Effects of wind and wind-sand flow on membrane permeability and membrane protection system of corn seedling leaf

Corn seedlings are often harmed by wind and wind-blown sand flowing in semi-arid, wind-sand areas of west of Northeast China in spring. In order to understand the physiological response mechanism of corn seedlings to wind and wind-blown sand damages, net-wind and wind-blown sand experiments were conducted in the spring of 2013 in Horqin Sand Land of eastern Inner Mongolia. The experiments included six wind speed treatments 0 m·s^-1 (CK), 6 m·s^-1, 9 m·s^-1, 12 m·s^-1, 15 m·s^-1 and 18 m·s^-1 and six wind-sand flow strengths 0 g·cm^-1·min^-1 (CK), 1.00 g·cm^-1·min^-1, 28.30 g·cm^-1·min^-1, 63.28 g·cm^-1·min^-1, 111.82 g·cm ^-1·min^-1 and 172.93 g·cm^-1·min^-1, which were corresponding to the above wind speeds. The results showed that with increasing wind speed in the net-wind experiment, MDA content and POD activity apparently increased. Also membrane permeability, SOD and CAT activities, and soluble sugar and proline contents fluctuated with changing wind speed. Compared with CK, SOD activities in 12 18 m·s^-1 treatments and POD activities in 6 m·s^-1 and 12 18 m·s^-1 treatments, CAT activities in 6 m·s^-1 and 12 m·s^-1 treatments, soluble sugar content in 6 m·s^-1 treatment and prolin content in 18 m·s^-1 treatment increased significantly. With increasing wind speed under the wind-sand flow experiment, MDA content, SOD activity and soluble sugar content apparently decreased, membrane permeability and POD activity increased significantly, CAT activity and proline content did not significantly change. The only exception was for proline content in 18 m·s^-1 treatment where wind-blown sand strength reached 172.93 g·cm^-1·min^-1. The results suggested that while the 10 min net-wind blow had no significant effect on cell membranes of corn seedlings, wind-blown sand stress caused significant damage to seedling membrane structure. POD played an important role in protecting seedling cell membranes against damage of wind and wind-blown sand stress. Also proline played an osmotic adjustment role under 18 m·s^-1 net-wind and wind-blown sand stress.