In particular in agriculture, the application of remote sensing has become of increasing importance in recent years. This involves detecting the condition or even changes in the optical properties of leaves. The optical properties are based on interactions between light and the various components in plant tissues, for example pigments, water, cellulose, proteins.
Part of the incident light spectrum is absorbed by the leaf tissue, while the remaining spectrum is reflected. By detecting and quantifying the absorbed and reflected wavelengths, it is possible to assess various physiological and anatomical parameters. Thus, the development of plants and its responses to nutrient deficiencies, diseases, drought and water stress or environmental changes can be evaluated.
For this purpose, the methodology of remote sensing through, for example, field spectrometry and the analysis of satellite images, is used and compared with parallel data collection through field sampling. Apart from its non-invasive aspect, which allows in vivo observations of plants, this methodology is particularly useful as it allows continuous monitoring of plant development over time with high spatial resolution. Therefore, it is possible to fully follow the entire life cycle of plants.
Early detection of nutrient deficiencies is one of the main focuses of research at IAPN and, particularly, special attention is given to the role of magnesium (Mg) in plant physiological processes.
Being one of the plant essential macronutrients, Mg participates in many physiological processes by being a cofactor of many enzymes involved in respiration, membrane transport, photosynthesis, and the synthesis of DNA and RNA, a structural stabilizer of several nucleotides, and part of the ring structure of the chlorophyll molecule. Its deficiency in crops can affect plant biomass and yield formation severely. Under Mg deficiency, due to the mobility of Mg in the phloem and its recycling from chlorophyll degradation, the chlorophyll in the vascular bundles remains unaffected for longer periods than the chlorophyll in the cells between the bundles. This situation causes the typical intervenous pattern of chlorosis that occurs first in older leaves, leading to senescence and premature abscission eventually.
However, similarly to other nutrient deficiencies, when plants display visible symptoms or even before they appear, plant growth and development has already been severely compromised, thus decreasing yield considerably. Therefore, the presymptomatic and non-invasive detection of Mg deficiencies in plants, e.g., through remote sensing, is crucial for crop monitoring and to alleviate stress at early stages of plant development, thus avoiding irreversible damage and mitigate yield losses substantially.