Effect of Soil Drought on Biomass Production, Physiological Attributes and Antioxidant Enzymes Activities of Potato Cultivars

The effects of water deficit on the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX), and also on total antioxidant capacity, ion leakage, proline content, chlorophyll fluorescence, gas exchange, chlorophyll and carotenoid content and plant dry mass of potato cultivars (Solanum tuberosum L.) were investigated. For this purpose, the response of ten potato cultivars (Agria, Arinda, Marfona, Banba, Born, Sante, Milva, Satina, Jelly and Spirit) was studied under two irrigation regimes (70 and 20% of soil available water). Water deficit increased the activity of antioxidant enzymes, ion leakage and proline content but decreased total antioxidant capacity, F-v/F-m, gas exchanges, chlorophyll, carotenoid and plant dry mass in all potato cultivars. Based on stress tolerance index (STI), Agria and Born were the most tolerant and sensitive cultivars to water stress, respectively. Positive correlations were found between total antioxidant capacity and the activities of CAT, APX and POX under control irrigation. Proline content positively correlated with plant dry mass and negatively with photosynthesis, transpiration and carbon dioxide concentration in the sub-stomatal chamber under water deficit treatment. The highest increases in ion leakage under water deficit were observed in the most sensitive cultivars. The results of this experiment, therefore, showed that proline accumulation and ion leakage may be related to water stress tolerance of potato cultivars. Also, increased chlorophyll and carotenoid content in resistant cultivars supported potato plants to tolerate water deficit.