Foliar spray of ascorbic acid improves salinity tolerance in Solanum tuberosum L.

With an objective to working out an efficient newer approach for improving salt tolerance in potato, non-enzymatic antioxidant ascorbic acid (AA) was tested in an experiment involving its foliar application to pot-grown potato plants. Potato tubers were sown into 8×14 cm earthen pots filled with 10 kg clay-loam soil. The pots were arranged in a randomized complete block design with 10 replicates. The treatments were: control without salt and ascorbic acid (T1), without salt and with foliar spray of ascorbic acid (T2), salt treated-plants with ascorbic acid spray (T3), and with salt and without ascorbic acid (T4). Ascorbic acid (0.5 mM) was sprayed manually once on the leaves in the early morning after every 5 days interval. After two months of salt and ascorbic acid treatments, different growth (fresh/dry weight of tubers, shoot length and number of shoots) and biochemical (total soluble protein contents, peroxidase, catalase, and superoxide dismutase activity) parameters were studied. The response of control potato plants to high level of salinity was reflected by decrease in tuber fresh/dry weight, shoot length and shoot number plant^-1. On the other hand, foliar application of ascorbic acid to control and salinized (120 mM of NaCl) plants not only promoted growth parameters but also resulted in an increase in protein contents and antioxidant enzyme activity as compared to plants without ascorbic acid treatment. Up-regulation of POD, CAT and SOD activities indicated that these enzymes were somehow involved in the scavenging process of reactive oxygen species in potato.