Antioxidant metabolism variation associated with salt tolerance of six maize (Zea mays L.) cultivars

Salt stress is a major limiting factor for crop production in many regions. This study examined antioxidant metabolism variation associated with salt stress tolerance of six maize cultivars (Luyu39, Huanong138, Xianyu335, Aoyu3007, Yayu8, Jinping618) under growth chamber environments. The seedlings of six cultivars were subjected to seven NaCl concentrations ranging from 0 to 295 mM for 20 days. The salt stress tolerance of the six cultivars varied largely, with their salt tolerance threshold values ranging from 184.5 to 303.4 mM. Luyu39 had the highest threshold value and was considered as salt tolerant cultivar, and Jinping618 had the lowest threshold (184.5 mM) and was considered as salt sensitive cultivar. Luyu39 had lower MDA content, higher antioxidant enzyme (SOD, CAT, and POD) activity, and lower proline content when compared to Jinping618 at 245 mM and 295 mM NaCl levels. The results suggest that MDA, antioxidant enzyme activity, and proline content can be used as metabolic markers to evaluate relative salt tolerance of different maize cultivars under severe salt stress (245 mM or higher concentration NaCl) conditions.