Journal of Agricultural Technology 2010, Vol. 6(3): 543-558 543 Responses of root uptake to high temperature of tomato plants (Lycopersicon esculentum Mill.) in soil-less culture Falah, M.A.F. * , Wajima, T. 2 , Yasutake, D. 2 , Sago, Y. 3 and Kitano, M. 3 1 Faculty of Agricultural Technology, Gadjah Mada University, Sosio Yustisia No 1, Bulaksumur Yogyakarta,55281, Indonesia. 2 Faculty of Agriculture, Kochi University, Monobe B 200, Nankoku, Kochi, Japan. 3 Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. Falah, M.A.F., Wajima, T., Yasutake, D., Sago, Y. and Kitano, M. (2010). Responses of root uptake to high temperature of tomato plants ( Lycopersicon esculentum Mill.) in soil-less culture. Journal of Agricultural Technology 6(3): 543-558. In plant production, high temperature stress frequently causes physiological disorders and yield depression, and information about physiological functions of intact roots is essential. However, there have been difficulties in measurement of physiological functions of intact roots in the plant production systems. Effects of high solution temperature on water and nutrients uptake by roots of tomato plants cultivated in the NFT system were analyzed. Dynamic and simultaneous evaluation of water and nutrients uptake by roots was developed in the NFT system. Rates of water and nutrients uptake by roots were evaluated simultaneously on the basis of time courses analyses of water balance and nutrients balance in the systems, and these also enabled estimation of nutrients concentration in root xylem sap. Rates of water and nutrients uptake by roots varied depending on solar radiation. The short-term effect of high solution temperature activated water and nutrients uptake through decrease in water viscosity and affected membranes transport. On the other hand, the long-term effects of high solution temperature caused growth depression and browning in roots, and these resulted in depressed water and nutrients uptake rates. The long-term effects of high solution temperature were considered to relate to the reduced oxygen solubility and the increased enzymatic oxidization of phenolic compounds in root epidermal and cortex tissues. The long-term effect of high solution temperature decreased nutrients concentration in root xylem sap, and the root xylem sap concentrations of N, K and Ca became lower than those in the nutrient solution. This indicates that active processes involved in root uptake of those nutrients were retarded by the long-term treatment with * Corresponding author: Mohammad Affan Fajar Falah; e-mail: affan_ff@yahoo.com Journal of Agricultural Technology 2010 Vol. 6(3): 543-558 Available online http://www.ijat-rmutto.com ISSN 1686-9141