Effect of osmotic stress on growth and osmolytes accumulation in sugar beet (Beta vulgaris L.) plants

To investigate the effects of osmotic stress on plant growth, and ions and compatible solutes accumulations of sugar beet (Beta vulgaris L.), in the present study, two-month-old plants were subjected to different degrees of osmotic stress (-0.5, -1.0, and -1.5 MPa) induced by sorbitol for 7 days. The results showed that fresh weight and water content in both leaf blade and leaf petiole significantly decreased by osmotic stress. With the increase of osmotic stress, Na+ concentration in leaf blade showed the significantly increasing trend. However, osmotic stress significantly reduced K+ concentration in lateral root. It was observed that osmotic stress of -1.5 MPa remarkably increased sucrose accumulation in storage root compared to control. In addition, plants accumulated more sucrose and fructose in storage root than in other tissues. Proline concentrations in leaf blade, leaf petiole and storage root significantly increased by osmotic stress of -1.0 MPa and -1.5 MPa; in leaf blade it was to a higher degree than in leaf petiole and storage root. These results suggested that sugar beet plants can adapt to osmotic stress by accumulating more osmolytes, such as Na+, sucrose and proline.