Linking Tissue Damage to Hyperspectral Reflectance for Non-Invasive Monitoring of Apple Fruit in Orchards

Abstract

Reflected light carries ample information about the biochemical composition, tissue architecture, and physiological condition of plants. Recent technical progress has paved the way for affordable imaging hyperspectrometers (IH) providing spatially resolved spectral information on plants on different levels, from individual plant organs to communities. The extraction of sensible information from hyperspectral images is difficult due to inherent complexity of plant tissue and canopy optics, especially when recorded under ambient sunlight. We report on the changes in hyperspectral reflectance accompanying the accumulation of anthocyanins in healthy apple (cultivars Ligol, Gala, Golden Delicious) fruits as well as in fruits affected by pigment breakdown during sunscald development and phytopathogen attacks. The measurements made outdoors with a snapshot IH were compared with traditional “point-type” reflectance measured with a spectrophotometer under controlled illumination conditions. The spectra captured by the IH were suitable for processing using the approaches previously developed for “point-type” apple fruit and leaf reflectance spectra. The validity of this approach was tested by constructing a novel index mBRI (modified browning reflectance index) for detection of tissue damages on the background of the anthocyanin absorption. The index was suggested in the form of mBRI = (R640−1 + R800−1) − R678−1. Difficulties of the interpretation of fruit hyperspectral reflectance images recorded in situ are discussed with possible implications for plant physiology and precision horticulture practices.

Circle Fitting Based Image Segmentation and Multi-Scale Block Local Binary Pattern Based Distinction of Ring Rot and Anthracnose on Apple Fruits

“…Hyperspectral imaging technology has been used to detect bruises ( Xing et al, 2005 ; Ferrari et al, 2015 ; Tan et al, 2018 ; Zhang and Li, 2018 ) and insect damage ( Tian et al, 2015 ; Rady et al, 2017 ) on apple fruits. The advantages of hyperspectral imaging technology with the characteristic of combining images with spectra can be used to detect apple diseases ( Jarolmasjed et al, 2018 ; Shuaibu et al, 2018 ; Solovchenko et al, 2021 ).…”

Global trends in the development of agricultural robotics

“…According to scientists, the introduction of digital technologies in agriculture based on artificial intelligence technologies and robotic systems will allow achieving more than threefold growth in labor productivity, increasing crop yields, and reducing anthropogenic impact on the environment and humans [1][2][3].…”

Comparison of the Non-Invasive Monitoring of Fresh-Cut Lettuce Condition with Imaging Reflectance Hyperspectrometer and Imaging PAM-Fluorimeter

“…Light reflected by plant carries ample information about its biochemical composition, tissue architecture, and physiological condition [3]. Developmental changes in pigment composition as well as those induced by environmental stresses and attacks of phytopathogens manifest themselves as specific changes in plant reflection properties [4][5][6] linked with changes in pigment content and composition. Chlorophylls are central to capture and transform light energy in photosynthesis.…”