Comparative study of local and introduced chard (Perpetual spinach) varieties grown under salt stress. Mehdaoui, M., Mhamdi, R., Mhadhbi, H., Gouia, H., and Debouba, M. (Tunisia)

Abstract

Unfortunately, many traditional crop germplasms are being abandoned by local farmers and newly introduced varieties are used instead, without any rigorous ecophysiological study regarding their adaptive potential to local environment. In Tunisian arid regions, where salt water is often used for irrigation, a commercial chard (Perpetual spinach) variety Sais has been introduced and is currently replacing an inherited one Arbi of Medenine. In the present work, we aimed to assess the differential response of these two chard varieties (Arbi, Medenine and Sais, Italy) to two salt treatments (7 and 14 g NaCl/l). In both Arbi and Sais shoots, salinity increase led to an endogenous accumulation of sodium and proline associated with a decrease in potassium levels. The lipid peroxidation products (Malondialdehyde, MDA) accumulation in Arbi was considerably greater than in Sais, indicating a higher degree of lipid peroxidation at 14 g/l salt treatment. Salinity stimulated the superoxide dismutase (SOD, E.C. 1.15.1.1), catalase (CAT, EC 1.11.1.6) and guaïacol peroxidase (GPX, EC 1.11.1.7) activities in Arbi shoot, even under severe salt stress (14 g/l). In contrast, these antioxidant enzymes were inhibited by NaCl in Sais shoots. It could be concluded that introduced chard (Sais) exhibited better growth and displayed similar metabolite levels relative to local one (Arbi), but the local chard seems to have stronger antioxidant system that may insure better adaption to water salinity.

Keywords

• Growth
• oxidative stress
• Perpetual spinach
• potassium
• sodium