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The Community Land Model version 4 overestimates gross primary production (GPP) compared with estimates from FLUXNET eddy covariance towers. The revised model of Bonan et al. (2011) is consistent with FLUXNET, but values for the leaf‐level photosynthetic parameterVcmaxthat yield realistic GPP at the canopy‐scale are lower than observed in the global synthesis of Kattge et al. (2009), except for tropical broadleaf evergreen trees. We investigate this discrepancy betweenVcmaxand canopy fluxes. A multilayer model with explicit calculation of light absorption and photosynthesis for sunlit and shaded leaves at depths in the canopy gives insight to the scale mismatch between leaf and canopy. We evaluate the model with light‐response curves at individual FLUXNET towers and with empirically upscaled annual GPP. Biases in the multilayer canopy with observedVcmaxare similar, or improved, compared with the standard two‐leaf canopy and its lowVcmax, though the Amazon is an exception. The difference relates to light absorption by shaded leaves in the two‐leaf canopy, and resulting higher photosynthesis when the canopy scaling parameterKn is low, but observationally constrained. Larger Kndecreases shaded leaf photosynthesis and reduces the difference between the two‐leaf and multilayer canopies. The low modelVcmaxis diagnosed from nitrogen reduction of GPP in simulations with carbon‐nitrogen biogeochemistry. Our results show that the imposed nitrogen reduction compensates for deficiency in the two‐leaf canopy that produces high GPP. Leaf trait databases (Vcmax), within‐canopy profiles of photosynthetic capacity (Kn), tower fluxes, and empirically upscaled fields provide important complementary information for model evaluation. Key Points CLM overestimates gross primary production Shaded leaf photosynthesis erroneously contributes to high GPP Multi‐scale leaf, canopy, and global data are needed for model evaluation

Switchgrass (Panicum virgatum L.) is a prominent bioenergy crop with robust resilience to environmental stresses. However, our knowledge regarding how precipitation changes affect switchgrass photosynthesis and its responses to light and CO2 remains limited. To address this knowledge gap, we conducted a field precipitation experiment with five different treatments, including −50%, −33%, 0%, +33%, and +50% of ambient precipitation. To determine the responses of leaf photosynthesis to CO2 concentration and light, we measured leaf net photosynthesis of switchgrass under different CO2 concentrations and light levels in 2020 and 2021 for each of the five precipitation treatments. We first evaluated four light and CO2 response models (i.e., rectangular hyperbola model, nonrectangular hyperbola model, exponential model, and the modified rectangular hyperbola model) using the measurements in the ambient precipitation treatment. Based on the fitting criteria, we selected the nonrectangular hyperbola model as the optimal model and applied it to all precipitation treatments, and estimated model parameters. Overall, the model fit field measurements well for the light and CO2 response curves. Precipitation change did not influence the maximum net photosynthetic rate (Pmax) but influenced other model parameters including quantum yield (α), convexity (θ), dark respiration (Rd), light compensation point (LCP), and saturated light point (LSP). Specifically, the mean Pmax of five precipitation treatments was 17.6 μmol CO2 m−2 s−1, and the ambient treatment tended to have a higher Pmax. The +33% treatment had the highest α, and the ambient treatment had lower θ and LCP, higher Rd, and relatively lower LSP. Furthermore, precipitation significantly influenced all model parameters of CO2 response. The ambient treatment had the highest Pmax, largest α, and lowest θ, Rd, and CO2 compensation point LCP. Overall, this study improved our understanding of how switchgrass leaf photosynthesis responds to diverse environmental factors, providing valuable insights for accurately modeling switchgrass ecophysiology and productivity. Limited research exists on how precipitation changes affect switchgrass photosynthesis and its responses to light and CO2. To address this gap, we conducted a field experiment with five precipitation treatments (−50%, −33%, +0%, +33%, and +50% of ambient levels) to investigate switchgrass leaf photosynthesis under varying CO2 concentrations and light levels during 2020 and 2021. Additionally, we assessed four light and CO2 response models to identify the most suitable one. This study enhances our understanding of switchgrass photosynthesis in diverse environmental conditions, offering valuable insights for accurately modeling switchgrass ecophysiology and productivity.

Premise Controlling light flux density during carbon dioxide assimilation measurements is essential in photosynthesis research. Commercial lamps are expensive and are based on monochromatic light‐emitting diodes (LEDs), which deviate significantly in their spectral distribution compared to sunlight. Methods and Results Using LED‐emitted white light with a color temperature similar to sunlight, we developed a cost‐effective lamp compatible with the LI‐6800 Portable Photosynthesis System. When coupled with customized software, the lamp can be controlled via the LI‐6800 console by a user or Python scripts. Testing and calibration show that the lamp meets the quality needed to estimate photosynthesis parameters. Conclusions The lamp can be built using a basic electronics lab and a 3D printer. Calibration instructions are supplied and only require equipment commonly available at plant science laboratories. The lamp is a cost‐effective alternative to perform photosynthesis research coupled with the popular LI‐6800 photosynthesis measuring system. Resumen Premisa Controlar la densidad del flujo luminoso durante las mediciones de asimilación de dióxido de carbono es esencial para la investigación en fotosíntesis. Las lámparas comerciales son costosas y se basan en diodos emisores de luz (LED) monocromáticos, que se desvían significativamente en su distribución espectral en comparación con la luz solar. Métodos y Resultados Utilizando luz blanca emitida por un LED con una temperatura de color similar a la luz solar, desarrollamos una lámpara accesible y compatible con el Sistema de Fotosíntesis Portátil LI‐6800. Cuando se combina con software personalizado, la lámpara puede ser controlada a través de la consola del LI‐6800, por un usuario o mediante código de Python. Las pruebas y calibraciones demuestran que la lámpara cumple con la calidad necesaria para estimar parámetros de fotosíntesis. Conclusiones La lámpara puede ser construida utilizando un laboratorio básico de electrónica y una impresora 3D. Se proporcionan instrucciones de calibración que solo requieren equipo comúnmente disponible en laboratorios de ciencias vegetales. La lámpara es una alternativa rentable para realizar investigación en fotosíntesis junto con el popular sistema de medición de fotosíntesis LI‐6800.

LaTiO2N photocatalysts are attractive because they are responsive to visible light up to a wavelength of 600 nm. However, during the nitridation process to produce LaTiO2N from La2Ti2O7, the introduction of defects can cause a reduction in the hydrogen evolution activity of the photocatalyst, which limits its application to overall water splitting. Such defects can arise due to the change in crystal structure and the occurrence of overnitridation. Herein, it is demonstrated that nitridation of a metastable La–Ti oxide obtained by flame spray pyrolysis (FSP) can suppress the formation of such defects. A detailed analysis of the transition pathway during nitridation reveals that a combination of FSP and Al doping is essential for suppressing mesopore formation resulting from the volume change and Ti4+ reduction due to overnitridation. This leads to an increase in the apparent quantum yield for Al‐doped LaTiO2N during the visible‐light‐driven hydrogen evolution reaction, compared to that for undoped LaTiO2N. In the present study, insights are provided into the importance of minimizing structural changes during the synthesis of oxynitride photocatalysts by designing isostructural precursors for enhanced photocatalytic activity. Flame spray pyrolysis enables the synthesis of La–Ti oxides with a simple perovskite‐type structure, and Al doping promotes the formation of the simple perovskite‐type La–Ti oxides. The Al‐doped LaTiO2N obtained by nitridation has a reduced defect concentration due to suppressed structural change, which contributes to the improvement of hydrogen evolution activity.

This study presents a pioneering investigation of hybrid bismuth‐tin (BiSn) liquid metal particles for photothermal applications. It is shown that the intrinsic core–shell structure of liquid metal particles can be instrumentalized to combine the broadband absorption characteristics of defect‐rich nano‐oxides and the high light‐to‐heat conversion efficiency of metallic particles. Even though bismuth or tin does not show any photothermal characteristics alone, optimization of the core–shell structure of BiSn particles leads to the discovery of novel, highly efficient photothermal materials. Particles with optimized structures can absorb 85% of broadband light and achieve over 90% photothermal conversion efficiency. It is demonstrated that these particles can be used as a solar absorber for solar water evaporation systems owing to their broadband absorption capability and become a non‐carbon alternative enabling scalable applications. We also showcased their use in polymer actuators in which a near‐infrared (NIR) response stems from their oxide shell, and fast heating/cooling rates achieved by the metal core enable rapid response and local movement. These findings underscore the potential of BiSn liquid metal‐derived core–shell particles for diverse applications, capitalizing on their outstanding photothermal properties as well as their facile and scalable synthesis conditions. This study introduces the liquid metal‐derived bismuth‐tin (BiSn) core–shell particles as novel photothermal materials. The unique structure combines the broadband absorption of a defect‐rich SnO shell with the high heat conversion of BiSn core. These particles outperform with their remarkable photothermal conversion efficiencies and fast responsiveness, thus opening the way for breakthroughs in solar energy systems and NIR‐sensitive technologies.

Background The modification effect of leaching fraction (LF) on the physiological responses of plants to irrigation water salinity (EC iw ) remains unknown. Here, leaf gas exchange, photosynthetic light–response and CO 2 –response curves, and total carbon (C) and nitrogen (N) accumulation in hot pepper leaves were investigated under three EC iw levels (0.9, 4.7 and 7.0 dS m − 1 ) and two LFs treatments (0.17 and 0.29). Results Leaf stomatal conductance was more sensitive to EC iw than the net photosynthesis rate, leading to higher intrinsic water use efficiency (WUE) in higher EC iw , whereas the LF did not affect the intrinsic WUE. Carbon isotope discrimination was inhibited by EC iw , but was not affected by LF. EC iw reduced the carboxylation efficiency, photosynthetic capacity, photorespiration rate, apparent quantum yield of CO 2 and irradiance–saturated rate of gross photosynthesis; however, LF did not influence any of these responses. Total C and N accumulation in plants leaves was markedly increased with either decreasing EC iw or increasing LF. Conclusions The present study shows that higher EC iw depressed leaf gas exchange, photosynthesis capacity and total C and N accumulation in leaves, but enhanced intrinsic WUE. Somewhat surprisingly, higher LF did not affect the intrinsic WUE but enhanced the total C and N accumulation in leaves.

1. In this paper we determine whether interspecific variation in entire photosynthetic light-response curves correlates with the leaf traits of the 'leaf economics spectrum' (LES) and the degree to which such traits can predict interspecific variation in light-response curves. This question is important because light-response curves are included in many ecosystem models of plant productivity and gas exchange but such models do not take into account interspecific variation in such response curves. 2. We answer this question using original observations from 260 leaves from 130 plants of 65 different species of herbaceous (25) and woody (40) angiosperms. Herbs were grown in growth chambers and gas exchange measurements were taken in the laboratory. Leaf traits and gas exchange measurements for the woody plants were taken in the field. Leaf traits measured were leaf mass per area (LMA), leaf nitrogen concentration (N) and leaf chlorophyll concentration (Chl). We fitted the Mitscherlich and Michaelis-Menten equations of the light-response curve separately for each leaf. This gave (for the Mitscherlich equation) the light compensation point (φ), the quantum yield at the light compensation point (q(φ)), and maximum net photosynthesis (Amax) and (for the Michaelis-Menten equation), the maximum gross photosynthesis (Gmax), the half saturation coefficient (k) and the dark respiration rate (Rd). 3. Amax and q(φ) were highly correlated with the measured leaf traits but φ was not. All three parameters of the Michaelis-Menten equations were correlated with the leaf traits. Allometric equations predicting the parameters of the Mitscherlich and Michaelis-Menten equations by N and LMA are presented. Replacing the leaf-specific parameters by these general allometric equations based on leaf N and LMA gave good predictions of net photosynthetic rates over the entire range of irradiance (r = 0·79-0·98) but with a downward bias for the herbs when the most general allometric equations are used. 4. These results further extend the generality of the LES and may allow available information from large leaf trait data bases to be incorporated into ecosystem models of plant growth and gas exchange.

Providing an adequate quantity and quality of food for the escalating human population under changing climatic conditions is currently a great challenge. In outdoor cultures, sunlight provides energy (through photosynthesis) for photosynthetic organisms. They also use light quality to sense and respond to their environment. To increase the production capacity, controlled growing systems using artificial lighting have been taken into consideration. Recent development of light-emitting diode (LED) technologies presents an enormous potential for improving plant growth and making systems more sustainable. This review uses selected examples to show how LED can mimic natural light to ensure the growth and development of photosynthetic organisms, and how changes in intensity and wavelength can manipulate the plant metabolism with the aim to produce functionalized foods.

Aspergillus nidulans senses red and blue-light and employs a phytochrome and a Neurospora crassa White Collar (WC) homologous system for light perception and transmits this information into developmental decisions. Under light conditions it undergoes asexual development and in the dark it develops sexually. The phytochrome FphA consists of a light sensory domain and a signal output domain, consisting of a histidine kinase and a response regulator domain. Previously it was shown that the phytochrome FphA directly interacts with the WC-2 homologue, LreB and another regulator, VeA. In this paper we mapped the interaction of FphA with LreB to the histidine kinase and the response regulator domain at the C-terminus in vivo using the bimolecular fluorescence complementation assay and in vitro by co-immunoprecipitation. In comparison, VeA interacted with FphA only at the histidine kinase domain. We present evidence that VeA occurs as a phosphorylated and a non-phosphorylated form in the cell. The phosphorylation status of the protein was independent of the light receptors FphA, LreB and the WC-1 homologue LreA.

Aim: Extrapolation of tower CO2 fluxes will be greatly facilitated if robust relationships between flux components and remotely sensed factors are established. Long-term measurements at five Northern Great Plains locations were used to obtain relationships between CO2 fluxes and photosynthetically active radiation (Q), other on-site factors, and Normalized Difference Vegetation Index (NDVI) from the SPOT VEGETATION data set. Location: CO2 flux data from the following stations and years were analysed: Lethbridge, Alberta 1998-2001; Fort Peck, MT 2000, 2002; Miles City, MT 2000-01; Mandan, ND 1999-2001; and Cheyenne, WY 1997-98. Results: Analyses based on light-response functions allowed partitioning net CO2 flux (F) into gross primary productivity (Pg) and ecosystem respiration (Re). Weekly averages of daytime respiration, γday, estimated from light responses were closely correlated with weekly averages of measured night-time respiration, γnight (R2 0.64 to 0.95). Daytime respiration tended to be higher than night-time respiration, and regressions of γday on γnight for all sites were different from 1 : 1 relationships. Over 13 site-years, gross primary production varied from 459 to 2491 g CO2 m-2 year-1, ecosystem respiration from 996 to 1881 g CO2 m-2 year-1, and net ecosystem exchange from -537 (source) to +610 g CO2 m-2 year-1 (sink). Maximum daily ecological light-use efficiencies, epsilon d,max = Pg/Q, were in the range 0.014 to 0.032 mol CO2 (mol incident quanta)-1. Main conclusions: Ten-day average Pg was significantly more highly correlated with NDVI than 10-day average daytime flux, Pd (R2 = 0.46 to 0.77 for Pg-NDVI and 0.05 to 0.58 for Pd-NDVI relationships). Ten-day average Re was also positively correlated with NDVI, with R2 values from 0.57 to 0.77. Patterns of the relationships of Pg and Re with NDVI and other factors indicate possibilities for establishing multivariate functions allowing scaling-up local fluxes to larger areas using GIS data, temporal NDVI, and other factors.