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Automated and intelligent light supplement systems have been widely applied in greenhouses in recent years. Among them, the light environment regulation model can be the core content of the system. However, the existing models cannot consider the comprehensive influence of light quality and light intensity, as well as the double optimization of net photosynthetic rate and light use efficiency. In this study, a collaborative control method was proposed for the light quality and light intensity using multi-objective optimization, particularly for the efficient supplemental illumination of cucumbers in greenhouses. Firstly, a multi-factor coupled photosynthetic experiment was designed to obtain the net photosynthetic rate of cucumber leaves. The model of net photosynthetic rate was then established using support vector regression with temperature, carbon dioxide concentration, photosynthetic photon flux density and light quality ratio as the input, while the net photosynthetic rate as the output. Furthermore, the light use efficiency was calculated at the leaf scale, according to the definition. Secondly, a multi-objective optimization model was constructed with the light use efficiency and net photosynthetic rate as optimization targets, while the light quality and light intensity as control variables. The non-inferior solution set was solved using the multi-objective particle swarm optimization. Technique for order preference by similarity to ideal solution was used to select the control single point of light quality and light intensity, in order to narrow the regulation interval for the less subjectivity of manual selection. Finally, the red and blue light demand were calculated according to the multiple relationship of light quality and light intensity. And then the red and blue light models were fitted by support vector regression with the temperature and carbon dioxide concentration as the input. The control experiments were carried out to compare with the fixed light quality supplement and the photosynthetic maximum supplement, in order to verify the superiority. The theoretical verification experiment showed that the net photosynthetic rate decreased by 21.39%, whereas, the light demand decreased by 59.40%, compared with the photosynthetic maximum supplement. The net photosynthetic rate increased by 3.66% and 9.69%, respectively, compared with the fixed light quality of 0.5 and 0.8. The practical verification experiment was also carried out to further verify the energy efficiency. The results showed that the physiological indicators were better than the fixed light quality supplement under similar power consumption, indicating significant differences in the stem diameter, dry weight and strong seedling index. There was no significant difference in physiological indicators, but the power consumption decreased by 27.43%, compared with the photosynthetic maximum supplement. The consumption of light and electrical energy resources was effectively saved to keep the physiological indicators almost unchanged. The model construction can be expected to serve as the new perspective for the greenhouse light supplement. This study can provide a new light supplement strategy for the facility's agricultural regulation and the efficient utilization of agricultural production resources. [ABSTRACT FROM AUTHOR]

[Objective] Resource use efficiencies are key indicators for acclimation of a plant to environmental conditions, which is one of the main concerns in the area of climate change ecology. The controlling machanisms of light use efficiency (LUE) and water use efficiency (WUE) of understory shrub species in response to environmental changes remain unclear. Met hods] The seasonal variation in LUE and WUE and its envrionmental controls for an understory shrub, Spiraea salicifolia, in a typical deciduous forest in Songshan of Beijing were examined through in-situ measurements of leaf photosynthetic parameters and environmental factors in the full leafing stage from June to September 201 9. Results] LUE and WUE showed obvious seasonal variations, averaging ().03 mol/mol and 8.32/imol/mmol, respectively. Photosynthetically active radiation (PAR) and air temperature (Ta) were the main factors controlling the LUE, showing an exponential and a linear negative relationship, respectively. PAR and vapor preassure difference (VPD) were the main factors controlling WUE, with which both showed the linear negative relationship. The VPT) limited transpiration by affecting stomatai conductance (g5), which affected WUE. The seasonal variation in both LUE and WUE was not affected by soil water content (SWC). There was con ver gen cy between LUE and WUE in response to environmental factors. Conclusion], Ta and VPD, rather than SWC: were the main limiting factors for resource use efficiencies of the shrub Spiraea salicifolia in understory of the research area. The shrub Spiraea salicifolia in understory showed a resource conservation strategy under the condition of limited resources, specifically, under the condition of limited light, the shrub Spiraea salicifolia in understory maximized the use of light energy for photosynthesis and thus had a high light energy utilization efficiency. [ABSTRACT FROM AUTHOR]

Light use efficiency (LUE) is a key parameter connecting light absorption and carbon fixation and understanding the relationship between fluorescence and photosynthesis. Based on the absorbed energy dissipation pathways, LUE can be divided into light use efficiency of photosynthetic (LUEp) and light use efficiency of fluorescence (LUEf). The relationship between LUEp and LUEf of poplar and cork oak and the differences between species were explored in this study, to better understand the mechanism links between solar-induced chlorophyll fluorescence (SIF) and gross primary productivity (GPP) in deciduous broadleaf forests. In this study, the poplar (Populus alba x Populus gllandulosa) and cork oak (Quercus variabilis BI.) seedlings were used as the objects to measure the divergences in SIF and net photosynthetic rate (Pn) under the same soil moisture and nutrient conditions, to explore the responses of LUEp/LUEf to photosynthetically active radiation (PAR). The results showed that, (1) SIF was driven by incident PAR, SIF and PAR were significantly positively correlated. The coefficient of determination (R²) of poplar and cork oak were 0.965 and 0.973, respectively, and LUEf was higher in poplar. Pn gradually increased with increasing PAR. The light saturation point (LSP) of poplar was significantly higher than that of cork oak, which were 998.59 and 674 μmolCO2·m-2·s-1, respectively. (2) Pn first increased with the increasing SIF, and then the Pn of poplar was gradually saturated, while that of cork oak continued to slowly increase. (3) LUEp and LUEf showed significant negative linear correlation, and LUEp/LUEf decreased exponentially with increasing PAR, there was no significant difference in the change pattern and amplitude between tree species. During the daytime, with the increase of PAR, LUEf changed slightly, while LUEp decreased significantly, and the proportion of light energy allocation to carbon assimilation decreased. Therefore, Pn saturated under high light intensity, SIF and GPP showed exponential correlation in intraday scale, and the exponential relationship was consistent across tree species. [ABSTRACT FROM AUTHOR]

The Photochemical Reflectance Index (PRI) has great potential for estimating Light Use Efficiency (LUE). Mixed canopy structure under different lighting and observation geometries can affect the remote sensing observations of the PRI, leading to some errors in estimating vegetation photosynthesis. Multi-angle observation is an effective method for resolving differences in observation geometry. Fitting multi-angle observations to a Bidirectional Reflectance Distribution Function (BRDF) can normalize PRI to a common solar-observation target position, resulting in a significant increase in the correlation between canopy PRI and LUE, and has been well used in forest ecosystems. However, studies on the standardization of multi-angle PRI by BRDF models on crop canopies are still not well developed. To investigate the ability of the improved PRI by BRDF model to estimate the LUE of rice canopies, this paper used multi-angle rice canopy reflection data and contemporaneous flux data from the National Meteorological Station in Shouxian, Anhui, a semi-empirical, kernel-driven BRDF model was used to standardize the multi-angle PRI for each half-hourly from 09:00 to 15:00 during the observation period. This paper explored the BRDF model simulated PRI values and the model parameter characteristics under different physiological and non-physiological conditions. The results showed that the BRDF model fitting was poorly at low Clearness Index (CI) and became better as the CI increased, with the best performance at CI = 0.9 (R² = 0.41). The parameters of the BRDF model are influenced by light conditions and vegetation status, where the isotropic weights (ki) correlated well with LUE for different CI ranges (linear regression coefficients R² > 0.3 for all CI ranges), with the best correlation at 0.6 ≤ CI < 0.7 (R² = 0.63); the daily variation of volume scattering weights (kv) showed a "U-shape" during the observation period, which was consistent with the daily variation of LUE. After correction by the BRDF model, the R² of the exponential regression between PRI and LUE increased from 0.46 (P<0.05) to 0.8 (P<0.01). Compared with the PRI from simple multi-angle remote sensing observations, the angular correction by the BRDF model improved the ability of PRI estimating LUE; this study also demonstrated the feasibility that multi-angle canopy spectral observations can use the BRDF model to improve vegetation indices tracking plant physiological activity. This study has reference value for processing multi-angle vegetation remote sensing observation data and for remote sensing estimation of physiological activities related to photosynthesis in regional vegetation. The BRDF model can be practiced in multi-angle satellite observations to achieve the monitoring of photosynthetic capacity in a large area of farming area. Subsequent experiments in different farming areas will be carried out to calibrate the wider band spectral observations available from satellite data to achieve a comprehensive understanding of the correlation between LUE variation and spectral reflectance in lutein and fluorescence-related absorption characteristics, and to provide some reference for the calibration of parameters in agricultural areas in the global productivity model. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Crop yield is dependent on crop biomass and harvest index. The increases in crop yield in the past benefit mainly from the increase in harvest index, the increase in biomass has been small. Light use efficiency is a bottleneck to further increase crop biomass and yield. Wheat (Triticum aestivum L.) is a widely cultivated cereal crop globally, providing energy to up to 20% of the world's population. It is necessary to reveal the intrinsic mechanism and extrinsic factors affecting the light use efficiency of wheat, which is important for improving the utilization efficiency of crop resources and productivity. Achieving high light efficient production of wheat under limited natural resources has become the focus of study at home and abroad. Here, the definition of light use efficiency, the main processes, the characteristics of light use efficiency in wheat were summarized from relevant references, showing a more significant potential to improve light use efficiency. The effects of external factors such as light, water, nutrient and tillage system on wheat light use efficiency were summarized. The results indicated that light use efficiency was regulated by internal factors such as photosynthesis at the individual plant scale, and by abiotic factors such as temperature, precipitation and tillage practices at the field scale. The current problems and the adaptation mechanism of wheat in the context of climate change were also analyzed, aiming to provide a theoretical reference for the practical research of the high light use efficiency of wheat. Future research on light use efficiency can use high-throughput phenotypic observation techniques combined with molecular markers to design ideotypes in the target environment, providing scientific evidence for crop breeding. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Taking two rice cultivars (Liangyoupeijiu and Wuxiangjing 14) with different plant types as test materials, a 2-year field experiment was conducted to study the relationships of rice canopy photosynthetically active radiation (PAR) interception and light use efficiency to grain yield under three planting densities and five nitrogen (N) application rates. From tillering to maturing stage, the average PAR reflectance in all treatments was 3. 45%. The ratio of reflected PAR to the total loss of PAR from tillering to heading stage was 10. 90%, which was significantly lower than that (22. 06%) from heading to maturiting stage. The PAR conversion efficiency from tillering to maturing stage decreased with increasing planting density but increased with increasing nitrogen rate, and the conversion efficiency was significantly higher from tillering to heading than from heading to maturing stage. The PAR use efficiency from tillering to maturing stage increased with the increase of planting density and nitrogen application rate, and the average PAR use efficiency of Liangyou-peijiu (1. 83 g·MJ-1) was significantly higher than that of Wuxiangjing 14 (1. 42 g·MJ-1). Due to the longer growth period of Wuxiangjing 14, its incident PAR and intercepted PAR under midium and high planting densities were higher, as compared with Liangyoupeijiu. The grain yield was significantly positively correlated with the canopy PAR interceptance and use efficiency at different growth stages, but less correlated with the PAR conversion efficiency. To increase the canopy PAR use efficiency and conversion efficiency on the basis of maintaining higher PAR interception rate could be an effective way to increase rice yield. [ABSTRACT FROM AUTHOR]

We examined the differences of maximum light use efficiency (LUE max ), most effective light intensity (PAR e ), light compensation point (LCP) and light saturation point (LSP) in diffe-rent vertical positions and different phenological periods of tree crown in Larix principis-rupprechtii plantation in Saihanba Mechanical Forest Farm of Hebei Province. We analyzed the main influencing factors for all the variables. The results showed that LUE max increased with the increasing crown depth, and that PAR e , LCP and LSP decreased with the increasing crown depth. Such a result indicated that upper crown had higher utilization efficiency to strong light and that the lower crown was more efficient to adapt to weak light environment. During the leaf development in the growth period, the LUE max approximately increased except in July, while the changes of other photosynthe-tic-light factors showed a tendency of unimodal curve. Environmental factors were significantly correlated with the indices of light response, mainly due to the stress reaction of leaf stomata to surrounding environment. Understanding the spatial and seasonal changes of the photosynthetic-light indicators was important for formulating scientific management measures, optimizing stand structure, improving local microenvironment and maximizing forest productivity.

A nitrogen management experiment with three nitrogen levels (0, 120, and 180 kg·hm -2 , namely N 0 , N 120 , N 180 ) and three nitrogen allocation modes (N A : base fertilizer 100%; N B : base fertilizer 70% + seedling fertilizer 30%; N C : base fertilizer 60% + jointing fertilizer 40%) was conducted at four sites (Chongqing, Renshou, Guanghan and Xichang) during two consecutive years, the SPAD value, canopy photosynthetic rate (CAP), photosynthetically active radia-tion (PAR) interception efficiency and grain yield were determined, and the nitrogen use efficiency and PAR use efficiency were calculated. The results showed that the SPAD of upper-most three leaves, CAP, PAR interception efficiency and grain yield were promoted with increasing nitrogen fertilizer, but nitrogen fertilizer use efficiency, productivity efficiency, uptake efficiency and use efficiency were decreased. The promoting effects of nitrogen fertilizer postponing were different among nitrogen levels, with the highest SPAD in N 180 treatment and the highest CAP in N 120 treatment. The light use efficiency of different nitrogen fertilization patterns differed among four sites. Furthermore, nitrogenous fertilizer postponing significantly increased nitrogen agricultural fertilizer use efficiency, productivity efficiency, uptake efficiency and apparent nitrogen recovery efficiency, but declined nitrogen use efficiency, and the performance of N C was better than N B. Among different sites, Guanghan had the highest SPAD, CAP, PAR interception efficiency and grain yield, Xichang had higher SPAD and nitrogen use efficiency, lower CAP and PAR use efficiency, Chongqing and Renshou had the lowest SPAD, light use efficiency, nitrogen use efficiency and grain yield. Biomass had significant positive relationships with grain yield, CPA, SPAD, and PAR interception efficiency. Therefore, the increase of nitrogen fertilizer could promote yield at all sites, and nitrogenous fertilizer postponing could further optimize grain yield component and improve nitrogen and light use effi-ciency. But the effects depended on the years and sites, thus a target nitrogen management mode should be site-specifically made.

In the Forestry Experimental Station of Shandong Agricultural University, we determined the photosynthetic physiological and biochemical indexes including photosynthetic parameters, chlorophyll fluorescence, and chlorophyll content of one-year-old poplar seedlings under different doses (0.17, 0.33, 0.67, 1.00, 1.33 and 1.67 g·kg -1 ) of Chaetomium globosmn ND35 fungus fertilizer treatment to study the effects of fungus fertilizer on photosynthesis of poplar in replanted soil. The results showed that with the increase of fungus fertilizer dose, the chlorophyll content of poplar lea-ves (Chl) showed an increasing trend, while the physiological indexes such as electron transport rate (ETR), net photosynthetic rate (P n ), quantum efficiency (Φ), nitrate reductase (NR) activity and root vigor showed an increasing first and then decreasing trend. Meanwhile, the heat dissipation that depended on xanthophyll cycle decreased and non-photochemical quenching (NPQ) increased first and then decreased. When the dose of C. globosmn ND35 fungus fertilizer was 0.67 g·kg -1 or 1.00 g·kg -1 , excess light energy of photosynthetic apparatus was reduced, and photosynthetic apparatus distributed more light energy to the direction of photochemical reactions, which improved the energy use efficiency. Applying an appropriate amount (0.67-1.00 g·kg -1 ) of C. globosmn ND35 fungus fertilizer could improve root physiological activity and light use ability of poplar leaves, which was conducive to the improvement of operating states of photosynthetic apparatus, and then increased the photosynthetic efficiency of the poplar leaves.