Salinity tolerance of quinoa (Chenopodium quinoa Willd) as assessed by chloroplast ultrastructure and photosynthetic performance

•100 mM NaCl treatment has no apparent effect on plant biomass production.•No significant change of chloroplast ultrastructure was observed under 100 mM NaCl.•Swelling of thylakoids induced reduction of stacking leading to more spillover.•Donor side intactness demonstrated by the constant Fk/Fj ratio and antenna size.•High PSII efficiency was confirmed by the stability of OEC complex.