the influence of salinity on the different polyamine fractions (free, conjugated, and bound) was compared in a natrophilic halophyte (beta vulgaris l. cv. ic) and a salt sensitive glycophyte (nicotiana rustica l. cv. basmas). low-level salinity (25 mm nacl) and high salinity (150 and 50 mm nacl for sugar beet and tobacco, respectively) were supplied in hydroponics. under low salinity shoot dry ...