Influence of Surface Structure, Pigmentation and Particulate Matter on Plant Reflectance and Fluorescence

Abstract

Optical properties of plant leaves are relevant to evaluatetheir physiological state and stress effect. The main objectiveof this work was to study how variegation, pigment composi-tion or reective features modies leaves' photophysicalbehavior. For this purpose, green leaves (Ficus benjamina),purple leaves (Tradescantia pallida), green leaves covered bywhite trichomes (Cineraria maritima) and variegated leaves(Codiaeum aucubifolium) were analyzed. Firstly, foliar sur-face morphology was evaluated by scanning electron micro-scopy. UV-vis and near-IR reectance and transmittancespectra were obtained to calculate absorption (k) and scatter-ing (s) coefcients. The theoretical approaches of Pile ofPlates and Kubelka– Munk's theory resulted still valid fornonstandard leaves with differing surface conditions. How-ever, frequently used spectral indices were not reliable forpredicting water content, when leaves differed from conven-tional ones. The proportionality between the absorption fac-tor and chromophore/pigment concentration was also lost forhairy leaves. A simplied model to describe these facts waspresented here. Fluorescence spectra were recorded and cor-rected, due to light re-absorption. Water-optical parameterconnection and pigment-optical parameter connection werethoroughly discussed. Leaf surface morphology and pigmen-tation have not only inuenced the optical features of leavesbut also played a role in the effect that particulate mattercould cause on leaf photosynthesis.