Growth and Photosynthetic Response of Two Persimmon Rootstocks (<i>Diospyros kaki</i> and <i>D. virginiana</i>) under Different Salinity Levels

<p><span lang="EN-GB" style="font-size: 12.0pt; font-family: Garamond Premr Pro">Salinity continues to be a major factor in reduced crop productivity and profit in many arid and semiarid regions. Seedlings of <i>Diospyros kaki</i> Thunb. and <i>D. virginiana</i> L. are commonly used as rootstock in persimmon cultivation. In this study we have evaluated the effects of different salinity levels on photosynthetic capacity and plant development of <i>D. kaki</i> and <i>D. virginiana</i>. Salinity was provided by adding 50 mM, 75 mM and 100 mM NaCl to nutrient solution. In order to determine the effects of different salinity levels on plant growth, leaf number, plant height, shoot and root dry mass were recorded. Besides leaf Na, Cl, K and Ca concentrations were determined. Also leaf chlorophyll concentration, chlorophyll fluorescence (<i>Fv’/Fm’</i>) and leaf gas exchange parameters including leaf net photosynthetic rate (<i>P</i>_N), stomatal conductance (<i>g_S</i>), leaf transpiration rate (<i>E</i>), and CO₂ substomatal concentration (<i>C</i>i) were investigated. Significant decrease of leaf number, shoot length and plant dry mass by increasing salinity levels was observed in both rootstocks. <i>D. virginiana</i> was less affected in terms of plant growth under salinity stress. Leaf chlorophyll concentration reduction was higher in the leaves of <i>D. kaki</i> in comparison to <i>D. virginiana</i> in 100 mM NaCl treatment. By increasing salinity levels <i>P</i>_N, <i>g</i>_S and <i>E</i> markedly decreased in both rootstocks and <i>D. kaki</i> was more affected from salinity in terms of leaf gas exchange parameters. In addition there was no significant difference but slight decreases were recorded in leaf chlorophyll fluorescences of both rootstocks.</span></p>