Effects of NaCl stress on seed germination, early seedling growth and physiological characteristics of cauliflower (Brassica oleracea L. var. botrytis L.)

Abstract

Effects of salt stress on seed germination, early seedling growth and some physiological characteristics were evaluated for four cauliflower species in seven treatments of salinity including 0 (control), 34, 68, 102, 136, 170 and 204 mM NaCl in a three replicated randomized completely block design (RCBD). This result shows that different treatments of salinity had considerable effect on the germination percentage, vigor index, seedling height, root length, peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and root activities, malondialdehyde (MDA), soluble protein, chlorophyll and carotenoid contents. Germination percentage and vigor index of four species showed considerable decrease with increasing salinity up to 204 mM NaCl except for germination at 34 mM NaCl. The seedling growth was significantly affected by all salinity levels. Particularly at 136 mM and 170 mM NaCl, seedling height and root length of all species were reduced significantly. POD and root activities of all four species were reduced gradually as salinity increased. SOD activities and chlorophyll and carotenoid contents of these species increased first at 34, 68 and 102 mM NaCl and then decreased at 136 and 170 mM NaCl. Both CAT activity and soluble protein content showed the reversed changing trend with SOD etc. MDA Contents of these four species showed considerable increase with increasing salinity up to 204 mM NaCl. Key words: Salt stress, cauliflower, germination, physiological characteristics, antioxidative enzyme, MDA.