Modified Photochemical Reflectance Indices as New Tool for Revealing Influence of Drought and Heat on Pea and Wheat Plants

Abstract

In environmental conditions, plants can be affected by the action of numerous abiotic stressors. These stressors can induce both damage of physiological processes and adaptive changes including signaling-based changes. Development of optical methods of revealing influence of stressors on plants is an important task for plant investigations. The photochemical reflectance index (PRI) based on plant reflectance at 531 nm (measuring wavelength) and 570 nm (reference wavelength) can be effective tool of revealing plant stress changes (mainly, photosynthetic changes); however, its efficiency is strongly varied at different conditions. Earlier, we proposed series of modified PRIs with moderate shifts of the measuring wavelength and showed that these indices can be effective for revealing photosynthetic changes under fluctuations in light intensity. The current work was devoted to the analysis of sensitivity of these modified PRIs to action of drought and short-term heat stress. Investigation of spatially-fixed leaves of pea plants showed that the modified PRI with the shorter measuring wavelength (515 nm) was increased under response of drought and heat; by contrast, the modified PRI with the longer wavelength (555 nm) was decreased under response to these stressors. Changes of investigated indices could be related to parameters of photosynthetic light reactions; however, these relations were stronger for the modified PRI with the 555 nm measuring wavelength. Investigation of canopy of pea (vegetation room) and wheat (vegetation room and open-ground) supported these results. Thus, moderate changes in the measuring wavelengths of PRI can strongly modify the efficiency of their use for the estimation of plant physiological changes (mainly photosynthetic changes) under action of stressors. It is probable that the modified PRI with the 555 nm measuring wavelength (or similar indices) can be an effective tool for revealing photosynthetic changes induced by stressors.

A review of different multispectral indices for monitoring plant health in mid-mountain sites

“…In the third step (3), the we substituted wavelength closest to promising indices with one another to evaluated influence of the shift in the central wavelength. Also, the photochemical reflectance index (PRI) was split into its slow relaxing 515 nm and fast relaxing 550 nm components to check for improved reaction in accordance with studies conducted by Sukhova et al [16].…”

“…To avoid overflow, we expanded the datatype of the images before performing the calculation using the specified formulas. Most of the selected indices are based on the results from the study conducted by Einzmann et al [4] on pine trees, with some new indices for evaluating the relationship between nitrogen consumption and photosynthetic activity [14,15,16].…”

“…Therefore, it is important to define the minimum physical requirements when selecting the most suitable system. Many studies have shown that a complete recording of the visual and infrared spectrum is not necessary for evaluating plant health, and instead, a few specific wavelength combinations in the form of vegetation indices may be sufficient [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The vegetation indices encompass a broad spectrum of wavelengths and capture various changes in the plant's reflectance behavior that are related to specific types of stress.…”

Development of a longevity prediction model for cut roses using hyperspectral imaging and a convolutional neural network

“…Hyperspectral imaging is a non-contact method that analyses a wide range of light spectrums by scanning objects with hyperspectral cameras ( Lowe et al., 2017 ; Cao et al., 2022 ; Xiang et al., 2022 ). The reflectance of light from plants at different wavelengths can be used to obtain information about various plant statuses and conditions ( Sun J et al., 2021 ; Sukhova and Yudina, 2022 ). In this study, HSI of cut roses was used to observe distinct wavelength ranges of plants in various physiological states, such as GMD infection, water stress response, and senescence induction.…”

The Influence of Soil Salt Stress on Modified Photochemical Reflectance Indices in Pea Plants

“…However, there are works that show that changes in PRI(531, 570) induced by the action of stressors can have both positive and negative directions under different experimental conditions [37,38], e.g., a short-term water shortage increases the photochemical reflectance index (PRI) but long-term soil drought decreases this index [42]. This variability of the direction of PRI(531, 570) changes obstructs the application and interpretation of this index and requires further development of methods of plant remote sensing on the basis of the photochemical reflectance index.…”