ARBUSCULAR MYCORRHIZAL COLONIZATION DOES NOT ALLEVIATE SODIUM CHLORIDE-SALINITY STRESS IN VINCA [CATHARANTHUS ROSEUS (L.) G. DON]

We conducted a study to determine if inoculation with arbuscular mycorrhizal fungi (AMF) would enhance the tolerance of vinca [Catharanthus roseus (L.) G. Don] plants to sodium chloride (NaCl)-induced salinity in irrigation water. Vinca tolerated salinity levels up to 40 mM. Chlorophyll concentration, proline synthesis, and total antioxidant activity were increased with saline irrigation, while leaf potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and boron (B) content decreased, suggesting a detrimental salinity effect. Despite the limited effect of increasing salinity on N content, NaCl-stressed vinca plants showed a marked decrease in nitrate reductase activity, which was associated with decreased leaf K and Fe total content. Mycorrhizal inoculation resulted in reduced growth when compared to non-AMF plants, regardless of salinity level. The K/sodium (Na) ratio decreased dramatically with increasing salinity regardless of AMF treatment. Suggesting, that the AMF isolate was not able to selectively uptake K and Ca, and avoid uptake of Na.