Effects of waterlogging stress on growth, physiological and piochemistry characteristics of Magnolia wufengensis

ObjectiveMagnolia wufengensis has fleshy roots, which are very sensitive to water. In this paper, the waterlogging stress test of Magnolia wufengensis was carried out to investigate the effects of waterlogging environment on its growth, physiological and biochemical characteristics, which provided a theoretical basis for determining the suitable water environment for the growth of Magnolia wufengensis and its promotion work.

MethodOne-year-old Magnolia wufengensis seedlings were used as experimental materials, and potted waterlogging method was utilized for 5 treatments: control (CK), waterlogging for 4 days (W4), 7 days (W7), 11 days (W11) and 15 days (W15). The growth, physiological and biochemical indexes of seedlings on days 1, 4, 7, 11, 15 after waterlogging and on the 2nd (R2), 5th (R5), and 8th (R8) days after stress relief were measured to analyze the response of Magnolia wufengensis seedings to waterlogging stress and self-recovery ability after waterlogging stress.

ResultWith the increase of waterlogging stress time, the survival rates of W4, W7, and W11 decreased to 95.00%, 70.00%, and 60.00%, respectively, and all W15 seedlings died after 2 days of stress relief; the growth of seedling height and ground diameter decreased, and the growth of W11 seedlings restored to a basic standstill after stress relief; the content of chlorophyll showed a downward trend, and the difference between W11, W15 and CK was significant; Net photosynthetic rate (P_n), transpiration rate (T_r) and stomatal conductance (G_s) showed a downward trend. Net photosynthetic rate and was significantly lower than CK in all treatments; the difference of stomatal conductance between W11, W15 and CK was significant; the transpiration rate was significantly different from CK except W4. Soluble protein content and malondialdehyde content gradually increased. The malondialdehyde content was significantly different from CK in all treatments, and soluble protein content was significantly different from CK except for W4. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities showed the same trend, which increased first and then decreased. SOD and POD under W11 and W15 treatments were significantly different from CK, and CAT activities were significantly different from CK except W4.

ConclusionWith the increase of waterlogging stress time, the growth and physiological activities of Magnolia wufengensis seedlings were inhibited to extent, but they had certain recovery ability after the relief of waterlogging stress, and the shorter the stress time was, the stronger the recovery ability was. The waterlogging stress lasts for about 11 days. And it can basically reduce the damage by regulating the activity of the protective enzyme system and the content of osmotic adjustment substance, and maintain the normal physiological and metabolic functions of the plant body. Thus, the result indicates that Magnolia wufengensis has a certain tolerance to waterlog. When the waterlogging stress lasts for 15 days, it exceeded the regulation capacity of the plant itself, which will lead to its death.