Effects of Soil Acid stress on Root Ultrastructure and Enzyme Protection System of Sedum aizoon L.

Abstract

This experiment studied the effects of four different soil pH values (3.4, 4.4, 5.5, 6.6) on the growth and enzyme protection system of Sedum aizoon L. by simulating soil acidification. Results showed that: Sedum aizoon L. grew best in the control soil. With the decrease of soil pH, plant height and aboveground fresh were gradually inhibited, but mild stress (pH 5.5) could promote the growth of root length and increase the aboveground fresh, while moderate and severe stress could inhibit its increase. When the soil pH was in the range of 4.6 - 6.6, the activities of SOD,CAT, APX, GR, soluble sugar, soluble protein, proline and mad in the plant increased significantly, but the relative electrical conductivity of the root system was not significantly different from that of the control. After the soil pH was lower than 4.6, except APX activity continued to increase, SOD, CAT, GR activity and soluble sugar, soluble protein, proline content decreased significantly, and root relative conductivity and MDA content increased significantly, which indicated that severe soil acid stress would reduce root protective enzyme activity, cause osmotic adjustment imbalance, and lead to slow or even stop plant growth.