Field spectroscopy

Leaf dorsoventrality as a paramount factor determining spectral performance in field-grown wheat under contrasting water regimes 

Spectroscopy can be defined as the interaction between matter and electromagnetic radiation (Skoog and West, 2007). It’s well known that materials in the nature (as well as synthetic materials) have a characteristic spectral signature as a result of their physiochemical properties. In other words, reflectance, absorption and transmittance traits along the electromagnetic spectra are material-dependent. These traits enable to obtain a huge amount of information of materials characteristics and have been extensively used in Physics and Chemistry.

The employment of spectroscopic techniques in Plant Biology has also demonstrated its usefulness in several areas as Agriculture, Botany, Pharmacology, Plant Ecology and even Taxonomy. Plant spectroscopy is based on the spectral characteristics of leaves and other photosynthetic tissues which in turn depend on the concentration of absorbing compounds (such as chlorophylls, carotenoids, water, cellulose, lignin, starch, proteins, etc) and the internal scattering of non-absorbed light (Jacquemoud and Ustin, 2008).

Some studies have aimed the establishment of empirical relationships between plant biochemical and physical properties and optical characteristics but these are still scarce. Moreover, these studies are strongly dependent on environmental conditions and plant type. On the other hand spectral characteristics at the plant canopy level (i.e. crops, forest and grassland) may be employed to assess several traits (i.e. grain yield, forest health, forage quality) but canopy architecture and atmospheric effect must also be considered. Therefore more studies addressing those issues are needed in order to contribute the development of many Plant Biology knowledge areas.

In this sense, we are now focusing on biochemical and anatomical characterisation of plant tissues derived from their spectral signature in field conditions. Secondly, we are interested in the implication of spectroscopic techniques on plant breeding under abiotic stress conditions. Additionally these may be employed for the calibration of analytical parameters of interest for breeders such as isotope composition and water content in plant tissues as well as the expected production. Another technical aspect for us is the use of spectroradiometer data for the comparison with multispectral sensors performance at the aerial scale (RPAS).