Calatayud A, Roca D, Martínez P F
Department of Horticulture, Instituto Valenciano de Investigaciones Agrarias I.V.I.A., Ctra. Moncada-Naquera km. 4.5, 46113 Moncada, Valencia, Spain.
Plant Physiol Biochem. 2006 Oct;44(10):564-73. doi: 10.1016/j.plaphy.2006.09.015. Epub 2006 Oct 9.
Spatial-temporal changes were examined by imaging chlorophyll (Chl) a fluorescence in four leaf areas, two central and two external of rose plants (Rosa x hybrida) cv. Grand Gala for 9 days, under progressive water stress. New fluorescence parameters based on the lake model have recently been used to determine Q(A) redox state and excitation energy fluxes in order to gain a better understanding of the mechanisms that occur under drought stress. Chlorophyll fluorescence images showed a spatial variation in the leaves. The lower values for F(o), F(M), phi(2), q(P) and q(L) were found in the internal leaf area while higher values of non-photochemical quenching calculated from Stern-Volmer quenching (NPQ) and phi(NPQ). phi(Po) were more homogeneous throughout leaf. Temporal changes were also observed during the experiment, a 10% decrease in relative water content (RWC) (between day 1 and 2), led to a decrease in photochemical quenching and an increase in non-photochemical processes. Chlorophyll fluorescence parameters were more or less constant till day 8. At the end of the experiment (day 9), energy dissipation by downregulation, electron transport and Q(A) redox state, decreased and phi(NO) increased to compensate the change. Chlorophyll fluorescence parameters based on the lake model q(L), phi(NPQ) and phi(NO) have been found more appropriate for estimating the fraction of open centres, the quantum yield of regulated energy dissipation in photosystem II (PSII) and the quantum yield of non-regulated energy dissipation in PSII, respectively. The F(s)/F(o) ratio is strongly correlated with NPQ and phi(NPQ) up to a RWC of 20%. This coincides with a greater decrease in photochemical quenching and non-photochemical quenching and an increase in phi(NO).
在渐进性水分胁迫下，对玫瑰（Rosa x hybrida）品种“大花月季”的四个叶区（两个中央叶区和两个外部叶区）的叶绿素（Chl）a荧光进行了9天的成像，以研究其时空变化。最近，基于湖泊模型的新荧光参数已被用于确定Q(A)氧化还原状态和激发能通量，以便更好地理解干旱胁迫下发生的机制。叶绿素荧光图像显示叶片存在空间变化。在内部叶区发现F(o)、F(M)、phi(2)、q(P)和q(L)的值较低，而根据斯特恩-沃尔默猝灭计算的非光化学猝灭（NPQ）和phi(NPQ)、phi(Po)的值在整个叶片中更为均匀。在实验过程中也观察到了时间变化，相对含水量（RWC）在第1天和第2天之间下降了10%，导致光化学猝灭降低，非光化学过程增加。直到第8天，叶绿素荧光参数或多或少保持恒定。在实验结束时（第9天），通过下调、电子传递和Q(A)氧化还原状态的能量耗散减少，phi(NO)增加以补偿变化。已发现基于湖泊模型的叶绿素荧光参数q(L)、phi(NPQ)和phi(NO)分别更适合于估计开放中心的比例、光系统II（PSII）中调节能量耗散的量子产率和PSII中未调节能量耗散的量子产率。在RWC达到20%之前，F(s)/F(o)比值与NPQ和phi(NPQ)密切相关。这与光化学猝灭和非光化学猝灭的更大下降以及phi(NO)的增加相吻合。
