Nitrate Reductase Activity Research Articles

The Identification of AMT Family Genes and Their Expression, Function, and Regulation in Chenopodium quinoa

Quinoa (Chenopodium quinoa) is an Andean allotetraploid pseudocereal crop with higher protein content and balanced amino acid composition in the seeds. Ammonium (NH4+), a direct source of organic nitrogen assimilation, mainly transported by specific transmembrane ammonium transporters (AMTs), plays important roles in the development, yield, and quality of crops. Many AMTs and their functions have been identified in major crops; however, no systematic analyses of AMTs and their regulatory networks, which is important to increase the yield and protein accumulation in the seeds of quinoa, have been performed to date. In this study, the CqAMTs were identified, followed by the quantification of the gene expression, while the regulatory networks were predicted based on weighted gene co-expression network analysis (WGCNA), with the putative transcriptional factors (TFs) having binding sites on the promoters of CqAMTs, nitrate transporters (CqNRTs), and glutamine-synthases (CqGSs), as well as the putative TF expression being correlated with the phenotypes and activities of GSs, glutamate synthase (GOGAT), nitrite reductase (NiR), and nitrate reductase (NR) of quinoa roots. The results showed a total of 12 members of the CqAMT family with varying expressions in different organs and in the same organs at different developmental stages. Complementation expression analyses in the triple mep1/2/3 mutant of yeast showed that except for CqAMT2.2b, 11/12 CqAMTs restored the uptake of NH4+ in the host yeast. CqAMT1.2a was found to mainly locate on the cell membrane, while TFs (e.g., CqNLPs, CqG2Ls, B3 TFs, CqbHLHs, CqZFs, CqMYBs, CqNF-YA/YB/YC, CqNACs, and CqWRKY) were predicted to be predominantly involved in the regulation, transportation, and assimilation of nitrogen. These results provide the functions of CqAMTs and their possible regulatory networks, which will lead to improved nitrogen use efficiency (NUE) in quinoa as well as other major crops.

Lignin-based controlled-release urea improves choy sum growth by regulating soil nitrogen nutrients and bacterial diversity.

Lignin, as one of the few renewable resources among aromatic compounds, exhibits significant potential for applications in the agricultural sector. Nonetheless, there has been relatively limited research on the effects of lignin-based controlled-release urea (LCRU) on soil nitrogen nutrition and bacterial diversity. In this paper, the impact of LCRU on the growth of choy sum was investigated through a two-season field experiment. The findings suggest that the plant height, stem diameter, SPAD value, and above-ground dry weight under LCRU application surpassed those with conventional urea (CU), increasing by 40.27%, 26.97%, 52.02%, and 38.62%, respectively. Furthermore, the condition that the urea content was reduced by 15% (LCRU15) caused improvements of 24.76%, 26.97%, 43.23%, and 30.86% in the respective variables. Additionally, compared with the CU, the contents of vitamin C, soluble sugar, and soluble protein in choy sum were increased by the LCRU and LCRU15 treatments, and yet no significant differences were observed between the LCRU and LCRU15 treatments. Notably, the nitrogen used efficiency of choy sum increased to 68.90% with the LCRU15 treatment, compared to 64.29% with the LCRU treatment. The levels of soil available nitrogen, NO3 --N, and NH4 +-N were augmented by the LCRU and LCRU15 treatments. Meanwhile, soil urease and nitrate reductase activities were increased by 22.4%-28.6% and 12.3%-14.5%, respectively. Moreover, soil high-throughput sequencing results illustrated that the LCRU15 treatment enhanced the diversity and abundance of bacteria, particularly the abundance of Actinobacteria, Firmicutes, and Cyanobacteria, which can accelerate the decomposition of organic matter. In short, LCRU improves choy sum yield by influencing soil properties, enzyme activity, and microbial communities. These findings are anticipated to offer practical value for the sustainable application of LCRU in agriculture.

Effect of Potassium Optimization on Wheat Drought Tolerance in Controlled Conditions

Potassium is an essential nutrient that influences key processes in plants, including osmotic regulation, photosynthesis, and nitrogen assimilation. This study investigated the drought tolerance of wheat (Triticum spp.) plants treated with sufficient potassium (SK, 1 mM) and low potassium (LK, 0.05 mM) under PEG-induced drought stress. Plant physiological development, canopy temperature, photosynthetic efficiency, antioxidant defense enzymes, and nitrogen assimilation enzymes were assessed. In non-drought conditions, LK increased canopy temperature and reduced dry matter yield and photosynthetic performance, with these effects becoming more pronounced under drought stress. SK-treated plants exhibited higher biomass, chlorophyll content, maximum quantum efficiency of photosystem II, and lower canopy temperatures, even under drought conditions. Furthermore, LK restricted the accumulation of key osmotic regulators, including proline, amino acids, and soluble sugars. Under drought stress, LK plants also showed increased hydrogen peroxide and superoxide anion levels, while SK plants had lower reactive oxygen species accumulation and higher antioxidant enzyme activities (catalase and superoxide dismutase). Additionally, LK resulted in reduced activity of nitrogen assimilation enzymes (nitrate reductase, NR, and nitrite reductase, NiR) under both normal and drought conditions. In contrast, SK-treated wheat seedlings maintained higher NR and NiR activities and higher soluble protein content during drought stress. These findings underscore the critical role of potassium management in enhancing wheat yield, particularly in water-scarce regions, as optimal potassium supply strengthens essential physiological and biochemical mechanisms that improve plant tolerance to drought stress.

Nitrogen form differently modulates nitrogen uptake and utilization and related gene expression between two tea cultivars

Nitrogen (N) is essential for the growth and development of tea plants, and ammonium (NH4+) and nitrate (NO3-) are crucial N sources for tea yield and amino acid contents. However, the uptake and utilization of different N forms in tea plants are different. Reasonable N form is an important means to enhance the growth and development of tea plants. Therefore, supplying suitable N forms may be effective way to optimize N use efficiency. A hydroponic trial was conducted with 'Chuancha No.2′ (CC) and 'Emeiwenchun' (EW) tea cultivars with N form treatments: NH4+ and NO3-. The results showed that there were significant difference in the NH4+/NO3- uptake kinetics, dynamic changes in 15N abundance, enzyme activities, and related gene expression in N metabolism between CC and EW after NH4+/NO3- treatment. In CC and EW, NH4+ and NO3- uptake followed Michaelis-Menten kinetics at low N concentrations (< 1 mmol L-1), but CC exhibited a slightly higher uptake rate than EW when supplied with 2 mmol L-1 NH4+. In a 0-24h 15N tracing experiment, CC roots accumulated 15N faster than EW under NH4+. NH4+-fed CC exhibited higher GS activities and higher expression levels of CsAMTs and genes involved in N utilization, such as CsNR, CsGS2, CsGDH1, and CsTS1, compared to EW. When NO3- was provided, EW roots accumulated more 15N than CC roots from 8-24 h, which could be attributed to the higher NR activities and higher expression levels of CsNRT1.5, CsNR, CsGS1.1 and CsGS1.2 than those in CC. In summary, the two tea varieties exhibited distinct characteristics of N uptake and utilization, as well as gene expression patterns under NH4+/NO3- treatments. CC demonstrated an advantage in NH4+ uptake and assimilation, while EW exhibited an advantage in NO3-.

Bacteriocinogenic Activity of Lysinibacillus fusiformis NR_042072.1 Isolated from Cow Milk

The prevailing increase in the search for bio-preservative in the food industry has raised a global concern. Biological substances with health benefits and no toxicity are being considered as alternatives to chemical in food processing. Bacteriocin which are proteinous substances with preservative properties are now gaining attention in this regard and the search for new organisms for the production is becoming global. This study was focused on study of bacteriocinogenic activity of a local strain of Lysinibacillus fusiformis NR_042072.1 isolated from fresh cow milk obtained from Gaa Mobolohunduro, Tanke, Ilorin, Kwara State, Nigeria. Lactic acid bacteria was isolated from Cow milk, characterized and identified using standard microbiological methods. Bacteriocin was extracted from the isolate, partially purified and characterized using standard methods; and the antibacterial activity against some food borne bacteria which are Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis was determined using agar well diffusion method. Effect of certain physicochemical parameters on the antibacterial activity of the bacteriocin was also determined. The isolate was identified as Lysinibacillus fusiformis NR_042072.1. The bacteriocin showed antibacterial action against Escherichia coli and Pseudomonas aeruginosa with zone of inhibition of 17.0±0.5 and 20.0±1.0 mm against respectively. The bacteriocin was active within temperature of 4-50 0C, pH 5-7.5, bile salt concentration of 0.6-1.0 % and in the presence of the enzymes trypsin and pepsin. In conclusion, bacteriocin produced by Lysinibacillus fusiformis NR_042072.1 could be used to control food spoilage caused by the test organisms.

Nitrate assimilation pathway is impacted in young tobacco plants overexpressing a constitutively active nitrate reductase or displaying a defective CLCNt2

BackgroundWe have previously shown that the expression of a constitutively active nitrate reductase variant and the suppression of CLCNt2 gene function (belonging to the chloride channel (CLC) gene family) in field-grown tobacco reduces tobacco-specific nitrosamines (TSNA) accumulation in cured leaves and cigarette smoke. In both cases, TSNA reductions resulted from a strong diminution of free nitrate in the leaf, as nitrate is a precursor of the TSNA-producing nitrosating agents formed during tobacco curing and smoking. These nitrosating agents modify tobacco alkaloids to produce TSNAs, the most problematic of which are NNN (N-nitrosonornicotine) and NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone). The expression of a deregulated nitrate reductase enzyme (DNR) that is no longer responsive to light regulation is believed to diminish free nitrate pools by immediately channeling incoming nitrate into the nitrate assimilation pathway. The reduction in nitrate observed when the two tobacco gene copies encoding the vacuolar nitrate transporter CLCNt2 were down-regulated by RNAi-mediated suppression or knocked out using the CRISPR-Cas technology was mechanistically distinct; likely attributable to the inability of the tobacco cell to efficiently sequester nitrate into the vacuole where this metabolite is protected from further assimilation. In this study, we used transcriptomic and metabolomic analyses to compare the nitrate assimilation response in tobacco plants either expressing DNR or lacking CLCNt2 function.ResultsWhen grown in a controlled environment, both DNR and CLCNt2-KO (CLCKO) plants exhibited (1) reduced nitrate content in the leaf; (2) increased N-assimilation into the amino acids Gln and Asn; and (3) a similar pattern of differential regulation of several genes controlling stress responses, including water stress, and cell wall metabolism in comparison to wild-type plants. Differences in gene regulation were also observed between DNR and CLCKO plants, including genes encoding nitrite reductase and asparagine synthetase.ConclusionsOur data suggest that even though both DNR and CLCKO plants display common characteristics with respect to nitrate assimilation, cellular responses, water stress, and cell wall remodeling, notable differences in gene regulatory patterns between the two low nitrate plants are also observed. These findings open new avenues in using plants fixing more nitrogen into amino acids for plant improvement or nutrition perspectives.

Improving the Microenvironmental of Spring Soybean Culture and Increasing the Yield by Optimization of Water and Nitrogen

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm−2, N1), medium nitrogen (225 kg·hm−2, N2), and high nitrogen (300 k kg·hm−2, N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p &lt; 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p &lt; 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p &lt; 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m3 hm−2 and a nitrogen application rate of 300 kg·hm−2 can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.

Achieving Stable Partial Denitrification by Selective Inhibition of Nitrite Reductase with the Biosafe Aprotic Solvent DMSO.

The recently proposed partial denitrification (PD), terminating nitrate reduction to nitrite, has been regarded as a promising alternative to nitrite supplying for anammox bacteria. The most important aspect of the PD process for engineering application is the stable and continuous supply of nitrite. However, the activity of nitrate reductase is often higher than that of nitrite reductase (NIR), making it difficult to accumulate nitrite during the denitrification process. Herein, a strategy for achieving efficient and stable partial denitrification using the biosafe additive dimethyl sulfoxide (DMSO) was constructed, and the mechanism of DMSO inhibiting NIR was analyzed. DMSO addition reduced the expression of NIR gene, and 1% DMSO addition can significantly inhibit NIR enzyme activity to achieve a stable PD process. When the DMSO concentration increased to 3.5%, the NIR enzyme activity was almost inhibited with the enzyme activity of only 0.95 mg nitrite/min. However, the addition of DMSO has almost no inhibitory effect on the nitrate reductase (NAR) enzyme. The affinity constant of DMSO with the NAR enzyme is -2.4 kcal/mol, while the affinity constant of DMSO with the NIR enzyme is as high as -3.1 kcal/mol. DMSO shows a higher affinity for NIR. Moreover, DMSO and nitrite occupy the same catalytic cavity in the NIR enzyme, which is the fundamental reason why DMSO selectively inhibits the NIR enzyme. This study provides a new idea for realizing efficient and stable partial denitrification function.

Straw return amplifies the stimulated impact of night-warming on N2O emissions from wheat fields in a rice-wheat rotation system

ContextThe rise in winter and spring nighttime temperatures is a hallmark of global climate change, and warming has been proven to stimulate N2O emissions from wheat fields. However, it remains elusive whether this increasing effect is influenced by straw return, a practice considered globally as a future climate-smart agricultural strategy. Objectives or methodsA 3-year field experiment (2020−2023) was conducted with two straw treatments (S0: straw removal; S1: straw return) and two warming treatments (W0: no-warming; W1: night-warming) to quantify the effects of straw return and night-warming on N2O emissions from wheat fields in a rice-wheat rotation system. ResultsStraw return (S1) boosted post-jointing N2O production, whereas night-warming (W1) stimulated N2O emissions before the booting stage. Notably, the interaction between straw return and night-warming significantly affected seasonal cumulative N2O emissions, with W1 causing an 11.1 % increase under S0 and a more substantial 18.1 % increase observed under S1. Moreover, both S1 and W1 increased N2O warming potential, yield-scaled, and biomass-scaled N2O emissions. Compared to S0W0, soil dissolved organic C and inorganic N content increased in S1W1, while pH declined. Both S1 and W1 enhanced soil nitrification enzyme activity, nitrate reductase activity, and nitrite reductase activity in comparison to their respective controls. Additionally, S1W1 increased N2O production and inhibited N2O reduction by upregulating AOB-amoA and nirS gene abundances and downregulating nosZ gene expression, as evidenced by the elevated (nirS+nirK)/nosZ ratio. Random forest analysis identified that denitrification enzyme activity was the most important factor influencing N2O emissions. Conclusions or implicationsOur findings suggest that rice straw return may amplify the increasing effect of night-warming on N2O emissions from wheat fields. From an environmental protection perspective, straw return under the context of future warming will lead to an increased risk of N2O emissions, which may further exacerbate climate warming.

Nitrate reductase activity in ‘Syrah’ grapevine under three irrigation strategies

The objective of this study was to evaluate the activity of the enzyme nitrate reductase in ‘Syrah’ grapevine under three irrigation strategies. Irrigation was applied by a drip system, and the treatments were started 45 days after production pruning. The statistical design was completely randomized in a 3 x 5 factorial, corresponding to three irrigation strategies: controlled deficit irrigation, deficit irrigation and full irrigation, and five collections along the cycle: at 54, 60, 73, 87 and 101 days after pruning. Deficit irrigation and controlled deficit irrigation treatments caused longer water deficit to plants and reduced nitrate reductase activity. Full irrigation treatment promoted the highest values of leaf water potential and nitrate reductase activity at the end of the cycle. Leaf water potential and leaf age influence nitrate reductase activity.

Nitrogen at the crossroads of light: Integration of light signalling and plant nitrogen metabolism.

Plants have developed complex mechanisms to perceive, transduce, and respond to environmental signals, such as light, which are essential for acquiring and allocating resources, including nitrogen (N). This review delves into the complex interaction between light signals and N metabolism, emphasising light-mediated regulation of N uptake and assimilation. Firstly, we discuss the details of light-mediated regulation of N uptake and assimilation, focusing on the light-responsive activity of nitrate reductase (NR) and nitrate transporters. Secondly, we discuss the influence of light on N-dependent developmental plasticity, elucidating how N availability regulates crucial developmental transitions such as flowering time, shoot branching, and root growth, as well as how light modulates these processes. Additionally, we discuss the molecular interaction between light and N signalling, focusing on photoreceptors and transcription factors such as HY5, which are necessary for N uptake and assimilation under varying light conditions. A recent understanding of the nitrate signalling and perception of low N is also highlighted. The insilico transcriptome analysis suggests a reprogramming of N signalling genes by shade and identifies NLP7, bZIP1, CPK30, CBL1, LBD37, LBD38 and HRS1 as crucial molecular regulators integrating light-regulated N metabolism.

Relationships between C/N metabolism and rice growth related indicators under alternating drought and flooding stress

The increasing frequency of drought and flooding events due to climate change exposes rice to intensified alternating drought and flooding stress during different growth stages. To elucidate the impacts of alternating drought and flooding stress on rice growth and carbon (C) and nitrogen (N) metabolism, five irrigation regimes were established: alternating cycle of light drought-flooding-light drought during the tillering stage (T-LD), heavy drought-flooding-heavy drought during the tillering stage (T-HD), light drought-flooding-light drought during the jointing stage (J-LD), heavy drought-flooding-heavy drought during the jointing stage (J-HD), and frequent irrigation with shallow water depth (0–5 cm) for growth stages except for the maturation stage (CK). The results indicated that the tiller numbers, K+ concentrations in leaves, and above-ground biomass subjected to T-HD and T-LD treatments were significantly lower than in CK, J-HD and J-LD. Compared to CK, T-LD enhanced chlorophyll content and nitrate reductase activity (NRA) in rice leaves, leading to elevated photosynthetic rates (Pn) and improved δ13C values. The δ15N values under the CK, T-HD, and T-LD treatments were significantly greater than those under the J-HD and J-LD treatments (p<0.05). Additionally, NRA showed a significant positive correlation with leaf N concentration during the jointing stage. Path analysis indicates that δ13C, leaf water content, tiller number, leaf area, K⁺ concentration, and N concentration were directly related to above-ground biomass, whereas photosynthetic parameters indirectly affected biomass through N-metabolism related indicators. This result offers a theoretical support for the scheduling of irrigation and drainage practices in the field.

Efficient removal of nitrate and ammonium by strain Pseudomonas poae EH-E3 under acidic pH and low-temperature conditions

The combined effect of low temperature and an acidic environment may restrict the growth and metabolic activity of microorganisms involved in nitrogen removal. To overcome poor biological nitrogen removal efficiency during low-temperature treatment of acidic wastewater, a novel pure strain of Pseudomonas poae EH-E3 was successfully isolated and screened based on its strong heterotrophic nitrification and aerobic denitrification capacity. Strain EH-E3 could completely eliminate inorganic nitrogen sources of nitrate within 30h and ammonium within 20h at 15 °C and pH 5.0, with corresponding removal efficiencies for total nitrogen of 95.13% and 91.35%, respectively. Nitrogen balance testing indicated that strain EH-E3 removed 43.25% of ammonium, 45.72% of nitrate, and 51.20% of nitrite in the form of gaseous products. Enzyme activity assays revealed that the specific activities of ammonia monooxygenase, nitrate reductase, and nitrite reductase were 0.533, 0.956, and 0.011 U/mg proteins, respectively. These findings suggest that strain EH-E3 has strong potential for use in low-temperature treatment of acidic wastewater.

Combined application of earthworms and plant growth promoting rhizobacteria improve metal uptake, photosynthetic efficiency and modulate secondary metabolites levels under chromium metal toxicity in Brassica juncea L

Chromium (Cr) toxicity impairs essential morphological and metabolic activities in plants. The present investigation was carried out to evaluate the beneficial role of plant growth promoting rhizobacterial strains namely Pseudomonas aeruginosa (M1), Burkholderia gladioli (M2) and earthworms (Eisenia fetida) in alleviating Cr toxicity in 10 days old Brassica juncea L. The findings delineated that addition of earthworms and PGPR restored growth, boosted Cr uptake and showed upregulation of metal transporter genes (SULTR 1-4). Supplementation of rhizospheric amendments reinstated Cr induced impairment in photosynthetic attributes. Gaseous exchange attributes, the efficiency of PS II, the content of total phenols, anthocyanin and flavonoids was enhanced with application of earthworms along with PGPR. Confocal imaging of primary photosynthetic pigment (chlorophyll), accessory photosynthetic pigment (carotenoids) and total phenols showed maximum fluorescence with combined inoculation of earthworms and both microbial strains (M1M2). The gene expression analysis revealed that Phyotene synthase (PSY), Photosystem II core protein psb A, psb B were down regulated in Cr stressed seedlings which upon supplementation with earthworms and PGPR were upregulated. Further, Phenylalanine ammonialyase (PAL), chalcone synthase (CHS) were upregulated with addition of earthworms and PGPR. Increased nitric oxide content, enhanced activity and upregulation of nitrate reductase (NR) gene was observed with addition of PGPR and earthworms

Intercropping maize with leguminous green manure can compensate for the losses in grain yield and N uptake caused by a reduced N supply

A critical challenge for global food security and sustainable agriculture is enhancing crop yields while reducing chemical N inputs. Improving N use efficiency in crops is essential for increasing agricultural productivity. The aim of this study was to evaluate the impacts of intercropping maize with leguminous green manure on grain yield and N utilization under reduced N-fertilization conditions. A field experiment with a split-plot design was conducted in northwestern China from 2018 to 2021. The main plots consisted of two cropping systems: monocropped maize (SM) and intercropped maize/common vetch (IM). The subplots had three N levels: zero N application (N0, 0 kg ha-1), a 25% reduction from the traditional chemical N supply (N1, 270 kg ha-1), and the traditional chemical N supply (N2, 360 kg ha-1). The results showed that the negative effects of N reduction on maize grain yield and N uptake were compensated by intercropping leguminous green manure, and the improvements increased with cultivation years. The integrated system involving maize/leguminous green manure intercropping and a reduced N supply enhanced N translocation from maize vegetative organs to grains and increased the nitrate reductase and glutamine synthetase activities in maize leaves. The supercompensatory effect in maize leaves increased year by year, reaching values of 16.1, 21.3, and 25.5% in 2019, 2020, and 2021, respectively. These findings suggest that maize intercropping with leguminous green manure under reduced chemical N input can enhance N assimilation and uptake in the intercropped maize. By using this strategy, chemical fertilizer is effectively replaced by leguminous green manure, thereby improving N use efficiency and maintaining stable yields in the maize-based intercropping system.

Nitrogen Assimilation, Biomass, and Yield in Response to Application of Algal Extracts, Rhizobium sp., and Trichoderma asperellum as Biofertilizers in Hybrid Maize

Nitrogen is essential for plants’ growth, yield, and crop quality, and its deficiency limits food production worldwide. In addition, excessive fertilization and inefficient use of N can increase production costs and cause environmental problems. A possible solution to this problem is the application of biofertilizers, which improve N assimilation and increase biomass and yield. Therefore, the objective of this research was to evaluate the impact of the application of a combination of green and red algae (Ulva lactuca and Solieria spp.), Rhizobium sp., Trichoderma asperellum, and the combination of the above three biofertilizers on N assimilation. A completely randomized design was performed, with 10 plants per treatment and five treatments: T1 = control; T2 = algal extracts; T3 = Rhizobium sp.; T4 = T. asperellum; T5 = T2 + T3 + T4. Our analyses showed that the biofertilizers’ application was better than the control. The application of Rhizobium sp. had the best performance amongst all of the biofertilizers, with the highest nitrate reductase activity in maize leaves, which enhanced photosynthesis, increasing biomass and yield. The use of Rhizobium sp. showed increases in biomass (13.4%) and yield (11.82%) compared to the control. This research shows that biofertilizers can be a key component for sustainable agricultural practices.

Improving Peanut (Arachis hyphogaea L.) Productivity by Optimizing Nitrogen and Potassium Fertilization

Due to their high nutritious, peanuts (Arachis hyphogaea L.) are a popular kind among consumers. For growth and productivity, peanut plants need vital nutrients including N, P, K, Ca, Mg and K. P is especially necessary for the development of blooms, pods, and seeds. A 2 × 4 factorial design was employed in the study, and it was repeated three times. Factor II consists of P fertilizers (SP36: 36 % P2O5), specifically 0, 50, 100, and 150 kg P2O5/ha. Factor I sources of N are NO3- (potassium nitrate) and NH4+ (ammonium sulfate). The criteria that were observed were the amount of chlorophyll in the fifth leaf from the tip of the plant, NR activity, yield of the peanut pod, height of the peanut plant, and biomass of the peanut. The nitrogen source treatment has a major impact on ANR levels, yield, plant height, and chlorophyll. There is a greater interaction when using nitrate as a N fertilizer. Higher P2O5 NR yields, P up to 150 kg, Chlorophyll, height of peanut plants, peanut biomass, and yield of peanut pods are observed. Similarly, increased application of N fertilizer (ammonium, P up to 150 kg P2O5) results in higher NR yields. Height of the peanut plants, biomass, yield of the peanut pods, and chlorophyll.

Effects of Biochar and Nitrogen Fertilizer Application Ratio on Leaf Physiology and Soil Characteristics of Bambusa tuldoides ‘Swolleninternode’

As one of the main bamboo species in coastal sandy land protection forests, Bambusa tuldoides ‘Swolleninternode’ can effectively improve the structure of forest tree species, increase the diversity of tree species and enhance the protection efficiency. However, research on the cultivation and utilization of B. tuldoides is still relatively scarce. Therefore, in this study, B. tuldoides was used as the research object. By applying biochar and nitrogen fertilizer, the effects of different biochar and nitrogen fertilizer ratios on the physiology and soil characteristics of bamboo were analyzed, and the optimal ratio scheme was identified. The results showed that the ratio of the T5 (A2B2C3) treatment had the best effect on the total chlorophyll, non-structural carbohydrate and nutrient contents of B. tuldoides leaves, and the contents under treatments was generally higher than under the control, CK. The activities of soil invertase, nitrate reductase and nitrite reductase were significantly increased under biochar treatment, and the effects of the T5 treatment were the best. The results of principal component analysis showed that the absolute values of the coefficient of leaf potassium, phosphorus content and soil total nitrogen were larger and more important, and the comprehensive evaluation of the T5 treatment was the highest.

Assessing the effects of NapA gene overexpression on denitrification and denitrogenation in magnetospirillum gryphiswaldense MSR-1.

Previous research on Magnetospirillum gryphiswaldense MSR-1 found that MSR-1 has a good denitrification nitrogen removal ability and specific application prospects in the sewage biological nitrogen removal field. Therefore, this study selected the essential denitrification gene NapA in MSR-1-wt for overexpression, and the overexpressed MSR-1-NapA was successfully constructed. Q-PCR amplification experiment and AGAR gel electrophoresis experiment proved that the relative transcription level of the NapA gene was increased by more than four times, and the denitrification ability of MSR-1-wt and MSR-1-NapA was further determined by enzyme activity experiment, denitrification experiment, and flow cytometry. The results showed that overexpression of the NapA gene increased nitrate reductase activity in MSR-1-NapA by more than four times. In the solution with a nitrate concentration of 118.33 ± 3.23mgN/L, the denitrification efficiency of MSR-1-NapA was superior to that of MSR-1-wt, significantly enhancing both the denitrification and nitrogen removal capacities of MSR-1. This indicates its greater potential for biological nitrogen removal in wastewater treatment.

Combined effect of molybdenum and nitrogen fertilization on nitrogen metabolism and amino acid content in tobacco leaves

IntroductionThis study investigated the combined effects of molybdenum (Mo) and nitrogen (N) fertilization on N metabolism and amino acid content in the leaves of flue-cured tobacco (Nicotiana tabacum L.) during its mature stage through a pot experiment.MethodsDifferent application levels of Mo (0, 0.15, 0.30 mg/kg soil) and N (0.06, 0.24, 0.42 g/kg soil) were set to observe and analyze changes in leaf quality, N, and amino acid content in the tobacco plants.ResultsThe results revealed that the N fertilizer application level exhibited a primary effect on regulating the total nitrogen, nitrate nitrogen, soluble protein, and amino acid nitrogen concentrations within tobacco leaves, while the effectiveness of Mo fertilization was influenced by the level of N applied. Specifically, under the conditions of 0.24 g/kg soil N and 0.30 mg/kg soil Mo application, the N content, N accumulation, and dry matter mass of the tobacco plants increased significantly by 110%, 204%, and 48%, respectively. Concurrently, nitrate reductase activity increased by 107-fold, and the nitrate nitrogen content was relatively low, contributing to enhanced tobacco yield and safety. Moreover, this treatment led to a notable (170%) increase in free amino acid nitrogen content, with minimal impact on total amino acids and soluble proteins. Notably, it effectively increased the content of free amino acids beneficial to the sensory quality of tobacco (such as histidine, arginine, aspartic acid, isoleucine, and glutamic acid) without reducing the total amino acid content, while simultaneously reducing other amino acids that might affect quality. Therefore, the combined application of 0.30 mg/kg soil Mo and 0.24 g/kg soil N specifically optimized the amino acid composition in tobacco leaves, positively impacting overall quality and market competitiveness.DiscussionThis study provides a theoretical basis for the rational application of Mo fertilizer in Mo-deficient areas to improve the yield and quality of flue-cured tobacco.