PHOTOSYNTHETIC CHARACTERISTICS IN MULBERRY DURING WATER-STRESS AND REWATERING

Three-month-old plants of mulberry (Morus alba L. cv. Kanva-2) were su bjected to a drought stress by withholding water supply. As the leaf w ater potential (Psi(w)) was dropping progressively with the severity o f treatment and increasing stress duration, the values of leaf area, d ry mass accumulation, total chlorophyll (Chl) content, net photosynthe tic rate (P-N), Stomatal conductance (g(s)), and transpiration rate (E ) were declined. The photosystem 2 (PS2) photochemical efficiency sign ificantly decreased only at a severe stress treatment. The intercellul ar CO2 concentration (C-i) remained unaltered during a mild stress, ye t it increased under moderate and severe stresses. The C-i/g(s) ratio reflected the mesophyll efficiency during water stress. Rewatering of the plants led to an almost complete recovery of P-N, E, and g(s), ind icating that a shortterm stress brings about reversible effects only.