Higher Photosynthetic Rates Research Articles

Physiological basis for yield variations in dicoccum wheat genotypes under water stress condition

A field experiment was conducted to study “Physiological basis for yield variations in dicoccum wheat genotypes under water stress condition” during rabi 2018 at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad. The experiment was laid out in split plot design. The main plot consists of water regimes irrigated (providing irrigation during germination, tillering, flowering and grain filling stages) and creating stress (only two protective irrigations during germination and grain filling stages). Sub plot consists of 10 genotypes viz., DDK-50439, DDK-50427, DDK-50438, DDK-50044, DDK-50019, DDK-1044, DDK-50050, DDK-1029, HW-1098 and local. It was noticed from the investigation that, among the genotypes, DDK-1029 recorded higher grain yield (66.91 q ha-1) followed by DDK-1044 (62.229 q ha-1) as compared to other genotypes and the lowest was observed in local (44.39 q ha-1). The high yielding genotypes DDK-1029 and DDK-1044 had higher photosynthetic rate (20.62 and 19.18 µmol CO2 m-2 sec-1), transpiration rate (5.44 and 5.26 µmol H2O m-2 sec-1), stomatal conductance (0.48 and 0.38 µmol m-2 sec-1) and relative water content (84.5 and 82.21%) over other genotypes and the lowest values in these parameters were found in local. The reduction in grain yield in other genotypes was due to moisture stress where significantly reduced number of tillers, spike length and number of grains per spike. The genotypes DDK-1029 and DDK-1044 had higher grain yield in both irrigated and moisture stress conditions with minimum per cent yield reduction as compared to other genotypes. This indicates that, the genotypes DDK-1029 and DDK-1044 are to be most suited for drought tolerance.

Photoperiod modulates growth and pigments and 20-hydroxyecdysone accumulation in Brazilian ginseng [Pfaffia glomerata (Spreng.) Pedersen] grown in vitro

Photoperiod regulates different morphophysiological processes in plants, directly impacting photosynthetic performance and, consequently, primary and secondary metabolism. To date, there are no studies reporting the influence of photoperiod on the biosynthesis of phytoecdysteroids, such as 20-hydroxyecdisone (20-E). Here, we evaluated the effects of photoperiod on the development and metabolism of in vitro grown Pfaffia glomerata, an important medicinal species and producer of 20-E. Two P. glomerata accessions (Ac22 and Ac43) were cultivated for 40 days under different photoperiods: 4, 8, 16, and 24 h. Then, growth, physiological performance, 20-E content and gene expression related to the synthesis of this compound were evaluated. Longer photoperiods resulted in higher photosynthetic rates, growth, and biomass accumulation in both accessions. P. glomerata showed great plasticity to the different photoperiods tested and no sign of photoinhibition (Fv/Fm). Primary metabolism was modulated by photoperiod, with marked differences in the production of soluble sugars, starch, and amino acids. Anthocyanin production was also affected by the photoperiod. However, the accessions showed contrasting responses, in which longer photoperiods led to the highest anthocyanin contents in Ac22 and the lowest in Ac43, reflecting different adaptive strategies the light conditions. As a result of better photosynthetic performance and higher carbon availability, P. glomerata accumulated more 20-E during longer photoperiods. In this way, growing P. glomerata plants for longer photoperiods may represent a strategy for obtaining plants with larger biomass and higher 20-E yields. Photoperiod regulates the primary and secondary metabolism of P. glomerata plants grown in vitro, and longer photoperiods increase growth, photosynthetic performance, and accumulation of the phytoecdysteroid 20-hydroxyecdysone (20-E).

Cadmium phytotoxicity, related physiological changes in Pontederia cordata: antioxidative, osmoregulatory substances, phytochelatins, photosynthesis, and chlorophyll fluorescence

Pontederia cordata is a heavy metal accumulator, while the heavy metal tolerance mechanisms of this plant are not well understood. Hydroponic experiments were used to assess the effects of Cd2+ on antioxidative activities, osmoregulatory substances and photosynthesis in leaves. Exposure of 5mgL-1 Cd2+ for 7days, the photosynthetic apparatus functioned normally and sustained a relatively high photosynthetic rate, and good growth was observed. Under 50 and 75mgL-1 Cd2+, accelerated lipid peroxidation and increased peroxidase activity (POD; E.C.1.11.1.7) were detected, while no significant differences were observed in superoxide dismutase (SOD; E.C.1.15.1.1) and catalase (CAT; E.C.1.11.1.6) activities, as well as in lutein, ascorbic acid, and glutathione contains of leaves. Proline content increased, while soluble sugar and soluble protein contents decreased under 75mgL-1 Cd2+. Cd2+ at different concentrations induced a reduction in carotenoid, total carotenoid, and ascorbic acid-dehydroascorbate contents. A significant increase in phytochelatin content was induced by 75mgL-1. Chlorophyll content decreased under Cd stress and disturbed photosynthesis, causing dramatic reductions in photosynthetic parameters. Stomatal closure was responsible for a reduced photosynthetic rate under Cd2+ exposure. Cd2+ concentrations of no less than 25mgL-1 disorganized the photosynthetic apparatus, induced the partial closure, and decreased activity of the photosystem II (PS II) reaction center, thus disturbing light conversion and utilization, thereby decreasing the photosynthetic efficiency in PS II.

Collective Pulsing in Xeniid Corals: Part I-Using Computer Vision and Information Theory to Search for Coordination.

Xeniid corals (Cnidaria: Alcyonacea), a family of soft corals, include species displaying a characteristic pulsing behavior. This behavior has been shown to increase oxygen diffusion away from the coral tissue, resulting in higher photosynthetic rates from mutualistic symbionts. Maintaining such a pulsing behavior comes at a high energetic cost, and it has been proposed that coordinating the pulse of individual polyps within a colony might enhance the efficiency of fluid transport. In this paper, we test whether patterns of collective pulsing emerge in coral colonies and investigate possible interactions between polyps within a colony. We video recorded different colonies of Heteroxenia sp. in a laboratory environment. Our methodology is based on the systematic integration of a computer vision algorithm (ISOMAP) and an information-theoretic approach (transfer entropy), offering a vantage point to assess coordination in collective pulsing. Perhaps surprisingly, we did not detect any form of collective pulsing behavior in the colonies. Using artificial data sets, however, we do demonstrate that our methodology is capable of detecting even weak information transfer. The lack of a coordination is consistent with previous work on many cnidarians where coordination between actively pulsing polyps and medusa has not been observed. In our companion paper, we show that there is no fluid dynamic benefit of coordinated pulsing, supporting this result. The lack of coordination coupled with no obvious fluid dynamic benefit to grouping suggests that there may be non-fluid mechanical advantages to forming colonies, such as predator avoidance and defense.

Variations in photosynthesis associated traits and grain yield of minor millets

Photosynthesis is one of the important processes, and understanding its variability can be one of the approaches to improve crop productivity. It is presumed that most of the minor millets have C4 type of photosynthetic carbon fixation. However, research on quantifying the variability in photosynthesis associated traits in minor millets is limited. Objectives of this study were to (1) quantify the variation in leaf anatomical, physiological and yield traits among the minor millets and (2) to assess whether photosynthesis associated traits had a relationship with grain yield in minor millet. The result indicated that finger millet, little millet, barnyard millet, proso millet, foxtail millet and kodo millet had C4 leaf anatomy, and among them, finger millet had an increased vascular bundle and bundle sheath cell size. Among the minor millets, at ambient light, temperature and CO2 levels, the photosynthetic rate, stomatal conductance, intrinsic water use efficiency, number of major and minor veins, and grain yield were higher in foxtail millet. The CO2 response curve indicates that proso millet had a higher photosynthetic rate at higher concentrations of CO2 than other minor millets. However, the light response curve suggests that foxtail millet had a higher photosynthetic rate at higher light intensity levels. Among the minor millets studied, there was no relationship between mean photosynthesis associated traits over different growth stages with grain yield.

The possible role of extra magnesium and nitrogen supply to alleviate stress caused by high irradiation and temperature in lemon trees

Citrus trees are subjected to variation of environmental conditions throughout the annual cycle, especially during the flowering and fruit set. Heat waves have affected the environmental conditions required for optimum crop growth and have reduced fruit yield and quality worldwide. This study aimed to evaluate an extra supply of magnesium (Mg) and/or nitrogen (N) to increase citrus tolerance to excessive increased irradiation and consequent air temperature. Young lemon trees were grown in a greenhouse with extra Mg, N and Mg + N supply for five months and then exposed to heat for 12 days. After imposing stress condition, photosynthetic and enzymatic antioxidant system parameters were assessed to evaluate the impact of the extra nutrient supply in alleviating stress induced by combination of elevated irradiance and air temperature. Extra nutrient supply increased plant tolerance to the environmental stress, allowing maintenance of high photosynthetic and transpiration rates and low ratio of apparent electron transport rate per photosynthetic carbon assimilated. Enhanced Mg supply also increased activity of the antioxidant enzyme system and decreased the oxidative stress of plants. Trees treated with extra N exhibited increased chlorophyll concentrations and ability to harvest light energy. Citrus trees under stressed condition, such as elevated air temperature and radiation, associated to heat waves, exhibited less damage in the photosynthetic mechanism and high activity of the antioxidant enzymatic system when supplied with extra nutrient. It was concluded that extra Mg and N supply are important tools to prevent damages and enhance lemon trees biochemical and physiological responses to alleviate the harmful effects of unfavorable environmental condition.

A Novel Microalgae Harvesting Method Using Laser Micromachined Glass Fiber Reinforced Polymers

Microalgae are an ideal source for next-generation biofuels due to their high photosynthetic rate. However, a key process limitation in microalgal biofuel production is harvesting of biomass and extraction of lipids in a cost-effective manner. The harvesting of the algal biomass amounts to approximately 20 to 30% of the total cost of the cultivation; hence, developing an efficient and universal harvesting method will make the commercialization of microalgal bio-cultures sustainable. In this study, we developed, demonstrated, and evaluated a novel harvesting method based on Glass Reinforced Fiber Polymer (GFRP) panels, suitable for industrial-scale installations. The proposed method was based on previous observations of preferential micro-algae development on glass surfaces, as well as in the assumption that the microalgae cells would prefer to attach to and grow on substrates with a similar size as them. At first, we developed a laser micromachining protocol for removing the resin and revealing the glass fibers of the GFRP, available for algal adhesion, thus acting as a microalgae biomass harvesting center. Surface micromachining was realized using a ns pulsed ultraviolet laser emitting at 355 nm. This laser ensured high machining quality of the GFRP, because of its selective material ablation, precise energy deposition, and narrow heat affected zone. A specially built open pond system was used for the cultivation of the microalgae species Scenedesmus rubescens, which was suitable for biofuel production. The cultivation was used for the experimental evaluation of the proposed harvesting method. The cultivation duration was set to 16 days in order for the culture to operate at the exponential growth phase. The biomass maximum recovery due to microalgae attachment on the GFRP surface was 13.54 g/m2, a yield comparable to other studies in the literature. Furthermore, the GFRP surfaces could be upscaled to industrial dimensions and positioned in any geometry dictated by the photobioreactor design. In this study, the glass fiber reinforced polymer used was suitable for the adhesion of Scenedesmus rubescens due to its fiber thickness. Other microalgae species could be cultivated, adhere, and harvested using GFRP of different fiber sizes and/or with a modified laser treatment. These very encouraging results validated GFRPs’ harvesting capabilities as an attachment substrate for microalgae. Additional studies with more algae species will further strengthen the method.

High Photosynthetic Rates in a Solanum pennellii Chromosome 2 QTL Is Explained by Biochemical and Photochemical Changes.

Enhanced photosynthesis is strictly associated with to productivity and it can be accomplished by genetic approaches through identification of genetic variation. By using a Solanum pennellii introgression lines (ILs) population, it was previously verified that, under normal (CO2), IL 2–5 and 2–6 display increased photosynthetic rates by up to 20% in comparison with their parental background (M82). However, the physiological mechanisms involved in the enhanced CO2 assimilation exhibited by these lines remained unknown, precluding their use for further biotechnological applications. Thereby, here we attempted to uncover the physiological factors involved in the upregulation of photosynthesis in ILs 2–5 and 2–6 under normal (CO2) as well as under elevated (CO2). The results provide evidence for increased biochemical capacity (higher maximum carboxylation velocity and maximum electron transport rate) in plants from IL 2–5 and 2–6, whereas the diffusive components (stomatal and mesophyll conductances) were unaltered in these ILs in comparison to M82. Our analyses revealed that the higher photosynthetic rate observed in these ILs was associated with higher levels of starch as well as total protein levels, specially increased RuBisCO content. Further analyses performed in plants under high (CO2) confirmed that biochemical properties are involved in genetic variation on chromosome 2 related to enhanced photosynthesis.

Leaf traits and performance vary with plant age and water availability in Artemisia californica.

Leaf functional traits are strongly tied to growth strategies and ecological processes across species, but few efforts have linked intraspecific trait variation to performance across ontogenetic and environmental gradients. Plants are believed to shift towards more resource-conservative traits in stressful environments and as they age. However, uncertainty as to how intraspecific trait variation aligns with plant age and performance in the context of environmental variation may limit our ability to use traits to infer ecological processes at larger scales. We measured leaf physiological and morphological traits, canopy volume and flowering effort for Artemisia californica (California sagebrush), a dominant shrub species in the coastal sage scrub community, under conditions of 50, 100 and 150 % ambient precipitation for 3 years. Plant age was a stronger driver of variation in traits and performance than water availability. Older plants demonstrated trait values consistent with a more conservative resource-use strategy, and trait values were less sensitive to drought. Several trait correlations were consistent across years and treatments; for example, plants with high photosynthetic rates tended to have high stomatal conductance, leaf nitrogen concentration and light-use efficiency. However, the trade-off between leaf construction and leaf nitrogen evident in older plants was absent for first-year plants. While few traits correlated with plant growth and flowering effort, we observed a positive correlation between leaf mass per area and performance in some groups of older plants. Overall, our results suggest that trait sensitivity to the environment is most visible during earlier stages of development, after which intraspecific trait variation and relationships may stabilize. While plant age plays a major role in intraspecific trait variation and sensitivity (and thus trait-based inferences), the direct influence of environment on growth and fecundity is just as critical to predicting plant performance in a changing environment.

The suitability of Ulva fasciata, Ulva compressa, and Hypnea musciformis for production in an outdoor spray cultivation system, with respect to biomass yield and protein content

Land-based seaweed ponds can produce 500–700 t of fresh weight (FW) ha−1 year−1, but their profitability can be cut by the cost of pond construction, including ground leveling, infrastructure cost, and water agitation. A potentially cost-effective, land-based seaweed culture approach where seaweed grow on substrates by spray culture has been examined. We measured the yield and biomass quality of three intertidal cultivable seaweeds, Ulva fasciata, Ulva compressa, and Hypnea musciformis, in spray (known elsewhere also as film or drip culture) and pond culture approaches, varying surface inclination and nutrient loading. These technical details are necessary for the evaluation of the approach and for upscaling. The best yield (up to 84 g FW m−2 day−1, 44–84% of yield in ponds) and quality (protein content and additional parameters) of spray-grown U. fasciata was obtained on 6°-inclined trays with highly fertilized water. The highest protein content (24.5%), but with reduced yield, was obtained on 80°-inclined trays. H. musciformis and U. compressa, apparently thanks to their stringy morphologies, yielded in spray culture up to 286 g FW m−2 day−1 and 172 g FW m−2 day−1, respectively. The overall quality and resilience of spray-grown algae profited from nutrient enrichment, and the best yields were achieved with enrichment of 10 g N and 1 g P m−2 day−1 in H. musciformis and 15 g N and 1.5 g P m−2 day−1 in both Ulva species. Biomass growth occurred in layers, which visibly differed in color and consistency. A thin bleached top thalli layer protected the biomass below from dehydration and bleaching and allowed there a high photosynthetic rate. A spray culture of Ulva sp. on seawater-sprayed cement tiles, with minimal maintenance, yielded up to 50 g FW m−2 of tile day−1. Economically, spray culture appears to be particularly suitable to the stringy algae.

Constitutive expression of Asparaginase in Gossypium hirsutum triggers insecticidal activity against Bemisia tabaci

Whitefly infestation of cotton crop imparts enormous damage to cotton yield by severely affecting plant health, vigour and transmitting Cotton Leaf Curl Virus (CLCuV). Genetic modification of cotton helps to overcome both the direct whitefly infestation as well as CLCuV based cotton yield losses. We have constitutively overexpressed asparaginase (ZmASN) gene in Gossypium hirsutum to overcome the cotton yield losses imparted by whitefly infestation. We achieved 2.54% transformation efficiency in CIM-482 by Agrobacterium-mediated shoot apex transformation method. The relative qRT-PCR revealed 40-fold higher transcripts of asparaginase in transgenic cotton line vs. non-transgenic cotton lines. Metabolic analysis showed higher contents of aspartic acid and glutamic acid in seeds and phloem sap of the transgenic cotton lines. Phenotypically, the transgenic cotton lines showed vigorous growth and height, greater number of bolls, and yield. Among six representative transgenic cotton lines, line 14 had higher photosynthetic rate, stomatal conductance, smooth fiber surface, increased fiber convolutions (SEM analysis) and 95% whitefly mortality as compared to non-transgenic cotton line. The gene integration analysis by fluorescence in situ hybridization showed single copy gene integration at chromosome number 1. Collectively, asparaginase gene demonstrated potential to control whitefly infestation, post-infestation damages and improve cotton plant health and yield: a pre-requisite for farmer’s community.

Physiological Mechanism Involved in the Response to Four Lettuce Varieties to a Pre-transplant Root Restriction and a 6, benzyl aminopurine (BAP) Spray

Vegetable yield is positively related to the environment and negatively affected by the pot root restriction during both the nursery and post-transplant stages. Root restriction is a physical stress imposed on the root system when plants are grown in small containers, which leads to a pronounced decrease in root and shoot growth at both the transplant and pot stages. Based on the assumption that the plant responses are mainly associated with a negative hormonal signaling from roots, some researchers have proposed that these abiotic stresses may be overridden by using a pre-transplant spray with benzyl amino purine (BAP), a synthetic cytokinin able to regulate plant metabolism. Although the physiological mechanisms induced by BAP have been described, the implementation of commercial applications of BAP for vegetables is still a pending issue. The aim of this work was to analyze growth changes in four lettuce genotypes in the presence of different root restrictions degree by the use of different plug cell volumes but sprayed with a single BAP spray under the hypothesis that it would play a role as abiotic stress alleviators. Our results showed that the higher biomass accumulation in lettuce plants non root-limited and BAP-sprayed ones are supported by higher photosynthetic rates, by higher leaf number initiation and expansion and by photo assimilate partition to shoots. Understanding the plant responses to this hormonal manipulation and the physiological mechanism involved will allow adjusting the agronomic advice for different vegetables and reaching commercial yields to each of them.

Using species distribution models to locate the potential cradles of the allopolyploid Gypsophila bermejoi G. López (Caryophyllaceae).

Polyploidy has been an influential force in plant evolution, playing a crucial role in diversification. Differences in polyploid and diploid distributions have been long noted, with polyploid taxa especially abundant in harsh environments. These plants have higher photosynthetic rates and/or higher tolerance to water deficits. Moreover, there is data pointing to an increase in the rate of unreduced gamete formation by plants under conditions of stress. Accordingly, a higher frequency of polyploid individuals would be expected in populations living under extreme environments, a phenomenon that may be relevant when considering the origin of allopolyploid species. Hybridization between distinct autopolyploids is known to produce allopolyploids and hence, a high frequency of compatible autopolyploids in an area could enhance the formation of stable populations of the corresponding allopolyploid hybrid. Here we consider the allopolyploid species Gypsophila bermejoi G. López and its parental taxa G. struthium L. subsp. struthium and G. tomentosa L. We have used Species Distribution Models to locate areas with low bioclimatic suitability for both parental taxa during the Last Glacial Maximum (LGM), hypothesizing that the rate of tetraploid hybrid formation would be higher than expected where low suitability areas of both parental species overlap. We selected those areas taking into account the strict gypsophyllic nature of these taxa. There is data pointing to a post-glacial origin of the current G. bermejoi populations and according to our hypothesis, such locations could be centers for hybrid tetraploid formation or potential cradles of this species. Indeed, potential Mid-Holocene cradles were also identified in this manner. The evolution of bioclimatic suitability in both LGM and Mid-Holocene cradles was studied to assess the possible survival of the hybrids, and the current distribution of G. bermejoi proved to be consistent with our hypothesis.

Overexpression of the potato StEPF2 gene confers enhanced drought tolerance in Arabidopsis

Epidermal patterning factor 2 (EPF2) is a negative regulator of stomatal development, and is essential for plant growth, development, and environmental stress responses. However, the role of EPF2 in potato (Solanum tuberosum) has not been investigated to date. Here, we cloned and characterized the potato EPF2-like gene (StEPF2). StEPF2 is predominantly intercellular space localized and its transcripts were rhythmically expressed, and showed the highest expression in apical unexpanded leaves. Expression of StEPF2 was markedly down-regulated in response to abscisic acid and sodium chloride treatments; however, upon the application of polyethylene glycol, the expression of StEPF2 peaked at 4 h and then decreased gradually. Overexpression of StEPF2 in Arabidopsis (OE) substantially reduced stomatal density and photosynthetic rate, but had little effects on plant growth. Under drought stress, OE lines maintained higher photosynthetic rates, photosystem II efficiency, and instantaneous water use efficiency than wild-type (WT) plants. Moreover, OE lines showed less water loss and hydrogen peroxide accumulation in detached leaves compared with WT plants. Thus, our results suggest that StEPF2 acts as a negative regulator of stomatal development in potato, indicating that the role of EPF2 is conserved across plant species. Overall, StEPF2 represents an important target for the development of drought-tolerant potato cultivars via genetic engineering.

ALTERAÇÕES FISIOLÓGICAS NO CRESCIMENTO INICIAL DE PINHEIRA (Annona squamosa L.) SUBMETIDA AO ESTRESSE HÍDRICO

The objective of this work was to evaluate two accessions of sugar apple, cv. Crioula (with thick wax layer in the leaves) and cv. Verdinha (no wax deposition in the leaves) during initial growth under water stress conditions in two seasons: rainy season (July and August 2017) and dry season (January 2018). The work was carried out in a greenhouse, in a 2 x 4 factorial scheme, with two accessions of sugar apple and four stress times after irrigation suspension in a completely randomized design with 6 replicates. Were evaluated the physiological variables. The results showed that during the rainy season there was a higher photosynthetic rate (35,44 mol de CO2 m-2 s-1). in the two accessions, regardless of the level of stress. The maximum value of stomatal conductance (0.69 mol m-2 s-1) and minimum (0.02 mol m-2 s-1) were observed in seedlings evaluated in the dry season. The cv. Verdinha presented higher transpiration rate (5,49 mmol H2O m-2) in dry season. The plants evaluated in the rainy season presented greater leaf water potential. The physiological changes evidenced that the two accessions of A. squamosa have high adaptability capacity under conditions of water stress, independent of the wax deposition in the leaves.

Mineral nutrients, photosynthetic pigments and storage carbohydrates in turions of 21 aquatic plant species

Turions are vegetative, dormant overwintering storage organs produced by perennial aquatic plants in autumn. They are storage organs for non-structural carbohydrates and also mineral substances (N, P). Contents of photosynthetic pigments (chlorophyll a and b, carotenoids), storage carbohydrates (starch and five free sugars) and of mineral nutrients (N, P) were estimated in mature autumnal turions of 21 aquatic species from three different ecological groups and eight families; carbohydrates were also measured in the turions of eight species after an overwintering outdoors or in a refrigerator for 4-5 months. The mean turion N and P content was slightly higher than that reported in leaves or shoots of submerged aquatic plants. Assuming effective reutilization, >54% of the total N and >70% of the total P amount in mature turions could be theoretically allocated to newly sprouting shoots. The chlorophyll a+b contents in turions were the same to 2-6 times lower than those in adult leaves/shoots of submerged plants, but they ensure very high photosynthetic rates in sprouting turions. Starch and free sugars (total non-structural carbohydrates, TNC) created the main reserve substances in mature turions with variable ratios in different species. In mature turions, only TNC was significantly different between the rooted/unrooted species after application of a phylogenetic correction; the variability of other biochemical parameters has rather a taxonomic background. About 20% of the autumnal TNC content in turions declined over winter but the rest is available to support turion germination and sprouting. However, what is the minimal TNC pool remains unknown.

Phycoremediation coupled biomethane production employing sewage wastewater: Energy balance and feasibility analysis

In the present work Chlorella pyrenoidosa, Scenedesmus abundans and Anabaena ambigua have been evaluated for their biomass, phycoremediation efficiency and biomethane production potential by cultivating them in the primary treated sewage waste water (PTSWW) under controlled conditions. By the end of 25-day experiment, up to 52–88% reduction was observed in the nutrient concentration from the 3:1 ratio of PTSWW. Co-digestion of microalgal biomass (dry) with cow dung was performed to estimate biomethane potential. Biogas yield of 618–925 ml g−1 VS with 48–65% of methane content was obtained employing the microalgal species cultivated in PTSWW. Microalgae appeared notably competent at nutrient sequestration from PTSWW with significant microalgal biomass productivity for biogas production. Energy balance studies revealed the feasibility of coupling the remediation with energy generation. High photosynthetic rate and biomass generation ability along with nutrient confiscation supports employment of microalgae as a potential next generation biofuel source with waste management.

Biorreguladores em feijoeiro cultivado sob dois regimes hídricos

Restrições na disponibilidade hídrica favorecem eventuais danos à cultura do feijoeiro, e o uso de biorreguladores aprimora a sinalização vegetal e potencializa a indução de tolerância ao déficit hídrico. Este estudo objetivou caracterizar alterações fisiológicas, bioquímicas e biométricas em plantas de feijão submetidas à aplicação foliar de biorreguladores sob diferentes regimes hídricos. O ensaio consistiu na aplicação de um controle (água) e três biorreguladores (5 µM de ácido abscísico - ABA; 50 µM de metil jasmonato - MeJA e 5 µM de ABA + 50 µM de MeJA), além de apresentar dois regimes hídricos (60 e 80% da capacidade de campo), num esquema fatorial 4 x 2. Foram analisados: conteúdo de pigmentos fotossintetizantes, trocas gasosas foliares e índices biométricos das plantas de feijoeiro. Com resultado observou-se que o tratamento ABA+MeJA incrementou a concentração de clorofila b, atividades de ascorbato peroxidase (APX) e catalase (CAT), enquanto a taxa fotossintética foi estimulada pela mistura de biorreguladores aos 36 dias após o plantio (DAP), ABA e MeJA, isolados, propiciaram maior taxa fotossintética no feijoeiro aos 34 DAP, enquanto para as variáveis biométricas somente foram influenciadas pelos regimes hídricos, com relação aos mecanismos bioquímicos, constatou-se que o tratamento ABA+MeJA incrementou a atividade das enzimas antioxidantes e melhorou as respostas de trocas gasosas em condição de menor disponibilidade hídrica. Os biorreguladores avaliados nesta pesquisa são benéficos na modulação da fisiologia vegetal em plantas sob estresse hídrico, entretanto o suprimento de água adequado retrata um melhor desenvolvimento das plantas.

Exogenous Root Uptake of Glycine Betaine Mitigates Improved Tolerance to Salinity Stress in Avicenna germinans under Ambient and Elevated CO2 Conditions

In recent years, climate change has caused unpredictable variations in sea levels and an increase in atmospheric CO2 levels. Increasing temperatures and subsequent rates of evaporation have been demonstrated to cause increased coastal salinity in certain areas, which induces abiotic stress, in mangroves systems. The osmolyte, glycine betaine, has been shown in numerous studies to increase the tolerance of plants to environmental stressors, including salt stress. A handful of studies have demonstrated that increased CO2 concentrations confer increased salt tolerance and photosynthetic productivity of different mangrove species. Avicenna germinans, commonly referred to as the black mangrove, is native to Pacific and Atlantic coasts, and produces glycine betaine endogenously. This study sought to characterize the response of A. germinans exposed to increasing saline conditions, grown under normal and high CO2 concentrations. Elucidation of the role glycine betaine accumulation plays in tolerance to abiotic stress was investigated. A. germinans seedlings were subjected to increasing levels of salt stress (15–90 ppt) and treated with a dose response of glycine betaine (0–50 μM). Half of the seedlings were grown under ambient (400 ppm) CO2 conditions, and the other half were grown under elevated (800 ppm) CO2 conditions. Increased salinity tolerance and higher photosynthetic rates were observed among seedlings exposed to elevated CO2 conditions, as indicated by increased survival rates and qualitative health observations. This research may provide insights into potential consequences posed by climate change, as well as characterizing the glycine betaine signaling pathway in this mangrove species. Looking into the future, the knowledge obtained through this study may potentially contribute to our predictions of mangrove adaptability and therefore conferred protection of our coastlines in an ever‐changing world.

Application of high-throughput plant phenotyping for assessing biophysical traits and drought response in two oak species under controlled environment

Early plant selection for desirable traits is important in tree improvement programs and sustainable forest management. In this study, we demonstrate the use of image based high-throughput plant phenotyping (HTPP, LemnaTec 3D Scanalyzer, Germany), with Red, Green, Blue (RGB), and hyperspectral cameras, to quantify Quercus bicolor and Quercus prinoides seedlings growth and development [plant height, projected leaf area (LA), plant/canopy width, ConvexHull, and plant aspect ratio], and assess their response to a dry-down period, under controlled environment. HTPP images were validated against low throughput measurements, including gas exchange, leaf spectral properties, and morphological traits. Using HTPP, we recorded significant differences in growth dynamic in examined species, with faster initial growth rate early in the growing season, higher photosynthetic rates, larger LA, and seedling dimension, in Q. bicolor, compared to Q. prinoides. This has ecological implications on species responses to shading and timing of drought stress, as well as their competitive relationship with each other and with other species under changing climate. HTTP showed that both growth and leaf expansion ceased under dry-down treatment. Image derived and measured morphological traits were highly and significantly correlated under both well-watered and dry-down conditions for both species. To obtain meaningful physiological information using spectrometry, we calculated 12 vegetation indices (VIs) from both HTPP and handheld spectrometers. Vogelmann and Maccioni indices had the highest correlations across methods, suggesting their potential use for assessing oak seedlings performance and health. Our results emphasized the importance of VIs ground truthing, since VIs performance can vary significantly between species and treatments. HTPP tools can successfully be used to effectively assess forest seedlings of the two Quercus species, important for early plant selection for forest management purposes and tree improvement programs.