Salinity thresholds and genotypic variability of cabbage (Brassica oleracea L.) grown under saline stress

Background Two botanical varieties of cabbage, namely Savoy (Brassica oleracea var. Sabauda L.) and White (Brassica oleracea var. Capitata L.) were used in order to understand the morphological, physiological and biochemical elements of functional salt stress response. Thirteen salt concentrations (range 0 to 300 mM NaCl) were considered in Exp. 1# and out of them three (0, 100 and 200 mM NaCl) were used in Exp. 2#. Results Exp. 1# enabled to define two salinity thresholds (100 and 200 mM NaCl), associated with morphological and physiological adaptations. In Exp. 2#, moderate salinity (100 mM NaCl) had lower effects on Savoy than in White cabbage yield (respectively – 16% and −62% from control). Concurrently, 100 mM NaCl resulted in a significant increase of antioxidant enzymes from control conditions, that was greater in Savoy (+289, +423 and +88% respectively) as compared to White (+114, +356 and +28% respectively) cabbage. Ions accumulation resulted to be a key determinant in tissue osmotic adjustment (mainly in Savoy) whereas the contribution of organic osmolites was negligible. Conclusions Higher antioxidative enzymatic activities in Savoy vs White cabbage upon 100 mM NaCl were associated with improved water relations, thus suggesting a possible physiological pathway for alleviating perceived salt stress