Physiological and biochemical responses of two maize cultivars (Corralejo and Tlaltizapon) under salt stress

The aim of the present work was to study the effect of different concentrations of NaCl (0, 50 and 100mM) in two cultivars of maize (Corralejo and Tlaltizapan), on their nutritional and photosynthetic comportment. The measures focused on the physiological parameters (growth weight, hydration and nutritional status of plants) and biochemical (chlorophyll, PEPC activity, activity of some anti-oxidant enzymes and lipid peroxidation). Analysis of morphological parameters showed a yellowing of the extremity of leaves, at 100 mM of NaCl. These visual symptoms are associated with a decrease of chlorophyll. A decrease in potential growth was found in two cultivars, but less significant in Corralejo. The best salt tolerance of the latter was due to a better hydration of the leaves, to a lesser accumulation of Na+ and Cl- in its leaves and a better selectivity K/Na. To identify the biochemical characteristics associated with the physiological behavior, we conducted measures activity of PEPC, the protein, catalase and peroxidase on the fourth leaf from the bottom. A negative correlation between the activity of PEPC and Na+ amount was found at 50 mM in the sensitive cultivar and at 100 mM of NaCl in tolerant cultivar Corralejo. Furthermore, the antioxidant response was marked by a greater accumulation of malondialdehyde, in Tlaltizapan at 100 mM of NaCl. At the same concentration, catalase peroxidase and SOD activities weren't decreased in this cultivar. This suggests that salt has created a stress oxidative state only in Tlaltizapan leaves. These results showed a better performance of Corralejo cultivar compared to Tlaltizapan cultivar, at 50 and 100 mM of NaCl.