Measurements Of Chlorophyll Content Research Articles

Effects of shading on photosynthetic characteristics and yield at different growth stages of potato.

We examined the effects of shading photosynthetic characteristics, yield, and tolerance to low light in two potato varieties (Jizhangshu 12 and Jizhangshu 8) at four growth stages (seedling, seedling/budding, budding/early flowering and flowering/harvest). There were three shading treatments (0(CK), 20% and 50%). The results showed that at both 20% and 50% shading rates, the SPAD value (a measure of leaf cellular chlorophyll content) of the two varieties decreased significantly at the seedling stage compared with CK treatment. No significant change in the SPAD value occurred at the seedling/budding stage or the budding/early-flowering stage. However, the SPAD value increased marginally after shading at the initial flowering stage. Under the 50% shading regime, the SPAD values of both varieties followed the same trend as the 20% regime. The range of changes at different growth stages remained similar. The only exception was that shading at the beginning of flowering increased SPAD value. Shading had little effect on leaf stomatal conductance (gs) at each developmental stage. There was no significant difference between all treatments and the control, except that the gsvalue of Jizhangshu 8 decreased significantly (43.9%) compared with the control under 50% shading at the beginning of flowering. After the shading treatment, the intercellular CO2 concentration (Ci) of leaves showed an upward trend. 50% shading at the seedling and seedling/budding stages could significantly increase Ci, but not at other stages. The net photosynthetic rate (Pn) of the four periods were all decreased after 15 d of shading. The Pn reduction of the two varieties, 50% shading, was greater than 20% shading. The decline range of Pn of Jizhangshu 12 was less than that of Jizhangshu 8 at all stages, except for that at the seedling stage. The yield of shading treatments decreased in all four stages, with the decrease rate of 50% shading treatment being greater than that of the 20% shading treatment. 'Jizhangshu 12'was not tolerant to low light at the seedling stage but performed better than 'Jizhangshu 8' at other stages. The comprehensive analysis of two test varieties implied that varieties with strong tolerance to low light experienced a smaller boost in intercellular CO2 concentration and a smaller drop in net photosynthetic rate, stomatal conductance, and yield post-shading.

Mapping Canopy Chlorophyll Content in a Temperate Forest Using Airborne Hyperspectral Data

Chlorophyll content, as the primary pigment driving photosynthesis, is directly affected by many natural and anthropogenic disturbances and stressors. Accurate and timely estimation of canopy chlorophyll content (CCC) is essential for effective ecosystem monitoring to allow for successful management interventions to occur. Hyperspectral remote sensing offers the possibility to accurately estimate and map canopy chlorophyll content. In the past, research has predominantly focused on the use of hyperspectral data on canopy chlorophyll content retrieval of crops and grassland ecosystems. Therefore, in this study, a temperate mixed forest, the Bavarian Forest National Park in Germany, was chosen as the study site. We compared different statistical models (narrowband vegetation indices (VIs), partial least squares regression (PLSR) and random forest (RF)) in their accuracy to predict CCC using airborne hyperspectral data. The airborne hyperspectral imagery was acquired by the AisaFenix sensor (623 bands; 3.5 nm spectral resolution in the visible near-infrared (VNIR) region, and 12 nm spectral resolution in the shortwave infrared (SWIR) region; 3 m spatial resolution) on July 6, 2017. In situ leaf chlorophyll content and leaf area index measurements were sampled from the upper canopy of coniferous, mixed, and deciduous forest stands in July and August 2017. The study yielded the highest retrieval accuracies with PLSR (root mean square error (RMSE) = 0.25 g/m2, R2 = 0.66). It further indicated specific spectral regions within the visible (390–400 nm and 470–540 nm), red edge (680–780 nm), near-infrared (1050–1100 nm) and shortwave infrared regions (2000–2270 nm) that were important for CCC retrieval. The results showed that forest CCC can be mapped with relatively high accuracies using image spectroscopy.

Dry matter content association with time of on-tree maturation, quality at harvest, and changes in quality after controlled atmosphere storage for ‘Royal Gala’ apples

On-tree maturation was monitored in a commercial ‘Royal Gala’ apple orchard in two separate years (2016 and 2017) and was found to advance more quickly in 2017 as compared with 2016. Dry matter was predicted using a handheld infrared spectrometer and dry matter content (relative to fresh weight) was 18.2% in 2016 and 14.7% in 2017. The lower average dry matter content in 2017 was hypothesized to be associated with accelerated maturation on the tree. Apples were harvested for storage testing, in both years, at a target maturity at which internal ethylene levels had reached approximately 1 μL·L−1, starch clearing index was between 2 and 4 on the Cornell starch chart, and IAD value (measure of relative chlorophyll content in the peel) was approximately 0.5. Consequent, instrumentally measured flesh quality changes were monitored after ultra-low oxygen, controlled atmosphere (CA) storage (0.7 kPa O2 + 1.0 kPa CO2) at 0.5 °C for 3 and 6 mo. The firmness, soluble solids, and titratable acidity were much higher in the apples from the 2016 harvest. While these quality measures declined during 3 and 6 mo of storage, they were consistently higher in the apples from the 2016 season. These results show that when dry matter contents were higher for ‘Royal Gala’ apples from this orchard, harvest maturity was delayed and fruit were much firmer and had higher contents of soluble solids and somewhat higher titratable acidity at harvest and after ultra-low oxygen CA storage for up to 6 mo.

Evaluation of a portable chlorophyll optical meter to estimate chlorophyll concentration in the green seaweed Ulva ohnoi

In situ measurement of chlorophyll concentration, with an optical meter, in the green seaweed Ulva ohnoi is presented to estimate the absolute chlorophyll content. The MC-100 optical meter (Apogee Instruments) was used during the study; the optical meter gives chlorophyll content in relative units as Chlorophyll Content Index units (CCI). Absolute chlorophyll content, in μmol m−2, was determined by extraction with dimethylformamide, and the chlorophyll concentration was measured with a spectrophotometer. Equations to convert CCI from optical meter to absolute chlorophyll content were presented for total chlorophyll, chlorophyll a, and chlorophyll b. Highly linear relationships (r2 above 0.9, n = 130) were found for total chlorophyll, chlorophyll a, and chlorophyll b. In situ non-destructive estimation of U. ohnoi chlorophyll content using the MC-100 portable chlorophyll optical meter was considered convenient, fast, and accurate.

δ15N as a cultivar selection tool for differentiating alfalfa varieties under biosaline conditions

The potential of “biosaline agriculture” relies on easy-to-apply tools to select plant genotypes that are best adapted to saline conditions. We aimed to determine the effects of salinity-sodicity on the functional response of alfalfa varieties by evaluating instantaneous vs integrated plant-based measurements for the selection of alfalfa cultivars in biosaline agriculture. Functional responses of three alfalfa varieties were evaluated in a greenhouse study under different saline-sodic conditions. Physiological parameters included instantaneous (gas exchange and chlorophyll fluorescence) vs time-integrated (carbon isotope discrimination -∆13C- and nitrogen isotope composition -δ15N-; specific leaf weight and chlorophyll content) measurements. From all assessed physiological traits, only δ15N was able to effectively discriminate among genotypes WL656HQ, PGI908S and SW8421S, and showed the highest correlation with biomass production at all experimental stages. On average, the δ15N increased by a factor of 3.3 as salinity increased from the non-saline control treatment (ECiw ~ 0.4 dS m−1) to the highest salinity level (ECiw ~ 10.0 dS m−1) indicating that biological N fixation was significantly limited by salinity. Specific leaf weight was also significantly correlated with dry matter although to a much lesser extent than was δ15N. δ15N was found to be the best proxy for assessing alfalfa varieties for their adaptation potential in saline conditions. This parameter was able to discriminate alfalfa’s functional response within a narrow range of irrigation water salinity. δ15N was also capable of differentiating between alfalfa varieties classified as tolerant to salinity defined at a particular plant growth stage, making this an excellent tool for genotypic selection.

Differences in iron acquisition strategies of calcicole plant species from xerothermic grasslands

Little is known about iron (Fe) acquisition of calcicole species from xerothermic grasslands and their resistance to Fe-dependent chlorosis. In this study an experiment was designed to investigate effects of opposing soil types (acidic Podzol vs slightly alkaline Rendzina) and addition of HBED-chelated Fe (five doses of 5 and 25 μmol kg−1 soil every two weeks). Selected calcicole plant species occurring on xerothermic grasslands, Aster amellus L. (Aa), Betonica officinalis L. (Bo), Prunella grandiflora (L.) Scholler (Pg), Salvia verticillata L. (Sv) and Veronica teucrium L. (Vt), were tested in a pot experiment under field conditions. Responses of plants were described using measurements of chlorosis, growth, chlorophyll content and fluorescence, activity of antioxidant enzymes and content of elements, including Ca, Mg, Fe, Mn, Zn and Cu. Some Podzol-grown plants showed arrested growth (up to 80% significant reduction of root and shoot fresh weight (FW) compared to Rendzina-grown plant, depending on species) but no signs of Fe-dependent chlorosis, whereas the same species grown on Rendzina performed very differentially. Lime chlorosis on Rendzina was induced in Aa, Bo and Pg (c.a. 30–40% significant reduction of chlorophyll content compared to Fe-supplied plants) but not in Sv and Vt. Fe-HBED treatment totally diminished chlorosis in species-dependent dose (5 μmol kg−1 soil for Aa and Pg and 25 μmol kg−1 soil for Bo) but significantly slowed growth (up to 50% significant reduction of root FW and 65% reduction of shoot FW compared to non-Fe-treated Rendzina-grown plant, depending on species). Chlorosis negatively affected functioning of photosynthetic apparatus alternating quantum yield of primary PSII photochemistry (FV/FM), light energy dissipation (DI0/RC) and performance index (PIABS) and Fe-HBED significantly alleviated these perturbations. Activity of antioxidant enzymes suggested Fe-HBED-caused alleviation of oxidative stress. Reduction of chlorosis did not rely on improved Fe accumulation, nor on altered partitioning on root-shoot axis, but a relation between chlorosis and manganese (Mn) in roots was observed. The results seem to indicate more complex interaction between Fe and Mn in induction of soil-dependent chlorosis than one might expect. Availability of Fe on the slightly alkaline soil limited functioning of the studied calcicole species in specific manner and probably created micro habitats. Ultimately, it can be clearly seen that xerothermic grasslands are composed of chlorosis-resistant and chlorosis-susceptible species.

Relationships between chlorophyll content of vine leaves, predawn leaf water potential at veraison, and chemical and sensory attributes of wine.

Water deficit and iron deficiency (iron chlorosis) are common environmental stresses that affect grapevine production in the Mediterranean area. Studies on the impact of both stresses, when they act simultaneously, are rare. The main objective of this investigation was to evaluate the combined effects of the incidence of iron chlorosis and the vine water status on quality of Tempranillo wine. For this, 20 non-irrigated vineyard subzones (10 m × 10 m each), from non-affected to moderately affected by iron chlorosis, were monitored in the Ribera del Duero area (north-central Spain) during two consecutive seasons. Factorial analyses of variance were performed to study the effects of predawn leaf water potential and foliar chlorophyll content, both measured at veraison, on chemical and sensory characteristics of wine. With an impact much greater than water status, the incidence of iron stress decreased pH of the wine and enhanced sensory attributes as tonality, layer intensity, flavour intensity, and persistence in the mouth. There were increases in red colour, astringency, and persistence of the wine associated with chlorosis, although they might be restricted in water-deficit conditions. The results have demonstrated that mild to moderate iron stress can have positive effects on chemical and sensory attributes of Tempranillo wine. Measurements of foliar chlorophyll content at veraison could be very useful to map quality potential in rainfed vineyards affected by iron deficiency. © 2020 Society of Chemical Industry.

Differential responses of sorghum genotypes to sugarcane aphid feeding.

The findings of this study suggest that known resistant sorghum genotypes compensate for feeding pressure of sugarcane aphid by maintaining/increasing photosynthetic capacity and/or have higher chlorophyll content than susceptible genotypes. Knowledge of the physiological response of sorghum, (Sorghum bicolor (L.) Moench), to sugarcane aphid (SCA), Melanaphis sacchari (Zehnter) feeding will provide baseline information on defense responses and resistance mechanisms. This study documented the impact of SCA feeding on seven sorghum genotypes by measuring chlorophyll content, photosynthetic rate, stomatal conductance, and carbon assimilation for a 14-d post-infestation evaluation. Carbon assimilation (A/Ci) curves were recorded at 3, 6, 9, and 15 d after aphid infestation to describe the pattern of physiological response of resistant and susceptible sorghums over time. Chlorophyll loss from resistant genotypes was significantly lower (≤ 10% loss) than from susceptible cultivars. Most resistant genotypes compensated for aphid feeding by either increasing or maintaining photosynthetic rate and stomatal conductance. Carbon assimilation curves over time showed that infested resistant plants had delayed photosynthetic decreases, whereas susceptible plants rapidly lost photosynthetic capacity. This research also investigated the influence of aphid density (0, 50, 100, and 200 nymphs/plant) on the photosynthetic rates of 28-d-old resistant and susceptible sorghums measured at 72-h post-infestation. Although there were no visual symptoms in susceptible sorghums, photosynthetic rates were impaired when infested with ≥ 100 SCA. In contrast, resistant plants were able to compensate for SCA feeding. Differences in the physiological responses of susceptible versus resistant sorghums indicate that resistant sorghum plants can tolerate some physiological impacts of SCA feeding and maintain photosynthetic integrity.

Evaluating Prediction Models for Mapping Canopy Chlorophyll Content Across Biomes

Accurate measurement of canopy chlorophyll content (CCC) is essential for the understanding of terrestrial ecosystem dynamics through monitoring and evaluating properties such as carbon and water flux, productivity, light use efficiency as well as nutritional and environmental stresses. Information on the amount and distribution of CCC helps to assess and report biodiversity indicators related to ecosystem processes and functional aspects. Therefore, measuring CCC continuously and globally from earth observation data is critical to monitor the status of the biosphere. However, generic and robust methods for regional and global mapping of CCC are not well defined. This study aimed at examining the spatiotemporal consistency and scalability of selected methods for CCC mapping across biomes. Four methods (i.e., radiative transfer models (RTMs) inversion using a look-up table (LUT), the biophysical processor approach integrated into the Sentinel application platform (SNAP toolbox), simple ratio vegetation index (SRVI), and partial least square regression (PLSR)) were evaluated. Similarities and differences among CCC products generated by applying the four methods on actual Sentinel-2 data in four biomes (temperate forest, tropical forest, wetland, and Arctic tundra) were examined by computing statistical measures and spatiotemporal consistency pairwise comparisons. Pairwise comparison of CCC predictions by the selected methods demonstrated strong agreement. The highest correlation (R2 = 0.93, RMSE = 0.4371 g/m2) was obtained between CCC predictions of PROSAIL inversion by LUT and SNAP toolbox approach in a wetland when a single Sentinel-2 image was used. However, when time-series data were used, it was PROSAIL inversion against SRVI (R2 = 0.88, RMSE = 0.19) that showed greatest similarity to the single date predictions (R2 = 0.83, RMSE = 0.17 g/m2) in this biome. Generally, the CCC products obtained using the SNAP toolbox approach resulted in a systematic over/under-estimation of CCC. RTMs inversion by LUT (INFORM and PROSAIL) resulted in a non-biased, spatiotemporally consistent prediction of CCC with a range closer to expectations. Therefore, the RTM inversion using LUT approaches particularly, INFORM for ‘forest’ and PROSAIL for ‘short vegetation’ ecosystems, are recommended for CCC mapping from Sentinel-2 data for worldwide mapping of CCC. Additional validation of the two RTMs with field data of CCC across biomes is required in the future.

SPAD-502 and atLEAF CHL PLUS values provide good estimation of the chlorophyll content for Hevea brasiliensis Müll. Arg. Leaves

Measurement of chlorophyll content using destructive methods is not efficient due to a large number of samples, cost, and time needed. Estimationof chlorophyll content by nondestructive methods using handheld chlorophyll meter may be considered to improve efficiency. This research aimed to determine the formula to convert SPAD-502 and atLEAF CHL PLUS values (relative indicator of chlorophyll content) to estimated (absolute) rubber leaves chlorophyll content. Twenty leaves of rubber plant were measured using SPAD-502 and atLEAF CHL PLUS at the same time to determine SPAD-502 and atLEAF CHL PLUS values. The measured leaves were then collected to determine the chlorophyll content using a standard laboratory procedure. Regression and correlation analyses (among 3 methods) were conducted using SAS v.9 software. The results showed that between SPAD-502 and atLEAF CHL PLUS values were closely correlated, hence both of the devices can substitute each other to estimate rubber leaf chlorophyll content. In addition, the relationship between atLEAF CHL PLUS and SPAD-502 values with actual chlorophyll content of rubber clone SP 217, PB 260, GT1, and all clones (general) were significant with high coefficient of determination (R2) as well as low Root Mean Square Error (RMSE) and Coefficient of Variation (CV). Therefore, by using formula determined in this study, both atLEAF CHL PLUS and SPAD-502 can be suggested for accurate, fast, and non-destructive estimation of chlorophyll content of rubber plant leaf.

A novel method for leaf chlorophyll retrieval based on harmonic analysis: a case study on Spartina alterniflora

Spartina alterniflora is the main invasive vegetation in wetland ecosystems, and information on its chlorophyll content is important data for quantitative research on the key ecological functions of wetland ecosystems. The Dongtan wetland of the Yangtze River estuary was used as the experimental research area, and the artificial cultivation field of Eupatorium was taken as the research object. To prevent uncertainty in the calculation of the chlorophyll content inversion factor for Spartina alterniflora leaves, harmonic analysis theory was adopted in this study. First, the original measured spectral data in the range of 400 nm ~ 1000 nm were decomposed and reconstructed by empirical mode decomposition (EMD), and the harmonic characteristic parameters of the EMD reconstruction spectral data were obtained by harmonic analysis (HA). Meanwhile, using the PROSPECT-D radiation transfer model, the simulated data was used to validate the inversion model. Based on these harmonic characteristic parameters, harmonic analysis-back propagation (HA-BP) and stepwise multiple linear regression (SMLR) models were established. Finally, the model was validated with data simulated by the PROSPECT-D model and compared the measured chlorophyll contents using the inversion values of the two models. The results show that the inversion accuracy of the HA-BP model was highest for the measured data. The determination coefficient (R2) and root mean square error (RMSE) of the model were 0.8528 and 6.8968 (μg/cm2), respectively, and the inversion accuracy of the simulated data was slightly lower than that of the measured data. The results show that the original spectral noise could be effectively suppressed by EMD and reconstruction, while harmonic analysis could compress the signal and prevent uncertainty in the spectral parameter calculation. Thus, the harmonic decomposition method could be applied to the inversion of Spartina alterniflora chlorophyll contents. The methods in this research provide a theoretical basis and technical support for the use of frequency domain parameters for the inversion of vegetation pigment contents.

Multi-Spatial Resolution Satellite and sUAS Imagery for Precision Agriculture on Smallholder Farms in Malawi

A collection of spectral indices, derived from a range of remote sensing imagery spatial resolutions, are compared to on-farm measurements of maize chlorophyll content and yield at two trial farms in central Malawi to evaluate what spatial resolutions are most effective for relating multispectral images with crop status. Single and multiple linear regressions were tested for spatial resolutions ranging from 7 cm to 20 m using a small unmanned aerial system (<small>sUAS</small>) and satellite imagery from Planet, <small>SPOT</small> 6, Pléiades, and Sentinel-2. Results suggest that imagery with spatial resolutions nearer the maize plant scale (i.e., 14–27 cm) are most effective for relating spectral signals with crop health on smallholder farms in Malawi. Consistent with other studies, green-band indices were more strongly correlated with maize chlorophyll content and yield than conventional red-band indices, and multivariable models often outperformed single variable models.

Discriminating trees species from the relationship between spectral reflectance and chlorophyll contents of mangrove forest in Malaysia

Abstract In situ spectral signatures of 19 mangrove species were measured to investigate whether mangrove species could be discriminated through spectral reflectance data. The study was conducted at Matang Mangrove Forest Reserve and the spectral signatures were recorded by using a handheld spectroradiometer. The reflectance data was analysed using one-way ANOVA to identify bands that exhibit significant difference (at 99.99% level) across the mangrove species. Potential important wave bands that can be used to discriminate mangrove species were identified by using linear discriminant analysis (LDA) (at 99.95% level). The study successfully discriminated 7 wave bands within visible region (400–700 nm), 9 wave bands within NIR region (701–1000 nm), 16 wave bands within SWIR-1 region (1001–1830 nm), and 19 wave bands within SWIR-2 region (1831–2500 nm). Previous studies indicated that the leaf spectral reflectance for mangrove species was reported to provide poor reflectance at visible region (400–700 nm) due to high chlorophyll concentration. Leaf surface reflectance appeared to be the most important factor in this variation. By conducting the laboratory measurement of leaf chlorophyll contents at three different absorbance viz. 1) A662, 2) A663, and 3) A645, the relationship with spectral reflectance of individual mangrove species was identified. Overall, spectral reflectance measurement pairing with leaf chlorophyll measurement provides a sound basis for classifying mangrove trees species (R2 > 80%). The study has shown that there are possibilities for discriminating mangrove trees species from chlorophyll content-to spectra linkages.

Comparison of SHD and Open-Center Training Systems in Almond Tree Orchards cv. ‘Soleta’

The increase in the demand for almonds, the development of novel self-fertile and late-flowering varieties, and the establishment of plantations in new irrigated areas have led to significant progress in the productive techniques of almond tree cultivation. One of the most important has been the increase in planting density, due to the development of dwarfing rootstocks. This paper presents a comparison between two training systems with ‘Soleta’ almond cultivar: a super high density (SHD) system using Rootpac-20 dwarfing rootstock versus an open-center training system using GF-677 rootstock. To this end, several parameters related to chlorophyll content (fluorescence and SPAD) and light interception (from photosynthetically active radiation (PAR) measurements) were monitored throughout two vegetative cycles, and other productive conditions (flowering, fruit set and production) were tracked at specific times of the cycle. The open-center system resulted in higher PAR interception than the SHD system, but also in the presence of poorly illuminated fractions of the canopy. Differences were observed between both systems in terms of average fruit weight and yield per canopy volume. Lower yields were obtained in SHD system than in open-center, which may be significantly increased by adapting the inter-row spacing. However, the degree of efficiency in the use of resources or productive inputs, such as irrigation, was favorable to the new SHD training system, so its potential to become a reference system in modern plantations (using over-the-row harvesters similar to those used for vine and olive trees) seems promising.

A Storable Mediatorless Electrochemical Biosensor for Herbicide Detection.

A novel mediatorless photo-bioelectrochemical sensor operated with a biofilm of the cyanobacterium Synechocystis PCC6803 wt. for herbicide detection with long term stability (>20 days) was successfully developed and tested. Photoanodic current generation was obtained in the absence of artificial mediators. The inhibitory effect on photocurrent of three commonly used herbicides (i.e., atrazine, diuron, and paraquat) was used as a means of measuring their concentrations in aqueous solution. The injection of atrazine and diuron into the algal medium caused an immediate photocurrent drop due to the inhibition of photosynthetic electron transport. The detected concentrations were suitable for environmental analysis, as revealed by a comparison with the freshwater quality benchmarks set by the Environmental Protection Agency of the United States (US EPA). In contrast, paraquat caused an initial increase (~2 h) of the photocurrent effect of about 200%, as this compound can act as a redox mediator between the cells and the anode. A relatively long-term stability of the biosensor was demonstrated, by keeping anodes colonized with cyanobacterial biofilm in the dark at 4 °C. After 22 days of storage, the performance in terms of the photocurrent was comparable with the freshly prepared biosensor. This result was confirmed by the measurement of chlorophyll content, which demonstrated preservation of the cyanobacterial biofilm. The capacity of this biosensor to recover after a cold season or other prolonged environmental stresses could be a key advantage in field applications, such as in water bodies and agriculture. This study is a step forward in the biotechnological development and implementation of storable mediatorless electrochemical biosensors for herbicide detection.

Identification of salt-responsive genes from C4 halophyte Suaeda nudiflora through suppression subtractive hybridization and expression analysis under individual and combined treatment of salt and elevated carbon dioxide conditions

Salinization of soil is a prime abiotic stress that limits agriculture productivity worldwide. To Study the mechanisms that halophytes take up to survive under high salt condition is important in engineering salinity stress tolerance in sensitive species. Suaeda nudiflora is a halophyte plant that grows in the saline environment and extreme high tidal belt. The species have high capability to produce high protein biomass in salty soils due to C4 photosynthesis. The physiological and biochemical changes in S. nudiflora under salinity stress were studied by measuring chlorophyll content, electrolytic leakage, level of lipid peroxidation and total soluble sugars. Increased lipid peroxidation and electrolytic leakage was observed in salt stressed S. nudiflora compared to control plants. A suppression subtractive hybridization strategy was employed to identify differentially expressed genes under salt treatment in S. nudiflora. A total of 333 positive clones were identified and screened. Of these, 250 expressed sequence tags were identified. cDNA subtraction library resulted in 33 contigs and 138 singletons. The functional annotation and metabolic pathways identification were performed using the Blast2GO program. In addition, we analyzed the expression patterns of 18 genes associated with salt stress-responsive pathways by semi-quantitative PCR under salt and elevated carbon dioxide (CO2) conditions. Several of the analyzed genes showed an increase in expression levels under different time points of salt treatment and at different concentrations of salt. When the same genes were studied for its expression under elevated CO2 concentrations, most of the known salt responsive genes showed higher expression under the combined treatment of elevated CO2 concentrations (500ppm) and NaCl treatment (200mM) compare to ambient condition. This implies that salt responsive genes are enhanced at elevated CO2 concentrations.

Whole leaf photosynthetic light response in a carnivorous plant species Sarracenia alata

Photosynthetic light-response curves of mature leaves of Sarracenia alata were generated and characterized using a custom built chamber (2.79 L) capable of accommodating whole leaves, or pitchers, coupled to a LI-COR 6400XT Portable Photosynthesis System. In addition to generating light-response curves, chlorophyll content, leaf area, and dry mass measurements were obtained for each pitcher. Gas-exchange variables from the light-response curves are reported on a leaf area and dry mass basis. Calculated light-saturated photosynthesis was found to be 2.09 µmol(CO2) m-2 s-1 with a light-saturation point of 315.14 µmol(photon) m-2 s-1, light-compensation point of 40.25 µmol(photon) m-2 s-1, dark respiration rate of -0.57 µmol(CO2) m-2 s-1, and apparent quantum efficiency of 0.033. The use of a large custom built chamber proved to be successful and the data presented indicate that adequate mixing and sampling was achieved. This study is the first to document photosynthetic response of S. alta. The data from this study indicate that S. alata collected from our study site photosynthetically performed like that of a shade-adapted C3 plant and the measurements were consistent with those published for other species of Sarracenia.

Genetic analysis and fine mapping of a qualitative trait locus wpb1 for albino panicle branches in rice

Chloroplast plays an important role in the plant life cycle. However, the details of its development remain elusive in rice. In this study, we report the fine-mapping of a novel rice gene wpb1 (white panicle branch 1), which affects chloroplast biogenesis, from a tropical japonica variety that results in an albino panicle branches at and after the heading stage. The wpb1 variety was crossed with Nipponbare to generate the F2 and BC1F2 populations. Green and white panicle branch phenotypes with a 3:1 segregation ratio was observed in the F2 population. Bulked segregant analysis (BSA) based on whole genome resequencing was conducted to determine the wpb1 locus. A candidate interval spanning from 11.35 to 23.79M (physical position) on chromosome 1 was identified. The results of BSA analysis were verified by a 40K rice SNP-array using the BC1F2 population. A large-scale F2 population was used to pinpoint wpb1, and the locus was further narrowed down to a 95-kb interval. Furthermore, our results showed that the expression levels of the majority of the genes involved in Chl biosynthesis, photosynthesis and chloroplast development were remarkably affected in wpb1 variety and in F2 plants with a white panicle branch phenotype. In line with the results mentioned above, anatomical structural examination and chlorophyll (Chl) content measurement suggested that wpb1 might play an important role in the regulation of chloroplast development. Further cloning and functional characterization of the wpb1 gene will shed light on the molecular mechanism underlying chloroplast development in rice.

Estimating canopy LAI and chlorophyll of tropical forest plantation (North India) using Sentinel-2 data

With the free and full access to images from Sentinel-2 satellite, the interest to use this data for quantitative retrieval of vegetation parameters is ever-increasing. LAI and chlorophyll are two key variables which are desired for studying productivity, nutrient and stress status of vegetation. Studies carried out on croplands using simulated Sentinel-2 MSI and parametric approach have identified vegetation indices (VIs) with high sensitivity to LAI and chlorophyll. To test how Sentinel-2 red-edge based VIs perform for retrieval of LAI and Chlorophyll of tropical mixed forest canopies, this study has been performed. The field measurements of LAI and chlorophyll content were recorded in a total of 28 ESUs (Elementary Sampling Units) in Bhakra range in the Tarai Central Forest Division, Uttarakhand (India). The in-situ measurements were statistically correlated with Sentinel-2VIs and strength of correlation was validated using Predicted Residual Error Sum of Squares (PRESS) statistic. Field LAI corrected for foliage clumpiness effect improved correlation of VIs with LAI. Among all VIs tested, Normalized Difference Index (NDI) offered highest positive correlation (R2 = 0.79, p < 0.05) with LAI while Red-Edge Chlorophyll Index (RECI) (R2 = 0.83, RMSE = 0.24 g/m2, p < 0.05) and Simple Ratio (SR) 740/705 (R2 = 0.79, RMSE = 0.27 g/m2, p < 0.05) were the most closely related to chlorophyll content. VIs with red-edge and NIR combinations offered best results.

Changes in phytoplankton production and upwelling intensity off A Coru\xf1a (NW Spain) for the last 28\xa0years

The analysis of a 28-year-long (1989–2016) series of monthly measurements of chlorophyll concentrations and primary production rates at a shelf station off A Coruña (NW Spain) provided evidence of changes at several time scales that were only partly related to upwelling intensity. Chlorophyll determinations were made in acetonic extracts and primary production rates by the measurement of 14C-uptake by natural phytoplankton populations in simulated in situ conditions. Wavelet analysis revealed multiple modes of variation in both series, particularly at high frequencies, but some were only significant for part of the series. For instance, the seasonal cycle was not uniform through the series despite the annual repetition of maxima and minima. At multiannual time scales, both series were divided in three quasi-decadal periods characterized by significant increases in mean values. Fluctuations in chlorophyll and primary production covaried with changes in upwelling intensity at annual scales, but annual means showed low correlation. Changes in dissolved nutrient concentrations from continental sources were the likely drivers of the observed changes in productivity at large time scales. Increases in the decadal mean rates of production and concentrations of chlorophyll were driven by increased intensity of spring blooms associated to increased nutrients and low salinity water in the surface. In contrast, blooms caused by upwelling nutrients remained unchanged along the series. This study illustrates the complexity of interactions in coastal upwelling areas at large time scales, where changes in continental nutrient inputs may affect phytoplankton production more than variations in upwelling intensity.