Nitrogen Use Efficiency In Plants Research Articles

Interactive Effects of Biochar and Nitrogen Fertilizer on Plant Performance Mediated by Soil Microbial Community in a Eucalypt Plantation

Interest in improving plant nitrogen use efficiency (NUE) in conjunction with reduced usage of nitrogen (N) fertilizers in forestry management is growing. Although biochar amendment is widely applied to increase soil nutrient availability and NUE, the mechanism underlying their positive effects remains little understood. We treated the economically important eucalypt species with biochar (BC), N-enriched fertilizer with 15N isotope labeling (NF), and biochar plus 15N-labeled fertilizer (NFB). Moreover, we determined plant N absorption and soil N availability, soil bacterial community composition and its putative keystone taxa, and plant NUE and competition index under different treatments. Our results indicated that NF and NFB significantly increased plant atom % 15N in both eucalypt stem, root, and foliar, as well as the competition index of eucalypt to forbs for acquiring N. NF and BC increased the network complexity of keystone taxa by shifting putative keystone taxa, including phylum Proteobacteria, Chloroflexi, Actinobacteria, Acidobacteria, and Firmicutes. Piecewise structural equation modeling indicated that variations in plant performance were best directly and positively predicted by soil Proteobacteria. This study highlights the importance of interactive effects between biochar and N fertilizer on plant performance mediated by soil microbial community. The change in soil putative keystone taxa has the potential to be a suitable predictor for plant performance in terms of biochar. Our findings may provide important implications for improving fertilization and afforestation management.

Response of tomato (Solanum lycopersicum) to varying levels of irrigation and nitrogen under trickle fertigation

An experiment was conducted during 2022 and 2023 at Lovely Professional University, Jalandhar, Punjab to study the response of tomato (Solanum lycopersicum L.) to 3 irrigation levels [I1, 70%; I2, 85% and I3, 100% of IWR] and 3 nitrogen fertilization levels [N1, 70%; N2, 85% and N3, 100% of RDN] in split plot design. On individual effect basis, the fruit yield first increased with the increase in amount of applied irrigation water in I2 (95.6 t/ha) and then decreased in I3 (93.5 t/ha). Irrigation water use efficiency (IWUE) was the highest in I2 (3.73 t/ha-cm). Plant growth, tomato yield and IWUE were significantly higher in N2 than that were found in N1 and N3. Nitrogen use efficiency (NUE) decreased with increasing nitrogen levels (N2 and N3) but it increased with increasing amount of water applied (I3). The treatments having deficit irrigation level as I1 and I2, significantly enhanced the lycopene content (27 to 33 µg/g) and reduced the nitrate content (74 to 95 mg/kg) in the fruit over full irrigation level I3. Nitrate content was highest in N3 (100 mg/kg). Among all the combination of irrigation and nitrogen fertilization levels the interaction of I2N2 (85% of IWR and RDN) was found the best to grow the drip-irrigated tomato crop. This combination gave optimum plant growth (87.5 cm), fruit yield (100 t/ha), IWUE (3.93 t/ha-cm), NUE (0.79 t/kg) and good quality fruit. The findings can be utilized for irrigation planning and nitrogen management in tomato cultivation and to conserve available fresh water resources in water scare regions of Punjab. In order to promote trickle fertigation at village level, the awareness programs for farmers could be conducted.

Genome-Wide Identification and Characterization of Long Non-Coding RNAs in Roots of Rice Seedlings under Nitrogen Deficiency

Long non-coding RNAs (lncRNAs) regulate gene expression in eukaryotic organisms. Research suggests that lncRNAs may be involved in the regulation of nitrogen use efficiency in plants. In this study, we identified 1628 lncRNAs based on the transcriptomic sequencing of rice roots under low-nitrogen (LN) treatment through the implementation of an integrated bioinformatics pipeline. After 4 h of LN treatment, 50 lncRNAs and 373 mRNAs were significantly upregulated, and 17 lncRNAs and 578 mRNAs were significantly downregulated. After 48 h LN treatment, 43 lncRNAs and 536 mRNAs were significantly upregulated, and 42 lncRNAs and 947 mRNAs were significantly downregulated. Moreover, the interaction network among the identified lncRNAs and mRNAs was investigated and one of the LN-induced lncRNAs (lncRNA24320.6) was further characterized. lncRNA24320.6 was demonstrated to positively regulate the expression of a flavonoid 3′-hydroxylase 5 gene (OsF3′H5). The overexpression of lncRNA24320.6 was shown to improve nitrogen absorption and promote growth in rice seedlings under LN conditions. Our results provide valuable insights into the roles of lncRNAs in the rice response to nitrogen starvation.

Effects of microbial fertilizer and irrigation amount on growth, physiology and water use efficiency of tomato in greenhouse

A pot experiment was conducted to investigate the effect of microbial fertilizer and irrigation regime on growth, physiology, water use efficiency (WUE) of tomato plants and soil nutrients. Microbial fertilizers: bacillus subtilis fertilizer (B.s.), bacillus polymyxa fertilizer (B.p.) and combined bacillus species (B.c.) were used as microbial fertilizers in the study, and plants treated without bacillus fertilizer were taken as control (CK). Three irrigation levels were set, i.e., full irrigation (I1) which plants were irrigated to 95 % field capacity (θf), and two deficit irrigations which were 2/3 I1 (I2) and 1/3 I1 (I3), respectively. The result showed that microbial fertilizers enhanced leaf photosynthesis rate (An), transpiration rate (Tr), relative chlorophyll content (CHL), nitrogen index balance (NBI) and leaf water potential (Ψl) in addition to increased plant root length, root surface area, root volume; and promoted plant water consumption, dry matter (DM) and plant water use efficiency (WUE). The content of nitrogen in leaf ([N]leaf), nitrogen use efficiency (NUE), the mineral nitrogen and soil microbial nitrogen content (MBN) were significantly improved by microbial fertilizer. Compared to CK, B.s., B.p. and B.c. increased An by 17.96 %, 11.77 % and 6.83 %, respectively. B.s. fertilizer significantly increased MBN and root length by 21.99 % and 55.08 % than CK. Deficit irrigations decreased An, Tr, stomatal conductance (gs), and improved intrinsic water use efficiency (WUEi) and instantaneous water use efficiency (WUEinst). Deficit irrigation depressed leaf area, Ψl, CHL, NBI, root length, root surface area and root volume, hereby declined plant water consumption, and optimized plant WUE. In this study, microbial fertilizers mitigated negative effects of deficit irrigation on photosynthesis and DM and improved WUE. Compare to CK and other microbial fertilizers, B.s fertilizer treated plants possessed enhanced plant water status, higher leaf gas exchange rates, more developed root system, higher plant nitrogen accumulation and NUE. Hereby, the B.s. fertilizer is an optimal strategy to mitigate water stress in tomato plants and promoted plants growth.

MiRNA mediated regulation of nitrogen response and nitrogen use efficiency of plants: the case of wheat.

Nitrogen (N) is needed for plant growth and development and is the major limiting nutrient due to its higher demand in agricultural production globally. The use of N fertilizers has increased considerably in recent years to achieve higher cereal yields. High N inputs coupled with declining N use efficiency (NUE) result in the degradation of the environment. Plants have developed multidimensional strategies in response to changes in N availability in soil. These strategies include N stress-induced responses such as changes in gene expression patterns. Several N stress-induced genes and other regulatory factors, such as microRNAs (miRNAs), have been identified in different plant species, opening a new avenue of research in plant biology. This review presents a general overview of miRNA-mediated regulation of N response and NUE. Further, the in-silico target predictions and the predicted miRNA-gene network for nutrient metabolism/homeostasis in wheat provide novel insights. The information on N-regulated miRNAs and the differentially expressed target transcripts are necessary resources forgenetic improvement of NUE by genome editing.

Improving tomato nitrogen use efficiency with lignite-derived humic substances

Improving plant nitrogen use efficiency (NUE) is critical in sustainable cropping systems. Humic substances (HS), a type of plant biostimulant, have the potential to increase plant nitrogen (N) uptake and assimilation, while having the ability to change soil environment using their stable and solid products as soil amendments. In this two-year field study, the effects of lignite-derived HS soil amendments applied to topsoil at a rate of 1.5 t/ha was evaluated at two levels of N inputs (90 and 180 kg/ha) on tomato (Solanum lycopersicum cv. ‘Camaro’) growth performance, nitrogen use status, and soil property changes. HS increased plant canopy growth (leaf area index, LAI), shoot and fruit biomass, total N and NUE across different growth stages. During early growth, increased NUE caused by HS application was mainly due to increased nitrogen uptake efficiency (NUpE) under high N input management, while during the mid-late growth period, HS reduced the detrimental effects of N stress caused by low N input, as evidenced by improved biomass accumulation and NUE resulting from increased nitrogen utilization efficiency (NUtE). Overall, HS application improved the yield of tomatoes grown under low N input by 35.2% and 31.1%, in the first and second years of the experiment, respectively. Low N input reduced tomato plant normalized difference vegetation index (NDVI), LAI, biomass accumulation and total N, but improved plant NUE, NUpE and NutE compared with the high N input treatment. At the end-season, HS treated soil had lower soil NO3-N retention, which was positively correlated with increased plant total N. Soil organic matter content was improved after incorporating HS for two years. These results show that lignite-derived solid HS can be used as a soil amendment to sustainably improve the productivity and resource use efficiency of tomatoes and improve their soil environment.

Biochar-extracted liquor stimulates nitrogen related gene expression on improving nitrogen utilization in rice seedling.

Biochar has been shown to be an effective soil amendment for promoting plant growth and improving nitrogen (N) utilization. However, the physiological and molecular mechanisms behind such stimulation remain unclear. In this study, we investigated whether biochar-extracted liquor including 21 organic molecules enhance the nitrogen use efficiency (NUE) of rice plants using two N forms (NH4 +-N and NO3 --N). A hydroponic experiment was conducted, and biochar-extracted liquor (between 1 and 3% by weight) was applied to rice seedlings. The results showed that biochar-extracted liquor significantly improved phenotypic and physiological traits of rice seedlings. Biochar-extracted liquor dramatically upregulated the expression of rice N metabolism-related genes such as OsAMT1.1, OsGS1.1, and OsGS2. Rice seedlings preferentially absorbed NH4 +-N than NO3 --N (p < 0.05), and the uptake of NH4 +-N by rice seedlings was significantly increased by 33.60% under the treatment of biochar-extracted liquor. The results from molecular docking showed that OsAMT1.1protein can theoretically interact with 2-Acetyl-5-methylfuran, trans-2,4-Dimethylthiane, S, S-dioxide, 2,2-Diethylacetamide, and 1,2-Dimethylaziridine in the biochar-extracted liquor. These four organic compounds have similar biological function as the OsAMT1.1 protein ligand in driving NH4 +-N uptakes by rice plants. This study highlights the importance of biochar-extracted liquor in promoting plant growth and NUE. The use of low doses of biochar-extracted liquor could be an important way to reduce N input in order to achieve the purpose of reducing fertilizer use and increasing efficiency in agricultural production.

Unlocking the potentials of nitrate transporters at improving plant nitrogen use efficiency.

Nitrate ( ) transporters have been identified as the primary targets involved in plant nitrogen (N) uptake, transport, assimilation, and remobilization, all of which are key determinants of nitrogen use efficiency (NUE). However, less attention has been directed toward the influence of plant nutrients and environmental cues on the expression and activities of transporters. To better understand how these transporters function in improving plant NUE, this review critically examined the roles of transporters in N uptake, transport, and distribution processes. It also described their influence on crop productivity and NUE, especially when co-expressed with other transcription factors, and discussed these transporters' functional roles in helping plants cope with adverse environmental conditions. We equally established the possible impacts of transporters on the uptake and utilization efficiency of other plant nutrients while suggesting possible strategic approaches to improving NUE in plants. Understanding the specificity of these determinants is crucial to achieving better N utilization efficiency in crops within a given environment.

Understanding the physiological, genetic and molecular basis of nitrogen deficiency tolerance and their application in rice improvement

Nitrogen (N) is a major nutrient required for growth and yield of rice plants. Several factors including plant, edapic and climate conditions influence the criticle yield response curve of the plants. Apart from breeding for N responsive rice varieties, excessive use of nitrogenous fertilizers have become a general farmers practice to boost rice productivity under intensive cropping system. Now, it is imperative to orient the crop improvement programme for sustainable crop production strategy as well as to achieve the evergreen revolution through improving nitrogen use efficiency (NUE) under global climate change condition. To develop N-efficient rice varieties under crop breeding programs, it is crucial to comprehend the physiological, genetic and molecular features associated with tolerance to nitrogen deprivation. It has always been challenging for a rice breeders to develop rice varieties with high nitrogen use efficiency (NUE), as it is highly complex physiological trait involving several component traits and its dynamic interaction with environemental factor. NUE is a polygenic traits controlled by number of quantitative trait loci's at genomic level. Till date, researchers targeted component traits for increasing NUE such as, nitrogen uptake/absorption, transport from root to shoot, assimilation, utilisation, remobilisation, reasssssmilation and partitioning /redistribution. Here, we described a short summary of the physiological, genetic and molecular underpinnings of nitrogen deficit tolerance and how these prior art information can be used for improving NUE in rice. Insight from our discussions may facilitate the breeders to improve the NUE of rice plants in future.

Impacts of maize hybrids with different nitrogen use efficiency on root-associated microbiota based on distinct rhizosphere soil metabolites.

Plant genotypes shape root-associated microbiota that affect plant nutrient acquisition and productivity. It is unclear how maize hybrids modify root-associated microbiota and their functions and relationship with nitrogen use efficiency (NUE) by regulating rhizosphere soil metabolites. Here, two N-efficient (NE) (ZD958, DMY3) and two N-inefficient (NIE) maize hybrids (YD9953, LY99) were used to investigate this issue under low N (60 kg N ha-1 , LN) and high N (180 kg N ha-1 , HN) field conditions. NE hybrids had higher yield than NIE hybrids under LN but not HN. NE and NIE hybrids recruited only distinct root-associated bacterial microbiota in LN. The bacterial network stability was stronger in NE than NIE hybrids. Compared with NIE hybrids, NE hybrids recruited more bacterial taxa that have been described as plant growth-promoting rhizobacteria (PGPR), and less related to denitrification and N competition; this resulted in low N2 O emission and high rhizosphere NO3 - -N accumulation. NE and NIE hybrids had distinct rhizosphere soil metabolite patterns, and their specific metabolites were closely related to microbiota and specific genera under LN. Our findings reveal the relationships among plant NUE, rhizosphere soil metabolites, root-associated microbiota, and soil nutrient cycling, and this information is informative for breeding NE crops.

Inhibitory Effect of Neem Seed Extract on Soil Nitrogen Mineralization under Chemical and Organic Amendments

Background: Improvement of nitrogen use efficiency (NUE) of chemical fertilizers and N-rich-organic amendments using natural mineralization inhibitors, like neem extract, was recommended to minimize nitrogen (N) loss. This study hence aimed to evaluate the effects of combined uses of neem seed extract with cricket feces on soil N mineralization and plant NUE. Methods: The treatment combinations included i) amending materials involving unamended (Un), chemical fertilizer at a recommended rate of 312.5 kg N ha-1, 100 kg P ha-1 and 100 kg K ha-1 (CF) and three rates of cricket feces (CrF) [3.125 (CrFlow), 6.25 (CrFmedium) and 12.5 (CrFhigh) Mg ha-1], ii) in combination without (-Nm) and with (+Nm) neem seed extract. Amaranth (Amaranthus tricolor) was employed to assay the plant’s NUE. Result: Neem seed extract inhibited the N mineralization under the Un (74%) and CF (84%) treatments, but not in any of the CrF treatments (-102%, -99% and -2% for CrFlow, CrFmedium and CrFhigh, respectively. In addition, the neem extract significantly decreased NUE parameters, including N recovery efficiency and agronomy NUE, only in CF treatment. Neem seed extract could only function as an N inhibitor in unamended and chemically fertilized soils.

The New Soil Conditioner DewEco Could Improve Sandy Soil’s Properties for Efficient Maize Growth

Sandy soil, one of the most abundant soil types in the world, often has lower crop productivity because of poor water and fertilizer retention capacity. The objective of this study was to investigate the effects of the new soil conditioner DewEco (fermented organic material consisted mainly of salt of L-lysine and citric acid) on sandy soil quality and plant growth. Serial dosages of DewEco and nitrogen (N) fertilizer were mixed into sandy soils and planted maize in a greenhouse. DewEco application increased large soil particle composition and decreased small soil particle composition. Soil porosity and the liquid phase increased as the DewEco dosage increased. DewEco also decreased soil pH and increased soil electrical conductivity, soil organic matter content, total nitrogen and available potassium. DewEco significantly enhanced the soil water-holding capacity and soil effective water content although it also increased the wilting coefficient. Finally, DewEco markedly promoted maize growth while improving water use efficiency (WUE) and nitrogen use efficiency (NUE). In addition, there was an interaction effect between DewEco and nitrogen fertilizer, such that the combined effects of DewEco and N exceeded the sum of their respective effects promoting plant growth. Thus, DewEco application can significantly enhance soil water content and nutrient levels by alleviating sandy soil’s physical and chemical properties, thereby promoting plant growth, WUE and NUE. This study indicates that DewEco is a useful eco-friendly sandy soil conditioner for arid and semi-arid regions.

Transcriptomic Dissection of Allotetraploid Rapeseed (Brassica napus L.) in Responses to Nitrate and Ammonium Regimes and Functional Analysis of BnaA2.Gln1;4 in Arabidopsis.

Plant roots acquire nitrogen predominantly as two inorganic forms, nitrate (NO3-) and ammonium (NH4+), to which plants respond differentially. Rapeseed (Brassica napus L.) is an important oil-crop species with very low nitrogen-use efficiency (NUE), the regulatory mechanism of which was elusive due to the vastness and complexity of the rapeseed genome. In this study, a comparative transcriptomic analysis was performed to investigate the differential signatures of nitrogen-starved rapeseed in responses to NO3- and NH4+ treatments and to identify the key genes regulating rapeseed NUE. The two nitrogen sources differentially affected the shoot and root transcriptome profiles, including those of genome-wide nitrogen transporter and transcription factor (TF)-related genes. Differential expression profiling showed that BnaA6.NRT2;1 and BnaA7.AMT1;3 might be the core transporters responsible for efficient NO3- and NH4+ uptake, respectively; the TF genes responsive to inorganic nitrogen, specifically responding to NO3-, and specifically responsive to NH4+ were also identified. The genes which were commonly and most significantly affected by both NO3- and NH4+ treatments were related to glutamine metabolism. Among the glutamine synthetase (GS) family genes, we found BnaA2.Gln1;4, significantly responsive to low-nitrogen conditions and showed higher transcription abundance and GS activity in the leaf veins, flower sepals, root cortex and stele, silique petiole and stem tissues. These characters were significantly different from those of AtGln1;4. The heterologous overexpression of BnaA2.Gln1;4 in Arabidopsis increased plant biomass, NUE, GS activity and total amino acid concentrations under both sufficient- and low-nitrogen conditions. Overall, this study provided novel information about the genes involved in the adaptation to different nitrogen regimes and identified some promising candidate genes for enhancing NUE in rapeseed.

Genetic Engineering and Genome Editing for Improving Nitrogen Use Efficiency in Plants.

Low nitrogen availability is one of the main limiting factors for plant growth and development, and high doses of N fertilizers are necessary to achieve high yields in agriculture. However, most N is not used by plants and pollutes the environment. This situation can be improved by enhancing the nitrogen use efficiency (NUE) in plants. NUE is a complex trait driven by multiple interactions between genetic and environmental factors, and its improvement requires a fundamental understanding of the key steps in plant N metabolism—uptake, assimilation, and remobilization. This review summarizes two decades of research into bioengineering modification of N metabolism to increase the biomass accumulation and yield in crops. The expression of structural and regulatory genes was most often altered using overexpression strategies, although RNAi and genome editing techniques were also used. Particular attention was paid to woody plants, which have great economic importance, play a crucial role in the ecosystems and have fundamental differences from herbaceous species. The review also considers the issue of unintended effects of transgenic plants with modified N metabolism, e.g., early flowering—a research topic which is currently receiving little attention. The future prospects of improving NUE in crops, essential for the development of sustainable agriculture, using various approaches and in the context of global climate change, are discussed.

Nitrogen Use Efficiency in Parent vs. Hybrid Canola under Varying Nitrogen Availabilities

Improving nitrogen use efficiency (NUE) is essential for sustainable agriculture, especially in high-N-demanding crops such as canola (Brassica napus). While advancements in above-ground agronomic practices have improved NUE, research on soil and below-ground processes are limited. Plant NUE—and its components, N uptake efficiency (NUpE), and N utilization efficiency (NUtE)—can be further improved by exploring crop variety and soil N cycling. Canola parental genotypes (NAM-0 and NAM-17) and hybrids (H151857 and H151816) were grown on a dark brown chernozem in Saskatchewan, Canada. Soil and plant samples were collected at the 5–6 leaf stage and flowering, and seeds were collected at harvest maturity. Soil N cycling varied with phenotypic stage, with higher potential ammonium oxidation rates at the 5–6 leaf stage and higher urease activity at flowering. Seed N uptake was higher under higher urea-N rates, while the converse was true for NUE metrics. Hybrids had higher yield, seed N uptake, NUtE, and NUE, with higher NUE potentially owing to higher NUtE at flowering, which led to higher yield and seed N allocation. Soil N cycling and soil N concentrations correlated for improved canola NUE, revealing below-ground breeding targets. Future studies should consider multiple root characteristics, including rhizosphere microbial N cycling, root exudates, and root system architecture, to determine the below-ground dynamics of plant NUE.

Transporters and transcription factors gene families involved in improving nitrogen use efficiency (NUE) and assimilation in rice (Oryza sativa L.).

Nitrogen (N) as a macronutrient is an important determinant of plant growth. The excessive usage of chemical fertilizers is increasing environmental pollution; hence, the improvement of crop's nitrogen use efficiency (NUE) is imperative for sustainable agriculture. N uptake, transportation, assimilation, and remobilization are four important determinants of plant NUE. Oryza sativa L. (rice) is a staple food for approximately half of the human population, around the globe and improvement in rice yield is pivotal for rice breeders. The N transporters, enzymes indulged in N assimilation, and several transcription factors affect the rice NUE and subsequent yield. Although, a couple of improvements have been made regarding rice NUE, the knowledge about regulatory mechanisms operating NUE is scarce. The current review provides a precise knowledge of how rice plants detect soil N and how this detection is translated into the language of responses that regulate the growth. Additionally, the transcription factors that control N-associated genes in rice are discussed in detail. This mechanistic insight will help the researchers to improve rice yield with minimized use of chemical fertilizers.

Grafting improves tomato yield under low nitrogen conditions by enhancing nitrogen metabolism in plants.

To alleviate the effects of increasingly severe environmental conditions and meet the increasing demand for organic agricultural products, this paper studied tomato grafting under low nitrogen conditions in an effort to enhance yield and improve fruit quality by enhancing nitrogen metabolism. In this study, we screened for two tomato genotypes, a high nitrogen use efficiency genotype ('TMS-150') and a low nitrogen use efficiency genotype ('0301111'), using rootstocks from 25 tomato genotypes and studied the effects of tomato grafting on plant yield, fruit quality, nitrogen content, activities of key nitrogen metabolism enzymes, and nitrogen use efficiency (NUE) under different nitrogen fertilizer conditions. The results showed that the yield of the tomato plants, the activities of key enzymes during nitrogen metabolism, the contents of different forms of nitrogen, and the efficiency of nitrogen use were lower at low nitrogen fertilization levels and higher at higher nitrogen fertilization levels, while the measured indicators were the highest under the N40 nitrogen fertilizer treatment. Grafting tomatoes with high-NUE tomato seedlings as the rootstock resulted in significant increases in the nitrogen content and the activity of key enzymes, enhanced the NUE of tomato plants, increased tomato yield, and improved fruit quality compared to those of the seedlings grafted with low-NUE rootstock. Our results indicate that tomato plants grafted with high-NUE rootstock presented enhanced absorption and utilization of nitrogen and increased plant yield by promoting nitrogen metabolism at different nitrogen levels.

Posttranslational Modifications: Regulation of Nitrogen Utilization and Signaling.

Nitrogen is the most important macroelement required for the composition of key molecules, such as nucleic acids, proteins and other organic compounds. As sessile organisms, plants have evolved sophisticated mechanisms to acquire nitrogen for their normal growth and development. Besides the transcriptional and translational regulation of nitrogen uptake, assimilation, remobilization and signal transduction, posttranslational modifications (PTMs) are shown to participate in these processes in plants. In addition to alterations in protein abundance, PTMs may dramatically increase the complexity of the proteome without the concomitant changes in gene transcription and have emerged as an important type of protein regulation in terms of protein function, subcellular localization and protein activity and stability. Herein, we briefly summarize recent advances on the posttranslational regulation of nitrogen uptake, assimilation, remobilization and nitrogen signaling and discuss the underlying mechanisms of PTMs as well as the signal output of such PTMs. Understanding these regulation mechanisms will provide novel insights for improving the nitrogen use efficiency of plants.

Effect of magnesium fertilizer combined with straw return on nitrogen use efficiency

AbstractImproving nitrogen use efficiency (NUE) has great significance for agriculture sustainable development and reducing environmental pollution. The effects of Mg fertilizer combined with straw return on yield, N uptake, and NUE of spring maize (Zea mays L.) were investigated for two consecutive years. The treatments included JM3 (straw + magnesium fertilizer), JM0 (straw + no magnesium fertilizer), WM3 (no straw + magnesium fertilizer), and WM0 (no magnesium fertilizer + no straw). The application of Mg fertilizer significantly improved yield. The application of straw and Mg fertilizer together improved yield even more significantly; the grain yield of the JM3 treatment was 5.28% higher than that of the WM0 treatments. The highest total N uptake was obtained from the JM3. Nitrogen remobilization from vegetation organs to grain was highest in the JM3 treatment. The agronomic efficiency of fertilizer nitrogen (AEN), recovery of applied fertilizer nitrogen (REN), partial factor productivity of fertilizer nitrogen (PFPN), and nitrogen harvest index (NHI) responded significantly to straw return and Mg fertilizer. The AEN, REN, PFPN, and NHI values for the JM3 treatment were 15.35, 24.63, 5.28, and 2.31% higher on average, respectively, than those for the WM0 treatments. Generally, these outcomes indicated that there was an interaction between Mg fertilizer and maize straw. The application of Mg fertilizer with straw return significantly improved the grain yield, N uptake, and NUE of maize plants. The combination of straw return and Mg application is a practical method for increasing maize production and supporting sustainable agriculture.

Rice NIN-LIKE PROTEIN 1 rapidly responds to nitrogen deficiency and improves yield and nitrogen use efficiency.

Nitrogen (N) is indispensable for crop growth and yield, but excessive agricultural application of nitrogenous fertilizers has generated severe environmental problems. A desirable and economical solution to cope with these issues is to improve crop nitrogen use efficiency (NUE). Plant NUE has been a focal point of intensive research worldwide, yet much still has to be learned about its genetic determinants and regulation. Here, we show that rice (Oryza sativa L.) NIN-LIKE PROTEIN 1 (OsNLP1) plays a fundamental role in N utilization. OsNLP1 protein localizes in the nucleus and its transcript level is rapidly induced by N starvation. Overexpression of OsNLP1 improves plant growth, grain yield, and NUE under different N conditions, while knockout of OsNLP1 impairs grain yield and NUE under N-limiting conditions. OsNLP1 regulates nitrate and ammonium utilization by cooperatively orchestrating multiple N uptake and assimilation genes. Chromatin immunoprecipitation and yeast one-hybrid assays showed that OsNLP1 can directly bind to the promoter of these genes to activate their expression. Therefore, our results demonstrate that OsNLP1 is a key regulator of N utilization and represents a potential target for improving NUE and yield in rice.