Tolerance of Kikuyu grass to long term salt stress is associated with the induction of antioxidant defences

The response of the antioxidant system to long term (15 d) salt stress (50, 100, 200 mM NaCl) was studied in kikuyu (Pennisetum clandestinum, Hochst.), a perennial grass with a well developed root system (often used as an erosion controlling ground cover) and with high nutritive properties as pasture. The activities of peroxidase, catalase, ascorbate peroxidase, ascorbate-free radical reductase, glutathione reductase and dehydroascorbate reductase enzymes involved in the detoxification from reactive oxygen species were investigated. The growth of kikuyu grass was inhibited at 200 mM NaCl. Salinity affected root length more than leaf length. Lower activities of catalase, ascorbate-free radical reductase, and dehydroascorbate reductase enzymes were observed in stressed plants. The tolerance of kikuyu grass to salt stress (up to 100 mM) appears to be related to up-regulation of ascorbate peroxidase, peroxidase and glutathione reductase enzymes.