Effect of drought and waterlogging on hydrophilic antioxidants and their activity in potato tubers.

Maintaining a strong antioxidant system is essential for preventing drought or waterlogging stresses damage in potato tubers. In the two-year pot experiment, the effect of long-term drought and waterlogging stresses on the content of phenolic acids, ascorbic acid, and antioxidant activity in potato tubers and relative water content of four cultivars was evaluated. Drought stress significantly (P < 0.05) decreased relative water content (RWC) in the leaves of all genotypes. The evaluation of the relationship between phenolic acid content and the level of plant stress expressed as RWC showed a negative correlation between RWC and most phenolic acids, but these correlations were not statistically significant, with the exception of l-tyrosine. A significant positive correlation was found between total and individual phenolic acid content and antioxidant activity (R = 0.657), confirming the main responsibility for the increase of antioxidant activity. The average tuber yield and weight as well as their average number correlated negatively with total phenolic acids. Drought stress decreased l-ascorbic acid content by reduction of biosynthesis, and its content was positively correlated with decreased RWC, tubers yield, weight, and number. The increase of phenolic antioxidants in potato under stress conditions can be a distinctive marker of cultivar resistance against abiotic stresses. [ABSTRACT FROM AUTHOR]