Abstract: Field experiments were conducted to understand the effects of lime application on biomass, saponin content and activities of enzymes: squaleneepoxidase (SE), dammaraneediol synthase (DS), cytochrome P450 mono-oxygenase and glycosyltransferase (GT) related to saponin synthesis of Panax notoginseng under cadmium stress(cadmium content 6 mg·kg^-2). The results show that the biomass of Panax notoginseng increased and Cd contents in Panax notoginseng decreased with the increase of lime application rates. Under Cd stress and application of 3 750 kg·hm^-2 lime, biomass and saponin content, SE and DS activities were the highest; Cd contents, P450 mono-oxygenase and GT activities in all parts of Panax notoginseng were the lowest. Cd contents in each part were in the order of fibrous root >rhizome>shoot> main root. The cytochrome P450 and GT activity in each part were significantly reduced by 11%, 21%, 28% and 13%, 33%, 40%, respectively, under 750, 2 250 and 3 750 kg·hm^-2 lime application compared with no lime application and the contents of R1, Rg1 and Rb1 improved, the SE and DS activities of the main root of Panax notoginseng increased significantly by 18%, 42%, 61% and 7%, 28%, 54%, respectively. Therefore, under Cd stress, the application of lime could alleviate the toxicity of Cd on Panax notoginseng, and reduce the inhibition of Cd stress on saponin content and related enzyme activities.

Key words: lime, cadmium, Panax notoginseng, saponin, enzyme