Photosynthesis Active Radiation Research Articles

Effects of solar photovoltaic installation on microclimate and soil properties in UiTM 50MWac Solar Park, Malaysia

Combining solar photovoltaic panels with agricultural crops on the same land were recently proposed as to maximise land use. However, most researchers were based on temperate climate whereas studies in the tropics have yet to be initiated. Thus, this study investigates the microclimate properties and soil properties for potential agricultural crops to be planted. We monitored photosynthesis active radiation (PAR), light intensity (LI), air humidity (RH), air temperature (AT), and wind speed (WS) in outskirt panels, under panels and row between panels at three different locations: highest point area, moderately sloped area and lowest point area. We also sampled the soil for analyses of chemical and physical properties. We found that PAR, LI, and WS remained low beneath the panels at all locations. Interestingly, no significant difference was detected in AT at different treatments. The accumulation of organic matter, moisture content, and soil bulk densities showed similarities between different treatments irrespective of locations. Soil infertility is reflected by low pH, CEC, exchangeable bases, available phosphorus. Besides, the result showed almost no amount of carbon, sulphur and nitrogen was found. This research might be the starting point of a potential agrivoltaic system in Malaysia that will benefit both farmers and engineers.

Characteristic of Stomatal Conductance and Optimal Stomatal Behaviour in an Arid Oasis of Northwestern China

Stomatal conductance (gs), the process that governs plant carbon uptake and water loss, is fundamental to most Land Surface Models (LSMs). With global change accelerating, more attention should be paid to investigating stomatal behavior, especially in extremely arid areas. In this study, gas exchange measurements and environmental/biological variables observations during growing seasons in 2016 and 2017 were combined to investigate diurnal and seasonal characteristics of gs and the applicability of the optimal stomatal conductance model in a desert oasis vineyard. The results showed that the responses of gs to environmental factors (photosynthesis active radiation, PAR; vapor pressure deficit, VPD; and temperature, T) formed hysteresis loops in the daytime. The stomatal conductance slope, g1, a parameter in the unified stomatal optimal model, varied in different growing seasons and correlated with the soil-to-leaf hydraulic conductance (KL). These results indicated the potential bias when using a constant g1 value to simulate gs and highlighted that the water-use strategy of oasis plants might not be consistent throughout the entire growing season. Our findings further help to achieve a better understanding of stomata behavior in responding to climate change and encourage future efforts toward a more accurate parameterization of gs to improve the modeling of LSMs.

Solar Radiation Transmittance Characteristics of Textile Woven Fabrics suitable for Greenhouse covering Materials

Nowadays, greenhouse covering materials have a vital role in terms of a protective cultivation process. Many farmers use polyfilms, rigid or semi-rigid plastic panels, and glazing materials as greenhouse covering materials in the present scenario. However, these plastic covering materials are known for their high cost, short service life, and cause of harmful environment. Solar transmittance property is one of the main criteria for choosing any greenhouse covering materials. This study prepares various woven fabrics made of polyester, cotton, and polyester–cotton blend yarns. Their solar transmittance characteristic is analyzed to develop fabric and compare it with a polyethylene film already used as a greenhouse cladding material to substitute for plastic materials. The solar transmission of polyester fabric is achieved as high as 70% in the photosynthesis active radiation, suitable for a commercial greenhouse material. In addition, the polyester fabric has tensile strength and extension much higher than that of commercial plastic greenhouse material.

DE EFFECT OF CLEAR AND DEFUSE GLASS COVERING MATERIALS ON FRUIT YIELD AND ENERGY EFFICIENCY OF GREENHOUSE CUCUMBER GROWN IN HOT CLIMATE

Using proper greenhouse covering materials can provide a suitable environment for plant growth in Saudi Arabia. The effects of three different greenhouse covering materials, clear glass, polycarbonate and diffuse tempered glass were used to evaluate its effect on cucumber productivity, water and energy use efficiency. Results show that either water or light use efficiency was higher in compartments covered with diffused or clear glass than polycarbonate compartment. Inconsequence, fruit yield of cucumber plants/m2 was significantly higher (58%) in clear and diffuse glass greenhouses as opposed to polycarbonate greenhouse. In term of the effect of cultivar or plant density, no significant differences on cucumber yield were found. Using of different covering materials did affect environmental data of greenhouses. Less light was transmitted through polycarbonate cover than clear or diffuse glass. The photosynthesis active radiation (P.A.R.) was 996, 1703, 1690 mol/m2/d, while the electricity consumption was 2.97, 3.44, and 2.88 kWh under polycarbonate, clear glass, and diffuse glass, respectively. Meanwhile, diffuse glass compartment revealed 16% lower of water consumption than other covering materials. In this respect, it could be concluded that using diffuse glass, as a greenhouse cover material, has a strong positive influence on crop productivity under Saudi Arabia climate.

Response of sweet potato yield components to stakes angle and mulch type: Sweet potato cultivation in the Papua highlands

This study aims to improve the ability of sweet potato plants to obtain photosynthetic active radiation through a combination of stake angle with mulch as a reflector. The experiments were arranged in a separate plot design with three replications. The main plot consisted of Cangkuang variety with 90° stakes and Cangkuang varieties with 60° stakes. The subplots consisted of no mulch, straw mulch, white sand mulch, clear plastic mulch, and black silver plastic mulch. The results showed that the use of mulch as a reflector on both stake angle was able to increase photosynthesis active radiation by 27.84% to 34.63% compared to without mulch at 16.82%, and the optimum leaf area index at the age of 100 DAP was 3.74 to 4.45 at stake angle of 90° and 3.23 to 4.10 at stake angle of 60°. The number of tubers per plant increased and reached the highest of 3.17 and 4.50 in straw mulch, the number of marketable tubers from 51.90% to 59.23% compared to without mulch of 41.97% for stakes angle of 90° and 44.67% to 65.83% compared without mulch of 32.47% for stakes angle of 60°.

Spatio-temporal characteristics of agro-climatic indices and extreme weather events during the growing season for summer maize (Zea mays L.) in Huanghuaihai region, China.

The stability of maize production is essential to global food security. Climate factors, such as temperature, precipitation, and solar radiation, directly affect the development of maize plants and hence the final grain yield. In this study, we investigated the spatial distributions and temporal trends of agro-climatic indices and severe weather indicators during the actual growing season for summer maize in Huanghuaihai region of China. The results showed that during the growing season, accumulated effective thermal time had significantly increased. From R3 to R6, accumulated effective thermal time, effective precipitation, and photosynthesis active radiation all showed an increasing trend, with the rate of 20.3°Cday, 1.1mm, and 7.3MJm-2 per decade, respectively. From VE to R3, most of the study years showed a > 50% ratio of high-temperature days to subtotal days and > 7 consecutive days without available precipitation. During most of the study years, there were at least 0.5 thunderstorm events from V6 to VT stage in the locations of study; days with strong winds accounted for more than half the subtotal days during the V6-VT stage. And potential risk of lodging may be reduced by the decrease in days with strong wind. The results of this study could be used in optimizing agricultural management in summer maize production in order to take advantage of beneficial climatic elements while combating adverse climatic elements.

Photosynthetic mechanism of tea yield and quality affected by different habitats

To understand photosynthetic mechanism of tea yield and quality, an experiment was conducted with four different typical habitats, including three intercropping patterns (S1:Osmanthus-Tea, S2:Michelia-Tea, S3:Osmanthus-Michelia-Tea) and a control (CK) at Changsha Agricutural Observation Station of Chinese Academy of Sciences. The photosynthetic physiological and ecological characteristics of tea yield and quality were examined. The results showed that the habitats S1, S2, S3 reduced the leaf temperature (TL), photosynthesis active radiation flux (PAR), net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs), as well as the tea polyphenol content. Habitats S1, S2, S3 significantly increased leaf relative humidity (RHS), total amino-acid content of tea, and the yield and quality of tea, with a pattern of S3>S1>S2>CK. The leaves in habitats S1 and S3 could be made into high-grade green tea and famous green tea respectively. Comprehensive indicators showed that habitat S3 is an ideal intercropping pattern for high quality and high yield of tea garden.

Effects of micro-sprinkling hose irrigation with different hose lengths on soil water distribution, dry matter accumulation, and grain yield of wheat fields

To explore the optimal hose length of micro-sprinkling hose irrigation in wheat fields, a field trial taking JiMai 22 as test material was carried out in two growing seasons (2015-2016 and 2016-2017). Three lengths of micro-sprinkling hoses with 80-mm width were used, including 60 m (T1), 80 m (T2) and 100 m (T3). The length of trial plot was equal to the hose length. The trial plots were divided to different sample sections every 20-m length along the irrigation direction, which were named as A, B, C, D and E sections, respectively, to examine the effects of micro-sprinkling hose irrigations with different hose lengths on soil water distribution, dry matter accumulation and grain yield of wheat fields. The results showed that: 1) After irrigation at the jointing and anthesis stages in the two growing seasons, the relative soil water content in the 0-40 cm soil layer showed T1<T2<T3 in the A section, T1, T2<T3 in the B section, T1>T2, T3 in the C section and T2>T3 in the D section. The CV of relative soil water content in different sections in the same treatment showed T1<T2<T3. 2) Leaf area index and the rate of canopy photosynthesis active radiation interception at 20 d and 30 d after anthesis, and dry matter accumulation amount after anthesis and at the maturity stage had no significant differences in the A or B section among different treatments. Those indices showed T1>T2, T3 in the C section and T2>T3 in the D section. Leaf area index and rate of canopy photosynthesis active radiation interception at 20 d and 30 d after anthesis and dry matter accumulation amount after anthesis showed T1, T2>T3, and dry matter accumulation amount at the maturity stage showed T1> T2>T3. 3) In the two growing seasons, grain yield in the A and B sections had no significant differences among different treatments, and that showed T1>T2, T3 in the C section and T2>T3 in the D section. Grain yield of each treatment showed T1, T2>T3. 4) The grain yield and water use efficiency showed T1> T2>T3, and the irrigation water use efficiency showed T1>T2>T3 among different treatments in the two growing seasons. Considering grain yield and water use efficiency, hose irrigation with micro-sprinkling hose at 80-mm width and 60-m length was optimal treatment for water-saving and high-yield irrigation, and the suboptimal length was 80 m under this condition. The results could provide theoretical basis for water-saving and high-yield irrigation with micro-sprinkling hose in wheat fields in Shandong Province.

Response of Tropical Terrestrial Gross Primary Production to the Super El Niño Event in 2015

AbstractThe gross primary production (GPP) in tropical terrestrial ecosystems plays a critical role in the global carbon cycle and climate change. The strong 2015–2016 El Niño event offers a unique opportunity to investigate how GPP in the tropical terrestrial ecosystems responds to climatic forcing. This study uses two GPP products and concurrent climate data to investigate the GPP anomalies and their underlying causes. We find that both GPP products show an enhanced GPP in 2015 for the tropical terrestrial ecosystem as a whole relative to the multiyear mean of 2001–2015, and this enhancement is the net result of GPP increase in tropical forests and decrease in nonforests. We show that the increased GPP in tropical forests during the El Nino event is consistent with increased photosynthesis active radiation as a result of a reduction in clouds, while the decreased GPP in nonforests is consistent with increased water stress as a result of a reduction of precipitation and an increase of temperature. These results reveal the strong coupling of ecosystem and climate that is different in forest and nonforest ecosystems and provide a test case for carbon cycle parameterization and carbon‐climate feedback simulation in models.

ESTIMATING GROSS PRIMARY PRODUCTION IN CROPLAND WITH HIGH SPATIAL AND TEMPORAL SCALE REMOTE SENSING DATA

Abstract. Satellite remote sensing data provide spatially continuous and temporally repetitive observations of land surfaces, and they have become increasingly important for monitoring large region of vegetation photosynthetic dynamic. But remote sensing data have their limitation on spatial and temporal scale, for example, higher spatial resolution data as Landsat data have 30-m spatial resolution but 16 days revisit period, while high temporal scale data such as geostationary data have 30-minute imaging period, which has lower spatial resolution (&gt; 1 km). The objective of this study is to investigate whether combining high spatial and temporal resolution remote sensing data can improve the gross primary production (GPP) estimation accuracy in cropland. For this analysis we used three years (from 2010 to 2012) Landsat based NDVI data, MOD13 vegetation index product and Geostationary Operational Environmental Satellite (GOES) geostationary data as input parameters to estimate GPP in a small region cropland of Nebraska, US. Then we validated the remote sensing based GPP with the in-situ measurement carbon flux data. Results showed that: 1) the overall correlation between GOES visible band and in-situ measurement photosynthesis active radiation (PAR) is about 50 % (R2 = 0.52) and the European Center for Medium-Range Weather Forecasts ERA-Interim reanalysis data can explain 64 % of PAR variance (R2 = 0.64); 2) estimating GPP with Landsat 30-m spatial resolution data and ERA daily meteorology data has the highest accuracy(R2 = 0.85, RMSE &lt; 3 gC/m2/day), which has better performance than using MODIS 1-km NDVI/EVI product import; 3) using daily meteorology data as input for GPP estimation in high spatial resolution data would have higher relevance than 8-day and 16-day input. Generally speaking, using the high spatial resolution and high frequency satellite based remote sensing data can improve GPP estimation accuracy in cropland.

Highly Effective Covering Materials with Quantum Dots for Greenhouses

The article considers the application of light-converting polymer films as cover materials for the cultivation of greenhouse crops in a covered soil. We analyse the impact of increasing the level of photosynthesis-active radiation (PAR) level in a greenhouse depending on the season, latitude, the angle of the sun, duration of daylight and on other parameters. The article presents some results of growing crops in greenhouse facilities located at the latitude of Moscow region. The results include a significant shorter vegetative stage, as well, as substantial increase in yield from 30 to 100 % in comparison with the reference conditions.

Towards a more flexible representation of water stress effects in the nonlinear Jarvis model

To better interpret summer maize stomatal conductance (gs) variation under conditions of changing water status at different growth stages, three water stress indicators, soil water content (SWC), leaf-air temperature difference (ΔT) and leaf level water stress index (CWSIL) were employed in Jarvis model, which were JS, JT and JC models respectively. Measurements of gs were conducted in a summer maize field experiment during the year 2012–2013. In the insufficient irrigation experiment, three levels of irrigation amount were applied at four different growth stages of summer maize. We constructed three scenarios to evaluate the performance of the three water stress indicators for estimating maize gs in a modified Jarvis model. Results showed that JT and JC models had better simulation accuracy than the JS model, especially at the late growth stage (Scenario 1) or considering the plant recovery compensation effects (Scenario 2). Scenario 3 indicated that the more environmental factors were adopted, the better prediction performance would be for JS model. While for JT model, two environmental factors (photosynthesis active radiation (PAR), and vapor pressure deficit (VPD)) seemed good enough to obtain a reliable simulation. When there were insufficient environmental data, CWSIL would be the best option. This study can be useful to understand the response of plant stomatal to changing water conditions and will further facilitate the application of the Jarvis model in various environments.

Effects of environmental factors on evapotranspiration characteristics of Haloxylon ammodendron plantation in the Minqin oasis-desert ectone, Northwest China.

This study continuously measured the evapotranspiration (ET) of degraded Haloxylon ammodendron shrub plantation of Minqin oasis-desert ectone using an eddy covariance system for ET, and TDR for soil moisture profile, analyzing ET in relation to the weather conditions and describing the responses of ET to the microclimate variables in different weather from July 2014 to June 2015. Results showed that the hourly ET dynamics had an apparent seasonal trend in the growing season. This trend gradually increased in the beginning of season from the low level of non-growing season, reached its maximum peak value (0.07 mm·h-1) in the most physiologically active period, and decreased to the minimum peak value (0.01 mm·h-1) in December. The diurnal change in ET of the plantation depended on the weather conditions. The ET fluctuated less with a small magnitude in a cloud day, but fluctuated obviously with a greater magnitude after rain if weather was clear. After a strong rainfall (>9 mm·d-1), ET increased sharply to a high level of 28 folds prior to rain, at which it took four clear days to gradually decease to the pre-rain ET level. The yearly ET over H. ammodendron plantation was 108 mm, equivalent to 98% of annual precipitation. Soil moisture was the water source for ET. Therefore, soil moisture was the dominant factor for theET over the plantation. Net radiation, photosynthesis active radiation, air temperature, and vapor pressure deficit were the microclimate variables to drive the transpiration of vegetation and evaporation over the soil surface, being the major factors forET over the plantation. The regression equation of ET to the dominant factor and major factors had a coefficient of multiple determination (R2) over 0.80.

Evaluation of inoculation with nitrogen and phosphorus biofertilizers on yield and radiation use efficiency of black cumin (Nigella sativa L.) under Mashhad climatic conditions

ABSTRACTThe purposes of this study were evaluate the effects of biofertilizers inoculation on growth indices, yield and radiation use efficiency (RUE) in black cumin under Mashhad climatic conditions. This field experiment was carried out based on a randomized complete block design with three replications. This experiment was performed at Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during two growing seasons 2007–2008 and 2008–2009. Treatments were (A) Azotobacter paspali, (B) Azospirillum brasilense, (C) Rhizophagus irregularis, A + C, B + C, A + B, A + B + C and control. In all treatments, except control, 100 g of seeds were inoculated with15 mg of each biofertilizer. Results indicated that leaf area index (LAI) and accumulative dry matter (DM) showed an increasing trend up to 1863°Cd and a short declining trend afterwards. The relation between accumulative DM and absorbed photosynthesis active radiation (PARa) was linear. Radiation use efficiency (RUE) fluctuated from 0.55 gMJ−1 (control) to 0.89 gMJ−1 (B+C). Inoculation with biofertilizers enhanced root development and hence availability of moisture and nutrients, particularly nitrogen and phosphorus. Since these ecological fertilizers produce many growth regulators for the plant which promote LAI and accumulative DM and therefore yield, PARa and RUE enhanced.

Approaches of climate factors affecting the spatial variation of annual gross primary productivity among terrestrial ecosystems in China

Analyzing the approaches that climatic factors affect the spatial variation of annual gross primary productivity (GPPyr) would improve our understanding on its spatial pattern. Based on network eddy covariance measurements and published data in literature, we separated GPPyr into radiation use efficiency (RUE) and annual absorbed photosynthesis active radiation (APARyr), where APARyr can be regarded as the product of the fraction of absorbed annual photosynthesis active radiation (FPARyr) and annual PAR (PARyr). Given that PARyr affects the spatial variation of GPPyr directly through itself, we investigated factors affecting the spatial variations of RUE and FPARyr, to reveal how climatic factors affect the spatial variation of GPPyr. Results suggest that the spatial variation of RUE was directly affected by annual mean air temperature (MAT) and annual mean CO2 mass concentration (ρcyr). The increasing MAT and ρcyr directly enhanced RUE. The increasing annual precipitation (MAP) directly prompted FPARyr. Therefore, MAT and ρcyr affected the spatial variation of GPPyr through altering RUE while the effect of MAP was achieved through altering FPARyr. Our study could also provide an alternative way for regional GPPyr assessment.

RESEARCH OF LEDS AS PHOTOSENSORS

In devices for measuring photovision applied sensors on the basis of photoresistors, photodiodes, vacuum and gas-filled photocells. These photosensors have to add filters and system filters. On the experimental data found that as of photosensors, you can use the LEDs. In laboratory tests, the LEDs of different colors of light react to individual optical radiation. LEDs are not sensitive to radiation with a wavelength longer than at which they emit light. Established that the maximum sensitivity of all LEDs a bit is shifted into the region of shorter wavelength than which the led emits. On the basis of led sensors can make the light meter, RGB-sensors, photosynthesis active radiation and measuring the near UV radiation. With the function of relative spectral luminous efficacy of monochromatic radiation for night vision coincides sensitivity of yellow led with a wavelength of 590 nm. With the function of relative spectral luminous efficacy of monochromatic radiation for daylight vision matches the sensitivity of red LEDs with a wavelength of 625 and 628 nm. To create RGB sensors need LEDs with operating wavelengths 660, 625 and 525 nm. There is no need to use corrective filters.

Spatial variability of water use efficiency in China's terrestrial ecosystems

Water use efficiency (WUE) reflects the coupling of carbon and water cycles. Analyzing the spatial variability of WUE can improve our understanding on the interaction between carbon and water cycles at a large scale, which also provides a basis for improving the regional carbon budget assessment. Based on China's eddy covariance measurements, we examined the spatial variation of China's WUE and its affecting factors. WUE showed a decreasing trend with the increasing altitude, which was the result of ecosystem type distribution resulting from the climatic gradient. After fully considering the vertical variation of WUE, we found that not only mean annual air temperature (MAT), mean annual precipitation (MAP), and mean leaf area index (MLAI) but also mean annual total photosynthesis active radiation (MAR) affected the spatial variation of WUE. With the increasing MAT, MAP, and MLAI, WUE increased significantly but the increasing MAR decreased WUE. The spatial variation of WUE could be directly depicted by MLAI and altitude, the equation including which explained 65% of the spatial variation of WUE. The effects of MAT and MAP on the spatial variation of WUE may be achieved through altering MLAI, while the mechanism underlying the effect of MAR on the spatial variation of WUE was still unclear, which should be the subject of future investigations. This study reveals the vertical variation of WUE and provides a new approach to generate the spatial variation in WUE, which will benefit the regional carbon budget assessment.

The Evaluation of Corn and Peanut Intercropping on Efficiency of Use the Environmental Resource and Soil Fertility

Order to study the effect of density, the control weed and various proportion corn (704 Variety) and peanut (Goli Variety) intercropping an experiment was conducted in 2012 in Research station of agriculture, University of Zabol. The experiment design was factorial in randomized complete block design with three replications. Experiment factors consisted of planting proportions in 4 levels (sole crop of corn, 50% corn + 50% peanut, 100% corn + 100% peanut and sole crop of peanut), control weed in 3 levels (non-weeding, once-weeding and twice-weeding) and the space between rows in 2 level (40 and 50 cm) has been considered. The evaluated Characteristics in environmental sources are (Photosynthetic Active Radiation, Temperature and soil Moisture), the nutrients of soil include (N, K, Na, Mg, Ca, and C) and to evaluate intercropping of pure was used land equivalent ratio and economical yield. All Characteristics of study were affected by planting system.There was significant interaction between planting system, weeding and density in the absorption of light, temperature and moisture of soil. The results showed that photosynthesis active radiation absorbed by the intercropping was higher than sole crop in both plants. The results showed that changes in soil nutrient capacity of single elements (Na and K) in the treatment of mixed and monoculture peanut was more than monoculture corn and divalent elements (Ca and Mg) in mixed and monoculture corn more than mixed replacement and peanut monoculture. The highest land equivalent ratio (1.048) was accounted additive intercropping. Generally the mixed cultures with increasing density and control weed caused increase soil fertility and amount of soil nutrients after harvest. Treatment 100% Corn +100% peanut was the best treatment because using sources and increasing soil fertility and crop yield in comparison to sole crop.

Photosynthesis active radiation at Sapporo Forest Meteorology Research site after a typhoon disturbance

Photosynthesis active radiation at Sapporo Forest Meteorology Research site after a typhoon disturbance

Effect of Plant Density and Nitrogen Rate on PAR Absorption and Maize Yield

A field experiment was conducted at the University of Zabol, The experimental farm in Southeast of Iran during 2007-08 to investigate the impacts of nitrogen (N) rate and plant density of maize (Zea mays L.) c.v. K.S.C 704. Split plot experimental treatments comprising three plant densities under title subplot included (P1 = 60,000 plants ha-1, P2 = 80,000 plants ha-1 and P3 = 100000 plants ha-1) and Four nitrogen rates (N1 = 200 kg ha-1, N2 = 250 kg ha-1, N3 = 300 kg ha-1 and N4 = 350 kg ha-1) were kept in main plots. Maize produced significantly as well as grain yield at high than at low density. Grain yield and Photosynthesis Active Radiation (PAR) absorption increase with increasing N rate and the highest amount of grain yield were obtained at N4 treatments. Grain yield and PAR absorption increase with increasing plant density and the highest amount of grain yield were obtained at P3 treatment. It is concluded that growing maize at high density with application of 350 kg h-1 N rate that could result in maximum Grain yield of maize and hence increase productivity of maize crop.