Abstract
Proper management of nutrients in agricultural systems is critically important for maximizing crop yields while simultaneously minimizing the health and environmental impacts of pollution from fertilizers. These goals can be achieved by timely confirmatory diagnostics of nutrient deficiencies in plants, which enable precise administration of fertilizers and other supplementation in fields. Traditionally, nutrient diagnostics are performed by wet-laboratory analyses, which are both time- and labor-consuming. Unmanned aerial vehicle (UAV) and satellite imaging have offered a non-invasive alternative. However, these imaging approaches do not have sufficient specificity, and they are only capable of detecting symptomatic stages of nutrient deficiencies. Raman spectroscopy (RS) is a non-invasive and non-destructive technique that can be used for confirmatory detection and identification of both biotic and abiotic stresses on plants. Herein, we show the use of a hand-held Raman spectrometer for highly accurate pre-symptomatic diagnostics of nitrogen, phosphorus, and potassium deficiencies in rice (Oryza sativa). Moreover, we demonstrate that RS can also be used for pre symptomatic diagnostics of medium and high salinity stresses. A Raman-based analysis is fast (1 s required for spectral acquisition), portable (measurements can be taken directly in the field), and label-free (no chemicals are needed). These advantages will allow RS to transform agricultural practices, enabling precision agriculture in the near future.
Highlights
Plants experience a wide range of environmental stresses that inhibit growth and reduce their ability to carry out normal cellular functions (Farber et al, 2019a)
Spectra collected from Nitrogen deficient (ND), phosphorus deficient (PD), and KD plants exhibited lower intensities of vibrational bands that originated from pectin, cellulose, xylan, aliphatic vibrations, and carotenoids, relative to the corresponding bands in the spectra of healthy rice (Figure 1)
We found that spectra collected from ND plants exhibited an increase in the 1604 cm−1 band, which can be assigned to phenylpropanoids, whereas plants with PD and KD did not exhibit this spectral change
Summary
Plants experience a wide range of environmental stresses that inhibit growth and reduce their ability to carry out normal cellular functions (Farber et al, 2019a). These stresses can have abiotic and biotic origins. Biotic stresses can be caused by various pathogens, including bacteria, viruses, and fungi These pests significantly affect the maturation of crops, reducing their productivity, and they can destroy entire agricultural ecosystems (Food and Agriculture Organization of the United Nations, 2009). Significant losses of crop yield can be caused by different abiotic stresses such as salinity, drought, and nutrient deficiency (Pandey et al, 2017). Detection and identification of these nutrient deficiencies can be used for a site- and dose-specific administration of fertilizers that will mitigate losses associated with these deficiencies (Waraich et al, 2012)
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