Use of a high-pressure flowmeter for evaluating hydraulic characteristics of plant organs and absorption functions of roots

The hydraulic characteristics of plant organs and the absorption functions of roots of corn and tomato plants were analyzed by using a specialized high-pressure flowmeter (HPFM), which was equipped with a root chamber as well as a coupling to connect to the plant organs. The HPFM can detect changes in the hydraulic properties of the respective parts of the plant body. The hydraulic resistances of the leaf and root decreased with an increase in the water flow rate; this dependence was remarkable at low water flow rates. On the other hand, the hydraulic resistance of the stem was only slightly affected by the water flow. However, a positive linear relationship between hydraulic conductance (reciprocal of resistance) and water flow rate was found for the shoot, stem, and root, respectively. Further, the rate of nutrient (NO3−) absorption by the root was evaluated from the water flow (root water absorption) and NO3− concentration in the xylem sap exuded from the root stump. The high-pressure flowmeter with the root chamber can be used for studying water and nutrient transport in plants and their responses to environmental elements.