Effects of sulfur nutrition on photosythesis and chlorophyll fluorescence of tobacco leaves
硫对烟草叶片光合特性和叶绿素荧光参数的影响

Chlorophyll (chl) contents, gas exchange and chlorophyll fluorescence parameters were measured to determine the effects of sulfur concentration in cultural solution (0-32 mmol/L) on photosynthetic characteristics of tobacco leaves. The results showed that chl.a, chl.b, total chl contents and chl.a/b were increased with the increase of sulfur concentration. But net photosynthetic rate, transpiration rate, stomatic conductance and intracellular CO2 concentration (Ci) were remarkably reduced with the increase of sulfur concentration. This showed that high sulfur concentration influenced gas exchange of tobacco leaves significantly. Effective quantum yield (EQY), photosynthetic electron transport rate (ETR), and photochemical quenching (qP) increased with the increase of sulfur concentration up to 8mmol/L. Further increase in sulfur concentration resulted in a decrease in these parameters. Non-photochemical quenching (NPQ) at 2 to 8 mmol/L of sulfur concentration was lower than at 0, 16, or 32 mmol/L. Optimal tobacco growth was observed when sulfur concentration in the cultural solution was 2 to 8 mmol/L.