硝酸根胁迫对黄瓜幼苗叶片光合速率、PSⅡ光化学效率及光能分配的影响  

Effects of NO_3^-stress on photosynthetic rate, photochemical efficiency of PSⅡ and light energy allocation in cucumber seedling leaves

作　　者：苏秀荣[1] 王秀峰[2] 杨凤娟[2] 魏珉[2] 

机构地区：[1]山东农业大学化学与材料科学学院,山东泰安271018 [2]山东农业大学园艺科学与工程学院,山东泰安271018

出　　处：《应用生态学报》2007年第7期1441-1446,共6页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(30471187);山东省自然科学基金资助项目(J01I02).

摘　　要：研究了不同浓度NO3-胁迫对黄瓜幼苗叶片光合速率、PSⅡ光化学效率及光能分配的影响.结果表明,当NO3-浓度较低时(14~98mmol·L-1),适当增加NO3-浓度,可增强黄瓜幼苗叶片对光的捕获能力,促进光合作用.随着NO3-浓度的进一步增加(140~182mmol.L-1),PSⅡ光化学效率降低,电子传递受到抑制,净光合速率降低;吸收的光能中,通过天线色素的热耗散增加,用于光化学反应的能量降低,光化学效率下降.140和182mmol·L-1NO3-处理黄瓜幼苗叶片6d后净光合速率(Pn)极显著下降,分别比对照降低了35%和78%;PSⅡ最大光化学效率(Fv/Fm)、天线转化效率(Fv’/Fm’)、实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)均低于对照,非光化学猝灭(NPQ)高于对照,激发能在两个光系统间的分配不平衡性(β/α-1)增大.高浓度NO3-处理的黄瓜幼苗叶片各荧光参数变化幅度比低浓度大.当光照增强时,高浓度NO3-胁迫下黄瓜幼苗叶片吸收的光能中应用于光化学反应的份额(P)显著降低,天线热耗散的份额(D)显著增加.天线热耗散是耗散过剩能量的主要途径.This paper studied the effects of different NO3^- concentration on the photosynthetic rate, photochemical efficiency, and absorbed light energy allocation in cucumber seedling leaves. The results indicated that when the available NO3^- concentration in the medium was low （ 14-98 mmol NO3^- ·L^-1 ）, an appropriate supplement of NO3^- could enhance the capability of cucumber leaves in capturing light energy, and promote the photosynthesis. However, with further increase of NO3^- , the photochemical efficiency of PS Ⅱ decreased, electron transfer restrained, and net photosynthetic rate as well as the absorbed light energy used in photochemical reaction of PS Ⅱ decreased. At the same time, the light energy used in antenna heat dissipation increased, while the photochemical efficiency decreased. After treated with 140 and 182 mmol NO3^- ·L^-1 for 6 days, the photosynthetic rate （ Pn ） Was decreased by 35% and 78%, respectively, maximal PS Ⅱ efficiency at open centers in the absence of NPQ （Fv/Fm） , antenna efficiency at open centers in the presence of NPQ （Fv^ ＇/Fm^＇ ）, actual PS Ⅱ efficiency （ ФpsⅡ ） and photochemical quenching （qp） were lower, non-photochemical quenching （NPQ） was higher, and the deviation from full balance between PSI and PS Ⅱ （β/a^- 1 ） was improved significantly, compared with the control. The fluctuant ranges of these chlorophyll fluorescence parameters were increased at higher NO3^- concentration, compared with those at lower NO3^- concentration. The absorbed light energy allocated to the photochemical reaction of PS Ⅱ （P） was reduced by high light intensity and high NO3^- concentration. Meanwhile, the proportion allocated in antenna heat dissipation （D） increased significantly. Antenna heat dissipation was the main way for excessive energy dissipation.

关 键 词：NO3-胁迫 光化学效率 光能分配 净光合速率 

分 类 号：S642.2[农业科学—蔬菜学] Q945.11[农业科学—园艺学]