Leaf stiffness of two Moraceae species based on leaf tensity determined by compressing different external gripping forces under dehydration stress

ABSTRACT Leaf water status determination based on mechanical and electrophysiological properties helps determine the inherent as well as instantaneous leaf dehydration tolerance synchronously. The leaf water potential (ΨL), physiological capacitance (CP) and gripping force (F) were determined with leaves of Broussonetia papyrifera (L.) Vent. and Morus alba L. Real-time leaf stiffness (LCSrt) and maximum leaf stiffness (LCSmax) were investigated by compressing a leaf with external gripping force. Results indicated that LT displayed good correlation with F. Compared to M. alba, a better instantaneous dehydration tolerance or pressure resistance in B. papyrifera was correlated to its persistent stronger LCSrt or LCSmax, respectively. B. papyrifera showed better flexibility and tolerance to wider range of pressure than M. alba. The higher leaf mechanical strength helped to maintain a higher outward pulling force of cell walls; thus, the subsequent negative pressure effectively inhibited cellular water loss. B. papyrifera exhibited better drought resistance than M. alba