Interactive effects of salinity and phosphorus availability on growth, water relations, nutritional status and photosynthetic activity of barley ( Hordeum vulgare L.)

The interactive effects of salinity and phosphorus availability on growth, water relations, nutritional status and photosynthetic activity were investigated in barley ( Hordeum vulgare L. cv. Manel). Seedlings were grown hydroponically under low or sufficient phosphorus (P) supply (5 or 180 μmol KH 2 PO 4 plant −1 week −1 , respectively), with or without 100 m m NaCl. Phosphorus deficiency or salinity significantly decreased whole plant growth, leaf water content, leaf osmotic potential and gas exchange parameters, with a more marked impact of P stress. The effect of both stresses was not additive since the response of plants to combined salinity and P deficiency was similar to that of plants grown under P deficiency alone. In addition, salt‐treated plants exposed to P deficiency showed higher salt tolerance compared to plants grown with sufficient P supply. This was related to plant ability to significantly increase root:shoot DW ratio, root length, K + /Na + ratio, leaf proline and soluble sugar concentrations and total non‐enzymatic antioxidant capacity, together with restricting Na + accumulation in the upper leaves. As a whole, our results indicate that under concomitant exposure to both salt and P deficiency, the impact of the latter constraint is pre‐dominant.