Effect of water deficit and sulphur dioxide on total soluble proteins, nitrate reductase activity and free proline content in sunflower leaves

Abstract

Sunflower (Helianthus annus L. cv. PSH-7) plants were subjected to different osmotic potentials, using polyethylene glycol-6000 (PEG-6000), after, prior to and during SO2 fumigation. Total soluble proteins and nitrate reductase activity (NRA) decreased, and free proline content increased with the increasing water stress. These biochemical parameters were more adversely affected in fumigated plants than in non-fumigated ones, when mild water stress was provided prior to and during fumigation. When severe water stress was given prior to and during fumigation, total soluble proteins, NRA and free proline content were nearly the same in fumigated and non-fumigated water-stressed plants; it is because the stomatal closure was observed in water-stressed plants. The leaf water potential decreased with the increasing water stress; however, it was not significantly affected due to SO2 fumigation. © 1992 Institute of Experimental Botany.