硫营养对重金属胁迫下玉米和小麦根系导水率的影响

Effects of Sulfur Nutrition on Root Hydraulic Conductivity of Maize and Wheat under Heavy Metals Stress

以‘秦单4号’玉米和‘小偃22’小麦为供试材料,通过室内玉米水培和小麦盆栽试验,采用静态压力室法测定了不同硫营养水平与不同重金属胁迫处理下根系导水率(Lpr)的变化。结果表明:玉米Lpr经100μmol/LHg2+、Zn2+、Cu2+胁迫处理后分别降低到CK的13%、79%和45%,Cu2+、Zn2+对其Lpr的抑制效应分别为同浓度Hg2+的62.9%及24.3%;施硫处理的玉米Lpr在无Cu2+胁迫条件下都极显著高于无硫处理,且低硫处理显著较高,在Cu2+胁迫条件下亦都极显著高于无硫处理,并且Cu2+胁迫对其Lpr的抑制效应随着硫浓度增大而逐渐减小;不施硫和施硫处理的小麦Lpr在500mg/kgZn2+胁迫下分别比相应CK降低36.89%和37.71%,在400mg/kgCu2+胁迫下则分别比相应CK降低了34.61%和12.29%。研究发现,重金属Cu2+、Zn2+对玉米和小麦根系导水率具有显著的抑制作用且Cu2+>Zn2+,施硫对Cu2+胁迫下的玉米和小麦根系导水率都具有显著的保护作用,并随硫浓度增加而增强。

At different heavy metal levels and different sulfur levels,with Hoagland solution and pot experi- ments,the hydraulic conductance （Lpr） of maize and wheat of roots were determined in a pressure cham- ber. The results showed that Cu^2＋ and Zn^2＋ restrain Lpr significantly. At the same concentration,the inhib- itive effect of Cu^2＋ is about 62.9% of Hg^2＋ ,the usual aquaporins inhibitor,and that of Zn^2＋ is only around 24.3% of Hg^2＋. The order of the impacts of these three heavy metals to Lpr was： Hg^2＋ 〉Cu^2＋〉Zn^2＋. Without heavy metals threats,there were no significant distinctions between various sulfdr nutrition treat- ments. Under stress of Cu^2＋ ,sulfur nutrition showed the protective function to the Lp, of maize root, and this effect enhanced with the increase of sulfur concentration. In pot experiments, according to Third Class Farmland Environmental Quality Standard for Soils,500 mg/kg Zn^2＋ and 400 mg/kg Cu^2＋ were added into the soil. The Lpr of wheat root was inhibited heavily in this condition. Compared to CK, under Zn^2＋ stress the Lpr declined 36.89% and 37.71% under -S （without sulfur addition） and 3-8 （added sulfur） treat- ments respectively, under Cu^2＋ stress the Lp, fall 34.61% and 12.29% under -S and 3-S treatments.Therefore, ＋S treatment could obviously maintain the Lpr of wheat root under Cu^2＋ stress.