Assessment of the Antioxidative Function of Electrolyzed-Reduced Water in Relation to Photoinhibition of Photosynthesis.

Abstract

Electrolyzed-reduced water (reduced water) is produced during electrolysis of KCl solution near cathodes, and exhibits high pH, and extremely negative oxidation-reduction potential. Shirahata et al. (Biochem. Biophys. Res. Commun. 234:269-274, 1997) reported that reduced water could scavenge reactive oxygen species. The objective of this research was to determine whether application of reduced water could suppress photooxidative damage of photosynthetic apparatus induced under low temperature and high-intensity of photosynthetic photon flux density (PPFD) conditions. Hydroponically-grown plants of spinach and sweet potato were treated with reduced water, and exposed to low temperature and high light intensity conditions, and the chlorophyll fluorescence parameters, phiPSII and Fv/Fm were measured. The photoinhibitory treatment caused decreases in phiPSII for both spinach and sweet potato even when the plants were irrigated, sprayed or showered with reduced water. In addition, phiPSII was measured for mesophyll cells of sweet potato suspended in reduced water. After the exposure to high-intensity of PPFD (12 000 mumol m-2 s-1), the phiPSII of the suspended cells in reduced water was nearly zero when pH of the suspensions was not adjusted. In the experimental conditions, the application of reduced water did not suppress photooxidative damage of photosynthesis induced by low temperatures and high light intensity