Internal Plant-water-status and Its Control

Abstract

The present paper deals with an experimental method for evaluating the plant water status. An apparatus which enables continuous and nondestructive measurement of internal plant water stress has been developed by making use of a strain-gauge. The apparatus shown in Fig. 1 was used to indicate the change in plant stem diameter.Experiments were carried out for two plants (Sunflower and Grapevine) to examine the relations between the change in stem diameter and other factors such as leaf water potential, water deficit and leaf temperature. The results show that the change in stem diameter has proved useful to indicate change in related factors.Stem diameter shows a linear relationships with water deficiency (Fig. 2) but when related to the water potential, it is represented by two straight lines which intersect at about -12 bars (Fig. 3). Under changing plant water condition stem diameter changes according to the change in the leaf temperature (Fig. 5, 6, 7). It is considered that this cyclic valiation was due to passive stomatal water movement. From these results it was concluded that the practical application of the present method has, therefore, been confirmed.