antioxidants in different potato genotypes: effect of drought and wounding stress

Potatoes are regarded as a significant antioxidant source in human nutrition. However, different types of environmental stress may affect the level of antioxidants in their tuber tissue. In this study, two purple breeding clones and the yellow fleshed cultivar (cv.) Agave were grown in the glasshouse under control with drought stress conditions for two consecutive years. After harvest, the tubers were analysed for concentrations of antioxidants measured as ascorbic acid equivalent (ACE) and trolox equivalent (TXE) in fresh tissue and after wounding. In addition, the peroxidase enzyme (POD) activities and total amounts of anthocyanins (Ac) were assayed. Drought stress caused a significant decrease in tuber yield but had no significant effect on Ac, POD, ACE and TXE. Wounding stress significantly induced the POD activity in control and drought stressed tubers of all genotypes. Also the ACE and TXE were notably increased by wounding in cv. Agave. This was less pronounced in the purple clones which in general displayed a higher level of antioxidants. The results revealed significant differences between genotypes and that the effect of drought stress on the level of antioxidants is smaller than that of wounding stress.