Memorias de investigación
Communications at congresses:
Application of hyperspectral image to identify salinity effects on lettuce leaves

Research Areas
  • Agriculture,
  • Engineering

thereby of agricultural soil. Saline soils represent a great area in the southeast of Spain, where are the main region of horticultural crops in the country. Lettuce (Lactuca sativa L.) is one of the most important crops in this region, being Murcia the main producer region in the European Union. This production is employed mainly for fresh consumption and ready-to-eat product. In general, lettuce presents a moderate sensitivity to salinity. In moderated levels of salinity lettuce crops do not show visible damages in the leaves and seem to be normal, although their growth and yield decrease. They could have deep green leaves, with more density and thickness, and more succulent tissues. When salinity induces imbalances in concentrations of certain mineral elements, necrosis, chlorosis and tipburn can appear in the leaves. However a moderate saline stress in lettuce crop can have positive effects in post-harvest conservation for fresh and ready-to-eat products because of less polyphenoloxidase and peroxidase activity after cutting. Therefore, lower enzymatic and microbiological degradation occur along the shelf-life. Hyperspectral image has been widely employed to detect salinity levels in soils and canopy in remote sensing, developing many indexes to estimate saline concentration in relation with reflectance at different wavelengths. However, there are no studies at laboratory level to ob-serve changes produced in the structure and composition of the leaf tissues when saline concentration is increasing. The aim of the present work is to apply hyperspectral imaging techniques as a non destructive procedure to identify the influence of saline stress in just harvested ?baby? lettuce. Four salt treatments were applied under a hydroponic growth system: a control treatment without NaCl (Ct) and three levels of salt through the addition of different concentrations of NaCl to the nutrient solution: S1 (50 mM NaCl), S2 (100 mM NaCl), S3 (150 mM NaCl). The application of salt treatments was proportionally established in three days and conducted for a total of 10 days. At the end of experiments, leaves were harvested and a sample of 10 leaves per treatment, with similar size, was selected for the acquisition of hyperspectral images. Hyperspectral images from the 40 selected leaves were taken with a hyperspectral vision system consisting in a CCD camera and a VIS-NIR spectrometer (Headwall Photonics HyperspecTM) working in the range of 400 ? 1000 nm. 189 wavelengths were considered along the range, obtaining a spectral resolution of 3.2 nm.
International Conference of Agricultural Engineering - AgEng 2014 Zurich
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Proc. Int. Conf. Agricultural Engineering, AgEng2014

Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: LPF-TAGRALIA: Técnicas Avanzadas en Agroalimentación
  • Departamento: Ingeniería Agroforestal