Photochemistry and Photophysics of variegated leaves

CUBA, NAHUEL; LAGORIO, MARÍA GABRIELA

Congreso; XIII ELAFOT 2017; 2017

Analysis of spectroscopic and photophysical properties of plants is relevant to evaluate thephysiological state of vegetation and stress factors. In fact, chlorophyll-afluorescence and reflectance are useful tools to monitor plant health.The main objective of this work was to study how variegation, alteratedpigment composition or the presence of certain reflective features modifythe leaves photophysical behaviour, in comparison to conventional greenleaves.For this purpose, homogeneous green leaves (Ficus benjamina), purpleleaves with high anthocyanin content (Tradescantia pallida), variegatedleaves with green and yellow sections originated from meristematic tissueunable to generate chloroplasts (Codiaeum aucubifolium), and green leavescovered by white trichomes (Cineraria maritima) were collected.Reflectance and transmitance spectra, both in the UV-vis and near-IR,were obtained to calculate absorption (k) and scattering (s) coefficients.Reflectance images were analysed with specialized software in order toobtain photosynthetic pigment content in a non-destructive way.Chlorophyl-a fluorescence emission spectra were recorded and additionallycorrected due to light-reabsorption [1]. Quantum efficiency of photosystemII (PSII), photochemical quenching (qP) and non-photochemicalquenching (NPQ) coefficients, which are correlated to plants?physiological state and health [2] were estimated from variable chlorophyllfluorescence (known as Kautsky kinetics). Finally, leaves images werecaptured by Scanning Electron Microscopy (SEM) to evaluate foliarsurface morphology.Non-destructive determination of water content in leaves could beachieved succesfully from their absorption coefficients and thickness. Onthe other hand, the photosynthetic parameters were interpreted in term of the leaves pigmentation.In conclusion, variegation showed a clear effect upon optical properties (reflectance and diffusetransmitance) and photosynthetic parameters obtained from the fluorescence of intact leaves.