胺鲜酯和镉对蓖麻幼苗光合生理特性的影响

RESPONSES OF PHOTOSYNTHETIC TRAITS OF CASTOR BEAN SEEDLINGS TO CADMIUM AND DIETHYL AMINOETHYL HEXANOATE

以蓖麻(Ricinus communis L.)为研究对象,通过水培试验研究胺鲜酯(DA-6)和镉(Cd)对蓖麻生长和光合生理特性的交互作用,探讨DA-6浸种对植物Cd毒害是否具有缓解作用。研究结果表明,50μmol.L-1CdCl2对蓖麻幼苗生长和光合作用具有抑制作用。Cd处理显著降低蓖麻叶片的光合速率(Pn)、气孔导度(Gs)和蒸腾速率(E),而胞间CO2浓度(Ci)则明显增大;在Cd胁迫下,蓖麻叶片的叶绿素a、b、a+b、类胡萝卜素含量以及叶绿素/类胡萝卜素比值均显著降低,而叶绿素a/b比值则显著增大;Cd胁迫导致F0增大,Fm、Fv/Fm、Fv/F0和ΦPS II显著降低。无论是否添加Cd,DA-6对蓖麻幼苗的生长均没有显著影响;同时,DA-6处理对蓖麻幼苗的镉积累也没有显著影响。在正常情况下,DA-6处理能提高蓖麻叶片的光合色素含量,但叶绿素a/b比值、叶绿素/类胡萝卜素比值以及叶绿素荧光参数和气体交换参数均没有显著影响。在Cd胁迫下,10和1000mg.L-1 DA-6处理不仅导致光合色素含量(Chl a、Chl b、Chl a+b和Car)和气体交换参数(Pn、E和Gs)降低,同时也导致Fm、Fv/Fm、Fv/F0和ΦPS II降低。可见DA-6不仅不能缓解Cd对蓖麻幼苗的毒害,而且通过降低光合色素含量和PS II的光化学活性,加重了Cd对光合作用的抑制作用。

To determine whether diethyl aminoethyl hexanoate（DA-6） pretreatment alleviated the cadmium（Cd） toxicity to castor bean（Ricinus communis L.） seedlings,tffects of Cd（0,50μmol.L-1CdCl2） and DA-6（0,0.1,10 and 1000mg.L-1）,and their interactions on plant growth and photosynthesis were investigated.Results showed that 50 μmol.L-1 CdCl2 inhibited plant growth and photosynthesis of castor seedlings.Under Cd exposure,the net photosynthetic rate（Pn）,stomatal conductance（Gs） and transpiration rate（E）,photosynthetic pigment contents（Chl a,Chl b,Chl a ＋ b,Car and Chl /Car） and chlorophyll fluorescence parameters（Fm,Fv /Fm,Fv /F0 and ΦPS II） decreased,whereas the intercellular CO2 concentration（Ci）,Chl a /b and F0 increased.Presoaking seeds with different concentrations of DA-6 did not change the plant growth regardless of Cd.In the absence of Cd,DA-6 pretreatment significantly enhanced the pigment contents（Chl a,Chl b,Chl a ＋ b and Car） in castor leaves,while the ratio of pigment content（Chl a /b,Chl /Car）,chlorophyll fluorescence parameters,and gas exchange parameters remained unaffected.In the present of Cd,presoaking seeds with 10 and 1000mg.L-1 DA-6 caused a reduction in pigment contents（Chl a,Chl b,Chl a ＋ b and Car）,gas exchange parameters（Pn,E and Gs）,as well as chlorophyll fluorescence parameters（Fm,Fv /Fm,Fv /F0 and ΦPS II） in castor seedlings.It was indicated that DA-6 presoaking might aggravate,rather than alleviate,the inhibition of Cd on photosynthesis of castor bean seedlings.