Complex Analysis of the Efficiency of Difference Reflectance Indices on the Basis of 400–700 nm Wavelengths for Revealing the Influences of Water Shortage and Heating on Plant Seedlings

Ekaterina Sukhova,Dmitry Kior,Lyubov Yudina,Ekaterina Gromova,Vladimir Sukhov,Anastasiia Ryabkova

doi:10.3390/rs13050962

Ekaterina Sukhova, Dmitry Kior + Show 4 more

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https://doi.org/10.3390/rs13050962

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Abstract

A drought, which can be often accompanied by increased temperature, is a key adverse factor for agricultural plants. Remote sensing of early plant changes under water shortage is a prospective way to improve plant cultivation; in particular, the sensing can be based on measurement of difference reflectance indices (RIs). We complexly analyzed the efficiency of RIs based on 400–700 nm wavelengths for revealing the influences of water shortage and short-term heating on plant seedlings. We measured spectra of reflected light in leaves of pea, wheat, and pumpkin under control and stress conditions. All possible RIs in the 400–700 nm range were calculated, significances of differences between experimental and control indices were estimated, and heatmaps of the significances were constructed. It was shown that the water shortage (pea seedlings) changed absolute values of large quantity of calculated RIs. Absolute values of some RIs were significantly changed for 1–5 or 2–5 days of the water shortage; they were strongly correlated to the potential quantum yield of photosystem II and relative water content in leaves. In contrast, the short-term heating (pea, wheat, and pumpkin seedlings) mainly influenced light-induced changes in RIs. Our results show new RIs, which are potentially sensitive to the action of stressors.

Highlights

Plant cultivation is an important branch of the world’s economy; the consumption of plant products increases from year to year
Pea seedlings were used in this experimental variant because our preliminary experiments showed that they were sensitive to the water shortage and suitable for investigation of the influence of water deficit on photosynthetic and spectral properties of leaves [54,92]
Our results show that the complex analysis of efficiencies of RIs, which is based on the calculation of all reflectance indices in the measured spectral range of reflected light, on following the estimation of significances and directions of differences between RIs in control and experimental plants, and on the construction of heatmaps of these significances and directions, which can be used for revealing new reflectance indices, and that are sensitive to stressors

Summary

Introduction

Plant cultivation is an important branch of the world’s economy; the consumption of plant products increases from year to year. The factors strongly influence photosynthesis [6,7], which is a basis of plant productivity. Water exchange and photosynthesis are important targets of the drought action [9,10]. Their changes are main reasons for the decrease in the plant productivity. The drought is often accompanied by the action of an increased temperature that can stimulate negative effects of the drought on the plant productivity [11]. It is important that even short-term water shortage (hours and days), which is induced by decreased irrigation [10,12] or the action of osmolitics [13,14], can induce numerous physiological and biochemical changes in plants. The short-term water shortage strongly influences photosynthetic processes and transpiration [10,12,14]; decreasing CO2 assimilation and efficiency of photosynthetic machinery, inducing stomata

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