[Physiological and biochemical mechanisms of brassinosteroid in improving anti-cadmium stress ability of Panax notoginseng].

In this study, the effect of brassinosteroid(BR) on the physiological and biochemical conditions of 2-year-old Panax notoginseng under the cadmium stress was investigated by the pot experiments. The results showed that cadmium treatment at 10 mg·kg~(-1) inhibited the root viability of P. notoginseng, significantly increased the content of H_2O_2 and MDA in the leaves and roots of P. noto-ginseng, caused oxidative damage of P. notoginseng, and reduced the activities of SOD and CAT. Cadmium stress reduced the chlorophyll content of P. notoginseng, increased leaf F_o, reduced F_m, F_v/F_m, and PIABS, and damaged the photosynthesis system of P. notoginseng. Cadmium treatment increased the soluble sugar content of P. notoginseng leaves and roots, inhibited the synthesis of soluble proteins, reduced the fresh weight and dry weight, and inhibited the growth of P. notoginseng. External spray application of 0.1 mg·L~(-1) BR reduced the H_2O_2 and MDA content in P. notoginseng leaves and roots under the cadmium stress, alleviated cadmium-induced oxidative damage to P. notoginseng, improved the antioxidant enzyme activity and root activity of P. notoginseng, increased the content of chlorophyll, reduced the F_o of P. notoginseng leaves, increased F_m, F_v/F_m, and PIABS, alleviated the cadmium-induced damage to the photosynthesis system, and improved the synthesis ability of soluble proteins. In summary, BR can enhance the anti-cadmium stress ability of P. notoginseng by regulating the antioxidant enzyme system and photosynthesis system of P. notoginseng under the cadmium stress. In the context of 0.1 mg·L~(-1) BR, P. notoginseng can better absorb and utilize light energy and synthesize more nutrients, which is more suitable for the growth and development of P. notoginseng.

[Effects of propiconazole on physiological and biochemical properties of Panax notoginseng and dietary risk assessment].

To study the residue and dietary risk of propiconazole in Panax notoginseng and the effects on physiological and bioche-mical properties of P. notoginseng, we conducted foliar spraying of propiconazole on P. notoginseng in pot experiments. The physiolo-gical and biochemical properties studied included leaf damage, osmoregulatory substance content, antioxidant enzyme system, non-enzymatic system, and saponin content in the main root. The results showed that at the same application concentration, the residual amount of propiconazole in each part of P. notoginseng increased with the increase in the times of application and decreased with the extension of harvest interval. After one-time application of propiconazole according to the recommended dose(132 g·hm~(-2)) for P. ginseng, the half-life was 11.37-13.67 days. After 1-2 times of application in P. notoginseng, propiconazole had a low risk of dietary intake and safety threat to the population. The propiconazole treatment at the recommended concentration and above significantly increased the malondialdehyde(MDA) content, relative conductivity, and osmoregulatory substances and caused the accumulation of reactive oxygen species in P. notoginseng leaves. The propiconazole treatment at half(66 g·hm~(-2)) of the recommended dose for P. ginseng significantly increased the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in P. notoginseng leaves. The propiconazole treatment at 132 g·hm~(-2) above inhibited the activities of glutathione reductase(GR) and glutathione S-transferase(GST), thereby reducing glutathione(GSH) content. Proconazole treatment changed the proportion of 5 main saponins in the main root of P. notoginseng. The treatment with 66 g·hm~(-2) propiconazole promoted the accumulation of saponins, while that with 132 g·hm~(-2) and above propiconazole significantly inhibited the accumulation of saponins. In summary, using propiconazole at 132 g·hm~(-2) to prevent and treat P. notoginseng diseases will cause stress on P. notoginseng, while propiconazole treatment at 66 g·hm~(-2) will not cause stress on P. notoginseng but promote the accumulation of saponins. The effect of propiconazole on P. notoginseng diseases remains to be studied.