Effects of Low Temperature on Photosynthesis and Antioxidant Enzyme Activities of Panax notoginseng during Seeding Stage
Xu, C.; Yang, Z.; Wang, M.; Zhang, X.; Zheng, Q.; Li, J.; Huang, H.; Wang, L.; Zou, Y.
International Journal of Agriculture and Biology 21(6): 1279-1286
In order to find out the low temperature (LT) meteorological disaster index of Panax notoginseng. One-year-old P. notoginseng seedlings were used as experimental materials. The LT treatments were 9,6,3 and 0 degrees C, with 25 degrees C as control. The experiments lasted for 7 d, and then all plants were moved to 25 degrees C for 5 d of recovery. The leaves of P. notoginseng showed different degrees of chlorosis after the LT treatment. With the extension of low temperature stress (LTS) time, the contents of Chlorophyll a (Chl a), Chlorophyll b (Chl b), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the leaves of P. notoginseng showed a tendency to increase first and then decrease. At 9 and 6 degrees C, all maxima appeared at 5d, but at 3 and 0 degrees C, appeared at 3d. Non-photochemical quenching (NPQ) at 9 and 6 degrees C increased with the prolongation of LT stress time, while at 3 and 0 degrees C, it increased first and then decreased, and both maxima appeared at 3d. Carotenoid, Chl a/b, maximum photosynthetic rate (P-ma(x)), apparent quantum efficiency (AQE), electron transport rate (ETR) and light saturation point (LSP) decreased under LTS. At 3 degrees C for 3d, these values were significantly lower than the control. Malondialdehyde (MDA) and light compensation point (LCP) were contrary to the P. After 5 d of recovery, the values of Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci), and stomatal limitation value (Ls) at 9 and 6 degrees C were recovered to normal levels, while 3 and 0 degrees C failed to recover. The results suggested that the key low temperature threshold point for P. notoginseng seedlings was 3 degrees C for 3d.. 2019 Friends Science Publishers