Effects of Cadmium and Aluminum Stress on Seed Germination and Photosynthetic Characters of Chenopodium quinoa Willd

PurposeTo study the effects of cadmium (Cd) and aluminum (Al) stress on quinoa seed germination and photosynthetic energy distribution of photosystem Ⅱ (PSⅡ), providing a theoretical basis for the selection, promotion, and large-scale planting of excellent quinoa varieties.

MethodsUsing Jingli No.1 and Qinghai No.1 quinoa varieties as experimental materials, effects of Cd²⁺ (CdCl₂) or Al³⁺ (AlCl₃) stress on the quinoa seed germination rate and seedling biomass, relative chlorophyll content, malondialdehyde content, oxygen free radical production rate, chlorophyll fluorescence dynamic curves, and fluorescence parameters were studied.

ResultsCdCl₂ inhibited the seed germination of quinoa, and the inhibition degree of Qinghai No.1 was greater than Jingli No.1. Low concentration of AlCl₃ (0.1 and 0.3 mmol/L) promoted seed germination of Qinghai No.1, but high concentration of AlCl₃ (0.5 and 1.0 mmol/L) reduced seed germination rate. Under CdCl₂ stress, fresh weight and relative chlorophyll content of Jingli No.1 were higher than that of Qinghai No.1. The maximum photochemical efficiency (F_v/F_m), photosynthetic performance index (PI_abs), number of active reaction centers per cross section (RC/CS) and other parameters of Jingli No.1 and Qinghai No.1 were decreased, but dissipated energy flux per cross section (DI_o/CS_m) and other parameters were increased, and the change range of Qinghai No.1 was larger than Jingli No.1. Under treated with low concentration of AlCl₃, there were no obvious changes in the fluorescence parameters of Jingli No.1, however, the parameters of Qinghai No.1 changed greatly. At high concentration of AlCl₃, F_v/F_m and PI_abs of Qinghai No.1 were lower than those of Jingli No.1.

ConclusionJingli No.1 had much higher tolerance to Cd²⁺ or Al³⁺ stress than Qinghai No.1. In the soil with Cd²⁺ or Al³⁺ concentrations less than 0.5 mmol/L, Jingli No.1 is more suitable for promotion. This means that Jingli No.1 can be used as an important candidate germplasm in heavy metal stress breeding of quinoa.