Main Article Content



This paper discusses the cooling effect of the root zone (the root zone cooling) at a floating hydroponic for the shallot production in tropical lowland by cooling the nutrient bath. The study was conducted at three different temperatures, i.e. low temperatures (8-10OC), medium temperature (13-15OC), and control (23-26OC) with variable responses that include wet weight, dry weight, number of bulbs and weight per bulb. Plant growth responses were analyzed using statistical methods Fisher's least significant difference (LSD), while the temperature distribution on a floating hydroponic was analyzed by computational fluid dynamics (CFD) simulation approach. CFD simulation approach was able to describe the temperature distribution on a floating hydroponic well, where the coefficients of determination (R2) for each treatment of low temperature, medium and controls are 0.983, 0.980 and 0.862 respectively. The results showed that the number of bulbs was the most responsive variable, where the induction of bulb formation at low temperature is more than 200% of the control temperature and more than 60% of the medium temperature.


Makalah ini membahas tentang efek pendinginan daerah perakaran (root zone cooling) pada hidroponik rakit apung untuk produksi bawang merah di dataran rendah tropika dengan pendinginan pada bak nutrient.Penelitian dilakukan dengan 3 suhu berbeda, yaitu pada suhu rendah (8-10OC), suhu sedang (13-15OC), dan kontrol (23-26OC) dengan variabel respon pertumbuhan tanaman bawang merah meliputi bobot basah, bobot kering, jumlah umbi dan bobot per umbi. Respon pertumbuhan tanaman dianalisis menggunakan metoda statistik Fisher's least significant difference (LSD), sedangkan distribusi suhu pada hidroponik rakit apung dianalisis melalui pendekatan simulasi computational fluid dynamics (CFD). Pendekatan simulasi CFD mampu menggambarkan sebaran suhu pada hidroponik rakit apung dengan baik dimana koefisien determinasi (R2) untuk masing-masing perlakuan dari suhu rendah, sedang dan kontrol berturut-turut sebesar 0.983, 0.980 dan 0.862. Hasil penelitian menunjukkan bahwa jumlah umbi merupakan variable yang paling responsif, dimana pada suhu rendah induksi pembentukan umbi bawang merah mencapai 200% lebih banyak dari pada suhu kontrol dan 60% lebih banyak dari suhu sedang.


bulb formation computational fluid dynamics low temperature root-zone cooling number of bulbs.

Article Details


  1. Benjamin, S.F., and C.A. Roberts. 2007. Threedimensional modeling of NOx and particulate traps using CFD: A porous medium approach.
  2. Applied Mathematical Modelling 31(11): 2446– 2460.
  3. Boulard, T., H. Fatnassi, H. Majdoubi, and L. Bouirden. 2008. Airflow and microclimate patterns in a one-hectare canary type greenhouse: An experimental and CFD assisted study. Acta Horticulturae, 801 (2): 837–845.
  4. Brewster, J.L. 2008. Onions and other vegetable alliums. 2ndEd. (Crop production science in horticulture series;15). Biddles Ltd. King's Lynn. ISBN: 978 1 84593 399 9. http://doi. org/10.1079/9781845933999.0000
  5. Cometti, N.N., D.M. Bremenkamp, K. Galon, L.R. Hell, and M.F. Zanotelli. 2013. Cooling and concentration of the nutrient solution in hydroponic lettuce crop. Horticultura Brasileira 31 (2): 287–292.
  6. Fita, G.T. 2004. Manipulation of flowering for seed production of shallot (Allium cepa L . var. ascalonicum Backer). (Thesis). The university of Hannover.
  7. Halder, A., and A.K. Datta. 2012. Surface heat and mass transfer coefficients for multiphase porous media transport models with rapid evaporation. Food and Bioproducts Processing 90 (3): 475– 490.
  8. He, J., P.T. Austin, and S.K. Lee. 2010. Effects of elevated root zone CO2 and air temperature on the photosynthetic gas exchange, nitrate uptake, and total reduced nitrogen content in aeroponically grown lettuce plants. Journal of Experimental Botany 61 (14): 3959–3969. http://
  10. He, J., S.K. Lee, and I.C. Dodd. 2001. Limitations to photosynthesis of lettuce grown under tropical conditions : alleviation by root-zone cooling.
  11. Journal of Experimental Botany, 52 (359):1323– 1330.
  12. Hilman, Y., R. Rosliani, and E. Palupi. 2014. The effect of altitude on flowering, production, and quality of true shallot seed. Jurnal Hortikultura,
  13. 24(2): 154–161.
  14. Jie, H. and L.S. Kong. 1998. Growth and photosynthetic characteristics of lettuce (Lactuca sativa L.) under fluctuating hot ambient temperatures with the manipulation of cool rootzone temperature. Journal of Plant Physiology,
  15. 152(45): 387–391. 1617(98)80252-6
  16. Malcolm, P., P. Holford, B. Mcglasson, J.Conroy, and I. Barchia. 2007. Growth and its partitioning in Prunus rootstocks in response to root zone
  17. temperature. Scientia Horticulturae, 112: 58–65.
  18. Mauk, C.S. and A.R. Langille. 1978. Physiology of Tuberization in Solanum tuberosum L. Plant Physiology, 62 (3): 438–442.
  19. Molina-Aiz, F.D., H. Fatnassi, T. Boulard, J.C. Roy, and D.L. Valera. 2010. Comparison of finite element and finite volume methods for simulation
  20. of natural ventilation in greenhouses. Computers and Electronics in Agriculture, 72 (2): 69–86.
  21. Moorby, J. and C.J. Graves. 1979. Root and air temperature effects on growth and yield of tomatoes and lettuce. Symposium on Research on Recirculating Water Culture 98.
  22. Pregitzer, K.S. and J.S. King. 2005. Effects of Soil Temperature on Nutrient Uptake. In Nutrient acquisition by plants Vol. 181, pp. 277–310. Springer-Verlag Berlin Heidelberg. http://doi. org/10.1007/3-540-27675-0_10
  23. Sobachkin, A., and G. Dumnov. 2013. Numerical Basis of CAD-Embedded CFD. NAFEMS World Congress 2013.
  24. Sumarni, E. 2013. Pengembangan root-zone cooling system untuk produksi benih kentang secara aeroponik di dataran rendah tropika basah. (Disertasi). Departemen Teknik Mesin dan Biosistem Fakultas Teknologi Pertanian, IPB. Bogor. Retrieved from bitstream/handle/123456789/66681/2013esu. pdf?sequence=1&isAllowed=y
  25. Sumarni, E., H. Suhardiyanto, K.B. Seminar, and S.K. Saptomo. 2013. Temperature distribution in aeroponics system with root zone cooling for
  26. the production of potato seed in tropical lowland. International Journal of Scientific & Engineering Research, 4(6):799–804.
  27. Sumarni, N., Suwandi, N. Gunaeni, and S. Putrasamedja. 2013. Effects of Varieties and GA 3 Application Methods on Flowering. Journal of Horticulture, 23(2):153–163.
  28. Suwandi. 2014. Budi Daya Bawang Merah di Luar Musim. 1stEd. Jakarta: IAARD Press. Thompson, H.C., R.W. Langhans, A.J. Both, and L.D. Albright. 1998. Shoot and root temperature effects on lettuce growth in a floating hydroponic system. Journal of American Society Horticulture Science, 123(3): 361–364.
  29. Torre, A.D., G. Montenegro, G.R. Tabor, and M.L. Wears. 2014. CFD characterization of flow regimes inside open cell foam substrates.
  30. International Journal of Heat and Fluid Flow, 50: 72–82. ijheatfluidflow.2014.05.005
  31. Yan, Q.Y., Z.Q. Duan, J.D. Mao, X. Li, and F. Dong. 2013. Low Root Zone Temperature Limits Nutrient Effects on Cucumber Seedling Growth and Induces Adversity Physiological Response. Journal of Integrative Agriculture, 12(8):1450–1460.
  32. 3119(13)60549-3
  33. Yong, H.E., Y. Jing, Z.H.U. Biao, and Z.H.U. Zhu-jun. 2014. Low root zone temperature exacerbates the ion imbalance and photosynthesis inhibition
  34. and induces antioxidant responses in tomato plants under salinity. Journal of Integrative Agriculture, 13(1):89–99.
  35. S2095-3119(13)60586-9.