Study on Plant Nutrition Indicator Using Leaf Spectral Transmittance for Nitrogen Detection

Abstract

Abstract. The low fertilizer utilization at growing season and environment pollution coursed by unreasonable fertilization are becoming global outstanding problems in agricultural production. Scientific and reasonable fertilization based on rapid and nondestructive plant nutrient detection will be a valuable solution for solving above problems. In this study, spectral transmittance in wavelength ranged from 300 to 1100 nm, chlorophyll content and nitrogen content of rice and cucumber leaves treated with culture solution in five different nitrogen levels were measured. According to the correlation analysis between them, 560, 650, and 720 nm as feature wavelengths and 940 nm as reference wavelength were determined for nitrogen detection. Correlation analysis between 21 spectral feature parameters composed by the transmittance at above wavelength, the leaf chlorophyll content and nitrogen content, and combined with their regression examination indicated that spectral feature parameters of (T940 -T560) / (T940 + T560), log (T940/T560) and log (T940/T650) are useful to conduct plant nutrient diagnosis with less than 8% relative error in rice and cucumber leaves. Therefore, the above spectral feature parameters as plant nitrogen indicators can be used to estimate the chlorophyll content and nitrogen content, furthermore support for non-destructive plant nutrient detection and fertilizer recommendation based on testing soil.

Proximal Optical Sensors for Nitrogen Management of Vegetable Crops: A Review

“…Most chlorophyll meters estimate the relative leaf chlorophyll content by measuring the absorbance and transmittance of radiation by the leaf of: (1) Red radiation, which chlorophyll absorbs; and (2) near infra-red (NIR) radiation, which chlorophyll transmits [ 19 , 43 ] ( Figure 1 ). Absorbance of red radiation increases with chlorophyll content, resulting in higher chlorophyll meter values [ 39 , 44 , 45 ]. These sensors are referred to as transmittance-based chlorophyll meters.…”

Different Responses of Various Chlorophyll Meters to Increasing Nitrogen Supply in Sweet Pepper

“…Most CMs determine relative leaf chl content by measuring absorbance and transmittance, by the leaf, of (1) red radiation, which chl absorbs, and (2) near infra-red (NIR) radiation, which chl transmits ( Fox and Walthall, 2008 ; Cerovic et al, 2012 ). Absorbance of red radiation increases with chl resulting in higher CM values ( Schepers et al, 1996 ; Daughtry et al, 2000 ; Hu et al, 2011 ). These CMs are often referred to as transmittance-based meters ( Padilla et al, 2018 ).…”