Simultaneous Measurements of Solution Absorption, Transpiration, Relative Plant Water Content and Growth1

Abstract

AbstractInstrumentation is described for the frequent and simultaneous measurement of solution absorption and relative green weight of large individual plants from which transpiration, relative plant water content, and plant growth are calculated. The method is sensitive, nondestructive, and most useful when used in connection with an automatic digital data acquisition system. The system is ideal for monitoring the dynamics of the water status of a large living plant. Measurements made on cotton plants are presented.Relative plant water content (RPWC), defined as the ratio of relative plant green weight at time of interest to that just prior to lights‐on, corrected for accumulated CO2 assimilation, was found to be a good measure of plant water status. Resolution of RPWC is at least 10 times better than leaf density measurements made with beta‐gauging techniques. The measurement is instantaneous and can be repeated as often as desired.