Maximum Growth Research Articles

Effect of Various pH Levels on the Growth and Sporulation of Trichoderma viride Isolates and Assessing their Antagonistic Activity against Soil-borne Pathogens

Trichoderma viride strains, which are filamentous fungi commonly found in soil, possess the ability to parasitize various fungi harmful to plants. In this study, ten strains of T. viride were isolated from different locations in Uttar Pradesh, India, and examined for their cultural, physiological, morphological, and antagonistic characteristics against soil-borne pathogens. The T. viride isolates were assessed at different pH levels for their growth, sporulation, and antagonistic efficacy under in vitro conditions using the dual culture technique against five major soil-borne pathogens that cause significant diseases in cereal and pulse crops. Among the ten isolates tested, the 49CP isolate from Sultanpur exhibited the maximum growth and sporulation at a pH of 6.5 as well as the highest inhibition percentages of mycelial growth in the pathogens: 63.23% against Fusarium oxysporum f. sp. ciceri, 65.85% against Sclerotium rolfsii, 53.33% against Sclerotinia sclerotiorum, 53.84% against Pythium sp., and 48.00% against Rhizoctonia bataticola. Trichoderma viride is also recognized for its effectiveness as a biocontrol agent against soil-borne pathogens, which are responsible for significant crop losses.

Feasibility of Fruit Waste-Derived Media for Microbial Culture: A Sustainable and Low-cost Approach

The present study, conducted at the College of Agriculture, Latur during 2023-2024, explores the viability of using fruit waste-derived media as a cost-effective alternative to conventional media for the growth of plant pathogens. The research focuses on the growth performance of Pseudomonas fluorescens, Fusarium oxysporum f. sp. udum, and Sclerotium rolfsii on media prepared from fruit peel of eight fruits (Banana, Pineapple, Papaya, Orange, Guava, Pomegranate, Dragon fruit, and Sapota). These fruit-based media were compared to traditional Nutrient Agar (NA) and Potato Dextrose Agar (PDA). Results revealed that Sclerotium rolfsii showed maximum growth on Papaya Dextrose Agar, while Pseudomonas fluorescens exhibited the most robust growth on Banana, Papaya and Dragon Fruit Dextrose Agar. Fusarium oxysporum f. sp. udum demonstrated the highest radial growth on Banana Dextrose Agar. The study also observed that fruit-based media significantly reduced costs compared to Potato Dextrose Agar and Nutrient Agar making them a sustainable and accessible option for microbiological research, particularly in resource-limited environments.

Biodegradation of crude oil using bacterial strains isolated from the oil contaminated soil of Shakar Dara oil fields of Pakistan

Oil spillage is an important environmental concern especially in areas near to the oil fields. Microorganisms present one of the most suitable and sustainable way of oil degradation and soil remediation for reuse. The present study was based on the identification of the oil degrading bacteria isolated from the oil contaminated soils located near the Shakar Dara oil fields of Kohat District, Pakistan. The rate of oil degradation by the selected bacterial isolates and the required optimum pH and temperature conditions were also assessed in the present study. Out of the total 15 bacterial isolates, 12 had noticeable oil degrading abilities. In the hydrocarbons sensitivity assays using 5% crude oil, 04 isolates denoted as M1, M2A, M3 and M7 displayed the maximum growth and were chosen for further optimization. The maximum growth was observed at pH 7 and at a mesophilic temperature range (37 °C–40 °C). The selected isolates M1, and M3 were identified as Stenotrophomonas, and Bacillus while, the isolates M2A and M7 were identified as Salmonella spp. respectively. The oil degrading efficiency of Stenotrophomonas sp. M1 was 43% followed by that of Bacillus sp. M3 as 34%. It was concluded that the selected indigenous bacterial strains specifically M1 and M3 aid in the removal of organic contaminants probably owing to some specific enzyme systems synthesized by bacteria. The novel strains being capable of degrading crude oils will help in understanding the activated enzyme machinery and further in the development of an indigenous technology for bioremediation of such contaminated areas.

Application of the Electrical Microbial Growth Analyzer Method for Efficiently Quantifying Viable Bacteria in Ready-to-Eat Sea Cucumber Products

Accurate and efficient quantification of viable bacteria in ready-to-eat food products is crucial for food safety and public health. The rapid and accurate assessment of foodborne bacteria in complex food matrices remains a significant challenge. Herein a culture-based approach was established for easily quantifying viable bacteria in ready-to-eat sea cucumber (RSC) products. Samples of the liquid companion within the package were directly transferred into test tubes to determine bacterial growth curves and growth rate curves, utilizing the electrical microbial growth analyzer. Viable bacteria in the samples were then quantified based on the time required to attain the maximum growth rate indicated on the growth rate curve. At a concentration of 5.0 × 103 CFU/mL of viable bacteria in the liquid companion, the recovery rates were 108.85–112.77% for Escherichia coli (E. coli) and 107.01–130.54% for Staphylococcus aureus (S. aureus), with standard deviations of 1.60 and 3.92, respectively. For the solid content in the package, the quantification was performed using the same methodology following an additional homogenization step. At a concentration of 5.0 × 103 CFU/mL of viable bacteria in the sample, the recovery rates were 91.94–102.24% for E. coli and 81.43–104.46% for S. aureus, with standard deviations of 2.34 and 2.38, respectively. In instances where the viable bacterial concentration was 5.0 × 103 CFU/mL in RSC products, the total time required for the quantification did not exceed 10.5 h. This method demonstrated advantages over traditional plate counting and PCR methods regarding simplicity and efficiency, representing a promising alternative for the quantification of viable bacteria in food like RSC products.

Physiological Effects of TolC-Dependent Multidrug Efflux Pumps in Escherichia coli: Impact on Motility and Growth Under Stress Conditions.

Enterobacteriaceae possess eight TolC-dependent multidrug efflux pumps: AcrAB-TolC, AcrAD-TolC, AcrEF-TolC, MdtEF-TolC, MdtABC-TolC, EmrAB-TolC, EmrYK-TolC, and MacAB-TolC, which efflux bile salts, antibiotics, metabolites, or other compounds. However, our understanding of their physiological roles remains limited, especially for less-studied pumps like EmrYK-TolC. In this study, we tested the effects on swimming motility and growth under stress conditions of Escherichia coli mutants individually deleted for each inner-membrane transporter component of all eight TolC-dependent pumps, a mutant deleted for the AcrB-accessory protein AcrZ, and a mutant simultaneously deleted for all eight pumps (ΔtolC). We found that all mutants tested, except the ΔemrY and ΔacrZ mutants, displayed increased swimming motility. Additionally, the loss of each individual TolC-dependent pump or AcrZ did not reduce growth and sometimes even enhanced it compared to the parental strain under various growth conditions: temperature (LB at 25, 30, 37, and 42°C), pH (LB at pH 6.0, 7.4, and 9.0; and LB buffered to pH 6.0, 7.4, and 8.25), LB with limited air exchange, and nutritional stress (M9-glucose or M9-glycerol). In contrast, the ΔtolC mutant grew significantly slower than the parental strain under all conditions tested except in LB-TRIS pH 7.4 and LB with limited air exchange. Overall, these findings indicate that while individual TolC-dependent pumps are generally dispensable for growth under many stress conditions in the absence of antimicrobials, possibly due to their partially overlapping substrate profiles, TolC-dependent efflux is required for maximal growth under most conditions.

Amino acid requirements of yellow mealworm and black soldier fly larvae

Abstract In order to achieve optimal growth and health of farm animals, a different amount/ratio of essential amino acids in the feed is necessary in each phase of life. Knowledge about which amino acids are essential and in which quantities/proportions they are best administered has already greatly advanced the pig and poultry sector and is still being generated today. For the still young, rapidly developing insect sector, this knowledge could mean a major step forward towards breeding optimization. Therefore, in this research the needs of the 2 most commercially reared insect species, namely mealworms (Tenebrio molitor) (MW) and black soldier fly larvae (Hermetia illucens) (BSF), were investigated. The focus was on requirements for lysine, methionine, threonine, phenylalanine and tryptophan based on evidence from the literature and those of pigs. Semi-artificial diets based on at least 25% wheat bran (MW) and chicken feed/water (30/70) (BSF) (basic feed important for structure and certain micronutrients) supplemented with sugar and synthetic amino acids were tested. The diets were isoenergetic and isoproteinous. Of the amino acids studied, one was administered in different doses per experiment. The non-essential glutamic acid was used as a substitute at lower doses. Growth, as measured by weight gain, and survival were observed. The following results were for MW and BSF respectively. For lysine from a content of 0.35 g/100 g diet and 0.53 g/100 g diet no extra growth was noticeable. For methionine this was from 0.13 g/100 g and 0.16 g/100 g. Each time more threonine was given, a significant difference could be noticed and the minimum doses were around 0.42 g/100 g and 0.49 g/100 g. With tryptophan, for MW, there were no differences between the different concentrations. At the lowest dose of 0.06 g/100 g the maximum growth was already reached, whereas for BSF this was at 0.13 g/100 g.

Evidence for widespread thermal acclimation of canopy photosynthesis.

Plants acclimate to temperature by adjusting their photosynthetic capacity over weeks to months. However, most evidence for photosynthetic acclimation derives from leaf-scale experiments. Here we address the scarcity of evidence for canopy-scale photosynthetic acclimation by examining the correlation between maximum photosynthetic rates (Amax,2,000) and growth temperature ( ) across a range of concurrent temperatures and canopy foliage quantity, using data from >200 eddy covariance sites. We detect widespread thermal acclimation of canopy-scale photosynthesis, demonstrated by enhanced Amax,2,000 under higher , across flux sites with adequate water availability. A 14-day period is identified as the most relevant timescale for acclimation across all sites, with a range of 12-25 days for different plant functional types. The mean apparent thermal acclimation rate across all ecosystems is 0.41 (-0.38-1.04 for 5th-95th percentile range) µmol m-2 s-1 °C-1, with croplands showing the largest acclimation rates and grasslands the lowest. Incorporating an optimality-based prediction of leaf photosynthetic capacities into a biochemical photosynthesis model is shown to improve the representation of thermal acclimation. Our results underscore the critical need for enhanced understanding and modelling of canopy-scale photosynthetic capacity to accurately predict plant responses to warmer growing seasons.

The alteration of interspecific interaction responded to various relative sowing time in wheat/maize intercropping

IntroductionAn interspecific interaction is an important reason for the yield advantage of interspecific cropping compared with sole cropping, and the relative sowing time of species is an important factor affecting interspecific competitiveness. Our purpose was to explore the effects of different relative sowing times on the interspecific competition-recovery phenomenon in wheat and maize intercropping systems.MethodsThree planting methods (wheat/maize intercropping, wheat and maize sole cropping) and different relative sowing times of wheat were used to carry out field experiments over two years. Sequential harvest of subplots was performed between 3 and 6 times, and the biomass data were fitted to logistic growth model.ResultsDelaying the sowing time of wheat reduced the wheat yield, biomass and nutrient acquisition and increased those of maize, but wheat still had an intercropping advantage during the co-growth period. At the same time, the nutrient acquisition of maize was still inhibited, but its recovery growth advanced. Changing the relative sowing time of wheat significantly changed the maximum instantaneous growth rates of wheat and maize. Delaying the relative sowing time of wheat significantly reduced its maximum instantaneous growth rate, while enhancing that of maize, leading to a balanced mutual benefit.ConclusionsDelaying the sowing time of wheat to the same sowing time as maize will change wheat/maize intercropping from asymmetrical interspecific facilitation to symmetrical interspecific facilitation. However, in this case, intercropped wheat still had an interspecific competitive advantage in the co-growth stage, and intercropped maize still underwent a competition-recovery process.

Proton Cyclotron Waves and Pickup Ion Ring Distribution Instabilities Upstream of Mars

AbstractProton cyclotron waves (PCWs) upstream of Mars are thought to be associated with the instabilities of pickup ions. The instabilities of pickup ions of ring distributions have larger maximum growth rates compared with beam distributions. However, observations revealed a notably‐reduced occurrence rate of PCWs for pickup ions of ring distributions. Linear instability analysis and a corresponding two‐dimensional particle‐in‐cell (PIC) simulation are performed to investigate the instabilities of pickup ion ring distributions upstream of Mars. Linear instability analysis indicates that a pickup ion ring distribution is unstable to the ion cyclotron, ion Bernstein, and mirror instabilities. The corresponding PIC simulation confirms the linear analysis results and further demonstrates that the pickup ions are scattered toward an isotropic shell distribution by the waves excited. Interestingly, the saturation energy of the waves is much lower than that driven by a corresponding pickup ion beam distribution, and mirror waves eventually dominate the system.

Improvement of the Sand Quality by Applying Microorganism Induced Calcium Carbonate Precipitation to Reduce Cement Usage

This research aimed to study the utilization of microorganisms in the soil. These microorganisms were applied to improve the quality of soil and sand to reduce cement consumption. The process of microbial-induced precipitation of calcium carbonate (MICP) was used in this study, a bonding process to create a binding between sand particles from the naturally occurring processes of microorganisms. The study was conducted to determine the maximum growth rate of bacteria (maximum growth curve) of five strains as follows Proteus mirabilis TISTR 100, Bacillus thuringiensis TISTR 126, Staphylococcus aureus TISTR 118, Bacillus sp. TISTR 658 and Bacillus megaterium TISTR 067 in Nutrient Broth (NB) culture medium at 37°C. Christensen's Urea Agar slant (UA) was a preliminary screen for urease-producing bacteria. The color change of indicator color was seen in the slant, comparing the results (+) and control (-). The researchers have selected bacterial strains capable of producing significant amounts of enzymes to hydrolyze urea. It was found that the amount of calcium carbonate sediment produced by five strains of bacteria, namely Proteus mirabilis TISTR 100, Bacillus thuringiensis TISTR 126, Staphylococcus aureus TISTR 118, Bacillus sp. TISTR 658 and Bacillus megaterium TISTR 067 had the amount of sediment produced as follows: 3.430, 3.080, 2.590, 1.985, and 1.615 mg/ml, respectively. It was found that the species Bacillus sp. TISTR 658 does not produce the most calcium carbonate sediment. Nevertheless, it made the sand samples stick together tightly and form the perfect lumps. Therefore, improving the sand's composition has shown the potential to apply the MICP process to reduce the cement used.

Exploring local lignocellulosic substrates for the production of edible mushrooms in Northwestern Argentina

La Rioja province annually produces approximately 75,000 tons of agricultural residues and derived materials from agro-industrial activities, which could potentially be incorporated into oyster mushroom cultivation. This study aimed to evaluate the viability of this lignocellulosic biomass as a substrate for the cultivation of edible mushrooms belonging to the genus Pleurotus. Initially, the mycelial growth of two species (P. ostreatus and P. djamor) was assessed by formulating combinations of local substrates. Experimental crops were grown employing the most promising substrates, which were subsequently selected for chemical characterization. It was found that both strains exhibited maximum mycelial growth in the substrate formulated with jojoba leaf litter. A comparison of the two strains revealed no direct correlation between mycelium growth and productive performance. The highest biological efficiency (BE) values were obtained when P. ostreatus was cultivated in treatments combining jojoba leaf litter and grape pomace with olive pomace. Furthermore, these treatments showed suitable chemical properties and were formulated from problematic waste generated in large quantities in the region without proper processing and disposal methods. In this context, there is potential to ensure a continuous supply of this lignocellulosic biomass for cultivating these mushroom species over an extended period of time, thus providing a sustainable alternative for these regional by-products.

Bayesian inversion of bacterial physiology and dissolved organic carbon biodegradability on water incubation data

In aquatic ecosystems, dissolved organic carbon (DOC) plays a significant role in the global carbon cycle. Microorganisms mineralize biodegradable DOC, releasing greenhouse gases (carbon dioxide, methane) into the atmosphere. Extensive research has focused on the concentrations and biodegradability of DOC in aquatic systems worldwide. However, little attention has been given to uncertainties regarding the physiological characteristics of heterotrophic bacteria, which are crucial for biogeochemical modeling. In this study, the physiological properties of heterotrophic bacteria and the properties of DOC biodegradability in water are inferred through a Bayesian inversion approach. To achieve this, treated and natural water samples collected from the Seine River basin, were inoculated and incubated in laboratory. During incubation, the concentrations of DOC and heterotrophic bacteria biomass were measured. Then, a multiple Monte Carlo Markov Chains method and the HSB model (High-weight polymers, Substrate, heterotrophic Bacteria) are applied on the water incubation data. The results indicate a higher biodegradable fraction of DOC in natural water compared to treated water and significant variability in the fraction of fast biodegradable DOC within 5 days in both water samples. The significant variability highlights the uncertainties/challenges in the HSB model parameterization. The seven water samples used in the paper serve as a proof of concept. They are from various origins and display the potential of the method to identify parameter values in a large range of values. Because mortality rate of heterotrophic bacteria at 20 ∘C (kd20) showed a remarkable stability at 0.013 h−1, we considered that this parameter can be fixed at this value. The maximum growth rates at 20 ∘C (μmax20) was 0.061 h−1 while optimal growth yield (Y) estimated at 0.34 for treated water and at 0.25 for natural water. All these parameter values are well in accordance with previous determinations.

The Role of Zooxanthellae in the Growth of the Giant Clam Tridacna maxima in Outdoor Aquaculture System, Red Sea, Egypt

The Role of Zooxanthellae in the Growth of the Giant Clam Tridacna maxima in Outdoor Aquaculture System, Red Sea, Egypt

Thermal Stability and Thermal Fatigue Resistance Improvement of New High Toughness 5% Cr Hot Working Die Steel

This work developed a new high toughness 5% Cr martensitic hot working die steel (GYDCK-20), which exhibits better thermal stability and thermal fatigue resistance than AISI H13 steel. The concrete study involves: conducting on the evolution of microstructures and mechanical properties of two steels during the 60-hour holding process at 600°C, as well as the thermal fatigue behavior under the cyclic heating-water quenching conditions. The experimental results showed that in the case of ensuring the same initial hardness of two steels (43-43.5 HRC), GYDCK-20 emerged better thermal stability and superior toughness after 60-hour holding process at 600°C. After thermal cycling was increased from 1000 to 2000 times, the average crack length growth rate of GYDCK-20 was 31.8% lower than that of H13 and the maximum crack width growth rate was 35.1% lower than that of H13. It was found that thermal fatigue cracking was dominated by transgranular propagation at lower cycle numbers, while more inclined to propagate along the grain boundaries at higher cycle numbers. The higher toughness of GYDCK-20 steel promotes the dispersion of thermal stress, thereby enhancing the thermal fatigue resistance. It is mainly attributed to the lower V content of GYDCK-20 steel, which reduces the density of large-sized MC primary carbides. On the other hand, the lower Si content promotes the dissolution of cementite particles, and the secondary carbides precipitate in a smaller and uniformly distributed form, which hinders the propagation of thermal fatigue cracks, while also delays the coarsening of the fatigue-adverse phase M23C6 carbides.

Three-dimensional elastic Rayleigh–Taylor instability at the cylindrical interface

This paper presents a linear analysis of elastic Rayleigh–Taylor instability at both cylindrical column and cylindrical shell interfaces. By considering the rotational part of the disturbance flow field, an exact solution is derived, revealing that the most unstable mode is two-dimensional in the cross section. As the column radius decreases, the maximum growth rate increases, while the corresponding azimuthal wave number decreases incrementally until it reaches 1. Thinning the cylindrical shell is found to be a destabilizing effect, leading to an increase in both the cutoff wave number and the most unstable azimuthal wave number. The maximum growth rate usually increases as the shell becomes thinner, except in cases with small radii where feedthrough effects occur. For thin shells with small radii, the cutoff axial wave number is determined by the radius rather than the shell thickness. Comparisons between the growth rates derived from the potential flow theory and the exact solution show significant discrepancies in cylindrical shells, mainly due to substantial deviations in the cutoff wave number.

The impact of temperature on the growth of Pseudomonas aeruginosa in mineral waters originated from different wells: A predictive approach

This study aimed to evaluate the behavior of Pseudomonas aeruginosa (PSA) in natural mineral water sourced from three different extraction wells and stored at various temperatures (10, 12, 20, 23, and 30 °C) to calculate the kinetic growth parameters of this microorganism through predictive modeling. The physicochemical characterization of waters was also evaluated at the time of collection, and included the analysis of 40 different minerals, and quality parameters such as pH, conductivity, oxidation-reduction potential (ORP), total dissolved solids (TDS), salinity (PSU), and temperature (T). PSA survived in raw mineral water incubated at 12, 20, 23, and 30 °C; however, no growth was observed at 10 °C. Growth curves started with an initial population of ~ 2.5–3 log CFU/mL, and final PSA populations ranged from 3.5 to 4.9 log CFU/mL. The maximum specific growth rate (μmax) at 30 °C varied among the wells, with Well P-07 showing the highest growth rate (0.2 h−1), followed by Well P-08 (0.195 h−1) and well P-01 (0.133 h−1). At 12 °C, well P-01 exhibited the highest growth rate (μmax = 0.22 h−1), indicating a influence of mineral composition in the growth of PSA. The lag time (λ) also varied, with minimum values of 2.4 ± 0.1 h at 30 °C and maximum values of 41.6 ± 0.2 h at 12 °C. From these primary estimated parameters, it was possible to obtain five robust secondary models to describe the influence of temperature on the maximum growth rates and lag phase of PSA in the well. The estimated PSA growth parameters at 20 and 23 °C were subjected to a hierarchical cluster analysis and correlation plots to verify the influence of the physicochemical composition of the waters on the PSA behavior at each well's specific annual average temperature. This analysis confirmed a positive relationship (p < 0.05) between the presence of minerals (Ca, Fe, Sr, Mn, Na) and ions (SO4−3, Cl−) and the PSA lag phase time. These results underscore the need for tailored water quality management strategies that consider chemical composition and temperature to address specific microbial contamination risks.

Metabolic Versatility of acetogens in syngas Fermentation: Responding to varying CO availability.

Syngas fermentation using acetogenic bacteria offers a promising route for sustainable chemical production. However, gas-liquid mass transfer limitations and efficient co-utilization of CO and H2 pose significant challenges. This study investigated the kinetics of syngas conversion to acetate by Acetobacterium wieringae and Clostridium species in batch conditions under varying initial CO partial pressures (19 - 110 kPa) in batch cultures. A. wieringae strains, exhibited superior growth in all gas compositions, with a maximum growth rate of 0.104 h-1. The distinct CO, H2, and CO2 consumption patterns revealed metabolic flexibility and adaptation to varying syngas compositions. Notably, A. wieringae strains and C. autoethanogenum achieved complete CO and H2 conversion, with C. autoethanogenum also exhibiting net CO2 uptake. These findings provide valuable insights into the distinct metabolic capabilities of these acetogens and contribute to the development of efficient and sustainable syngas fermentation processes.

Transformation of dolomite powder into value added fertilizer and its effect on growth and yield of tomato plant

In Dolomite industry, various purposes have led to the generation of large amount of dolomite powder during mechanical processing. Dolomite is a rich source of Ca and Mg and XRF analysis showed the presence of certain micro and ultra micro plant nutrients in it. In the raw form these nutrients are not in easily plant accessible form. In the present research, dolomite powder was converted into easily plant accessible form and its value-added fertilizer is formed by mixing vermicompost with chemically converted dolomite powder. Three types of experiments- control (simple soil), control with compost (soil + vermicompost), and different percentages [X, 2X, 3X, 4X &amp; 5X (X= 3%)] of value-added fertilizer with soil were performed on growth and yield of tomato plant. It was found that among all treatments, 5X showed maximum plant growth, crop yield with increased biomass.

Effect of Foliar Spray of Micro - Nutrients on Fruit Growth and Yield of Guava (Psidium guajava L.) cv. Lalit

Aim: To examine the effect of foliar spray of micro - nutrients on fruit growth and yield of guava (Psidium guajava L.) cv. Lalit. Study Design: The Randomized Block Design (RBD) experimental design was used. Place and Duration of Study: An experiment was carried out during Hasth Bahar flowering seasons of 2021-22 and 2022-23 at Horticulture Research Farm of Babasaheb Bhimrao Ambedkar University. Methodology: There were nineteen treatments with three replication. The variety selected for experiment was Lalit. Results: The foliar application of Borax 0.2%+Zinc 0.4% was found to be the best treatment in improving the morphological characteristics of guava such as fruit length (8.59 cm), fruit width (8.6cm), fruit volume (169.09 cm), fruit weight (174.99 g), peel weight (17.13g), pulp weight (155.32g),number of seed per fruit (212.49),seed weight per fruit (2.53g), seed weight kg per plant (1.23 kg), pulp and seed ratio (61.29) and specific gravity (1.03 g cc-1) of guava fruit. Conclusion: On the basis of the result obtained in the present investigation, it is concluded the combined foliar application of Borax 0.2%+Zinc 0.4% (T11). Therefore, combined spray Borax 0.2%+Zinc 0.4% (T11) can be advocated to guava growers for maximum growth and yield parameters of guava.

Morphophysiological, biochemical, and nutrient response of spinach (Spinacia oleracea L.) by foliar CeO2 nanoparticles under elevated CO2

Nanomaterials offer considerable benefits in improving plant growth and nutritional status owing to their inherent stability, and efficiency in essential nutrient absorption and delivery. Cerium oxide nanoparticles (CeO2 NPs) at optimum concentration could significantly influence plant morpho-physiology and nutritional status. However, it remains unclear how elevated CO2 and CeO2 NPs interactively affect plant growth and quality. Accordingly, the ultimate goal was to reveal whether CeO2 NPs could alter the impact of elevated CO2 on the nutrient composition of spinach. For this purpose, spinach plant morpho-physiological, biochemical traits, and nutritional contents were evaluated. Spinach was exposed to different foliar concentrations of CeO2 NPs (0, 25, 50, 100 mg/L) in open-top chambers (400 and 600 CO2 μmol/mol). Results showed that elevated CO2 enhanced spinach growth by increasing photosynthetic pigments, as evidenced by a higher photosynthetic rate (Pn). However, the maximum growth and photosynthetic pigments were observed at the highest concentration of CeO2 NPs (100 mg/L) under elevated CO2. Elevated CO2 resulted in a decreased stomatal conductance (gs) and transpiration rate (Tr), whereas CeO2 NPs enhanced these parameters. No significant changes were observed in any of the measured biochemical parameters due to increased levels of CO2. However, an increase in antioxidant enzymes, particularly in catalase (CAT; 14.37%) and ascorbate peroxidase (APX; 10.66%) activities, was observed in high CeO2 NPs (100 mg/L) treatment under elevated CO2 levels. Regarding plant nutrient content, elevated CO2 significantly decreases spinach roots and leaves macro and micronutrients as compared to ambient CO2 levels. CeO2 NPs, in a dose-dependent manner, with the highest increase observed in 100 mg/L CeO2 NPs treatment and increased roots and shoots magnesium (211.62–215.49%), iron (256.68–322.77%), zinc (225.89–181.49%), copper (21.99–138.09%), potassium (121.46–138.89%), calcium (118.22–91.32%), manganese (133.15–195.02%) under elevated CO2. Overall, CeO2 NPs improved spinach growth and biomass and reverted the adverse effects of elevated CO2 on its nutritional quality. These findings indicated that CeO2 NPs could be used as an effective approach to increase vegetable growth and nutritional values to ensure food security under future climatic conditions.