Antioxidant activity of enzymatic system of two different wheat (Triticum aestivum L.) cultivars growing under salt stress

Soil salinity and semi-arid and arid climate of Pakistan is a major constraint in agriculture and predominantly in foodstuff production. It limits crop yield and use of land previously uncultivated. Wheat is moderately salt tolerant. A great variation was observed between and within the cultivars (genotypes: S-24 salt tolerant and DN-27 salt sensitive) in relationship to the choice of salinity level (control and treatments: in increment of 25 mol/m(3) NaCl/day to a final level of 80 and 160 mol/m(3) NaCl into the nutrient solution) that will be used for screening purpose. Relative water content (RWC), membrane stability index and the activities of some antioxidant enzymes were determined after 20 and 40 days of salt stress exposure. As a result of activity enzymes, superoxide dismutase (SOD), peroxidase (POD) and catalase increased in S-24 with the increase of salt stress, while in DN-27 all the enzymes showed constant activity at all the stress levels. Meanwhile, relative water content and membrane stability index decrease the value as well as they increases the stress levels. It can be concluded that all three antioxidant enzymes were limiting factors for these genotypes and these reasons also led to the salt sensitivity in DN-27. Different selection methods should be applied to improve different traits in different conditions in wheat.