Spatial-temporal variations in rose leaves under water stress conditions studied by chlorophyll fluorescence imaging

• Published in: Plant physiology and biochemistry 2006-10, Vol.44 (10), p.564-573
• Main Authors: Calatayud, A., Roca, D., Martínez, P.F.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chlorophyll - chemistry; Chlorophyll - metabolism; Chlorophyll fluorescence; Economic plant physiology; Fluorescence; Fundamental and applied biological sciences. Psychology; Imaging; Non-photochemical quenching; Photochemical quenching; Plant Leaves - metabolism; Rosa - metabolism; Rose; Time Factors; Water - metabolism; Water relations, transpiration, stomata; Water stress
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2006.09.015

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, φ 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 φ NPQ. φ 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 φ NO increased to compensate the change. Chlorophyll fluorescence parameters based on the lake model q L, φ NPQ and φ 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 φ NPQ up to a RWC of 20%. This coincides with a greater decrease in photochemical quenching and non-photochemical quenching and an increase in φ NO.