黑麦草对NaHCO_3胁迫的光合生理响应  

Photosynthetic physiological response of Lolium perenne to NaHCO_3 stress

作　　者：刘建新[1] 王鑫[1] 王瑞娟[1] 贾海燕[1] 

机构地区：[1]陇东学院生命科学与技术学院甘肃省高校陇东生物资源保护与利用省级重点实验室,甘肃庆阳745000

出　　处：《草业学报》2012年第3期184-190,共7页Acta Prataculturae Sinica

基　　金：甘肃省庆阳市科技攻关计划项目(0802NKCM082)资助

摘　　要：为了探讨牧草对碱胁迫的光合生理响应,采用营养液砂培方法,研究了不同浓度NaHCO3(0,50,100,150,200mmol/L)胁迫对黑麦草幼苗叶片光合色素含量、气体交换参数、叶绿素荧光和叶黄素循环的影响。结果表明,1)随着NaHCO3浓度增大,叶绿素和类胡萝卜素含量逐渐降低,叶绿素a/b不断提高,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和气孔限制值(Ls)下降,胞间CO2浓度(Ci)升高,表明非气孔限制是碱胁迫下Pn降低的主要因素。2)PSⅡ初始荧光(Fo)随NaHCO3浓度提高明显上升,最大荧光(Fm)、最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)和光化学猝灭(qP)显著下降,非光化学猝灭(NPQ)呈增加趋势。3)随着NaHCO3浓度提高,天线转化效率(Fv′/Fm′)降低,激发能在2个光系统间的分配不平衡性(β/α-1)增大,叶片吸收的光能中用于光反应的比例(P)下降,而天线热耗散的比例(D)增加,叶黄素循环脱环氧化状态(A+Z)/(V+A+Z)呈先升后降趋势,表明依赖叶黄素循环的天线热耗散是碱胁迫下黑麦草耗散过剩光能的主要途径。To explore the photosynthetic physiological response of forage to alkaline stress,ryegrass（Lolium perenne） seedlings grown in sands in a greenhouse were exposed to NaHCO3 at concentrations of 0,50,100,150,or 200 mmol/L in Hoagland＇s nutrient solution.The effect of NaHCO3 stress on the photosynthetic pigment content,gas exchange and chlorophyll fluorescence parameters,and the xanthophyll cycle in the leaf was assessed.1） With an increase in NaHCO3 concentration,the chlorophyll and carotenoid contents decreased gradually,but the chlorophyll a/b increased continuously.Net photosynthetic rate（Pn）,stomatal conductance,transpiration rate,and stomatal limitation to Pn of ryegrass leaves decreased,but the intercellular CO2 concentration increased,suggesting that non-stomatal limitation was the main cause of the Pn decrease under alkaline stress.2） The initial fluorescence and non-photochemical quenching（NPQ） increased with increasing concentration of NaHCO3,while the maximum fluorescence value（Fm）,maximal photochemical efficiency（Fv/Fm）,actual yield（ΦPSⅡ）,and photochemical quenching of PSⅡ decreased significantly.3） With an increase in NaHCO3 concentration,the antenna efficiency at open centers in the presence of NPQ decreased,the deviation from full balance between PSI and PSⅡ improved,the absorbed light energy allocated to the photochemical reaction of PSⅡ reduced,while the proportion of energy lost during antenna heat dissipation increased significantly.The de-epoxidation extent of the xanthophyll cycle（A＋Z）/（V＋A＋Z） initially increased but then decreased,suggesting that antenna heat dissipation dependant on the xanthophyll cycle was the main mechanism for excessive energy dissipation.

关 键 词：黑麦草 NAHCO3胁迫 光合作用 叶绿素荧光 叶黄素循环 

分 类 号：S543.6[农业科学—作物学]