The inverse relationship between solar-induced fluorescence yield and photosynthetic capacity: benefits for field phenotyping

Abstract

Improving photosynthesis is considered a promising way to increase crop yield to feed a growing population. Realizing this goal requires non-destructive techniques to quantify photosynthetic variation among crop cultivars. Despite existing remote sensing-based approaches, it remains a question whether solar-induced fluorescence (SIF) can facilitate screening crop cultivars of improved photosynthetic capacity in plant breeding trials. Here we tested a hypothesis that SIF yield rather than SIF had a better relationship with the maximum electron transport rate (Jmax). Time-synchronized hyperspectral images and irradiance spectra of sunlight under clear-sky conditions were combined to estimate SIF and SIF yield, which were then correlated with ground-truth Vcmax and Jmax. With observations binned over time (i.e. group 1: 6, 7, and 12 July 2017; group 2: 31 July and 18 August 2017; and group 3: 24 and 25 July 2018), SIF yield showed a stronger negative relationship, compared with SIF, with photosynthetic variables. Using SIF yield for Jmax (Vcmax) predictions, the regression analysis exhibited an R2 of 0.62 (0.71) and root mean square error (RMSE) of 11.88 (46.86) μmol m–2 s–1 for group 1, an R2 of 0.85 (0.72) and RMSE of 13.51 (49.32) μmol m–2 s–1 for group 2, and an R2 of 0.92 (0.87) and RMSE of 15.23 (30.29) μmol m–2 s–1 for group 3. The combined use of hyperspectral images and irradiance measurements provides an alternative yet promising approach to characterization of photosynthetic parameters at plot level.

Emerging approaches to measure photosynthesis from the leaf to the ecosystem

“…Inspired by the successful leaf-level estimations of photosynthetic capacities, hyperspectral imaging (HSI) techniques are increasingly applied to canopy-scale measurements [73,78]. Imaging hyperspectral spectrometers provide more spatial information than a leaf-clip portable radiometer.…”

Inference of photosynthetic capacity parameters from chlorophyll a fluorescence is affected by redox state of PSII reaction centers

“…J max is a key determinant of the potential electron transport rate (J p ), which becomes the actual electron transport rate (J a ) when photosynthetic carboxylation is limited by the Ribulose 1,5-bisphosphate (RuBP) regeneration (Gu et al, 2019), often under low light conditions at the current CO 2 . Timely and accurate estimation of these photosynthetic capacity parameters is of vital importance for reliable prediction of large-scale carbon cycle dynamics and feedbacks to climate change using terrestrial biosphere models (TBMs) (Rogers et al, 2017;Walker et al, 2014) and for field-scale high-throughput crop phenotyping (Fu et al, 2021;Meacham-Hensold et al, 2019).…”

“…From the plant breeding perspective towards improving crop yields, increasing the carboxylation capacity of RuBisCO and optimizing electron transport chain are considered as promising genetic modification targets (Bailey-Serres et al, 2019;Simkin et al, 2015Simkin et al, , 2019South et al, 2019). Rapid high-throughput screening of V cmax and J max at the field scale will greatly accelerate the efficiency of selecting crop cultivars with enhanced photosynthesis (Fu et al, 2021).…”

Estimation of Maize Photosynthesis Traits Using Hyperspectral Lidar Backscattered Intensity

“…Traditionally, gas exchange measurements based on photosynthetic light response curves are used in photosynthetic capacity, while this time-consuming and laborious method cannot satisfy the requirement of high-throughput research quantifying hundreds to thousands of crop cultivars [12]. Sun-induced chlorophyll fluorescence (SIF) has been widely recognized as one proxy of photosynthesis capacity since the SIF signal emitted from chlorophyll a molecules results from the competition with photosynthesis and nonphotochemical quenching (NPQ, i.e., heat dissipation) [13][14][15].…”

“…The observed SIF signal, however, is not equal to the total emitted SIF due to its dependence on canopy structure, thus lessening its correlation with photosynthesis capacity [15,16]. Despite the SIF signal being successfully tested in the estimation of photosynthetic parameters at the small plot level [12], the quantitative measurement of SIF was based on the decoupling of reflected information and SIF signal within the upwelling radiation [16][17][18], presenting a challenge in the application of plant high-throughput phenotyping measurements. Optical reflectance reflects the interaction between target plants and incident radiation at a wide spectral domain, thus it has been gradually recognized as a potential tool for plant photosynthetic capability estimation.…”