Effects of soil salinization on Brassica napus L.

Morpho-physiological variations play an important role in plant adaptation to salt stress. We evaluated the morpho-biochemical changes, induced by a progressive salt exposure in cvs of Brassica napus L., that may lead to adaptation to saline soil. Basing on germination test on seeds of several cvs, exposed to increasing concentration of NaCl, we selected tolerant (T) and susceptible (S) genotypes. To evaluate their adaptation ability to salinity, 15 days old seedlings of Dynastie (T) and SY Saveo (S) cvs were irrigated with Hoagland solution added with 0 (control), 160 and 320 mM NaCl for 60 days. Gradual plant exposure to salinity reduced plant growth, size and number of leaves. Treated plants had higher amounts of proline, phenolics and pigments. Photochemical activity was not particularly affected by NaCl. The activity of polyphenol oxidase, ascorbate peroxidase and superoxide dismutase were differently enhanced in the two cvs. In these cvs the salt exposure elicited responses, i.e. a genotype dependent acclimation, that improve tolerance. This work represents a starting point to enhance the knowledge of stress response mechanisms in oil seed rape to select tolerant cvs for breeding and saline soil recovery programs.