| In this study,we used various concentrations of PEG solution to simulate drought stress to investigate the morphological, physiological, biochemical,and photosynthetic characteristics of 5 quinoa species, and evaluated their drought tolerance. The results showed that: (1) 15% PEG treatment significantly impacted the height increase rate, leaf area, and biomass of all species over the control(P<0.05).The species with the lowest increase rate of plant height, leaf area, and biomass were NK1, NK2, and NK5, which decreased by 44.38%, 25.39%, and 48.23% compared with the control, respectively.(2) With increasing drought stress, the relative water content in leaves of each quinoa specie decreased significantly(P<0.05), the leaf membrane permeability, malondialdehyde (MDA), and proline (Pro) contents were increased, Pro in NK2 and NK3 were 2.69 and 1.93 times of that in the control under 15%PEG treatment, respectively. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbic acid peroxidase (APX) were all initially rose and then declined.SOD, CAT,and APX activities reached the maximum at 5%PEG concentration, while POD activity reached the maximum at 10% concentration treatment.(3) With increasing drought stress, net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) decreased. The concentration of intercellular CO2(Ci) decreased first and then increased but chlorophyll (Chl) initially increased and then decreased later. Among all species,the decrease of NK5 Pn was the lowest, which was 51.15% lower than that of the control. In conclusion, the drought tolerance of quinoa was evaluated by the membership function method and the drought tolerance of different quinoa varieties ranked as NK5>NK1>NK2>NK4>NK3. |