Figure 1c shows that the stomatal conductance (G_s) changes with the time of zinc treatment and zinc concentration. Compared with the control group, the G_s concentration of all treatment groups with zinc concentration less than 400μmol/L was significantly higher than that of the control group, and increased significantly with the increase of zinc concentration, and increased significantly with the extension of zinc treatment time. However, when the zinc concentration is more than 400μmol/L, the G_s concentration decreases significantly with the increase of zinc concentration. When the zinc concentration was 400 μmol/L and the treatment time was 21 days, the G_sconcentration reached the maximum value, and there was significant difference compared with the control group.

It can be seen from Figure 1d that the carbon dioxide concentration (Ci) changes with the time of zinc treatment and zinc concentration. Compared with the control group, the carbon dioxide concentration of all the treatment groups with zinc concentration less than 400 μmol/L was significantly lower than that of the control group, and decreased slowly with the increase of zinc concentration. But when the zinc concentration is 400 μmol/L, the Ci concentration reaches the minimum value, and compared with the control group, there is a significant difference. But at the same zinc concentration, with the extension of zinc treatment time, the Ci decreased, but there was no significant difference. When the zinc concentration is more than 400 μmol/L, the Ci concentration increases gradually with the increase of zinc concentration and treatment time. When the zinc concentration was 2000 μmol/L and the treatment time was 21 days, the Ci concentration reached the maximum value, and there was significant difference compared with the control group.