Cd^(2＋)处理对5个柳树无性系气体交换参数及叶绿素荧光参数的影响

Effects of Cd^(2+) Stress on Photosynthetic and Fluorescent Parameters of Five Willow Clones

该实验以筛选的速生、抗逆性强的5个柳树无性系(‘竹柳’、‘苏柳172’、‘苏柳795’、‘旱快柳’、‘旱柳’)一年生扦插幼苗为试验材料,设置对照、轻度(30mg·L-1)、中度(60mg·L-1)和重度(90mg·L-1)4个重金属Cd2+处理水平,通过水培方式探究Cd2+对各柳树无性系气体交换参数、荧光参数及叶绿素含量的影响。结果显示:(1)在Cd2+浓度为30mg·L-1时,导致‘苏柳172’、‘苏柳795’和‘旱快柳’净光合速率降低的原因主要是气孔因素;当Cd2+浓度≥60mg·L-1时,‘苏柳172’、‘苏柳795’、‘旱快柳’及‘竹柳’净光合速率下降的主要原因是非气孔因素,而‘旱柳’在整个Cd2+胁迫过程中净光合速率下降的因素均属于非气孔限制型。(2)整个Cd2+胁迫过程中,‘苏柳172’、‘苏柳795’、‘旱快柳’和‘旱柳’叶片叶绿素含量和Chl a/Chl b值与对照相比均呈下降趋势,而竹柳先上升后下降至低于对照水平。(3)随着Cd2+胁迫程度的增加,叶片PSⅡ最大光化学量子产量(Fv/Fm)和光化学淬灭(qP)整体呈下降趋势,非光化学淬灭系数(NPQ)呈逐渐上升的趋势,而表观光合电子传递速率(ETR)先增加后下降,但5个柳树无性系叶绿素荧光参数的变化幅度以‘竹柳’最小,‘旱柳’最大。研究表明,5个柳树无性系均能在Cd2+浓度为30mg·L-1的培养液中正常生长,且竹柳的光合作用较对照有略微增加,且在90mg·L-1 Cd2+浓度下各无性系生长虽受到抑制但仍能存活,说明它们对重金属Cd2+胁迫都有一定的耐受性,并以‘竹柳’的耐受性最强。

In this hydroponic experiment,five selected willow clone（Salix matsudana Koidz cv.zhuliu,Salix jiangsuensis CL J-172,Salix jiangsuensis CL J-795,Salix matsudana var.anshanenensis,Salix matsudana）annual seedlings were grown in containers with four Cd2＋ concentrations（0,30,60 and 90 mg· L-1）,to explore gas exchange,fluorescence parameters and chlorophyll content on the clones with different concentrations of Cd2＋.The result showed that：（1）The reason that led to the decline of photosynthetic rate of Salix jiangsuensis CL J-172,Salix jiangsuensis CL J-795 and Salix matsudana var.anshanenensis in the Cd2＋ concentration of 30 mg·L-1 was stomatal factors,while it was mainly caused by nonstomata factors when Cd2＋ concentration≥ 60 mg·L-1.And the decline of photosynthetic rate of S.matsudana was caused by nonstomata factors under Cd2＋ stress.（2）With increasing Cd2＋ stress,the chlorophyll content and Chl a/Chl b value of Salix jiangsuensis CL J-172,Salix jiangsuensis CL J-795,Salix matsudana var.anshanenensis,Salix matsudana showed a downward trend while bamboo willow increased slightly first and then decreased;（3）With increasing Cd2＋stress,PSⅡ maximum photochemical quantum yield（Fv /Fm）and photochemical quenching（qP）consistently decreased;non-photochemical quenching coefficient（NPQ）is a rising trend,while the apparent photosynthetic electron transport rate（ETR）increased at the lower concentration and then decreased at the higher concentration,but there were some differences among willow clones about the variations,which bamboo willow has the smallest decrease,while S.matsudanais the maximum.（4）In summary,5 willow clones can grow normally with 30 mg·L-1 Cd2＋ concentration,and the photosynthesis of bamboo willow is increase slightly compared with the control;with 90 mg ·L-1 Cd2＋ concentration,the growth of all clones were limited but still survive.These results indicate that 5 willow clones can grow under Cd2＋ stress and bamboo willow showed a better endurance.