低温弱光胁迫及恢复对切花菊光合作用和叶绿素荧光参数的影响

以切花菊品种‘神马’为试材,在偏低温弱光(16℃/12℃,PFD100μmol.m-2.s-1)和临界低温弱光(12℃/8℃,PFD60μmol.m-2.s-1)下分别胁迫11d,然后转入正常条件(22℃/18℃,PFD450μmol.m-2.s-1)恢复11d,研究不同低温弱光强度及恢复对菊花光合作用和叶绿素荧光参数的影响.结果表明:低温弱光导致菊花叶片的净光合速率(Pn)和气孔限制值(Ls)下降,而胞间CO2浓度(Ci)上升.偏低温弱光胁迫下菊花叶片暗适应下最大光化学效率(Fv/Fm)和初始荧光(Fo)无明显变化,但光适应下最大光化学效率(Fv′/Fm′)在处理前期略有下降,后期则有所回升;而临界低温弱光处理的Fo明显升高,Fv/Fm和Fv′/Fm′显著降低.PSⅡ光合电子传递量子效率(ΦPSⅡ)、光化学猝灭系数(qP)和表观光合电子传递速率(ETR)均随着低温弱光胁迫程度的增加和时间的延长而降低;偏低温弱光处理植株在解除胁迫后能迅速恢复到对照水平,而临界低温弱光处理植株回升速度较慢;同时,低温弱光胁迫下吸收光强用于分配光化学反应部分(Prate)的比例减少,而天线热耗散(Drate)和反应中心的能量耗散(Ex)比例上升,但天线热耗散为过剩光能的主要分配途径.

Effects of low temperature-and weak light stress and its recovery on the photosynthesis and chlorophyll fluorescence parameters of cut flower chrysanthemum

The cut flower chrysanthemum ‘Jinba’ was respectively treated with l
ower temperature and weaker light (16 ℃/ 12 ℃, PFD 100  μmol·m^-2
·s^-1) and critical low temperature and weak light (12 ℃/8 ℃, PFD 60 μmol·m^-2·s^-1 ) for 11 days, and then transferred to normal condition (22 ℃/
18 ℃, PFD 450 μmol·m^-2·s^-1) for 11 days, aimed to study the low
temperature and weak light stress and its recovery on the photosynthesis and c
hlorophyll fluorescence of chrysanthemum leaves. Under the stress of lower tempe
rature and weaker light, the net photosynthetic rate (P_n) and stomatal lim
itation (L_s) of chrysanthemum leaves decreased while the intercellular CO₂ concentration (C_i) increased, the maximal photochemical efficiency of
PSⅡ(F_v/F_m) in dark and the initial fluorescence (F_o) had no o
bvious change, but the maximal photochemical efficiency of PSⅡ (F_v′/Fm′) in light increased after an initial decrease. Contrarily, under the stress
 of critical low temperature and weak light, the F_o increased, and the F_v/F_mand F_v′/F_m′decreased significantly. The quantum yield of
PSⅡ electron transport (Φ PSⅡ), photochemical quenching (qP),
and apparent photosynthetic electron transfer rate (ETR) of chrysanthemum le
aves decreased with increasing stress and time, and recovered quickly after the
release of lower temperature and weaker light stress but more slowly after the
 release of critical low temperature and weak light stress. At the same time,
the photochemistry react rate (Prate) decreased, but the hot dissipation of ante
nna (Drate) and the energy dissipation of PSⅡ (Ex) increase
d under the stress conditions. Drate was the main pathway of superfluous light a
llocation.