Photosynthetic and Ultrastructural Properties of Eggplant (Solanum melongena) under Salinity Stress

Salinity is one of the major problems facing crops worldwide. Salinity can severely affect plants in a negative manner. This study aimed to evaluate the impact of NaCl on morpho–physiological, biochemical, structural and ultrastructural properties in Solanum melongena seedlings under different NaCl concentrations. Plants treated with high concentrations of NaCl showed a nonsignificant decrease in shoot height compared to the controls. However, NaCl concentration of 50 mM and above significantly decreased leaf area, while 75 mM and above significantly reduced the photosynthetic rate (PN) and leaf total sugar content when compared with plants treated with less-concentrated NaCl and the controls. Thick root sections from plants grown in 100 and 150 mM NaCl exhibit severe deformation in the epidermal and cortical layers. Additionally, TEM micrographs of plants treated with 75, 100, and 150 mM exhibited bulgy chloroplasts with loss of integrity thylakoid membranes associated with large starch grains. The changes in plant ultrastructure observed in this study broaden our knowledge about the impact of salinity at the cellular level.