NaCl salinity-induced changes in water status, ion contents and photosynthetic properties of Shepherdia argentea (Pursh) Nutt. seedlings

Abstract

Two-year old seedlings of Silver buffaloberry (Shepherdia argentea (Pursh) Nutt.) were exposed to NaCl salinity (0, 200, 400 and 600 mmol/l) for 30 days. Leaf water potential (Ψ<sub>w</sub>), chlorophyll contents (Chl a, b, and a + b) and K<sup>+</sup> content decreased with an increase in salinity. Relative water content (RWC) declined significantly with<br />400 and 600 mmol/l NaCl. However, salinity induced an excessive accumulation of Na<sup>+</sup> in the leaves of plants. Light responses of photosynthesis showed that net photosynthetic rate (P<sub>N</sub>) values were continuously raised with the increase of photosynthetic photon flux density (PPFD) at all salinity levels and plants treated with 600 mmol/l salinity suffered from photoinhibition with the lowest P<sub>N</sub> values. The reduction of P<sub>N</sub> and stomatal conductance (g<sub>s</sub>) associated with a sharp increase of intercellular CO<sub>2</sub> concentration (C<sub>i</sub>) in the leaves at 600 mmol/l salt-treated plants showed that non-stomatal limitations might have prevailed over stomatal limitations under severe saline conditions, due to severe cellular dehydration, inhibited synthesis of chlorophyll and ionic imbalance and toxicity. It is concluded that S. argentea possesses high salt tolerance capacity and can be widely cultivated in salt-affected areas.