PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES TO NACl SALINITY STRESS IN THREE ROEGNERIA (POACEAE) SPECIES

This study aimed to identify the most tolerant species under salinity stress, amongst Roegneria turczaninovii (Drob.) Nevski var. macrathera Ohwi (R. turczaninovii), Roegneria stricta Keng (R. stricta) and Roegneria komarovii (Nevski) Nevski (R. komarovii). The seeds of three species were exposed to different NaCl concentrations (0, 75, 100, 125, 150, 175, 200, 225, 250 or 275 mmol/L) and the germination percentage (GP) was calculated after 7 days. Meanwhile, seedlings grown under normal condition at the two-leaf stage were subjected to 500 mL of NaCl solution (0, 30, 60, 90, 120, 150 or 180 mmol/L) for 7 days. Then the physical indicators such as plant height, root length, contents of chlorophyll (Chl), malondialdehyde (MDA), proline, soluble sugars, relative water content (RWC); and the biochemical changes including activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in three species under different concentrations of NaCl were determined. As a result, GP, plant height, root length, contents of Chl and RWC were reduced with the increase of concentration of NaCl, while MDA, proline, soluble sugars, SOD, POD and CAT were increased. R. komarovii achieved a higher GP; contents of Chl, RWC, proline, soluble sugars; SOD, POD and CAT activities; but a lower MDA content, compared to the other two species. Significant differences between any two species were detected (P < 0.05). R. komarovii is more resistant and tolerant in response to salinity stress than R. turczaninovii and R. stricta.