimeter in the tank. In this experiment, average PPFD of Sunagoke moss in the tank during the stirring was able to be measured using the integrated solarimeter. This method will be helpful to make effective light condition for high speed and mass culture of the Sunagoke moss in the plant factory system.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

623

Moreover, the study on effective culture period of the Sunagoke moss can be also performed because integrated light requirement for Sunagoke moss can be measured. However, because there is a great difference in the amount of light reception between in and on the water during the culture, average amount of light reception of the Sunagoke moss was lower than 50 μmol/m2s, although stirring was performed during the culture. Therefore more effective light radiation method is needed to develop.

3.3 Optimal light intensity and water temperature for high speed and mass culture in the water of the Sunagoke moss based on practical environmental condition.

According to the measurement of the average number of buds in every week, The results showed that the increment number of buds was found in the combination of 25oC of water temperature. The largest increment number of buds was found in the combination of 50 μmol/m2s of light intensity (Fig. 4). In this experiment, the most active budding in the whole week was found at the second week, then the third, the first and the last week, respectively. However, there was rarely found buds in the combination of 30 oC of water temperature.

Fig. 4. The increment of the average number of buds per week of the Sunagoke moss cultivated in the water in different combination of water temperature and light intensity. Fig. 5 shows the rate of budding in each sample of the combined environmental condition, which consist of ten mosses per the sample. It was also found that the most active budding rate was in the second week, except the environmental condition at 25 oC of water temperature and 50 μmol/m2s of light intensity (Fig. 5). In the water temperature of 25 oC, active budding rate was found at the first week. Moreover, it is found that the number of buds and budding rate has inverse relationship with the light intensity at the first week, but they have a proportional relationship with the light intensity at the second week (Fig. 4 and 5). However, in this experiment, over 80 percent of budding rate was found only in two environmental combinations from 12 combinations, which were 100 and 200 μmol/m2s of light intensity with 25 oC of water temperature.

In the environmental combination with 30 oC of water temperature, there was no bud observed, except 100 μmol/m2s of light intensity at the second week. It is considered that 30 oC of water temperature is stressful for Sunagoke moss. However, it is different with Murakami(2004)’s study where oxygen evolution rate was the most active in 30 and 40 oC of water temperature. It is considered that physiological activity of the Sunagoke moss was increased temporarily by stress from high water temperature. Meanwhile, number of buds and budding rate of the Sunagoke moss show a similar tendency with response to environmental condition (Fig. 4 and 5).

Fig. 5. Rate of budded the Sunagoke moss per week in different combination of light intensity and water temperature. Fig. 6 shows relationship between light intensity and the increment number of buds of the Sunagoke moss by different combination of environmental conditions. In the environmental combination using 15 oC of water temperature, it was showed a tendency to have inverse relationship between the light intensity and the increment number of buds. The largest number of buds was found at 50 μmol/m2s of light intensity. In the environmental combination using 20 oC of water temperature, the largest number of buds were found at 100 μmol/m2s of light intensity, but it was showed fewer buds at 50 and 200 μmol/m2s of light intensity. In the environmental combination using 25 oC of water temperature, it was showed larger number of buds than in other water temperature and it has proportional relationship with light intensity. The largest number of buds was found at 200 μmol/m2s of light intensity.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

624

Fig. 6. Mean number of buds per the Sunagoke moss cultivated in different combination of light intensity and water temperature. In this study, the effect of environmental combinations between water temperature and light intensity on the increment number of buds of Sunagoke moss, which is core for high speed and mass culture of the Sunagoke moss in the plant factory system, was observed. In the results, it showed a clear respond with light intensity in the 25oC of water temperature. The largest number of buds at each water temperature condition was different due to the light intensity. The 50 μmol/m2s of light intensity showed the most active budding in the 15 oC of water temperature, and the 100 μmol/m2s of light intensity showed the most active budding in the 20 oC of water temperature. They were considered as the effect of light intensity and temperature on photosynthetic. In other words, the optimum combination of light intensity and water temperature can be achieved at the combination of 50 μmol/m2s of light intensity at 15 oC of water temperature; 100 μmol/m2s of light intensity at 20 oC of water temperature; and 200 μmol/m2s of light intensity at 25 oC of water temperature. From the research results, we can conclude that it is possible to measure the average amount of light reception of the Sunagoke moss during the stirring in the tank, and it was found optimal environmental compositions for high speed production with various environmental conditions. For example, controlling water temperature can be very costly because water temperature is influenced by the season. Therefore, the best environmental composition can be used with seasonal environmental conditions. This research results entail the future research of effective light up methods and light wave.

REFERENCES

Atsuko, I. and Hideo, B., 2006. Effects of Sunlight on the

Mineral Content of Apple Fruit : Factors Affecting the Variation of Mineral Components of Apples Part VI. Nippon Shokuhin Kagaku Kogaku Kaishi 53:151-157.

Atsunori, M., Kimitoshi, H., Shinichi, K., Tomoko, O., Motoichi, K., and Katsusuke, M., 2006a. The Reduction

of Luminous Transmittance in a Microalgal Culture Tank with the Increase of Microalgal Density and Culture Liquid Thickness. Eco-engineering 18:3-8.

Atsunori, M., Shinichi, K., Mitsuo, T., Masashi, M., Motoichi, K., Kimitoshi, H., and Katsusuke, M., 2006b. Efficiency Improvement of a Food Microalgal Cultivation System in the Oyster Seed Production Plant. Eco-engineering 18:131-138

Gal, T., Unger, J. 2009. Detection of ventilation paths using high-resolution roughness parameter mapping in a large urban area. Building and Environment 44(1): 198-206.

Ichinose, M., Ishino, H., Kohri, K., Nagata, A. 2006. Evaluation of Rooftop Greenings as a Method of Heat-island Reduction Based on Actual Measurement. Journal of environmental engineering(605): 47-54 .

Irie, T. 2003. Study on effcet of open space in reducing heat island by presuming the temperature. The Japanese Institute of Landscape Architecture 66(5): 889-892.

Kagawa, H., Hayashi, T., Tanimoto, J., Katayama, T. 1998. Study on Effect of Lawn Surface on Thermal Environment in Urban Area: Part 1 Hygrothermal characteristics of lawn surface related to soil water content. Journal of architecture, planning and environmental engineering Transactions of AIJ(507): 7-12.

Kosaka, S.-i., Kato, M., Masuda, A., Horaguchi, K., and Murakami, K., 2005. Light Radiation System for Culturing Microalgae as Bait. Panasonic Electric Works Technical Report 53:20-25.

Koshimura, K., Murase, H., and Fukuda, H., 2006. Study on proliferation approach for growth of cultured Sunagoke moss as an active greening material. ISMAB 2006, November 23-25, 2006 Seoul, Korea.

Landsberg, H.E., 1981. The Urban Climate. Academic Press. Shaw, A.J. and Goffinet, B., 2000. Bryophyte biology.

Cambridgh University Press, New York. Lin, B., Li, X., Zhu, Y., Qin, Y. 2008. Numerical simulation

studies of the different vegetation patterns' effects on outdoor pedestrian thermal comfort. Journal of Wind Engineering and Industrial Aerodynamics 96(10-11): 1707-1718.

Masuda, A., Kosaka, S., Takahashi, M., Minoshima, M., Horaguchi, K., Morita, T., and Murakami, K., 2005. Development of an Experimental Facility in Consideration of Optical Radiant Environment for High-Density Culture of Microalgae as Aquaculture Initial Feed. Eco-engineering 17:215-222

Narita, K.-i., Mikami, T., Sugawara, H., Honjo, T. 2004. Observations of evaporation efficiency and thermal environment in Shinjyuku-Gyoen Park. Environmental information science Extra, Papers on environmental information science 18: 253-258.

Okumura, H., 2008. Study of the effeciental cultivation of marine microalge on mass algae cultivation system for mariculture breeding. Scientific reports of Hokkaido Fisheries Experimental Station 73:9-29.

Rizwan, A.M., Dennis, L.Y.C., and Liu, C., 2008. A review on the generation, determination and mitigation of Urban Heat Island. Journal of Environmental Sciences 20:120-128.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

625

Solecki, W. D., Rosenzweig, C., Parshall, L., Pope, G., Clark, M., Cox, J., Wiencke, M. 2005. Mitigation of the heat island effect in urban New Jersey. Global Environmental Change Part B: Environmental Hazards 6(1): 39-49.

Spronken-Smith, R. A., Oke, T. R., Lowry, W. P. 2000. Advection and the surface energy balance across an irrigated urban park. International Journal of Climatology 20(9): 1033-1047.

Takebayashi, H., Moriyama, M. 2007. Surface heat budget on green roof and high reflection roof for mitigation of urban heat island. Building and Environment 42(8): 2971-2979.

Uemura, S., 2004. Use of image data for production of seedling of Sunagoke moss. Osaka Prefecture University, Sakai, Japan, MS thesis .

Wong, N. H., Jusuf. S. K., Win, A. A. L.. Thu, H. K.. Negara, T. S., Xuchao, W., 2007. Environmental study of the impact of greenery in an institutional campus in the tropics. Building and Environment 42(8): 2949-2970.

Wong, N. H., Yu, C. 2005. Study of green areas and urban heat island in a tropical city. Habitat International 29(3): 547-558.

Yamada, H., Itano, A., and Amano, S., 2004. Relationship between Sunlight Exposure of Fruit and Fruit Temperature, Sorbitol and Early Watercore Occurrence in 'Orin' Apples (Growth Regulation). Horticultural research (Japan) 3:91-95.

Preprints of the 18th IFAC World CongressMilano (Italy) August 28 - September 2, 2011

626