弱光条件下辣椒幼苗叶片的气体交换和叶绿素荧光特性

 在人工气候室内, 研究了人工模拟弱光处理(75～100μmol·m^-2 ·s^-1 , 对照光强450～500μmol·m^-2 ·s^-1 ) 对不同基因型辣椒(Capsicum annuum L. ) 叶片光合作用气体交换、叶绿素荧光参数以及叶绿素含量的影响。结果表明, 弱光逆境下生长的辣椒幼苗净光合速率( Pn) 、暗呼吸速率(Rd) 、夜间呼吸速率(Rn) 不同程度下降, PSⅡ实际光化学效率( ФPSⅡ) 、光合电子传递速率( ETR) 和光化学猝灭系数( qP) 降低, 激发能向光化学反应分配的比例减少, 热耗散增加, 而弱光对PSⅡ的最大光化学效率( Fv/Fm) 无显著影响。辣椒叶片ФPSⅡ及ETR对光强( PPFD) 的响应曲线表明, ФPSⅡ随PPFD的升高而下降, 弱光下生长的叶片下降幅度较对照正常光照下的叶片大; 弱光下生长叶片的的电子传递速率的光饱和点低于正常光照下的叶片, 相应的饱和电子传递速率也较低。弱光处理使辣椒功能叶片SPAD值降低, 叶绿素合成受到抑制。弱光耐受性较好的材料, 如‘伏地尖’和‘上海圆椒’在弱光下Pn下降较少,并且有着相对较高的Fv/Fm以及ETR值。

Effects of Low Light Intensity on Gas Exchange and Chlorophyll Fluorescence Characteristics of Capsicum Seedlings

The effects of low light (75 - 100μmol·m^-2 ·s^-1 ) on photosynthetic gas exchange, chlorophyll fluorescence and chlorophyll contents in seedlings of different Capsicum were studied. The resultsshowed that under low light, net photosynthetic rate ( Pn) , dark resp iration rate, night resp iration rate, actualphotochemical efficiency of PS Ⅱ in the light ( ФPS Ⅱ) , electron transport rate ( ETR ) , photochemicalquenching ( qP) and excitation energy to PSⅡphotochemistry decreased, whereas the heat dissipation increased and no significant changes in maximal photochemical efficiency of PSⅡ in the dark ( Fv/Fm). Fromthe response curve of ФPSⅡ to light intensity, itwas seen thatwith the increase of light intensity, there was afaster decrease in ФPSⅡ. The response curve of ETR to light intensity indicated that Capsicum grown underlow light had lower saturate electron transport rate light and saturation point of electron transport rate, as compared with those grown under normal light. The SPAD value of leaves in Capsicum decreased which mean thatthe synthesis of chlorophyllwas inhibited under low light. Capsicum with lower net photosynthesis decreasing,higher Fv/Fm and ETR may possess potential low light-tolerance.