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以‘肉芙蓉’牡丹(Paeonia suffruticosa Andr.‘Roufurong’)叶片为材料,研究了100、700和1400μmol·m-2·s-1光强下不同温度(15、20、25、30、35和40℃)处理对叶片光合特性和叶绿素荧光参数的影响。结果表明:随光强增加,叶片最大光化学效率(Fv/Fm)、光系统Ⅱ实际光化学效率(ΦPSⅡ)、光下开放的PSⅡ反应中心激发能捕获效率(Fv′/Fm′)和光化学猝灭系数(qP)均显著下降,其中强光1400μmol·m-2·s-1下最低。与室温(25℃)处理的叶片相比,低温(15℃)和高温(40℃)处理叶片Fv/Fm、ΦPSⅡ、Fv′/Fm′、qP急剧下降。同时,随光强增加,PSⅠ激发能分配系数α显著性降低,PSⅡ激发能分配系数β却显著升高,激发能分配严重偏离平衡。强光高温胁迫下,虽然叶片热耗散(NPQ)能力迅速增加,但是由于光化学效率的下降,光化学反应对激发能的利用大幅度下降,同时,由于两光系统激发能分配严重偏离平衡状态,过多的激发能分配给PSⅡ,导致PSⅡ激发压(1-qP)增大,加剧了PSⅡ伤害程度。
The leaves of Paeonia suffruticosa Andr.’Roufurong ’were used to study the effects of different temperature (15, 20, 25, 30, 35 and 100 mg / 40 ℃) on leaf photosynthetic characteristics and chlorophyll fluorescence parameters. The results showed that the maximum photochemical efficiency (Fv / Fm), the actual photochemical efficiency (ΦPSⅡ) of the photosystem II, the capture efficiency (Fv ’/ Fm’) and the photochemical quenching The coefficients (qP) decreased significantly, with the lowest under 1400 μmol · m-2 · s-1. Compared with the leaves treated at room temperature (25 ℃), the leaf Fv / Fm, ΦPSⅡ, Fv ’/ Fm’ and qP declined sharply at low temperature (15 ℃) and high temperature (40 ℃). At the same time, with the increase of light intensity, the partition coefficient α of PS Ⅰ excitation energy decreased significantly while the distribution coefficient of β Ⅱ excitation energy β increased significantly, and the excitation energy distribution deviated seriously from equilibrium. Under high temperature and high light stress, although the ability of leaf heat dissipation (NPQ) increased rapidly, the use of photochemical reaction for excitation energy decreased significantly due to the decrease of photochemical efficiency. At the same time, due to the serious deviation of excitation energy distribution of the two light systems from the equilibrium state, Excessive excitation can be assigned to PSII, resulting in PS Ⅱ excitation pressure (1-qP) increases, exacerbated the injury degree of PS Ⅱ.