Response of growth and physiological changes of Sophora moorcroftiana seedlings to root-cutting intensity

This study focused on the effects of different root-cutting intensities on the growth and physiological indexes of Sophora moorcroftiana seedlings, and explored the optimal root-cutting intensity at the seedling stage. One-year-old seedlings of S. moorcroftiana were transplanted after cutting out 1/5 (C1/5), 1/4 (C1/4), 1/3 (C1/3), 1/2 (C1/2) of main roots, respectively, taking no cutting root (CK) seedlings as the control. The results showed that: 1) The survival rate of S. moorcroftiana seedlings was followed as C1/5＞CK＞C1/4＞C1/3＞C1/2, which indicated that moderate root-cutting treatments could improve the survival rate of S. moorcroftiana seedlings; however, with the increase of the root-cutting intensity, the survival rate of seedlings showed a downward trend. The height, ground diameter and biomass of young seedlings under the CK treatment were the highest, but C1/5 treatment had the highest water content of leaves and ratio of root to shoot, and the smallest ratio of height to diameter, which indicated that the moderate root-cutting treatments could improve the water content of leaves and seedling quality. 2) Root-cutting treatments significantly reduced the chlorophyll contents of S. moorcroftiana seedlings. In leaves, the malondialdehyde (MDA) content was the highest under the C1/2 treatment, and the proline content was the highest under the C1/5 treatment, and the activities of peroxidase (POD) and superoxide dismutase (SOD) were the highest under the C1/2 treatment. Moderate root-cutting treatments were beneficial to improve root activity. The MDA content in roots was significantly higher under the high root-cutting intensity than that under the CK and low root-cutting intensity. The activities of POD and SOD in roots were the highest under the C1/2 treatment. In conclusion, root-cutting treatments significantly affect the growth and physiological indexes of S. moorcroftiana seedlings, and the C1/5 root-cutting treatment has a better promotion effect on the growth and physiological indexes of S. moorcroftiana seedlings. It is suggested that moderate root-cutting treatment should be used to improve the survival rate of seedlings in the process of vegetation restoration and transplanting.