重金属对盐生草光合生理生长特性的影响

以盐生草幼苗为试验材料,分别设置0(CK)、50、100、200、400μg?g-1的Ni2+、Cu2+处理,研究重金属Ni2+和Cu2+对盐生草光合生理特性的影响.结果表明:盐生草叶片光合色素含量、净光合速率(Pn)、气孔导度Gs、蒸腾速率Tr、PSⅡ最大光化学效率Fv/Fm、非光化学猝灭系数qN及生长指标(株高、地上部干重和鲜重)在50μg?g-1的Ni2+处理时均达到最大值,后随Ni2+浓度继续增加,其叶片叶绿素a、叶绿素b、Pn、Gs、Tr、Fv/Fm、PSⅡ电子传递量子产率ΦPSⅡ、光化学猝灭系数qP、qN及各项生长指标逐步下降并低于对照水平,而细胞间隙CO2浓度(Ci)较对照呈增加趋势.在50μg?g-1的Cu2+处理时,盐生草叶片光合色素含量、Pn、Gs、Tr、Ci、Fv/Fm、ΦPSⅡ、qP、qN及各项生长指标均达峰值;在100μg?g-1Cu2+处理时,光合色素含量、Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qN及各项生长指标较对照仍有增加,而后随Cu2+浓度继续增加,其叶绿素a、叶绿素b、各光合参数、叶绿素荧光参数及生长指标均逐步降低并低于对照.可见,盐生草Pn在Ni2+胁迫下的下降主要是由非气孔限制所致,而Cu2+胁迫下的下降主要是由气孔限制所致;低浓度Ni2+和Cu2+对盐生草生长具有一定促进作用,过高浓度Ni2+和Cu2+则会通过抑制盐生草叶片叶绿素合成,影响其光合作用,从而抑制植株生长.

Photosynthesis and Physiological Characteristics in Halogeton glomeratus with Heavy Metal Treatments

Halogeton glomeratus seedlings were grown under different Ni2+ or Cu2+ concentrations 0(CK),50,100,200,400 μg·g-1].Their photosynthesis,chlorophyll fluorescence characteristics and growth parameters were studied.The results showed that photosynthetic pigment content,the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),maximal photochemical efficiency of PSⅡ(Fv/Fm),coefficient of nonphotochemical quenching(qN) and growth parameters of H.glomeratus were reached their peak value under 50 μg·g-1 Ni treatment.However chlorophyll a,chlorophyll b,Pn,Gs,Tr,Fv/Fm,quantum efficiency of electric transport of PSⅡ(ΦPSⅡ),coefficient of photochemical quenching(qP) and growth parameters of H.glomeratus decreased with increasing Ni concentration,while the intercellular CO2 concentration(Ci) increased significantly.The decline of Pn under Ni stress was mainly caused by the non-stomatal limitation.The photosynthetic pigment content,Pn,Gs,Tr,Ci,Fv/Fm,ΦPSⅡ,qP,qN and growth parameters of H.glomeratus reached their peak value at 50 μg·g-1 Cu2+ concentration,and photosynthetic pigment content,Pn,Gs,Tr,Fv/Fm,ΦPSⅡ,qN and growth parameters were still higher than control level at 100 μg·g-1 Cu2+ concentration.Then Chl a,Chl b,Pn,Gs,Tr,Ci,Fv/Fm,ΦPSⅡ,qP,qN and growth parameters decreased with increasing Cu2+ concentration.The decline of Pn under Cu2+ stress was mainly caused by the stomatal limitation.Treatment with lower concentration of Ni2+,Cu2+ promoted the growth of H.glomeratus,while with increasing Ni2+,Cu2+ concentration seedlings biomass decreased,which was probably associated with the negative effect of Ni2+,Cu2+ on photosynthetic pigments synthesis and photosynthesis.