硫对烟草叶片光合特性和叶绿素荧光参数的影响

通过液培试验,测定了不同硫营养水平(0～32 mmol/L)下烟草叶片的叶绿素含量、气体交换参数和叶绿素荧光参数.结果表明,随着硫浓度的升高,烟草叶片的Chl.a、Chl.b、总Chl的含量和Chl.a/b逐渐增加;类胡萝卜素呈先下降后升高的趋势;烟草叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)下降显著,气孔限制值(Ls)明显升高,这表明高硫对烟草叶片的气体交换参数影响较大.随着硫浓度的升高,烟草叶片光合有效量子产量(EQY)、光合电子传递速率(ETR)、光化学淬灭(qP)都表现为先升高后降低,一般是4 mmol/L和8 mmol/L处理相对较高,浓度超过8 mmol/L以后,以上参数显著下降.非光化学淬灭(NPQ) 0,16 mmol/L和32 mmol/L处理表现相对较高,2、4、8 mmol/L处理的相对较低,2～8 mmol/L浓度的处理最适宜烟草的生长,高硫或低硫都会导致烟草EQY、ETR、qP降低和NPQ的升高.

Effects of sulfur nutrition on photosythesis and chlorophyll fluorescence of tobacco leaves

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.