Objective  Rule of H₂S played on the growth of barley seedlings under Cd-stress was investigated to understand the mechanism and means to improve Cd-tolerance of the plants.

  Method  Treatment groups of Cd, NaHS, HA, Cd+NaHS, and Cd+HA with addition of CdCl₂ at 0.2 mmol·L⁻¹, exogenous H₂S donor NaHS at 50 μmol·L⁻¹ or H₂S synthesis inhibitor hydroxylamine HA at 1 mmol·L⁻¹ in medium were made for an indoor hydroponic barley seedling growth experiment. Effects of the treatments on the growth, leaf damage, osmotic regulator, antioxidant enzyme activity, chlorophyll content, and photosynthetic characteristics of the seedlings of Jinke 571 barley were monitored.

  Result  The H₂S addition in the hydroponic medium lessened the growth inhibition and leaf damage on the seedlings induced by Cd-stress. It increased the root length, plant height, and seedling biomass; decreased the leaf relative conductivity, malondialdehyde (MDA) and superoxide anion (O₂⁻) contents; enhanced the photosynthesis with increased chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate; and, improved the resistance to the external adversity imposed on them with increased osmotic regulatory substances (e.g., soluble sugar, proline, soluble protein) and antioxidant enzymatic activities on SOD, POD, CAT.

  Conclusion  Addition of H₂S donor NaHS at 50 μmol·L⁻¹ in hydroponic medium partially alleviated the ill-effects of Cd-stress on the barley seedlings suggesting its potential field application for barley farming to combat the pollution.