Nonlinear Relationship Between the Yield of Solar-Induced Chlorophyll Fluorescence and Photosynthetic Efficiency in Senescent Crops

Abstract

It has been demonstrated that solar-induced chlorophyll fluorescence (SIF) is linearly related to the primary production of photosynthesis (GPP) in various ecosystems. However, it is unknown whether such linear relationships have been established in senescent crops. SIF and GPP can be expressed as the products of absorbed photosynthetically active radiation (APAR) with the SIF yield and photosystem II (PSII) operating efficiency, respectively. Thus, the relationship between SIF and GPP can be represented by the relationship between the SIF yield and PSII operating efficiency when the APAR has the same value. Therefore, we analyzed the relationship between the SIF yield and the PSII operating efficiency to address the abovementioned question. Here, diurnal measurements of the canopy SIF (760 nm, F760) of soybean and sweet potato were manually measured and used to calculate the SIF yield. The PSII operating efficiency was calculated from measurements of the chlorophyll fluorescence at the leaf level using the FluorImager chlorophyll fluorescence imaging system. Meanwhile, field measurements of the gas exchange and other physiological parameters were also performed using commercial-grade devices. The results showed that the SIF yield was not linearly related to the PSII operating efficiency at the diurnal scale, reflecting the nonlinear relationship between SIF and GPP. This nonlinear relationship mainly resulted from the heterogeneity and diurnal dynamics of the PSII operating efficiency and from the intrinsic diurnal changes in the maximum efficiency of the PSII photochemistry and the proportion of opened PSII centers. Intensifying respiration was another factor that complicated the response of photosynthesis to the variation in environmental conditions and negatively impacted the relationship between the SIF yield and the PSII operating efficiency. The nonlinear relationship between the SIF yield and PSII efficiency might yield errors in the estimation of GPP using the SIF measurements of senescent crops.

The Links between Canopy Solar-Induced Chlorophyll Fluorescence and Gross Primary Production Responses to Meteorological Factors in the Growing Season in Deciduous Broadleaf Forest

“…This is mainly due to the fact that the high radiation is usually accompanied by high temperature during the midday/afternoon period, which may cause the plant photosynthesis "depression" in noon and afternoon, where NPQ is not affected by instantaneous stress and SIF increases with PAR, presenting the nonlinear relationship between SIF and GPP [31]. In the subsequent analysis, we find that the change of the relationship mainly depends on the magnitude of PAR, similar results were reported in a previous study [30]. In many studies, APAR is considered to be the main factor driving GPP/SIF changes [60,61].…”

“…On seasonal or interannual scales, model simulation and field measurement results testify that a clear linear relationship exists between SIF and GPP [12,23,28,29]. However, with increasing attention in the literature, nonlinear relationships between SIF and GPP have been revealed [30][31][32][33], which have provided evidence for fluorescence and photosynthesis divergence at smaller spatiotemporal scales [34]. ChlF contains lots of information related to photosynthesis regarding the light utility efficiency and is closely related to plant vitality and biological yield.…”

Solar‐Induced Chlorophyll Fluorescence as a Potential Proxy for Gross Primary Production and Methane Emission in a Cool‐Temperate Bog in Northern Japan

“…Another unique characteristic of wetlands is the effect of water inundation. However, a few ground‐based SIF studies have been conducted in wetlands, such as the coastal marsh (Huang et al., 2022), compared with the many studies undertaken in forests (Cheng et al., 2021; Lu et al., 2018; Magney, Bowling, et al., 2019; Nichol et al., 2019; H. Yang et al., 2017; X. Yang et al., 2015) and croplands (J. Chen et al., 2022; Dechant et al., 2020; He et al., 2020; L. Liu et al., 2017; L. Liu, Teng, et al., 2020; L. Liu, Zhao, et al., 2020; Miao et al., 2020; K. Yang et al., 2018). Therefore, it is important to evaluate the potential for SIF to represent photosynthesis and predict methane production, in conjunction with temperature and soil moisture, each of which can be remotely sensed from satellites.…”