Infrared Gas Analyzer Research Articles

Gas exchange and fluorescence of Brosimum alicastrum

Gas exchange measurements were taken with an infrared gas analyzer (IRGA) and chlorophyll fluorescence with a modulated amplitude pulse fluorimeter (Mini-PAM) on fully developed leaves of ramon (Brosimum alicastrum Swartz) a tropical rainforest tree, grown in its natural habitat as to collect basic information of its physiological behavior. Data showed that maximum f ixation of CO2 was 5 µmol m-2 s-1, photosynthetic eff iciency was 0.67 while the photosystem II was found to saturate at a photonic flux density (PFD) of 500 µmol at 15 h. A high correlation was found between photosynthesis and transpiration. Highest water use eff iciency occurred after 15 hours at a temperature of 30 °C, while chlorophyll levels remained constant. This is a shade tolerant, plant species thus it was found that initiates the photosynthetic process with low levels of light, presenting a light compensation point of 24 µmol m-2 s-1. In a parallel study, the same variables were measured in two sets of individuals of the same specie collected from two distant localities but growth in pots in the open. Photosynthetic variables of this plant species data showed very similar patterns. The results obtained suggest that, during the daylight hours and at higher temperatures, this species can carry out photosynthesis with high water use eff iciency. Based on the results, the conclusion is that this plant species can adapt to a diversity of environmental conditions.

Respostas funcionais foliares de plantas jovens de <i>Hevea brasiliensis</i> submetidas à deficiência hídrica e à reidratação

A deficiência hídrica é considerada um fator que produz danos significativos durante o período de estabelecimento e de crescimento dos plantios. O objetivo deste estudo foi investigar características morfofisiológicas e bioquímicas de folhas de mudas de seringueira em resposta à deficiência hídrica e, posterior, reidratação. Plantas jovens de Hevea brasiliensis do clone RRIM 600 - Rubber Research Institute of Malaysia foram divididas em dois tratamentos, tratamento 1 = plantas irrigadas (IR) e tratamento 2 = plantas não irrigadas (NI). Nestas plantas, a fotossíntese (A) foi acompanhada durante todo o período experimental (0, 10, 25, 32, 48, 52 e 68 dias). O potencial hídrico foliar (ψw) foi determinado usando-se uma câmara de pressão do tipo Scholander, a fotossíntese (A), condutância estomática (gs) e transpiração (E) foram determinadas usando-se um analisador de gás infravermelho (LI-6400XT, LI-COR, Lincoln, Nebraska, USA) e o conteúdo de carboidratos foliares e de prolina foram determinados por espectrofotometria (Amersham Biosciences Ultrospec 3100 pro). O ψw, A, gs, E e o conteúdo de amido foliar no tratamento NI foram reduzidos durante os primeiros 32 dias, em que A atingiu valores próximos a 0 μmol m-2s-1.Porém, houve aumento da concentração de açúcar solúvel total e de prolina (tratamento NI) neste mesmo período. A recuperação da fotossíntese (NI) ocorreu após 22 dias depois da reidratação, quando comparado ao tratamento (IR). Portanto, pode-se concluir que o clone RRIM 600 possui tolerância ao estresse hídrico em termos de como lidar com o estresse hídrico progressivo, mas a recuperação ao estresse foi relativamente lenta.

EFFECTS OF SHADE TREE SPATIAL DISTRIBUTION AND SPECIES ON PHOTOSYNTHETIC RATE OF COFFEE TREES

The use of shade trees in coffee fields have been motivated by climatic changes. However, microclimatic conditions in shaded coffee fields differ due to shade tree spatial distribution and species, altering physiological responses of coffee trees. This study aimed to evaluate the effects of shade tree spatial distribution and species on coffee trees photosynthetic rate in two growth seasons, of high (HSD) and low (LSD) sink demand. The experimental design consisted of randomized blocks with three replicates in split-split-plots. Plots were the shade tree species: <em>Anadenanthera falcata</em>, <em>Cassia grandis</em> and <em>Peltophorum dubium</em>. Split plot was formed by five distances between coffee trees and shade tree trunks: coffee trees on planting row of shade trees, distancing one (D1L) and five (D5L) meters from shade trees trunk; coffee trees on inter-rows of shade trees, parallel to D1L and D5L (D1E and D5E); coffee trees distancing 77 meters from shade tree trunks, in a full-sun field (PS). The split-split-plots correspond to coffee tree canopy exposure to the sun: branches facing North or South. Shade trees canopy density and occupation was evaluated with a convex densiometer. Photosynthetic rate (Pn)and photosynthetic active radiation (PAR) were measured with an Infrared Gas Analyzer (IRGA) on two time-frames, between 7.00 and 9.00 solar hours and between 11.00 and 13.00. Shade tree canopy density and occupation was not homogenous during the change of seasons and shift due to spatial distribution, which also changes PAR levels. Shade trees reduce PAR to more suitable values for coffee tree exploitation, especially on D1L and D5L. During HSD, shading did not affect P<sub>n</sub>, which was greater in branches facing North. Yet, in LSD, between 11.00 and 13.00, coffee trees shaded with <em>A. falcata</em> showed greater P<sub>n</sub> than at PS. Coffee trees shaded with <em>C. grandis</em> at D5L and D1E had greater values of P<sub>n</sub> than PS.

Physiological and molecular responses to drought stress in teak (Tectona grandis L.f.).

Drought stress is an increasingly common and worrying phenomenon because it causes a loss of production in both agriculture and forestry. Teak is a tropical tree which needs alternating rainy and dry seasons to produce high-quality wood. However, a robust understanding about the physiological characteristics and genes related to drought stress in this species is lacking. Consequently, after applying moderate and severe drought stress to teak seedlings, an infrared gas analyzer (IRGA) was used to measure different parameters in the leaves. Additionally, using the root transcriptome allowed finding and analyzing the expression of several drought-related genes. As a result, in both water deficit treatments a reduction in photosynthesis, transpiration, stomatal conductance and leaf relative water content was found. As well, an increase in free proline levels and intrinsic water use efficiency was found when compared to the control treatment. Furthermore, 977 transcripts from the root contigs showed functional annotation related to drought stress, and of these, TgTPS1, TgDREB1, TgAREB1 and TgPIP1 were selected. The expression analysis of those genes along with TgHSP1, TgHSP2, TgHSP3 and TgBI (other stress-related genes) showed that with moderate treatment, TgTPS1, TgDREB1, TgAREB1, TgPIP1, TgHSP3 and TgBI genes had higher expression than the control treatment, but with severe treatment only TgTPS1 and TgDREB1 showed higher expression than the control treatment. At the end, a schematic model for the physiological and molecular strategies under drought stress in teak from this study is provided. In conclusion, these physiological and biochemical adjustments in leaves and genetic changes in roots under severe and prolonged water shortage situations can be a limiting factor for teak plantlets’ growth. Further studies of those genes under different biotic and abiotic stress treatments are needed.

Analysis of gas exchange in trees of the Caatinga, Brazil

In the Brazilian semiarid region, the high temperatures in association with the high level of solar radiation and variations in the concentration of CO2 which of focus on plants may influence the physical conformation of vegetables and their growth. On the basis of the above, the objective of this work to evaluate the content of gas exchange and chlorophyll in plants typical of Caatinga, associating possible interference of the power plant Borborema thermal S/A. the study carried out in the period of 2014-2018 with botanical species in two areas of the caatinga of Paraiba. To analyze the variables used the infra Red Gas Analyzer (RGA) and the SPAD. In using SPAD equipment it was found that the species had higher SPAD value were Aspidosperma pyrifolium Mart., (SPAD=50) P300. As the analyzes of gas exchange by the LCpro+, obtained greater record in plant Aspidosperma pyrifolium Mart. In point (P400). The maximum values of E and points were recorded (P600) (E=3.44>335 mmol.H2O.m-².s-¹) and (P100) (E=3.16mmol.H2O.m-².s-¹), both second collection. The first collection the highest registered was E=2.30mmol.H2O.m-².s-¹ (P600), Ziziphus species Joazeiro. In relation of the Tukey test, it was found that the transpiration of tree species, were higher in the second collection, the range of confidence (a, b) were significantly different. It was concluded that the indexes were higher by SPAD the occasion of the 2ª collection. The Ci presented low variation between the two periods. It was so, a non-correlation between the collections and areas surveyed.

Effects of Experimental Warming on Growing Season Temperature and Carbon Exchange in an Alpine Tundra Ecosystem

Accurate assessing CO2 exchange of tundra ecosystems is essential for better understanding and prediction of the CO2 responses of tundra ecosystems to climate change. In this study, the effects of warming on growing season CO2 exchange in an alpine tundra ecosystem were examined with closed transparent chamber attached to an infrared gas analyzer. Compared to ambient controls, open-top chambers (OTCs) increased growing season air (15 cm above ground surface) and soil (10 cm in depth) temperature by 1 and 0.2°C, respectively. Compared to the controls, OTCs tended to increase the plant height of Dryas octopetala and Vaccinium uliginosum by 15.1% (but P > 0.05) and 7.5% (P > 0.05), respectively. During the growing season, OTC-warming increased net ecosystem CO2 exchange by 136% and gross ecosystem exchange by 63%, whereas no significant difference in ecosystem respiration was found. Our results suggest that the predicted air warming will increase ecosystem carbon uptake of the Changbai Mountain alpine tundra during growing season. However, there is an uncertainty about the net CO2 exchange of that ecosystem at an annual scale, because, due to the inaccessibility, we did not study the winter respiration. Further studies are, therefore, needed to estimate the annual and long-term trade-off between CO2 uptake and emission in that region.

Nitrogen Loading Enhances Stress Impact of Drought on a Semi-natural Temperate Grassland.

Two important threats to the sustainable functioning of seminatural grasslands in temperate zones are (1) nutrient loading due to agricultural fertilization and pollution, and (2) the increase of extreme drought events due to climate change. These threats may cause substantial shifts in species diversity and abundance and considerably affect the carbon and water balance of ecosystems. The synergistic effects between those two threats, however, can be complex and are poorly understood. Here, we experimentally investigated the effects of nitrogen addition and extreme drought (separately and in combination) on a seminatural temperate grassland, located in Freiburg (South Germany). To study the grassland response, we combined eddy-covariance techniques with open gas exchange systems. Open gas exchange chambers were connected to an infrared gas analyzer and water isotope spectrometer, which allowed the partitioning of net ecosystem exchange and evapotranspiration. Vegetation parameters were described by species richness, species abundance, and leaf area index. Our results suggest that grassland communities, strongly weakened in their stress response by nitrogen loading, can substantially lose their carbon sink function during drought. While nitrogen addition caused a significant loss in forb species (−25%), precipitation reduction promoted a strong dominance of grass species at season start. Consequently, the grass-dominated and species-poor community suffered from a strong above-ground dieback during the dry summer months, likely caused by lower water use efficiency and weaker drought adaptations of the species community. Over the growing season (April-September), the carbon sequestration of the studied grassland was reduced by more than 60% as a consequence of nitrogen addition. Nitrogen addition in combination with precipitation reduction decreased carbon sequestration by 73%. Eutrophication can severely threaten the resilient functioning of grasslands, in particular when drought periods will increase as predicted by future climate scenarios. Our findings emphasize the importance of preserving high diversity of grasslands to strengthen their resistance against extreme events such as droughts.

Capturing Gas Fluxes on Your Phone: An iOS- and Android-based Data-Logging Setup for EGM-4 Environmental Gas Monitoring Systems.

Mobile devices have become increasingly important for field monitoring to improve data capture efficiency, increase storage capacity, and replace heavy equipment. We introduce a quick and straightforward protocol to capture greenhouse gas (GHG) emission rates on mobile devices. We developed our setup on the widely used infrared gas analyzer (IRGA) EGM-4 by PP Systems. This IRGA has a limited internal storage capacity and requires an external device such as a laptop to conduct even modest field sampling. Furthermore, when raw data storage is required, carbon dioxide concentration resolution is reduced by the internal EGM-4 software settings, making the equipment less suitable for high-frequency measurements. Our protocol lets the user bring either an iOS or Android mobile device in to the field to connect to the EGM-4's data stream. For both platforms, a mobile console application was used to read, log, and share flux data. The raw data can be processed in either Python, R, or Matlab using the provided scripts that give the user flexibility to amend further postprocessing steps to obtain GHG fluxes. We demonstrate the flexible applicability of mobile devices for field recording and show that a cost-effective solution can enhance the operational life of superseded field equipment while also increasing the quality of the captured data.

CO2 uptake and chlorophyll a fluorescence of Suaeda fruticosa grown under diurnal rhythm and after transfer to continuous dark

Although only 2-4% of absorbed light is emitted as chlorophyll (Chl) a fluorescence, its measurement provides valuable information on photosynthesis of the plant, particularly of Photosystem II (PSII) and Photosystem I (PSI). In this paper, we have examined photosynthetic parameters of Suaeda fruticosa L. (family: Amaranthaceae), surviving under extreme xerohalophytic conditions, as influenced by diurnal rhythm or continuous dark condition. We report here CO2 gas exchange and the kinetics of Chl a fluorescence of S. fruticosa, made every 3hours (hrs) for 3days, using a portable infra-red gas analyzer and a Handy PEA fluorimeter. Our measurements on CO2 gas exchange show the maximum rate of photosynthesis to be at 08:00hrs under diurnal condition and at 05:00hrs under continuous dark. From the OJIP phase of Chl a fluorescence transient, we have inferred that the maximum quantum yield of PSII photochemistry must have increased during the night under diurnal rhythm, and between 11:00 and 17:00hrs under constant dark. Overall, our study has revealed novel insights into how photosynthetic reactions are affected by the photoperiodic cycles in S. fruticosa under high salinity. This study has further revealed a unique strategy operating in this xero-halophyte where the repair mechanism for damaged PSII operates during the dark, which, we suggest, contributes to its ecological adaptation and ability to survive and reproduce under extreme saline, high light, and drought conditions. We expect these investigations to help in identifying key genes and pathways for raising crops for saline and dry areas.

СОХРАНЕНИЕ ДЕКОРАТИВНЫХ КАЧЕСТВ СРЕЗКИ РОЗЫ (ROSA HYBRIDA)

The purpose of this work was to study the post-harvest physiology of cut roses (R. hybrida). The objects of study were the most popular varieties in floristics: Magady, Vendella, Red Naomi, First Red, Grandgala. Studies were carried out in the autumn-winter periods of 2016- 2018 on leafy flowering shoots in laboratory with natural diffused light at an air temperature of 18-20 °C. Sampling was carried out at the stages of half-release, complete dissolution, the beginning and completion of the aging of flowers. The study in the gas exchange dynamics of cut rose flower shoots using the infrared gas analyzer LI — COR 6400RX showed a decrease in the intensity of photosynthesis and maintaining a high level of transpiration intensity and stomatal conduction of the leaf with the development and aging of the flower. The high intensity of transpiration and the large leafiness of the shoot make it difficult to maintain water status, accelerate aging and the loss of the decorative qualities of the flower. Pulsating treatment with silver thiosulfate (4 mM AgNO3: 32 mM NaS2O3) was used as inhibitor of ethylene synthesis, and 1 μl L–1 1-methylcyclopropene (1- MCP) was inhibitor of ethylene sensitivity. The results of the use of the inhibitor method allow us to conclude that ethylene is involved in the regulation of only the final stages of flower aging in roses. As trigger of the aging process can be the threshold effect of one or several gradual biochemical processes associated with the mobilization of nutrients. Visible signs of aging are preceded by impaired membrane stability. The commercial drug Chrysal does not ensure the natural development of the flower, but only slightly retards wilting. The growing conditions and storage of cut roses should ensure the active functioning of the stomatal apparatus, preventing water stress in the post-harvest period. Its consequence consists not only in the loss of turgidity of the petals, but also in accelerating aging due to the accumulation of ethylene.

Deficiência de macronutrientes em <i>Cariniana estrellensis</i> (Raddi) Kintze

O conhecimento dos efeitos da nutrição mineral sobre a fisiologia vegetal de espécies nativas é um importante auxílio para que se obtenha o sucesso desejado quando estas são usadas no reflorestamento ou na recuperação de áreas degradadas. A presente pesquisa avaliou as consequências da deficiência de macronutrientes em Cariniana estrellensis (Raddi) Kintze (jequitibá-branco) nas taxas de assimilação de gás carbônico e de transpiração e na produção de biomassa desta espécie, que é amplamente utilizada na restauração florestal no Brasil. O experimento foi conduzido em casa de vegetação, em blocos ao acaso, com sete tratamentos e três repetições, empregando a técnica de diagnose por subtração de macronutrientes, com um tratamento controle no qual o jequitibá-branco foi cultivado em solução nutritiva completa, com todos os macros e micronutrientes. Os teores de nutrientes foram determinados por análise química nos diferentes órgãos do jequitibá-branco; através do analisador de gás por infravermelho portátil (Infrared Gás Analyzer – IRGA, modelo Li-cor 6400) foram determinadas as taxas de assimilação de gás carbônicoe de transpiração em folhas de três partes distintas das plantas, e ao final do experimento foi realizada a determinação da produção de biomassa seca. A deficiência dos macronutrientes, de um modo geral, prejudicou as taxas de assimilação de gás carbônico e de transpiração e, por conseguinte, a produção de biomassa seca das plantas jovens de jequitibá-branco foi menor em relação ao tratamento controle. Os resultados deste estudo sugerem que a implantação de florestas ou a recuperação de áreas degradadas por meio do reflorestamento que utilizam o jequitibá-branco certamente serão prejudicados se a complementação nutricional não for realizada quando o solo for deficiente em qualquer dos macronutrientes.

Characterization of bubbler performance for low-volatility liquid precursor delivery.

The performance of a bubbler to deliver the low-volatility, liquid cobalt precurso - -(tBu-acetylene) dicobalthexacarbonyl (CCTBA) for reduced-pressure chemical vapor deposition and atomic layer deposition processes was characterized. A relatively large process window was investigated by varying carrier gas flow rate, system pressure, and bubbler temperature. For this range of conditions, the CCTBA partial pressure was measured using a custom-designed non-dispersive infrared gas analyzer, and the CCTBA flow rates were derived from these partial pressure measurements. The dependence of CCTBA flow rate on these process parameters was modeled to obtain a deeper understanding of the factors influencing bubbler performance. Good agreement between measured and modeled CCTBA flow rates was obtained using a model in which a constant CCTBA partial pressure in the bubbler head space for a given bubbler temperature was assumed and in which the pressure drop between the bubbler head space and the pressure measurement location was included. The dependence of CCTBA head space partial pressure on temperature was parameterized in the form of the August equation, which is commonly used to describe the temperature-dependence of vapor pressure. While this report was focused specifically on CCTBA, the results are expected to apply to other low-volatility, liquid precursors of interest in vapor deposition processes.

Adjustment of CO2 flux measurements due to the bias in the EC150 infrared gas analyzer

During the Regional Approaches to Climate Change (REACCH) program, eddy covariance monitoring over agricultural fields were used to estimate annual carbon and water budgets in the inland Pacific Northwest. Here, we assess the effect of a bias in the high-frequency CO2 concentration measurements using the Campbell Scientific EC150 infra-red gas analyzer on the CO2 fluxes and field-scale carbon balances. The bias stems from using a lower frequency temperature measurement to calculate the CO2 density, which misses higher frequency temperature fluctuations. To generate the bias adjustment, data were collected over four similar agricultural sites as part of the Long-Term Agroecosystem Research network for multiple months using the same four instrument sets used in the REACCH project. The difference between the high-frequency and low-frequency CO2 fluxes were regressed against the kinematic heat fluxes to generate a correction equation for each instrument set, which were applied to the historical REACCH data to determine the effect of the bias on the measured and gap-filled flux values. The re-calculated positive biases in the measured fluxes were 40 gC-CO2 m−2 yr-1 to 126 gC-CO2 m−2 yr-1, indicating greater losses to the atmosphere than initially estimated. Once gap-filled, three out of fourteen site-years switched from weak carbon sinks to weak carbon sources. When the carbon exported via harvest was included in the budget calculation the bias correction still impacted the source/sink strength but did not change the sign of the carbon balance. Overall, the total net ecosystem exchange decreased between 300–470 gC-CO2 m-2 per site (29–46%) over the 4 crop-years from the bias adjustment process.

Photosynthetic Characterization and Response to Drought and Temperature in Wild Asparagus (Asparagus acutifolius L.)

The wild asparagus species Asparagus acutifolius L. is widespread in Mediterranean and subtropical environments, where its spears are consumed regularly. The species is known to have ecophysiologic plasticity, however there is no literature on this subject. This work aimed at assessing the photosynthetic characteristics of this wild species of asparagus, grown under full light (FL) and partial (i.e., about 40%) light (PL) conditions, and evaluating its ecophysiologic response to drought and temperature stress. The photosynthetic response to light of spears and of new cladodes (NC; current year) and old cladodes (OC; previous year) was measured using an infrared gas analyzer coupled with a climatized cuvette chamber. Cladodes net photosynthesis at high irradiance was also measured at varying air temperatures and decreasing soil water availability. Results indicate that developing spears were photosynthetically active with no difference between FL and PL treatments. Photosynthetic rates did not differ between NCs and OCs and were greater for FL cladodes, except at low irradiance. Well-watered plants were photosynthetically active from 0 to 45 °C, with a maximum photosynthetic rate of up to 9 µmol·m–2·s–1 at 30 °C and a decrease of about 60% at 45 °C. The species also demonstrated high tolerance to drought, with positive net photosynthesis even at predawn leaf water potential values of –2.4 MPa. Showing great ecophysiologic plasticity, this wild asparagus could be an interesting species in areas were conventional crop species are not profitable economically, or as an intercrop in agroforestry systems.

Phenotypic Variation and Genetic Architecture for Photosynthesis and Water Use Efficiency in Soybean (Glycine max L. Merr).

Photosynthesis (A) and intrinsic water use efficiency (WUE) are physiological traits directly influencing biomass production, conversion efficiency, and grain yield. Though the influence of physiological process on yield is widely known, studies assessing improvement strategies are rare due to laborious phenotyping and specialized equipment needs. This is one of the first studies to assess the genetic architecture underlying A and intrinsic WUE, as well as to evaluate the feasibility of implementing genomic prediction. A panel of 383 soybean recombinant inbred lines were evaluated in a multi-environment yield trial that included measurements of A and intrinsic WUE, using an infrared gas analyzer during R4–R5 growth stages. Genetic variability was found to support the possibility of genetic improvement through breeding. High genetic correlation between grain yield (GY) and A (0.80) was observed, suggesting increases in GY can be achieved through the improvement of A. Genome-wide association analysis revealed quantitative trait loci (QTLs) for these physiological traits. Cross-validation studies indicated high predictive ability (>0.65) for the implementation of genomic prediction as a viable strategy to improve physiological efficiency while reducing field phenotyping. This work provides core knowledge to develop new soybean cultivars with enhanced photosynthesis and water use efficiency through conventional breeding and genomic techniques.

CO2 fluxes from drained tropical peatland used for oil palm plantation in relation to peat characteristics and crop age after planting

Large expansion of oil palm plantation on peatland has changed its important role for carbon sink into a carbon source. Conversion of peat swamp forest with high carbon density into a monoculture of oil palm has released the significant amount of carbon into atmosphere either carbon previously stored in forest biomass or carbon stored in peat organic matter. Drainage canal to artificially lower groundwater level as a prerequisite of oil palm cultivation provides the favorable condition for soil microbes activities in decomposing peat organic matter resulted in CO2 flux increase. The fluctuation of groundwater level and variation of environmental factors near the peat surface may regulate the rate of CO2 released from the soil. We aimed to measure CO2 fluxes from two sites of oil palm plantation with different peat characteristics and analyzed the correlation with groundwater level, soil temperature, air temperature, gravimetric water content, peat pH, oxidative reductive potential, and crop age. The measurement has been conducted from September 2016 to April 2017 in West Kalimantan, Indonesia by using portable infrared gas analyzer EGM 4. In addition to soil sampling at the same time as the gas measurement, we collected soil samples for some peat characteristics analysis consist of bulk density, particle density, porosity, soil organic matter, ash content, carbon, and nitrogen content prior to CO2 flux measurement. Our result shows that the difference of peat chemical characteristics between two sites has resulted in different CO2 flux. Oil palm ages seemed to affect CO2 flux by regulating microclimatic condition around crop canopy. Another finding is the insignificant relationship between CO2 fluxes and groundwater level unless the groundwater level reached more than 50 cm from the peat surface. It implies that maintaining groundwater level-up to 50 cm resulting in similar CO2 flux.

Different Light Radiation Intensities on Cotton: A Physiological Approach

The luminosity and the temperature are factors that act directly in the photosynthetic process, where an elevation of the luminous intensity can cause a reduction of the assimilation of carbon, which consequently lowers the development of the cotton. The objective of this work was to assess the response of physiological parameters of cotton when subjected to different artificial light intensities. Two varieties of cotton IMA5801B2RF and IACRDN, were interacting with five artificial light intensities: 0 (control); 500; 1000; 1500 and 2000 μmol m−2 s−1 of photosynthetically active radiation provided by LED bulbs. The experiment was set in a randomized complete block design using a 2x5 factorial scheme. The variables measured were the rate of CO2 assimilation, transpiration, stomatal conductance, inner CO2 concentration in the substomatic chamber, and efficient use of water (for which a portable device of gas exchange was used). The cotton varieties responded positively to different luminous intensities until reaching the point of maximum saturation between 1400 and 1600 µmol m-1 s-1 of light, which provided a better rate of CO2 assimilation, concentration of CO2 in the substomatic chamber, and efficient use of water. Leaf transpiration and stomatal conductance showed a positive linear response with increasing light intensity. The ideal luminous intensity for the use of Infra-Red Gas Analyzer - IRGA was 1500 µmol m-1 s-1 for the tested cotton varieties.

Growth, Photosynthesis and Quality of Water Spinach (Ipomoea aquatica) as Influenced by Magnetic Nanoparticles (MNP) Application

Aims: To characterize the growth, carbon assimilation and quality of Ipomoea aquatica as influenced by magnetic nanoparticles (MNP) application as well as to determine the best rates of iron oxide nanoparticles that give high growth, carbon assimilation and quality of Ipomoea aquatica.
 Study Design: Ipomoea aquatica plants were exposed to four different treatments of magnetic iron oxide nanoparticles (Fe3O4) (0, 50, 100 and 150 mg L-1). The experiment was conducted in a randomized complete block design (RCBD) with 3 replications. One unit of experiment consisted of 8 plants and there were 96 plants used in the experiment.
 Place and Duration of Study: Department of Biology, Faculty of Science, Universiti Putra Malaysia, between March 2018 and July 2018.
 Methodology: The growth parameters measured included: plant height, basal diameter, total leaf number, leaf temperature, total chlorophyll content and plant biomass. The carbon assimilation parameters were measured using IRGA (Infrared Gas Analyzer, LICOR 6400 XT Portable Photosynthesis System). i.e. transpiration rate (E), stomatal conductance and water use efficiency (WUE). The chlorophyll fluorescence were measured by using Pocket PEA that measured maximum efficiency of photosystem ii, (fv/fm), maximum quantum yield of phytochemical and non-photochemical process in photosystem II (fv/fo), minimal fluorescence (fo), performance index (PI) and Density of Reaction Centers Per PSII Antenna Chlorophyll (RC/ABS). Total phenolics and flavonoids contents in leaves were measured using Folin-Ciocalteu method.
 Results: It was observed that plant height, shoot length, plant temperature, total biomass, and total chlorophyll content were significantly influenced (p≤0.05) by the different concentrations of magnetic nanoparticles. The net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), maximum efficiency of photosystem II (Fv/fm), maximum quantum yield of phytochemical and non-photochemical process in photosystem II (Fv/fo), performance index and the density of reaction centers per PSII antenna chlorophyll of Ipomoea aquatica were significantly reduced at higher concentration of magnetic nanoparticles. However, water use efficiency and minimal fluorescence value (Fo) of Ipomoea aquatica increased with increase of MNP concentration. In addition, the application of magnetic nanoparticles significantly influenced (P≤0.05) the total flavonoids and total phenolics content in water spinach. Both of these parameters were increased when higher concentration of magnetic nanoparticles was applied to Ipomoea aquatica. This study showed that MNP affected the growth, carbon assimilation and secondary metabolites production of Ipomoea aquatica.
 Conclusion: In conclusion, the higher concentration of magnetic nanoparticles reduced the growth rate and carbon assimilation of water spinach and enhanced the production of secondary metabolites.

The manipulation of aboveground litter input affects soil CO2 efflux in a subtropical liquidambar forest in China

Abstract: Litters on the forest floor represent an important organic carbon (C) sources from aboveground plants to the soil, which therefore have a significant influence on belowground processes such as soil respiration. In this study, dynamic property of soil respiration was investigated under aboveground litter manipulation treatments in a liquidambar forest in subtropical China. The purpose of this study was to examine the impacts of changing aboveground litter inputs on soil CO2 emission in forests. The litter manipulation included litter addition (LA), litter removal (LR) and litter control (LC) treatments. Each litter treatment had six replications. Soil respiration rates were measured using an infrared gas analyzer system (LI-COR 8100) with soil chambers. The results showed that mean soil respiration rates increased significantly in LA plots (mean ± SE: 2.21 ± 0.44 μmol m-2 s-1; P<0.05) and decreased slightly in LR plots (1.17 ± 0.16 μmol m-2 s-1) when compared to control plots (1.42 ± 0.20 μmol m-2 s-1). On average, LA treatment significantly increased annual soil respiration by about 56% (837.5 ± 165 gC m-2 year-1), while LR treatment decreased soil respiration by approximately 17% (443.1 ± 61.7 gC m-2 year-1) compared with the control (535.5 ± 75.7 gC m-2 year-1). The “priming effect” was a primary contributor to the increase of soil respiration in LA treatments and the reduction of soil CO2 efflux was mainly ascribed to the elimination of organic C sources in LR treatments. Soil temperature was the main factor affecting seasonal variation in soil respiration. Up to the 90% to 95% seasonal variation in soil respiration is explained by soil temperature within each of the litter treatments. Our study indicated that changes in litter inputs due to climate change and human practices would significantly affected soil CO2 emission and would subsequently affect C balance in subtropical forests.

Flux Puppy – An open-source software application and portable system design for low-cost manual measurements of CO2 and H2O fluxes

Manual chamber-based measurements of CO2 (and H2O) fluxes are important for understanding ecosystem carbon metabolism. Small opaque chambers can be used to measure leaf, stem and soil respiration. Larger transparent chambers can be used to measure net ecosystem exchange of CO2, and small jars often serve this purpose for laboratory incubations of soil and plant material. We developed an Android application (app), called Flux Puppy, to facilitate chamber-based flux measurements in the field and laboratory. The app is designed to run on an inexpensive handheld Android device, such as a tablet or phone, and it has a graphical user interface that communicates with a LI-COR LI-820 and LI-830 (CO2) or LI-840 and LI-850 (CO2/H2O) infrared gas analyzer. The app logs concentrations of CO2 and H2O, cell temperature and pressure at 1 Hz, displays the output graphically, and calculates the linear regression slope, R-squared, and standard error of the CO2 time series. A metadata screen allows users to enter operator, site, and plot information, as well as take a photograph using the Android device’s built-in camera, and log measurement location using the device GPS. Additionally, there is a notes field, which can be revised after the measurements are taken. Data files (the 1 s raw data, photograph, and metadata including statistics calculated from the raw data) are then transmitted off the device through file sharing options (Gmail, Outlook, Google Drive, Dropbox etc.). Because Flux Puppy code is open-source (available on GitHub) and the flux measurement system we describe is relatively inexpensive and straightforward to assemble, it should be of broad interest to the carbon cycling community.