Seedling quality is a prerequisite for successful field performance and therefore influences crop yields. Temperature and illumination are two major factors affecting seedling quality during nursery propagation. Subop...Seedling quality is a prerequisite for successful field performance and therefore influences crop yields. Temperature and illumination are two major factors affecting seedling quality during nursery propagation. Suboptimal temperature or light of nurseries generally result in leggy or weak seedlings and great economic loss. However, production of healthy seedlings is challenging due to the lack of knowledge in systemic management of nursery environments. In this study, we have established simulation models to predict how temperature and illumination coordinately influence the growth of tomato and cabbage seedlings. Specifically, correlation between seedling quality characteristics(root-shoot ratio, G value(growth function: defined as ratio of whole plant dry weight to days of seedling), healthy indexes) and TEP(thermal effectiveness and photosynthetically active radiation) were explored to establish the models, which were validated with independent test data. Our results suggested that the curve of healthy index 1(HI1) and TEP fitted well with high coefficient of determination(R2) in both species, indicating that the model is highly reliable. The HI1 simulation models for tomato and cabbage are HI1=0.0009e0.0308TEP-0.0015 and HI1= 0.0003e0.0671TEP-0.0003, respectively, which can be used for predicting vigors of tomato and cabbage seedlings grown under different temperature and light conditions.展开更多
Since trees and plants can absorb CO2, forests are widely regarded as a carbon sink that may control the amount of CO2 in the atmosphere. The CO2 uptake rate of plants is affected by the plant species and environmenta...Since trees and plants can absorb CO2, forests are widely regarded as a carbon sink that may control the amount of CO2 in the atmosphere. The CO2 uptake rate of plants is affected by the plant species and environmental conditions such as photosynthetically active radiation (PAR), temperature, water and nutrient contents. PAR is the most immediate environmental control on photosynthesis while air temperature affects both photorespiration and dark respiration. In the natural condition, PAR and temperature play an important role in net CO2 uptake. The effects of PAR and air temperature on the CO2 uptake of Pterocarpus macrocarpus grown in a natural habitat were studied in the present work. Due to many uncontrollable factors, a simple rectangular hyperbola could not represent the measured data. The data were divided into groups of 2oC intervals; CO2 uptake in each group may then be related to PAR by a rectangular hyperbola function. Using the obtained functions, the effect of PAR was removed from the original data. The PAR-independent CO2 uptake was then related to air temperature. Finally, the effects of PAR (I) and air temperature (Ta) on the CO2 uptake rate (A) were combined as: (-0.0575Ta2+2.6691Ta-23.264)I A= ——————————————— (-0.00766Ta2+0.40666Ta-3.99924) (-4.8794Ta2+227.13Ta-2456.9)+I展开更多
By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of thre...By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.展开更多
A long-term dataset of photosynthetically active radiation （Qp） is reconstructed from a broadband global solar radiation （Rs） dataset through an all-weather reconstruction model. This method is based on four years...A long-term dataset of photosynthetically active radiation （Qp） is reconstructed from a broadband global solar radiation （Rs） dataset through an all-weather reconstruction model. This method is based on four years＇ worth of data collected in Beijing. Observation data of Rs and Qp from 2005-2008 are used to investigate the temporal variability of Qp and its dependence on the clearness index and solar zenith angle. A simple and effcient all-weather empirically derived reconstruction model is proposed to reconstruct Qp from Rs. This reconstruction method is found to estimate instantaneous Qp with high accuracy. The annual mean of the daily values of Qp during the period 1958-2005 period is 25.06 mol m-2 d-1. The magnitude of the long-term trend for the annual averaged Qp is presented （-0.19 mol m-2 yr-1 from 1958-1997 and -0.12 mol m-2 yr-1 from 1958-2005）. The trend in Qp exhibits sharp decreases in the spring and summer and more gentle decreases in the autumn and winter.展开更多
Photosynthetically active radiation （PAR） is an important input parameter for estimating plant produc- tivity due to its key role in the growth and development of plants. However, a worldwide routine network for sys...Photosynthetically active radiation （PAR） is an important input parameter for estimating plant produc- tivity due to its key role in the growth and development of plants. However, a worldwide routine network for sys- tematic PAR measurements is not yet established, and PAR is often calculated as a constant fraction of total solar radiation （SR）. Although the ratio of PAR to SR （PAR/SR） has been reported from many places, few studies have been performed for dry regions. The present study was therefore carried out in an arid region of Mongolia to obtain PAP-JSR and examine its dependency on sky clearness （the clearness index）, water vapor in the atmosphere and aeolian dust. Continuous measurements of PAR and SR were taken every one second using quantum and pyranometer sensors, respectively, and the readings were averaged and recorded at intervals of 30 minutes for a period of 12 months. The lowest monthly mean daily PAR/SR occurred in April （0.420）, while the highest ratio was observed in July （0.459）. Mean daily PAR/SR during plant growing season （May-August） was estimated to be 0.442, which could be useful for modeling plant productivity in the study area. The annual mean daily PAR/SR （0.435） was lower than the values reported in many previous studies. This difference could be explained with the regional variation in climate： i.e. drier climatic condition in the study area. PAR/SR was negatively correlated with the clearness index （r= -0.36, P〈0.001）, but positively with atmospheric water vapor pressure （r=0.47, P〈0.001）. The average PAR/SR was significantly lower （P=0.02） on the dusty days compared to the non-dust days. Water vapor in the atmosphere was shown to be the strongest factor in the variation of PAR/SR. This is the first study examining PAR/SR under a semi-arid condition in Mongolia.展开更多
Measurement of photosynthetically active radiation (PAR) incident on photosynthetic organisms is a crucial measurement for understanding how organisms respond to various light conditions, and for calculating electron ...Measurement of photosynthetically active radiation (PAR) incident on photosynthetic organisms is a crucial measurement for understanding how organisms respond to various light conditions, and for calculating electron flow through the photosynthetic machinery. Measurements of PAR are typically performed in the region of the electromagnetic spectrum between 400 - 700 nm, which is the region of radiation that is responsible for promoting photosynthesis. Typically, to ensure that the sensor measures in this range, the implementation of long- and short-pass filters is required. Although this allows the exclusion of radiation outside of the PAR region, such filters can be expensive. Additionally, the implementation of autonomous PAR measurements requires costly commercial instruments. Here, a straight-forward, inexpensive apparatus has been designed and constructed using a sensor that can distinguish between red, green, blue and white light. The constructed apparatus was able to perform comparably to a commercial PAR sensor. Furthermore, the implementation of the device to measure PAR intensity over a three-day period shows how the apparatus can be implemented for use as a constant light monitor.展开更多
Miniature roses (Rosa sp.) and Kalanchoe blossfeldiana were grown at photon flux densities (PFD) ranging from 60 to 670 μmol·m-2·s-1 (associated with a temperature gradient from 20.0°C to 24.0°C [...Miniature roses (Rosa sp.) and Kalanchoe blossfeldiana were grown at photon flux densities (PFD) ranging from 60 to 670 μmol·m-2·s-1 (associated with a temperature gradient from 20.0°C to 24.0°C [TEMP1]) and from 50 to 370μmol·m-2-s-1 (associated with a temperature gradient from 22.5°C to 26.5°C [TEMP2]). The experiment was conducted in a greenhouse compartment at latitude 59° north in mid-winter. The daily photosynthetic active radiations (PAR) ranged from 4.3 to 48.2 and 3.6 to 26.6 mol·m-2·day-1 in the TEMP1 and TEMP2 treatments, respectively. Time until flowering in miniature roses decreased from about 50 to 35 days in the TEMP1 treatment and from 50 to 25 days in the TEMP2 treatment, when the PFD increased from 50 to 370μmol·m-2·s-1. In Kalanchoe time until flowering was decreased to the same extent (about 15 days) in both temperature treatments when PFD increased from 50 to 370 μmol·m-2·s-1. The number of flowers and the plant dry weight in miniature roses increased up to 300 – 400 μmol·m-2·s-1 PFD (21.6 - 28.8 mol·m-2 day-1 PAR), while flower stem fresh weight and plant dry weight in Kalanchoe increased up to 200 – 300 μmol·m-2·s-1 at TEMP1. Measurements of the diurnal carbon dioxide exchange rates (CER) in daylight in small plant stands of roses in summertime showed that CER was saturated at about 300 μmol·m-2·s-1 PFD at 370 μmol·mol-1 CO2 and at 400 – 500 μmol·m-2·s-1 PFD at 800 μmol·mol-1 CO2. For Kalanchoe similar results were obtained. Increasing the CO2 concentration from 370 to 800 μmol·mol-1 increased the CER in roses (48%) as well in Kalanchoe (69%). It was concluded that 15 to 20 mol·m-2·day-1 combined with about 24°C air temperature and high CO2 concentration will give a very good growth with lot of flowers within a short production time in miniature roses. For Kalanchoe 10 to 15 mol·m-2·day-1 combined with about 20°C and high CO2 produced a similar result.展开更多
In order to explore the law of photosynthetic active radiation in winter sunlight greenhouse in Panjin and serve the local facility agriculture better,based on the observed data of sunlight greenhouse microclimate and...In order to explore the law of photosynthetic active radiation in winter sunlight greenhouse in Panjin and serve the local facility agriculture better,based on the observed data of sunlight greenhouse microclimate and of the nearby weather station during winter in 2012,the methods of correlation analysis and stepwise regression analysis were adopted to study characteristics of photosynthetic active radiation in sunlight greenhouse and the ratio of photosynthetic active radiation to global radiation under different weather types during winter,and to set up forecast models of photosynthetic active radiation in sunlight greenhouse under different weather types during winter.The results showed that：（1） the daily variation of photosynthetic active radiation in sunlight greenhouse on sunny and cloudy days were both obvious,and photosynthetic active radiation in sunlight greenhouse was 1-38 W/m^2 when it＇s cloudy.（2） ηPARon typical cloudy day was the highest,on cloudy day was secondary and on sunny day was the minimum during winter;（3） the methods of stepwise regression analysis were respectively adopted to set up models of the highest daily maximum photosynthetic active radiation,the total daily photosynthetic active radiation,daily maximum global radiation,and the total daily global radiation in sunlight greenhouse associated with climate outside,the models passed the 0.01 level of significance,and fitting test had been carried out：4 factors were fitted well on sunny and cloudy day,but fitted poor on overcast day.展开更多
Hibiscus rosa-sinensis, Rosa sp. (miniature roses), Sinningia speciosa, Gerbera hybrida, Kalanchoe blossfeldiana, Hydrangea, Begonia x hiemalis, Calceolaria, Cyclamen persicum and Pelargonium domesticum were grown at ...Hibiscus rosa-sinensis, Rosa sp. (miniature roses), Sinningia speciosa, Gerbera hybrida, Kalanchoe blossfeldiana, Hydrangea, Begonia x hiemalis, Calceolaria, Cyclamen persicum and Pelargonium domesticum were grown at six photon flux densities (85, 130, 170, 215, 255 and 300 μmol·m-2·s-1, PFD) during lighting periods of 20 h·day-1 at three air temperatures (18°C, 21°C and 24°C) in midwinter at latitude 59° north. This corresponded to photosynthetic active radiations (PAR) ranging from 6.1 to 21.6 mol·m-2·day-1. Time until flowering decreased in all species except Cyclamen when the temperature increased from 18°C to 21°C, particularly at lower PFD levels. A further increase in temperature, from 21°C to 24°C, clearly decreased time until flowering in six of the ten tested species. Generally, this represented a reduction in the time until flowering between 20% and 40%. The dry weight of the plants at time of flowering increased up to 170 μmol·m-2·s-1 PFD (12.2 mol·m-2·day-1 PAR) in Hibiscus, miniature rose, Kalanchoe and Pelargonium, while the dry weight reached a maximum at 85 to 130 μmol·m-2·s-1 PFD mol·m-2·day-1 (6.1 to 9.4 mol·m-2·day-1)in the other species. Based on the present results a PAR level of 6 to 8 mol m-2·day-1 is recommended for Calceolaria and Cyclamen, of 8 to 10 mol·m-2·day-1 for Sinningia, Gerbera, Kalanchoe, Hydrangea and Begonia, of 10 to 12 mol·m-2·day-1 for Pelargonium and of 12 to 15 mol·m-2 day-1 for Hibiscus and miniature roses.展开更多
Non-photosynthetic components within a forest ecosystem account for a large proportion of the canopy but are not involved in photosynthesis.Therefore,the accuracy of gross primary production(GPP)estimates is expected ...Non-photosynthetic components within a forest ecosystem account for a large proportion of the canopy but are not involved in photosynthesis.Therefore,the accuracy of gross primary production(GPP)estimates is expected to improve by removing these components.However,their infl uence in GPP estimations has not been quantitatively evaluated for deciduous forests.Several vegetation indices have been used recently to estimate the fraction of photosynthetically active radiation absorbed by photosynthetic components(FAPAR_(green))for partitioning APAR green(photosynthetically active radiation absorbed by photosynthetic components).In this study,the enhanced vegetation index(EVI)estimated FAPAR_(green)and to separate the photosynthetically active radiation absorbed by photosynthetic components(APAR green)from total APAR observations(APAR_(total))at two deciduous forest sites.The eddy covariance-light use effi ciency(EC-LUE)algorithm was employed to evaluate the infl uence of non-photosynthetic components and to test the performance of APAR green in GPP estimation.The results show that the infl uence of non-photosynthetic components have a seasonal pattern at deciduous forest sites,large diff erences are observed with normalized root mean square error(RMSE*)values of APAR green-based GPP and APAR_(total)-based GPP between tower-based GPP during the early and end stages,while slight diff erences occurred during peak growth seasons.In addition,daily GPP estimation was significantly improved using the APAR green-based method,giving a higher coeffi cient of determination and lower normalized root mean square error against the GPP estimated by the APAR_(total)-based method.The results demonstrate the signifi cance of partitioning APAR green from APAR_(total)for accurate GPP estimation in deciduous forests.展开更多
植被吸收光合有效辐射(Absorbed Photosynthetically Active Radiation,APAR)是植被进行光合作用中实际吸收的太阳辐射量,是植被净第一性生产力的重要指标,也是生态系统的功能模型、作物生长模型、净初级生产力模型、气候模型等的重要...植被吸收光合有效辐射(Absorbed Photosynthetically Active Radiation,APAR)是植被进行光合作用中实际吸收的太阳辐射量,是植被净第一性生产力的重要指标,也是生态系统的功能模型、作物生长模型、净初级生产力模型、气候模型等的重要参数。因此高空间分辨率和精确性的植被吸收光合有效辐射对于高精度的区域生产力及光能利用率的研究具有重要意义。对CASA(Carnegie-Ames-Stanford Approach)模型进行了改进,利用30m×30m的数字高程模型(Digital Elevation Model,DEM)数据直接计算太阳辐射,从而将其作为CASA模型的输入参数。结合多源遥感数据、气象数据,研究2015-2020年江汉平原APAR的时空分布及其影响因素。顾及江汉平原的土地利用分布特点,着重分析了江汉平原农田APAR的时空特性,研究结果较好的反映了江汉平原APAR分布。实验结果表明:(1)2015-2020年APAR年总值在3.42×10^(13)MJ-3.73×10^(13)MJ之间,总体空间分布与植被类型的分布情况相符;(2)农田月均APAR值在4月、7月高于其他月份,表现出“双峰”的特征;(3)在空间分布上,水田APAR表现出明显的纬度地带性,而旱地APAR正好相反,这可能源于种植结构重心转移;(4)通过借助地理探测器,着重考虑与植被生长相关的12个因子(包括≧10℃积温、年总日照时数、年均气温、年总降雨量、农田种植结构、年散射辐射、农田施肥、土壤类型、土壤质地(砂土、粉砂土、黏土))进行分析,结果表明这12个因素对APAR空间变异性都具有很明显的影响。对CASA的改进方法可以适用于大范围高空间精度的计算。展开更多
在玉米生长期中,作了11次野外地物反射光谱的测试,测量了玉米植冠的叶面积指数。引用玉米植冠叶面积指数和它截取光合有效辐射系数(APAR)之间的理论公式和经验公式,用实测的玉米植冠的叶面积指数,计算出它吸收光合有效辐射系数,再分别...在玉米生长期中,作了11次野外地物反射光谱的测试,测量了玉米植冠的叶面积指数。引用玉米植冠叶面积指数和它截取光合有效辐射系数(APAR)之间的理论公式和经验公式,用实测的玉米植冠的叶面积指数,计算出它吸收光合有效辐射系数,再分别求出玉米植冠的 RVI、ND、PVI、GN 光谱指数和玉米植冠吸收光合有效辐射系数间的抛物线回归方程。得出的结论是,在20个回归方程中,利用 GN 光谱指数,并使用回归方程 APAR=0.2792+6.187GN-13.38GN^2来估算玉米植冠吸收光合有效辐射系数 APAR 是最可靠的。展开更多
考虑到植被可见光-近红外的光谱吸收特征与光合有效辐射吸收率(fraction of absorbed photosynthetically active radiation,FAPAR)有很好的关联,综合"高光谱曲线特征吸收峰自动识别法"与"光谱吸收特征参量化法",...考虑到植被可见光-近红外的光谱吸收特征与光合有效辐射吸收率(fraction of absorbed photosynthetically active radiation,FAPAR)有很好的关联,综合"高光谱曲线特征吸收峰自动识别法"与"光谱吸收特征参量化法",提取对FAPAR敏感的高光谱吸收特征参数,借鉴可见光-近红外植被指数的数学形式,尝试用优化组合后的可见光-近红外光谱吸收特征参数替代光谱反射率,构建新型植被指数估算植被FAPAR,并利用2014年和2015年内蒙古自治区中部与东部地区天然草地典型群落冠层实测光谱数据进行FAPAR估算建模与验证。结果表明:新型植被指数"SAI-VI"不仅有效提高了单个光谱吸收特征参数在高、低覆盖区域估算FAPAR的精度,而且相比五种与FAPAR有较好相关性的具有不同作用类型的可见光-近红外植被指数,其与FAPAR值的相关性更高(存在最大相关系数=0.801),以其为变量的指数模型预测FAPAR精度更高且稳定性较好(建模与检验的判定系数均最高且超过0.75,标准误差与平均误差系数也相应最小)。研究表明:融入可见光-近红外高光谱吸收特征的新型植被指数"SAI-VI",强化了可见光波段与近红外波段光谱吸收特征的差别,相较单一光谱吸收特征参数,在降低土壤背景影响的同时增强了对FAPAR变化的敏感度。同时,"SAI-VI"有效综合了对植被FAPAR敏感的光谱吸收特征信息,相较原始光谱反射率,能表达植被光合有效辐射吸收特征的更多细节信息,可作为植被冠层FAPAR反演的新参数,一定程度上弥补当前植被指数法估算FAPAR的不足。展开更多
A two-year field experiment was conducted to measure the effects of densification methods on photosynthesis and yield of densely planted wheat.Inter-plant and inter-row distances were used to define ratefixed pattern(...A two-year field experiment was conducted to measure the effects of densification methods on photosynthesis and yield of densely planted wheat.Inter-plant and inter-row distances were used to define ratefixed pattern(RR)and row-fixed pattern(RS)density treatments.Meanwhile,four nitrogen(N)rates(0,144,192,and 240 kg N ha-1,termed N0,N144,N192,and N240)were applied with three densities(225,292.5,and 360×10^(4)plants ha^(-1),termed D225,D292.5,and D360).The wheat canopy was clipped into three equal vertical layers(top,middle,and bottom layers),and their chlorophyll density(Ch D)and photosynthetically active radiation interception(FIPAR)were measured.Results showed that the response of Ch D and FIPAR to N rate,density,and pattern varied with different layers.N rate,density,and pattern had significant interaction effects on Ch D.The maximum values of whole-canopy Ch D in the two seasons appeared in N240 combined with D292.5 and D360 under RR,respectively.Across two growing seasons,FIPAR values of RR were higher than those of RS by 29.37%for the top layer and 5.68%for the middle layer,while lower than those of RS by 20.62%for the bottom layer on average.With a low N supply(N0),grain yield was not significantly affected by density for both patterns.At N240,increasing density significantly increased yield under RR,but D360 of RS significantly decreased yield by 3.72%and 9.00%versus D225 in two seasons,respectively.With an appropriate and sufficient N application,RR increased the yield of densely planted wheat more than RS.Additionally,the maximum yield in two seasons appeared in the combination of D360 with N144 or N192 rather than of D225 with N240 under both patterns,suggesting that dense planting combined with an appropriate N-reduction application is feasible to increase photosynthesis capacity and yield.展开更多
基金supported by the National Key Research and Development Program of China (2018YFD0201203)the Independent Innovation of Agricultural Science and Technology in Jiangsu Province, China (CX (15)1015)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘Seedling quality is a prerequisite for successful field performance and therefore influences crop yields. Temperature and illumination are two major factors affecting seedling quality during nursery propagation. Suboptimal temperature or light of nurseries generally result in leggy or weak seedlings and great economic loss. However, production of healthy seedlings is challenging due to the lack of knowledge in systemic management of nursery environments. In this study, we have established simulation models to predict how temperature and illumination coordinately influence the growth of tomato and cabbage seedlings. Specifically, correlation between seedling quality characteristics(root-shoot ratio, G value(growth function: defined as ratio of whole plant dry weight to days of seedling), healthy indexes) and TEP(thermal effectiveness and photosynthetically active radiation) were explored to establish the models, which were validated with independent test data. Our results suggested that the curve of healthy index 1(HI1) and TEP fitted well with high coefficient of determination(R2) in both species, indicating that the model is highly reliable. The HI1 simulation models for tomato and cabbage are HI1=0.0009e0.0308TEP-0.0015 and HI1= 0.0003e0.0671TEP-0.0003, respectively, which can be used for predicting vigors of tomato and cabbage seedlings grown under different temperature and light conditions.
文摘Since trees and plants can absorb CO2, forests are widely regarded as a carbon sink that may control the amount of CO2 in the atmosphere. The CO2 uptake rate of plants is affected by the plant species and environmental conditions such as photosynthetically active radiation (PAR), temperature, water and nutrient contents. PAR is the most immediate environmental control on photosynthesis while air temperature affects both photorespiration and dark respiration. In the natural condition, PAR and temperature play an important role in net CO2 uptake. The effects of PAR and air temperature on the CO2 uptake of Pterocarpus macrocarpus grown in a natural habitat were studied in the present work. Due to many uncontrollable factors, a simple rectangular hyperbola could not represent the measured data. The data were divided into groups of 2oC intervals; CO2 uptake in each group may then be related to PAR by a rectangular hyperbola function. Using the obtained functions, the effect of PAR was removed from the original data. The PAR-independent CO2 uptake was then related to air temperature. Finally, the effects of PAR (I) and air temperature (Ta) on the CO2 uptake rate (A) were combined as: (-0.0575Ta2+2.6691Ta-23.264)I A= ——————————————— (-0.00766Ta2+0.40666Ta-3.99924) (-4.8794Ta2+227.13Ta-2456.9)+I
基金supported by the National High-tech Research and Development Program of China (Grant No.2003AA212040 and No.2006AA100101)
文摘By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.
基金supported by the National Basic Research Program of China(No.2007CB407303)
文摘A long-term dataset of photosynthetically active radiation （Qp） is reconstructed from a broadband global solar radiation （Rs） dataset through an all-weather reconstruction model. This method is based on four years＇ worth of data collected in Beijing. Observation data of Rs and Qp from 2005-2008 are used to investigate the temporal variability of Qp and its dependence on the clearness index and solar zenith angle. A simple and effcient all-weather empirically derived reconstruction model is proposed to reconstruct Qp from Rs. This reconstruction method is found to estimate instantaneous Qp with high accuracy. The annual mean of the daily values of Qp during the period 1958-2005 period is 25.06 mol m-2 d-1. The magnitude of the long-term trend for the annual averaged Qp is presented （-0.19 mol m-2 yr-1 from 1958-1997 and -0.12 mol m-2 yr-1 from 1958-2005）. The trend in Qp exhibits sharp decreases in the spring and summer and more gentle decreases in the autumn and winter.
基金supported by the Global Center of Excellence for Dryland Science Program of the Japanese Society for the Promotion of Science
文摘Photosynthetically active radiation （PAR） is an important input parameter for estimating plant produc- tivity due to its key role in the growth and development of plants. However, a worldwide routine network for sys- tematic PAR measurements is not yet established, and PAR is often calculated as a constant fraction of total solar radiation （SR）. Although the ratio of PAR to SR （PAR/SR） has been reported from many places, few studies have been performed for dry regions. The present study was therefore carried out in an arid region of Mongolia to obtain PAP-JSR and examine its dependency on sky clearness （the clearness index）, water vapor in the atmosphere and aeolian dust. Continuous measurements of PAR and SR were taken every one second using quantum and pyranometer sensors, respectively, and the readings were averaged and recorded at intervals of 30 minutes for a period of 12 months. The lowest monthly mean daily PAR/SR occurred in April （0.420）, while the highest ratio was observed in July （0.459）. Mean daily PAR/SR during plant growing season （May-August） was estimated to be 0.442, which could be useful for modeling plant productivity in the study area. The annual mean daily PAR/SR （0.435） was lower than the values reported in many previous studies. This difference could be explained with the regional variation in climate： i.e. drier climatic condition in the study area. PAR/SR was negatively correlated with the clearness index （r= -0.36, P〈0.001）, but positively with atmospheric water vapor pressure （r=0.47, P〈0.001）. The average PAR/SR was significantly lower （P=0.02） on the dusty days compared to the non-dust days. Water vapor in the atmosphere was shown to be the strongest factor in the variation of PAR/SR. This is the first study examining PAR/SR under a semi-arid condition in Mongolia.
文摘Measurement of photosynthetically active radiation (PAR) incident on photosynthetic organisms is a crucial measurement for understanding how organisms respond to various light conditions, and for calculating electron flow through the photosynthetic machinery. Measurements of PAR are typically performed in the region of the electromagnetic spectrum between 400 - 700 nm, which is the region of radiation that is responsible for promoting photosynthesis. Typically, to ensure that the sensor measures in this range, the implementation of long- and short-pass filters is required. Although this allows the exclusion of radiation outside of the PAR region, such filters can be expensive. Additionally, the implementation of autonomous PAR measurements requires costly commercial instruments. Here, a straight-forward, inexpensive apparatus has been designed and constructed using a sensor that can distinguish between red, green, blue and white light. The constructed apparatus was able to perform comparably to a commercial PAR sensor. Furthermore, the implementation of the device to measure PAR intensity over a three-day period shows how the apparatus can be implemented for use as a constant light monitor.
基金This work was funded by the Agricultural bank of Norway and the Norwegian Growers Association.
文摘Miniature roses (Rosa sp.) and Kalanchoe blossfeldiana were grown at photon flux densities (PFD) ranging from 60 to 670 μmol·m-2·s-1 (associated with a temperature gradient from 20.0°C to 24.0°C [TEMP1]) and from 50 to 370μmol·m-2-s-1 (associated with a temperature gradient from 22.5°C to 26.5°C [TEMP2]). The experiment was conducted in a greenhouse compartment at latitude 59° north in mid-winter. The daily photosynthetic active radiations (PAR) ranged from 4.3 to 48.2 and 3.6 to 26.6 mol·m-2·day-1 in the TEMP1 and TEMP2 treatments, respectively. Time until flowering in miniature roses decreased from about 50 to 35 days in the TEMP1 treatment and from 50 to 25 days in the TEMP2 treatment, when the PFD increased from 50 to 370μmol·m-2·s-1. In Kalanchoe time until flowering was decreased to the same extent (about 15 days) in both temperature treatments when PFD increased from 50 to 370 μmol·m-2·s-1. The number of flowers and the plant dry weight in miniature roses increased up to 300 – 400 μmol·m-2·s-1 PFD (21.6 - 28.8 mol·m-2 day-1 PAR), while flower stem fresh weight and plant dry weight in Kalanchoe increased up to 200 – 300 μmol·m-2·s-1 at TEMP1. Measurements of the diurnal carbon dioxide exchange rates (CER) in daylight in small plant stands of roses in summertime showed that CER was saturated at about 300 μmol·m-2·s-1 PFD at 370 μmol·mol-1 CO2 and at 400 – 500 μmol·m-2·s-1 PFD at 800 μmol·mol-1 CO2. For Kalanchoe similar results were obtained. Increasing the CO2 concentration from 370 to 800 μmol·mol-1 increased the CER in roses (48%) as well in Kalanchoe (69%). It was concluded that 15 to 20 mol·m-2·day-1 combined with about 24°C air temperature and high CO2 concentration will give a very good growth with lot of flowers within a short production time in miniature roses. For Kalanchoe 10 to 15 mol·m-2·day-1 combined with about 20°C and high CO2 produced a similar result.
基金Supported by Special Program for Scientific Research in Public Service Industry"Studies on Professional Weather Report for Agricultural Production in Northeast China"(GYHY201206024)~~
文摘In order to explore the law of photosynthetic active radiation in winter sunlight greenhouse in Panjin and serve the local facility agriculture better,based on the observed data of sunlight greenhouse microclimate and of the nearby weather station during winter in 2012,the methods of correlation analysis and stepwise regression analysis were adopted to study characteristics of photosynthetic active radiation in sunlight greenhouse and the ratio of photosynthetic active radiation to global radiation under different weather types during winter,and to set up forecast models of photosynthetic active radiation in sunlight greenhouse under different weather types during winter.The results showed that：（1） the daily variation of photosynthetic active radiation in sunlight greenhouse on sunny and cloudy days were both obvious,and photosynthetic active radiation in sunlight greenhouse was 1-38 W/m^2 when it＇s cloudy.（2） ηPARon typical cloudy day was the highest,on cloudy day was secondary and on sunny day was the minimum during winter;（3） the methods of stepwise regression analysis were respectively adopted to set up models of the highest daily maximum photosynthetic active radiation,the total daily photosynthetic active radiation,daily maximum global radiation,and the total daily global radiation in sunlight greenhouse associated with climate outside,the models passed the 0.01 level of significance,and fitting test had been carried out：4 factors were fitted well on sunny and cloudy day,but fitted poor on overcast day.
基金funded by the Norwegian Research Council and the Norwegian Growers Association
文摘Hibiscus rosa-sinensis, Rosa sp. (miniature roses), Sinningia speciosa, Gerbera hybrida, Kalanchoe blossfeldiana, Hydrangea, Begonia x hiemalis, Calceolaria, Cyclamen persicum and Pelargonium domesticum were grown at six photon flux densities (85, 130, 170, 215, 255 and 300 μmol·m-2·s-1, PFD) during lighting periods of 20 h·day-1 at three air temperatures (18°C, 21°C and 24°C) in midwinter at latitude 59° north. This corresponded to photosynthetic active radiations (PAR) ranging from 6.1 to 21.6 mol·m-2·day-1. Time until flowering decreased in all species except Cyclamen when the temperature increased from 18°C to 21°C, particularly at lower PFD levels. A further increase in temperature, from 21°C to 24°C, clearly decreased time until flowering in six of the ten tested species. Generally, this represented a reduction in the time until flowering between 20% and 40%. The dry weight of the plants at time of flowering increased up to 170 μmol·m-2·s-1 PFD (12.2 mol·m-2·day-1 PAR) in Hibiscus, miniature rose, Kalanchoe and Pelargonium, while the dry weight reached a maximum at 85 to 130 μmol·m-2·s-1 PFD mol·m-2·day-1 (6.1 to 9.4 mol·m-2·day-1)in the other species. Based on the present results a PAR level of 6 to 8 mol m-2·day-1 is recommended for Calceolaria and Cyclamen, of 8 to 10 mol·m-2·day-1 for Sinningia, Gerbera, Kalanchoe, Hydrangea and Begonia, of 10 to 12 mol·m-2·day-1 for Pelargonium and of 12 to 15 mol·m-2 day-1 for Hibiscus and miniature roses.
基金funded by Innovative Research Program of the International Research Center of Big Data for Sustainable Development Goals(No.CBAS2022IRP01)the National Earth System Science Data Sharing Infrastructure(No.2005DKA32300)the National Natural Science Foundation of China(No.41825002).
文摘Non-photosynthetic components within a forest ecosystem account for a large proportion of the canopy but are not involved in photosynthesis.Therefore,the accuracy of gross primary production(GPP)estimates is expected to improve by removing these components.However,their infl uence in GPP estimations has not been quantitatively evaluated for deciduous forests.Several vegetation indices have been used recently to estimate the fraction of photosynthetically active radiation absorbed by photosynthetic components(FAPAR_(green))for partitioning APAR green(photosynthetically active radiation absorbed by photosynthetic components).In this study,the enhanced vegetation index(EVI)estimated FAPAR_(green)and to separate the photosynthetically active radiation absorbed by photosynthetic components(APAR green)from total APAR observations(APAR_(total))at two deciduous forest sites.The eddy covariance-light use effi ciency(EC-LUE)algorithm was employed to evaluate the infl uence of non-photosynthetic components and to test the performance of APAR green in GPP estimation.The results show that the infl uence of non-photosynthetic components have a seasonal pattern at deciduous forest sites,large diff erences are observed with normalized root mean square error(RMSE*)values of APAR green-based GPP and APAR_(total)-based GPP between tower-based GPP during the early and end stages,while slight diff erences occurred during peak growth seasons.In addition,daily GPP estimation was significantly improved using the APAR green-based method,giving a higher coeffi cient of determination and lower normalized root mean square error against the GPP estimated by the APAR_(total)-based method.The results demonstrate the signifi cance of partitioning APAR green from APAR_(total)for accurate GPP estimation in deciduous forests.
文摘在玉米生长期中,作了11次野外地物反射光谱的测试,测量了玉米植冠的叶面积指数。引用玉米植冠叶面积指数和它截取光合有效辐射系数(APAR)之间的理论公式和经验公式,用实测的玉米植冠的叶面积指数,计算出它吸收光合有效辐射系数,再分别求出玉米植冠的 RVI、ND、PVI、GN 光谱指数和玉米植冠吸收光合有效辐射系数间的抛物线回归方程。得出的结论是,在20个回归方程中,利用 GN 光谱指数,并使用回归方程 APAR=0.2792+6.187GN-13.38GN^2来估算玉米植冠吸收光合有效辐射系数 APAR 是最可靠的。
文摘考虑到植被可见光-近红外的光谱吸收特征与光合有效辐射吸收率(fraction of absorbed photosynthetically active radiation,FAPAR)有很好的关联,综合"高光谱曲线特征吸收峰自动识别法"与"光谱吸收特征参量化法",提取对FAPAR敏感的高光谱吸收特征参数,借鉴可见光-近红外植被指数的数学形式,尝试用优化组合后的可见光-近红外光谱吸收特征参数替代光谱反射率,构建新型植被指数估算植被FAPAR,并利用2014年和2015年内蒙古自治区中部与东部地区天然草地典型群落冠层实测光谱数据进行FAPAR估算建模与验证。结果表明:新型植被指数"SAI-VI"不仅有效提高了单个光谱吸收特征参数在高、低覆盖区域估算FAPAR的精度,而且相比五种与FAPAR有较好相关性的具有不同作用类型的可见光-近红外植被指数,其与FAPAR值的相关性更高(存在最大相关系数=0.801),以其为变量的指数模型预测FAPAR精度更高且稳定性较好(建模与检验的判定系数均最高且超过0.75,标准误差与平均误差系数也相应最小)。研究表明:融入可见光-近红外高光谱吸收特征的新型植被指数"SAI-VI",强化了可见光波段与近红外波段光谱吸收特征的差别,相较单一光谱吸收特征参数,在降低土壤背景影响的同时增强了对FAPAR变化的敏感度。同时,"SAI-VI"有效综合了对植被FAPAR敏感的光谱吸收特征信息,相较原始光谱反射率,能表达植被光合有效辐射吸收特征的更多细节信息,可作为植被冠层FAPAR反演的新参数,一定程度上弥补当前植被指数法估算FAPAR的不足。
基金supported by the National Key Research and Development Program of China(2022YFD2301402)the National Natural Science Foundation of China(32071903)+2 种基金the Jiangsu Provincial Key Technologies R&D Program of China(BE2019386)the Guidance Foundation of the Sanya Institute of Nanjing Agricultural University,China(NAUSY2D01)the Earmarked Fund for Jiangsu Agricultural Industry Technology System(JATS(2022)468,JATS(2022)168)。
文摘A two-year field experiment was conducted to measure the effects of densification methods on photosynthesis and yield of densely planted wheat.Inter-plant and inter-row distances were used to define ratefixed pattern(RR)and row-fixed pattern(RS)density treatments.Meanwhile,four nitrogen(N)rates(0,144,192,and 240 kg N ha-1,termed N0,N144,N192,and N240)were applied with three densities(225,292.5,and 360×10^(4)plants ha^(-1),termed D225,D292.5,and D360).The wheat canopy was clipped into three equal vertical layers(top,middle,and bottom layers),and their chlorophyll density(Ch D)and photosynthetically active radiation interception(FIPAR)were measured.Results showed that the response of Ch D and FIPAR to N rate,density,and pattern varied with different layers.N rate,density,and pattern had significant interaction effects on Ch D.The maximum values of whole-canopy Ch D in the two seasons appeared in N240 combined with D292.5 and D360 under RR,respectively.Across two growing seasons,FIPAR values of RR were higher than those of RS by 29.37%for the top layer and 5.68%for the middle layer,while lower than those of RS by 20.62%for the bottom layer on average.With a low N supply(N0),grain yield was not significantly affected by density for both patterns.At N240,increasing density significantly increased yield under RR,but D360 of RS significantly decreased yield by 3.72%and 9.00%versus D225 in two seasons,respectively.With an appropriate and sufficient N application,RR increased the yield of densely planted wheat more than RS.Additionally,the maximum yield in two seasons appeared in the combination of D360 with N144 or N192 rather than of D225 with N240 under both patterns,suggesting that dense planting combined with an appropriate N-reduction application is feasible to increase photosynthesis capacity and yield.
