Environmental and Physiological Studies on Measurement and Optimization of Root absorption and Translocation in Plants.

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The aim of this research is to newly develop the methodologies for evaluating functions of mass absorption in intact roots and mass accumulation into fruits and to analyze mechanisms of environmental effects on these functions from the point of view of optimization of transport phenomena in the plant-environment system. The main results obtained from 2002 to 2004 are summarized below :1.In the NFT liquid culture system, the new methodology was established for measurements of uptake rates of water and each inorganic ion and concentrations of the respective ions in.xylem sap in intact roots, and short term and long term effects of the high root temperature stress and effect of the short term salt stress were elucidated.2.Evaluations of fluxes of mass (sap, and soluble solids) into a tomato fruit via phloem and concentrations of soluble solids in the phloem sap were enabled, and effects of salt stress and water stress on mass accumulation into tomato fruits were analyzed with special reference to osmoregulation in phloem transport.3.The cooperative application of the high pressure flow meter and the pressure tank for intact root system of a whole plant enabled quantitative analyses of characteristics of root absorption under various root environments.4.A new method for evaluation of transpiration from plant canopy in a field was developed on the basis of stomatal closure by applying abscisic acid (ABA) to plants.5.By applying the new methodologies developed above, it was verified, for example, that the short-term salt stress treatment with the concentrated deep seawater at the stage of rapid fruit growth of tomato plants can induce the osmoregulation in phloem transport and results in production of high quality tomatoes enriched in sugar, acid, minerals and good flavor.