Nutrient uptake and use efficiencies in Medicago ciliaris under salinity

Salt-induced responses of Medicago ciliaris was studied under controlled conditions. Twenty-two-day old seedlings were cultivated for one month in a nutrient medium added or not with 75 mM sodium chloride (NaCl). Our results showed that this species is relatively salt-tolerant since the whole biomass production of salt-treated plants was affected a little (?30%) as compared to the control. The slight salt effect was mainly nutritional and concerned both macro potassium, calcium and magnesium (K, Ca, and Mg) and micro-nutrients iron (Fe). K and Fe uptake efficiencies were more affected than those of Ca and Mg. Nevertheless, M. ciliaris was able to counterbalance this impact by increasing both K and Fe use efficiencies. The enhancement of K use efficiency could be due in part to the plant aptitude to accumulate sodium (Na⁺) ions within its shoot tissues and to use them for osmotic adjustment. This “includer” behavior allowed M. ciliaris to maintain an adequate water status under saline conditions.