High resolution leaf spectral signature as a tool for foliar pigment estimation displaying potential for species differentiation.

Optical leaf profiles depend on foliar pigment type and content, as well as anatomical aspects and cellular ultrastructure, whose effects are shown in several species. Monocotyledon and Dicotyledon plants presenting natural pigment content variations and anatomical alterations were analyzed. Each plant species displays its own spectral signatures, which are, in turn, influenced by foliar pigment class (composition) and concentration, as well as anatomical and ultrastructural plant cell characteristics. Plants with no anthocyanin displayed increased reflectance and transmittance in the green spectral region (501-565 nm), while values decreased in the presence of anthocyanin. At wavelengths below 500 nm (350-500 nm), strong overlapping signatures of phenolics, carotenoids, chlorophylls, flavonoids and anthocyanins were observed. Using a partial least squares regression applied to 350-700 nm spectral data allowed for accurate estimations of different foliar pigment levels. In addition, a PCA and discriminant analysis were able to efficiently discriminate different species displaying spectra overlapping. The use of absorbance spectra only was able to discriminate species with 100 % confidence. Finally, a discussion on how different wavelengths are absorbed and on anatomical interference of light interaction in leaf profiles is presented.

Micropropagation of Cordyline terminalis.

This protocol describes an efficient and rapid method for large-scale multiplication of Cordyline terminalis in a cost-effective manner. Actively growing shoot tips were selected as explants. Murashige and Skoog (MS) basal medium was supplemented with different plant growth regulators at various developmental stages of C. terminalis. The highest percentage of regeneration (95 ± 2.8) and average number of shoot buds (60.2 ± 4.4) per explant were obtained in medium containing 80 mg /L adenine sulfate (AdSO(4)), 2 mg/L 6-benzyladenine (BA), and 0.1 mg/L indole-3-acetic acid (IAA). Thousands of micropropagated plants were produced within 4-5 months using this protocol.