Improved Biomass Production Research Articles

Stress reduction with co-culture of Miscanthus x giganteus and Pelargonium x hortorum in a pb contaminated soil to improve biomass production.

The industrial past of most regions in Lorraine and the intensification of activities on soils has increased the number of polluted sites. To rehabilitate these areas, several methods can be employed. In this study, co-culture of Miscanthus x giganteus and Pelargonium x hortorum was used to clean up a soil mainly contaminated by metallic elements including lead. The use of ornamental plants has been little studied, even if these species can be used to rehabilitate a site while improving its esthetics. At the end of the experiment, Pb concentrations were measured in the soil and plants. Furthermore, phytohormones were also measured to evaluate the defense mechanisms of the plants in front of pollutants. The results showed a reduction in Pb concentrations following the phytoremediation process implemented and that PxH was able to extract Pb from the soil. Results showed that co-culture was not beneficial to the development of MxG. Concerning the molecules synthesized by the plants under stress conditions, only salicin was found in MxG roots and aerial parts in particular for plants grown in individual culture. According to the results obtained, it seems that MxG is able to make compromises between the synthesis of protective molecules and its development.

Behaviour of ionic herbicides in different forestry soils derived from volcanic ash

Background: Weed control has been one of the most significant factors in forest establishment practices that can improve biomass production, and herbicides represent the most effective and convenient way to control weeds. The environmental concern about herbicides in this industry is because the herbicide-treated area is often located near water reservoirs or areas where rivers and creeks originate. This study aimed to determine the adsorption and degradation behaviours of seven ionic herbicides used in forestry production in five Chilean forestry soils and their relation to the leaching and to generate information to validate environmental predictive models. Methods: Adsorption and degradation of ionisable herbicides such as simazine, terbuthylazine, hexazinone, metsulfuron-methyl, indaziflam, flazasulfuron and glyphosate were studied in Andisol, Ultisol, Inceptisol, Entisol and Alfisol forestry soils, to be related to their leaching in 100-cm high and 11-cm diameter soil disturbed lysimeters. Herbicides were quantified using high-pressure liquid chromatography and gas chromatography. Relationships between soil physicochemical properties, herbicide adsorption and degradation, and herbicide leaching were determined. Results: In decreasing order, the herbicides were mobile in Entisol>Alfisol>Ultisol>Inceptisol>Andisol soils. On the other hand, the more leachable herbicides, from high to low, were: hexazinone, metsulfuron-methyl, simazine, glyphosate, terbuthylazine, flazasulfuron and indaziflam. The last two herbicides were not detected below 60 cm soil depth. In general, the maximum soil depth herbicide reached and the percentage mass leached up to 90 cm soil depth were inversely related to soil adsorption (1/Kd), soil porosity, humidity, silt, aluminium, and calcium soil content. Herbicide degradations were generally faster than referential published values. Conclusions: The environmental coefficients of ionic herbicides were more related to soil properties than their physicochemical properties. Persistence of herbicides in soil was smaller than that commonly reported in other studies or international databases and soil adsorption averages were generally higher than international reference values. The stronger relationship between ionic herbicide behaviour and forestry soil properties endorses the requirement to determine the environmental herbicides parameters in situ, avoiding using parameters estimated in other soils.

Overexpression of forage millet (Setaria italica) SiER genes enhances drought resistance of Arabidopsis thaliana.

ERECTA (ER) is a type of receptor-like kinase that contributes a crucial mission in various aspects of plant development, physiological metabolism, and abiotic stresses responses. This study aimed to explore the functional characteristics of the SiER family genes in millet (Setaria italica L.), focusing on the growth phenotype and drought resistance of Arabidopsis overexpressed SiER4_X1 and SiER1_X4 genes (SiERs ). The results revealed that overexpression of SiER4_X1 and SiER1_X4 genes in Arabidopsis significantly enhanced the leaf number, expanded leaf length and width, further promoted the silique number, length and diameter, and plant height and main stem thickness, ultimately leading to a substantial increase in individual plant biomass. Compared to the wild-type (WT), through simulated drought stress, the expression level of SiER genes was notably upregulated, transgenic Arabidopsis seeds exhibited stronger germination rates and root development; after experiencing drought conditions, the activities of antioxidant enzymes (superoxide dismutase and peroxidase) increased, while the levels of malondialdehyde and relative electrical conductivity decreased. These results indicate that overexpression of SiERs significantly enhanced both biomass production and drought resistance in Arabidopsis . The SiER4_X1 and SiER1_X4 genes emerge as promising candidate genes for improving biomass production and drought resistance in forage plants.

Carbonic anhydrase encapsulation using bamboo cellulose scaffolds for efficient CO2 capture and conversion

Utilizing carbonic anhydrase (CA) to catalyze CO2 hydration offers a sustainable and potent approach for carbon capture and utilization. To enhance CA's reusability and stability for successful industrial applications, enzyme immobilization is essential. In this study, delignified bamboo cellulose served as a renewable porous scaffold for immobilizing CA through oxidation-induced cellulose aldehydation followed by Schiff base linkage. The catalytic performance of the resulting immobilized CA was evaluated using both p-NPA hydrolysis and CO2 hydration models. Compared to free CA, immobilization onto the bamboo scaffold increased CA's optimal temperature and pH to approximately 45 °C and 9.0, respectively. Post-immobilization, CA activity demonstrated effective retention (>60 %), with larger scaffold sizes (i.e., 8 mm diameter and 5 mm height) positively impacting this aspect, even surpassing the activity of free CA. Furthermore, immobilized CA exhibited sustained reusability and high stability under thermal treatment and pH fluctuation, retaining >80 % activity even after 5 catalytic cycles. When introduced to microalgae culture, the immobilized CA improved biomass production by ∼16 %, accompanied by enhanced synthesis of essential biomolecules in microalgae. Collectively, the facile and green construction of immobilized CA onto bamboo cellulose block demonstrates great potential for the development of various CA-catalyzed CO2 conversion and utilization technologies.

The potential of bacterial endophytes on orchids

Orchids are one of the most exquisite and diverse plant species in nature. The seeds of orchids are non-endospermic and, therefore, dependent on endophytes for germination, growth, and adaptability. Orchids are prized for their beauty and therapeutic and culinary qualities by naturalists and the general public. Many orchid species are now endangered or vulnerable due to collectors' eagerness to take them. Current studies on orchids have concentrated on isolating and identifying the mycorrhizal and non-mycorrhizal endophytes that either directly or indirectly help orchids to grow, develop, and produce beneficial secondary metabolites. In orchids, bacterial endophytes play an essential role in the formation of mycorrhizae and the stability of relationships between plants and fungi. Endophytic bacteria can grow in orchids by producing phytohormones, doing photosynthesis, fixing nitrogen, promoting the mineral nutrition cycle, forming siderophores, and producing diverse beneficial metabolites to improve biomass production, stress tolerance, and biocontrol of potential phytopathogenic fungal species. This article examines how endophytic bacteria are associated with orchids and their potential growth-promoting abilities.

Macronutrients dynamics in copper-contaminated soils: Implications for hemp growth and its phytoremediation potential

Fibrous plants with higher biomass, particularly industrial hemp, have ability to withstand and accumulate significant quantities of heavy metals from contaminated environments. The present study aimed to evaluate the dynamics of different levels (ratios) of macronutrients nitrogen, phosphorus and potassium (NPK) viz., NPK1NPK (1:1:1); NPK2NPK (2:1:1); NPK3NPK (3:1:2); NPK4NPK (4:1:2) on hemp growth and Cu contents under various levels of Cu stress (100, 400 and 800 mg kg−1 on dry soil basis using CuSO4·5H2O). Results revealed that by increasing the Cu stress, growth and biomass decreased linearly and lipid per oxidation and enzymatic antioxidants increased. Balanced application of NPK improved the biomass and decreased the membrane damage by the modulation of malonaldehyde contents. Maximum concentration of Cu in roots (377.47 ± 4.90 mg kg−1), shoots (137.45 ± 5.60 mg kg−1) and (150.07 ± 3.57 mg kg−1) was recorded at Cu3NPK2 treatment as compared to control. Maximum translocation factor (TF) and bioaccumulation coefficients (BAC) in the shoots and leaves of hemp plant were noticed where Cu stress was applied at the rate of 100 mg kg−1. However, BAC and TF were below 1. The NPK2 treatment enhanced biomass and increase Cu content both in leaves and stems, rather than the roots. Our study suggests that balanced application of NPK is a practicable approach to alleviate Cu stress and improve biomass production of industrial hemp plant. These findings indicate that optimum nutrient supply, under Cu stress, can maximize the growth potential and overall health of industrial hemp, making it a viable option for phytoremediation and sustainable agriculture on contaminated soils.

Combined use of digestate and inorganic fertilizer alleviates the burden of class 1 integrons in perennial ryegrass rhizosphere without compromising aerial biomass production.

Antimicrobial resistance (AMR) is one of the main global health challenges. Anaerobic digestion (AD) can significantly reduce the burden of antibiotic resistance genes (ARGs) in animal manures. However, the reduction is often incomplete. The agronomic use of digestates requires assessments of their effects on soil ARGs. The objective of this study was to assess the effect of digestate on the abundance of ARGs and mobile genetic elements (MGEs) in the rhizosphere of ryegrass (Lolium perenne L.) and to determine whether half-dose replacement of digestate with urea (combined fertilizer) can be implemented as a safer approach while maintaining a similar biomass production. A greenhouse assay was conducted during 190days under a completely randomized design with two experimental factors: fertilizer type (unfertilized control and fertilized treatments with equal N dose: digestate, urea and combined fertilizer) and sampling date (16 and 148days after the last application). The results indicated that the digestate significantly increased the abundance of clinical class 1 integrons (intI1 gene) relative to the unfertilized control at both sampling dates (P < 0.05), while the combined fertilizer only increased them at the first sampling. Sixteen days after completing the fertilization scheme only the combined fertilizer and urea significantly increased the biomass production relative to the control (P < 0.05). Additionally, by the end of the assay, the combined fertilizer showed significantly lower levels of the macrolide-resistance gene ermB than digestate and a cumulative biomass similar to urea or digestate. Overall, the combined fertilizer can alleviate the burden of integrons and ermB while simultaneously improving biomass production.

Selection of microalgae in artificial digestate: Strategies towards an effective phycoremediation

Digestate is a complex by-product of anaerobic digestion and its composition depends on the digestor inputs. It can be exploited as a sustainable source of nutrients for microalgae cultivation but its unbalanced composition and toxic elements make the use challenging. Screening algae in a simplified synthetic digestate which mimics the main nutrient constraints of a real digestate is proposed as a reproducible and effective method to select suitable species for real digestate valorisation and remediation.Growth performance, nutrient removal and biomass composition of eight microalgae exposed to high amounts of NH4+, PO4− and organic-C were assessed. Using a score matrix, A. protothecoides, T. obliquus, C. reinhardtii, and E. gracilis were identified as the most promising species. Thus, three strategies were applied to improve outcomes: i) establishment of an algal consortium to improve biomass production, ii) K+ addition to the medium to promote K+ uptake over NH4+ and to reduce potential NH4+ toxicity, iii) P starvation as pretreatment for enhanced P removal by luxury uptake.The consortium was able to implement a short-term response displaying higher biomass production than single species (3.77 and 1.03–1.89 mg mL−1 respectively) in synthetic digestate while maintaining similar nutrient remediation, furthermore, its growth rate was 1.6 times higher than in the control condition. However, the strategies aiming to reduce NH4+ toxicity and higher P removal were not successful except for single cases. The proposed algal screening and the resulting designed consortium were respectively a reliable method and a powerful tool towards sustainable real digestate remediation.

Differential Mechanisms of Tolerance and Accumulation in Cajanus cajan (L.) Millsp. and Canavalia ensiformis (L.) DC in Response to Soil Manganese Concentration

ABSTRACT Cajanus cajan and Canavalia ensiformis are commonly used as cover crops due to their high biomass production, in addition they are also applied in recovery strategies for degraded areas. The objective of this study is to compare the tolerance, accumulation and translocation of Mn in the tissues of C. cajan and C. ensiformis, based on biomass production and the effects on the photosynthetic apparatus between species. The experiment was carried out in Red Latosol, contaminated with MnCl2 in the following concentrations: 0 (control), 80, 100, 120, 140 and 160 mg kg−1. Mn doses resulted in differentiated absorption, translocation and accumulation in plant organs, generating changes in the photosynthetic apparatus, reduction in dry mass and growth, and variations in tolerance and translocation levels between species. According to the results obtained, both species proved to be tolerant Mn and can be used in manganese management systems, they’re able to accumulate Mn in tissues, and not only maintain but also improve biomass production at intermediate doses, C. cajan indicates to be a better option for phytostabilization of Mn, on the other hand C. ensiformis, indicates to be a better option for phytoextraction of Mn in soils with contents up to 160 mg kg−1.

Determination of feed yield and quality parameters of whole crop durum wheat (Triticum durum Desf.) biomass under agrivoltaic system

AbstractAgrivoltaics represents a key technology for reaching sustainable development goals by reducing the competition between land used for food, for feed, and for electricity. It has been demonstrated that Agrivoltaics can increase land productivity and play a role in the expansion of renewable energy production. This work aimed to study the yield and nutritional characteristics, as well as feeding value for ruminants of Durum wheat biomass grown under agrivoltaic. Two years of controlled experiments revealed that the reduction in light moderately limited wheat yields in the phenological phase of soft dough in standard agrivoltaic trackers (i.e. with a Ground Coverage Ratio (GCR) = 13%), otherwise under extended trackers (i.e. GCR = 41%), the yields was reduced compared to control in whole light. The digestible neutral detergent fiber evaluated after 24 h of in situ rumen incubations increased with shading, resulting in different ratios of acid detergent lignin. More shaded theses also had superior crude and soluble proteins, acid detergent-insoluble protein, acid and neutral detergent fiber than the control. The biomass in the shaded treatments showed a better Ca: P ratio for ruminant nutrition. These characteristics are strategic in forage production, allowing a more flexible harvesting strategy. This additional contribution of the nutritional characteristics of Durum wheat produced on Agrivoltaic Systems could allow a better inclusion of the different types in diets and better management of silage or hay harvesting sites. These results might be helpful in improving biomass production and give valuable information on Durum Wheat under the Agrivoltaic System.

Detection of QTLs controlling flowering in a cross-pollinated F1 population of Miscanthus sinensis

Miscanthus is a perennial rhizomatous grass belonging to Andropogoneae, which is now used as lignocellulosic biomass crop. Miscanthus has a short history of domestication, so further breeding effort for improved biomass production is needed. Flowering plays a critical role in controlling vegetative growth and physiology of plant, so this study focused on finding quantitative trait locus controlling flowering of Miscanthus for use in marker assisted breeding. A cross-pollinated M. sinensis F1 population consisted of 278 progenies was produced, transplanted to the field and assessed in their flowering traits. Julian dates of flag leaf extension, first heading, half heading, first flowering, and half flowering were assessed in 2019, the third year after transplanting when Miscanthus was well established. The average Julian dates of the flowering traits were 198±9, 224±14, 233±14, 239±15 and 253±12, respectively, and showed a proximal normal distribution. Genotype by sequencing conducted by Illumina-hiseq using leaf DNA samples revealed the genetic map consisted of 1988 SNPs with average distance of 1.35 cM. Nine QTLs controlling flowering were detected exceeded 60% of LOD score threshold. These QTLs were neighboring 16 SNP markers, 5 of which were contained in known functional genes including RGL2 (gibberellin pathway regulation). Genetic map and marker information acquired through this study, including either annotated or not annotated markers, are expected to help understand and help breeding new Miscanthus in the future with desired flowering.

PagARGOS promotes low-lignin wood formation in poplar.

Wood formation, which occurs mainly through secondary xylem development, is important not only for supplying raw material for the 'ligno-chemical' industry but also for driving the storage of carbon. However, the complex mechanisms underlying the promotion of xylem formation remain to be elucidated. Here, we found that overexpression of Auxin-Regulated Gene involved in Organ Size (ARGOS) in hybrid poplar 84 K (Populus alba × Populus tremula var. glandulosa) enlarged organ size. In particular, PagARGOS promoted secondary growth of stems with increased xylem formation. To gain further insight into how PagARGOS regulates xylem development, we further carried out yeast two-hybrid screening and identified that the auxin transporter WALLS ARE THIN1 (WAT1) interacts with PagARGOS. Overexpression of PagARGOS up-regulated WAT1, activating a downstream auxin response promoting cambial cell division and xylem differentiation for wood formation. Moreover, overexpressing PagARGOS caused not only higher wood yield but also lower lignin content compared with wild-type controls. PagARGOS is therefore a potential candidate gene for engineering fast-growing and low-lignin trees with improved biomass production.

Potential of a chicken manure concentrate additive for Arthrospira maxima (Cyanophyceae): biochemical characterization and phycocyanin production

ABSTRACT Livestock manure is an eco-friendly and economical substrate for culturing microalgae. Chicken manure (CM) contains many organic nutrients, such as carbon, nitrogen and phosphorus, that are essential for microalgal growth. However, few studies have used CM to culture Arthrospira maxima, which has broad applications in the biofuel, pharmaceutical, food and feed industries, and is a candidate microalga for the treatment of animal waste. In this study, the use of CM concentrate (CMC) as an additive for A. maxima was evaluated. Zarrouk’s medium was combined with 0.5%, 1% and 1.5% (v/v) CMC. Fed-batch and batch culture methods were applied, and the biomass production and biochemical components of A. maxima were investigated. Fed-batch culture in a medium supplemented with 0.5% CMC resulted in the highest biomass production (1.86 ± 0.06 g l–1) and crude phycocyanin concentration (78.44 ± 0.20 mg g–1) on day 51 of culture, with significant differences compared to those in other groups (P < 0.05). However, significant differences among culture conditions were not observed in other biochemical components. This study demonstrates the newly established CMC-added cultivation method as a highly feasible strategy for industrial applications owing to its improved biomass production and nutritional advantages associated with increased phycocyanin concentration.

Cas9 deletion of lutein biosynthesis in the marine alga Picochlorum celeri reduces photosynthetic pigments while sustaining high biomass productivity.

Domestication of algae for food and renewable biofuels remains limited by the low photosynthetic efficiencies of processes that have evolved to be competitive for optimal light capture, incentivizing the development of large antennas in light-limiting conditions, thus decreasing efficient light utilization in cultivated ponds or photobioreactors. Reducing the pigment content to improve biomass productivity has been a strategy discussed for several decades and the ability to reduce pigment significantly is now fully at hand thanks to the widespread use of genome editing tools. Picochlorum celeri is one of the fastest growing marine algae identified and holds particular promise for outdoor cultivation, especially in saline water and warm climates. We show that while chlorophyll b is essential to sustain high biomass productivities under dense cultivation, removing Picochlorum celeri's main carotenoid, lutein, leads to a decreased total chlorophyll content, higher a/b ratio, reduced functional LHCII cross section and higher maximum quantum efficiencies at lower light intensities, resulting in an incremental increase in biomass productivity and increased PAR-to-biomass conversion efficiency. These findings further strengthen the existing strategies to improve photosynthetic efficiency and biomass production in algae.

Vegan grade medium component screening and concentration optimization for the fermentation of the probiotic strain Lactobacillus paracasei IMC 502® using Design of Experiments.

Lactobacillus paracasei IMC502® is a commercially successful probiotic strain. However, there are no reports that investigate growth medium composition in relation to improved biomass production for this strain. The major outcome of the present study is the design and optimization of a growth medium based on vegan components to be used in the cultivation of Lactobacillus paracasei IMC502®, by using Design of Experiments. Besides comparing different carbon sources, the use of plant-based peptones as nitrogen sources was considered. In particular, the use of guar peptone as the main nitrogen source, in the optimization of fermentation media for the production of probiotics, could replace other plant peptones (e.g. potato, rice, wheat, and soy) which are part of the human diet, thereby avoiding an increase in product and process prices. A model with R2 and adjusted R2 values higher than 95% was obtained. Model accuracy was equal to 94.11%. The vegan-optimized culture medium described in this study increased biomass production by about 65% compared to growth on De Man-Rogosa-Sharpe (MRS) medium. Moreover, this approach showed that most of the salts and trace elements generally present in MRS are not affecting biomass production, thus a simplified medium preparation can be proposed with higher probiotic biomass yield and titer. The possibility to obtain viable lactic acid bacteria at high density from vegetable derived nutrients will be of great interest to specific consumer communities, opening the way to follow this approach with other probiotics of impact for human health.

Is the application of bioactive anti‐stress substances with a seaweed‐derived biostimulant effective under adequate growth conditions?

AbstractThe use of biostimulants in agriculture is currently emerging as a resource to increase crop productivity and quality. Additionally, the concurrent application of other bioactive materials or bioregulators alongside biostimulants can prove valuable in mitigating oxidative stress induced by various abiotic stresses. However, in some cases, these compounds applied at inadequate doses produce toxic effects under non‐stressful conditions. Therefore, the objective of this study was to analyze the effects of applying various doses of a seaweed‐derived biostimulant containing additional bioactive compounds (Cytolan® Stress) under optimal growth conditions. Lettuce plants were grown under control conditions without biostimulants (control plants) and with two biostimulants Cytolan® (seaweed‐derived biostimulant with proline) and Cytolan® Stress applied foliarly at three doses (150, 300, and 500 mL/hL). Growth and quality parameters and physiological processes within primary and secondary metabolism were analyzed. The results identified the 300 mL/hL dose of Cytolan® Stress as the best treatment. Thus, it improved biomass production, induced photosynthetic activity, increased phytohormone, amino acids (AAs), and mineral nutrient profiles, and stimulated N assimilation. Besides, it substantially enhanced the antioxidant capacity and the concentration of various antioxidant compounds, leading to increased lettuce quality and potential stress tolerance. However, the 500 mL/hL Cytolan® Stress caused phytotoxic effects, underscoring the importance of applying the biostimulant at the proper dose.

Effect of plant growth-promoting molecules on improving biomass productivity in DISCOVR production strains

Phytohormones (Growth-Promoting Molecules, GPMs) have specific functions in the life cycle of a plant and are known to regulate plant growth, development, and stress responses independently, as well as through crosstalk with each other. These phytohormones are actively used in agriculture at scale, due to their efficiency at very low concentrations, and they also can be cost effective. Two phytohormones, auxin (indole-3-acetic acid, IAA) and gibberellic acid (GA), have also been shown to improve cell division, growth, and biomass production in algae. To test if phytohormones might have a similar beneficial result on potential algae biomass production strains, we evaluated the effect of IAA and GA3 on top-performing algae DISCOVR strains, Chlorella sorokiniana 1412, Monoraphidium minutum 26B-AM, Picochlorum celeri TG2-WT-CSM/EMRE, and Tetraselmis striata LANL1001 under laboratory conditions. Both GPMs showed growth promoting effects, but in contrast to previously published studies, we did not observe any increase in lipid accumulation with either IAA or GA3 supplementation. Then, to test phytohormone effects in a simulated outdoor environment, IAA treatments were conducted in environmental photobioreactors, revealing that IAA treatment significantly increased the growth and total biomass of M. minutum 26B-AM. In addition, investigation of the M. minutum 26B-AM genome combined with transcriptome data analysis revealed the presence of genes putatively involved in auxin biosynthesis and signaling, demonstrating that IAA pathways found in other algal species are also present in M. minutum 26B-AM. Finally, to begin to gauge whether GPM treatment is a viable approach for increasing biomass productivity in outdoor cultivation, we assessed, for the first time, the effects of adding GPMs to algae during scaled cultivation and the associated implications on economics for modeled large-scale algae farms.

Plant-soil synchrony in nutrient cycles: Learning from ecosystems to design sustainable agrosystems.

Redesigning agrosystems to include more ecological regulations can help feed a growing human population, preserve soils for future productivity, limit dependency on synthetic fertilizers, and reduce agriculture contribution to global changes such as eutrophication and warming. However, guidelines for redesigning cropping systems from natural systems to make them more sustainable remain limited. Synthetizing the knowledge on biogeochemical cycles in natural ecosystems, we outline four ecological systems that synchronize the supply of soluble nutrients by soil biota with the fluctuating nutrient demand of plants. This synchrony limits deficiencies and excesses of soluble nutrients, which usually penalize both production and regulating services of agrosystems such as nutrient retention and soil carbon storage. In the ecological systems outlined, synchrony emerges from plant-soil and plant-plant interactions, eco-physiological processes, soil physicochemical processes, and the dynamics of various nutrient reservoirs, including soil organic matter, soil minerals, atmosphere, and a common market. We discuss the relative importance of these ecological systems in regulating nutrient cycles depending on the pedoclimatic context and on the functional diversity of plants and microbes. We offer ideas about how these systems could be stimulated within agrosystems to improve their sustainability. A review of the latest advances in agronomy shows that some of the practices suggested to promote synchrony (e.g., reduced tillage, rotation with perennial plant cover, crop diversification) have already been tested and shown to be effective in reducing nutrient losses, fertilizer use, and N2 O emissions and/or improving biomass production and soil carbon storage. Our framework also highlights new management strategies and defines the conditions for the success of these nature-based practices allowing for site-specific modifications. This new synthetized knowledge should help practitioners to improve the long-term productivity of agrosystems while reducing the negative impact of agriculture on the environment and the climate.

Silicon (Si) mitigates the negative effects of iron deficiency in common bean (Phaseolus vulgaris L.) by improving photosystem activities and nutritional status

Silicon (Si) is the second most abundant element in the Earth's crust after oxygen. Its beneficial impact on crop development and yield, particularly under stressful conditions such as iron (Fe) deficiency, has been well documented. Fe deficiency is a critical constraint that limits crop production globally. The objective of this study was to investigate the effects of silicon (Na2SiO3) on common bean (Phaseolus vulgaris L. ‘Coco Rose’ variety) under iron-deficient conditions. The common bean plants were subjected to six treatments, which included three sufficient iron treatments (50 μM Fe) each paired with three varying silicon concentrations (0, 0.25, and 0.5 mM Si), and three iron-deficient treatments (0.1 μM Fe) each associated with the same silicon concentrations (0, 0.25, and 0.5 mM Si). The results indicate that iron deficiency had a negative impact on almost all the measured parameters. However, under silicon treatments, especially with 0.5 mM Si, the depressive effects of iron deficiency were significantly mitigated. The addition of 0.5 mM Si alleviated leaf chlorosis and improved biomass production, nutritional status, photosynthetic pigment content, photosynthetic gas exchange, and photosystem (PSI and PSII) activities. Interestingly, a greater beneficial effect of silicon was observed on PSII compared to PSI. This was accompanied by a significant augmentation in leaf iron concentration by 42%. Therefore, by enhancing the photosystem activities and nutritional status, among other mechanisms, silicon is capable of mitigating the adverse effects of iron-deficient conditions, making it a successful and effective solution to cope with this nutritional stress.

Optimizing SRT for improved biomass production and nutrient removal from wastewater secondary effluent in a continuous mode MPBR system with Monoraphidium sp.: An experimental and growth kinetics model approach

This study aimed to evaluate the impacts of solids retention time (SRT) and influent nutrient concentration on the specific growth rate and nutrient removal efficacy of Monoraphidium sp. in a continuous mode membrane photobioreactor (MPBR). At SRT of 1 d, maximum biomass productivity of 421 mg·L−1·d−1 and nutrient removal rates of 59.9 % and 79.8 % for total nitrogen (TN) and total phosphorus (TP) were achieved. After reducing the influent nutrient concentration, Monoraphidium sp. maintained high biomass productivity of 385 mg·L−1·d−1 and nutrient removal rates of >95 % for TN and TP. The most important factor in Monoraphidium sp. growth assessment was intracellular nitrogen concentration (QN) rather than extracellular nutrient concentration. Flynn modified Droop model showed a better fit when the dimensionless parameter (Kq) was 0.235 for the relationship between the specific growth rate (μ) and QN. The model also revealed that even at low nitrogen concentrations (0.1 mg·L−1), the nitrogen removal capacity of Monoraphidium sp. was equal to its maximum removal capacity. Even at different extracellular nutrient concentrations, the Flynn model showed a linear relationship between μ and light irradiance per unit algae biomass (Iavp), when Iavp was below 18 μmol·g−1·s−1. This study highlights the promising potential of Monoraphidium sp. in MPBR. It demonstrates that considering QN and Iavp is essential for optimizing MPBR to achieve high biomass production and inorganic nutrient removal from secondary wastewater effluent.