Ca^2＋对镉胁迫下玉米幼苗生长、光合特征和PSⅡ功能的影响  

Effects of exogenous Ca^(2+) on growth,photosynthetic characteristics and photosystem II function of maize seedlings under cadmium stress

作　　者：王玉萍[1,2] 常宏 李成[2] 梁延超[2] 卢萧[2] 

机构地区：[1]甘肃农业大学园艺学院,甘肃兰州730070 [2]甘肃省作物遗传改良与种质创新重点实验室,甘肃省干旱生境作物学重点实验室,甘肃农业大学,甘肃兰州730070 [3]甘肃省种子管理总站,甘肃兰州730000

出　　处：《草业学报》2016年第5期40-48,共9页Acta Prataculturae Sinica

基　　金：国家自然科学基金(31060063,31260094);甘肃省财政厅高等学校基本科研业务费资助

摘　　要：为探究钙(Ca^(2+))对玉米镉(Cd)胁迫的缓解作用,采用盆栽试验,研究了根部施加外源Ca^(2+)对Cd胁迫下玉米幼苗生长、光合特征及叶绿素荧光参数等生理指标的影响。结果显示,与对照(CK)相比,100mg/L的Cd处理显著降低了玉米幼苗株高、根、地上部生物量以及玉米叶片叶绿素a、叶绿素b和总叶绿素含量。同时,净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、PSⅡ最大光化学效率(F_v/F_m)、电子传递速率(ETR)、PSⅡ激发能捕获效率(F_v′/F_m′)、光化学淬灭系数(qP)和PSⅡ实际光化学效率(Φ_(PSⅡ))显著下降,而非光化学淬灭系数(NPQ)和胞间CO_2浓度(C_i)较CK显著上升。外源施加Ca^(2+)可以有效增加镉胁迫下幼苗生物量的积累,明显提高叶绿素a、叶绿素b和叶绿素总量,升高P_n,G_s,T_r,F_v/F_m,ETR,F_v′/F_m′,降低NPQ和C_i,增加幼苗生物量积累,Ca^(2+)浓度为7.5~10.0mmol/L时各指标变化幅度最明显,缓解胁迫的效果最佳。研究结果表明,Cd胁迫使玉米幼苗叶片PSⅡ原初光能转化效率降低,电子传递受到抑制,净光合速率降低。适宜浓度的外源Ca^(2+)能有效缓解Cd对光合机构的伤害,增强幼苗叶片对光的捕获能力,促进光合作用,增加幼苗的生物量,增强玉米幼苗对Cd胁迫的抗性。To investigate how calcium relieves cadmium toxicity in maize, the effects of exogenous Ca2＋ on growth properties, photosynthetic characteristics and chlorophyll fluorescence parameters of maize seedlings under cadmium stress were studied in a pot experiment. A treatment with 100 mg/L of cadmium obviously in hibited the growth of maize seedlings, decreased the biomass of plants, and decreased the contents of chloro phyll a, b and aq-b of leaves. At the same time, the net photosynthetic rate （Pn）, stomatal conductance （Gs）, transpiration rate （Tr）, the maximal PS Ⅱ efficiency （Fv/Fm）, photosynthetic electron transfer rate （ETR）, the efficiency of excitation energy capture by open PS Ⅱ centers （Fvr/Fmr）, photochemical quenching coeffi cient （qP）, and the actual PS Ⅱ efficiency （ФPsⅡ） were reduced whereas the intercellular CO2 concentration （Ci） and non-photochemical fluorescence quenching coefficient （NPQ） were increased under cadmium stress. Supply of exogenous Ca^2＋ under cadmium stress promoted the growth of seedlings, increased the biomass of plants and raised the contents of chlorophyll a, b and a＋b of leaves. At the same time, P., Gs, Tr, Fv/Fm, ETR, Fv/Fm, qP and ФPsⅡ of leaves tended to be increased with increased exogenous Ca^2＋ concentration, but i~ and NPQ were reduced. Among different Ca2＋ application rates, 7.5 to 10.0 mmol/L Ca^2＋ had the greatest alleviation of Cd toxicity effects. It is suggested that Cd stress led to a decrease in the photochemical efficiency of PS Ⅱ , reduction in electron transfer, and reduction in net photosynthetic rate. Exogenous Ca^2＋ at appropriate concentrations had favorable effects on seedling growth, including enhanced performance of the photosynthetic apparatus and capture of solar energy, effectively ameliorate Cd-induced depression of photosynthesis and en hancing the resistance of maize seedlings to Cd stress.

关 键 词：镉胁迫 玉米 钙 光合特性 PSⅡ功能 

分 类 号：S513[农业科学—作物学]