Interactive effects of Si and NaCl on growth, yield, photosynthesis, and ions content in strawberry (Fragaria × ananassa var Camarosa)

The effects of silicon (Si) (0, 1, and 2 mM) and sodium chloride (NaCl) salinity (0, 20, and 40 mM) on the yield, photosynthesis, and ion content in strawberry grown in hydroponics were investigated. Salinity caused a reduction in leaf area and plant biomass, regardless of Si supplement. Leaf area in Si ₁Na ₂₀ treatment was 37% higher than that of Si ₀Na ₂₀ treatment. Salinity at 20 mM concentration had a 25% yield reduction in absence of Si, corresponding to no reduction in the yield in the presence of Si compared with the Si treatment without salinity. The highest reduction of photosynthetic rate (Pn) was observed in Si ₁Na ₄₀ treatment; however, in the presence of Si, there was no reduction in the Pn rate at 20 mM NaCl concentration. An obvious positive relationship was found between potassium/sodium (K/Na) and Pn rate. Within each Si concentration, the increased salinity increased Na concentration in the leaf tissue. However, when Si was supplied to the salinity treatments Na concentration was significantly lower than that of the similar treatments without Si. Supplement of Si to the nutrient solution increased the Si concentration in the roots, and old and young leaves. A clear negative relationship (r ² = 0.71) was found between Si and Na concentration in the leaves. Salinity (NaCl ₄₀) increased the proline level 2.5-fold in the absence of Si, corresponding to no changes the proline level in the presence of 1 mM Si concentration compared with the Si treatment without salinity. The salinity (40 mM) increased the electroleakage by 50% compared with 0 mM NaCl treatment in the absence of Si supplement. Findings from this study lead to the conclusion that Si supplement to the nutrient solution ameliorated the deleterious effect of salinity on the strawberry growth; these effects were attributed to an enhanced K/Na ratio and the reduction in Na content and electroleakage ability in the leaf tissue.