Early Diagnosis and Management of Nitrogen Deficiency in Plants Utilizing Raman Spectroscopy

Abstract

Nutrient deficiency alters growth and development of crop plants and compromises yield. Real-time non-invasive monitoring of the nutritional status of crops would allow timely applications of fertilizers to optimize for growth and yield at different times of the plant's life cycle. Here, we used Raman spectroscopy to characterize Arabidopsis and two varieties of leafy vegetable crops under nitrogen sufficient and deficient conditions. We showed that the 1046 cm −1 Raman peak serves as a specific signature of nitrogen status in planta, which can be used for early diagnosis of nitrogen deficiency in plants before onset of any visible symptoms. Our research can be applied toward crop management for sustainable and precision agriculture.

The molecular–physiological functions of mineral macronutrients and their consequences for deficiency symptoms in plants

“…An example using mechanistic knowledge for diagnostic purposes is the use of time-resolved chlorophyll a fluorescence as a unique tool to monitor bioactive P in plants and to detect latent P deficiency (Frydenvang et al, 2015;Carstensen et al, 2018Carstensen et al, , 2019. Early detection of nitrogen status in plants using Raman spectroscopy was recently reported by Huang et al (2020). Further developments within these areas may pave the road for a future where crops can be fertilized according to their physiological demand rather than based on the classical practice, where bulk fertilization often leads to application of either too little or too much, with negative impacts on both environment, climate and the economy of farmers.…”

Portable Raman leaf-clip sensor for rapid detection of plant stress

“…The 4 These authors contributed equally: Shilpi Gupta and Chung Hao Huang. * email: chua@ mail.rockefeller.edu; rajeev@mit.edu leaf-clip format for optical sensing was first introduced by Inada 33,39 and transmission based leaf-clip sensors have been commercialized by several vendors 34,35 . These leaf-clip sensors for chlorophyll are affected by leaf anatomy, cuticle reflectance, leaf veins, and the flatness of leaves 36,37 .…”

“…Reference Raman measurements were performed in the laboratory and spectra were acquired using Kymera 328i spectrograph (Andor, UK) employing a 600 g mm −1 optical grating and 830 nm excitation. We measured the Raman spectra of leaf sections placed on a 100 µm thick fused silica slide, from two locations per leaf (one on each side of the midvein) from the entire cross-section of a leaf 39 . In Ref.…”

“…In Ref. 39 , nitrate measurements using this benchtop Raman instrument were validated against chemical analysis of nitrate 40 for several plant species. Further validation was acquired by measurements of wild-type Arabidopsis thaliana as well as mutants affected in metabolic pathways associated with nitrogen uptake.…”

A Novel Machine Learning Approach to Estimate Grapevine Leaf Nitrogen Concentration Using Aerial Multispectral Imagery

“…As discussed above, young leaves with less chlorophyll may exhibit a spectral response similar to leaves with low N concentration. In addition, many other stresses or diseases can lead to chlorophyll degradation in leaves, resulting in spectral patterns similar to leaves with low N concentration [61]. For instance, leaves with water stress in grapevine may exhibit similar spectral characteristics to leaves suffering from N deficiency as they tend to have a lower reflectivity in near-infrared and higher reflectivity in red edge and red bands compared to well-irrigated leaves [62].…”