Improvement Of Nitrogen Use Efficiency Research Articles

Evaluation of wheat (Triticum aestivum) genotypes for higher yield and enhanced nitrogen use efficiency in Indo-Gangetic Plains

Extensive research has been conducted on various nitrogen (N) management approaches to fulfil the growing needs of cereals while enhancing the efficiency of agricultural resource utilization. Nevertheless, the intensive agricultural model continues to prioritize the achievement of high crop yields and improving nitrogen use efficiency (NUE) as opposing targets. The primary aim of this study was to investigate whether a corresponding increase in N application is necessary to achieve higher crop yields. The study evaluated the effects of 3 N treatments (N0, N75, and N150) on 10 wheat (Triticum aestivum L.) genotypes during 2020–21 and 2021–22 at research farm of ICAR-Indian Agricultural Research Institute, New Delhi. In both growing seasons, the highest grain yield (GY) of 5.3 t/ha, agronomic efficiency (AEN) of 28.7 kg grain/kg N, and partial factor productivity of applied N (PFPN) of 60.2 kg grain/kg N were obtained by the HD 3249 genotype, followed by HD 3117. The application of N75 and N150 increased grain yields by 72.3 and142.6%, respectively, over N0. Significant relationships were observed between GY, PFPN and AEN at all N levels, and a decreasing trend was observed in both PFPN and AEN as the N application rate increased. The study results suggest that the adoption of genotype-specific nitrogen (N) rates could provide a mutually beneficial solution to meet the growing demand for food while improving NUE. Overall, based on GY and AEN, the research findings indicate that the genotypes HD 3249 and HD 3117 are efficient candidates for N use, with the potential for higher yields and NUE in the Indo-Gangetic plains of India.

Identification of quantitative trait loci controlling nitrogen use efficiency-related traits in rice at the seedling stage under salt condition by genome-wide association study.

Rice cultivation is facing both salt intrusion and overuse of nitrogen fertilizers. Hence, breeding new varieties aiming to improve nitrogen use efficiency (NUE), especially under salt conditions, is indispensable. We selected 2,391 rice accessions from the 3K Rice Genomes Project to evaluate the dry weight under two N concentrations [2.86 mM - standard N (SN), and 0.36 mM - low N (LN)] crossed with two NaCl concentrations [0 (0Na) and 60 mM (60Na)] at the seedling stage. Genome-wide association studies for shoot, root, and plant dry weight (DW) were carried out. A total of 55 QTLs - 32, 16, and 7 in the whole, indica, and japonica panel - associated with one of the tested traits were identified. Among these, 27 QTLs co-localized with previously identified QTLs for DW-related traits while the other 28 were newly detected; 24, 8, 11, and 4 QTLs were detected in SN-0Na, LN-0Na, SN-60Na, and LN-60Na, respectively, and the remaining 8 QTLs were for the relative plant DW between treatments. Three of the 11 QTLs in SN-60Na were close to the regions containing three QTLs detected in SN-0Na. Eleven candidate genes for eight important QTLs were identified. Only one of them was detected in both SN-0Na and SN-60Na, while 5, 0, 3, and 2 candidate genes were identified only once under SN-0Na, LN-0Na, SN-60Na, and LN-60Na, respectively. The identified QTLs and genes provide useful materials and genetic information for future functional characterization and genetic improvement of NUE in rice, especially under salt conditions.

Current Progress and Future Prospect of Wheat Genetics Research towards an Enhanced Nitrogen Use Efficiency.

To improve the yield and quality of wheat is of great importance for food security worldwide. One of the most effective and significant approaches to achieve this goal is to enhance the nitrogen use efficiency (NUE) in wheat. In this review, a comprehensive understanding of the factors involved in the process of the wheat nitrogen uptake, assimilation and remobilization of nitrogen in wheat were introduced. An appropriate definition of NUE is vital prior to its precise evaluation for the following gene identification and breeding process. Apart from grain yield (GY) and grain protein content (GPC), the commonly recognized major indicators of NUE, grain protein deviation (GPD) could also be considered as a potential trait for NUE evaluation. As a complex quantitative trait, NUE is affected by transporter proteins, kinases, transcription factors (TFs) and micro RNAs (miRNAs), which participate in the nitrogen uptake process, as well as key enzymes, circadian regulators, cross-talks between carbon metabolism, which are associated with nitrogen assimilation and remobilization. A series of quantitative genetic loci (QTLs) and linking markers were compiled in the hope to help discover more efficient and useful genetic resources for breeding program. For future NUE improvement, an exploration for other criteria during selection process that incorporates morphological, physiological and biochemical traits is needed. Applying new technologies from phenomics will allow high-throughput NUE phenotyping and accelerate the breeding process. A combination of multi-omics techniques and the previously verified QTLs and molecular markers will facilitate the NUE QTL-mapping and novel gene identification.

Long term nitrogen deficiency alters expression of miRNAs and alters nitrogen metabolism and root architecture in Indian dwarf wheat (Triticum sphaerococcum Perc.) genotypes

The important roles of plant microRNAs (miRNAs) in adaptation to nitrogen (N) deficiency in different crop species especially cereals (rice, wheat, maize) have been under discussion since last decade with little focus on potential wild relatives and landraces. Indian dwarf wheat (Triticum sphaerococcum Percival) is an important landrace native to the Indian subcontinent. Several unique features, especially high protein content and resistance to drought and yellow rust, make it a very potent landrace for breeding. Our aim in this study is to identify the contrasting Indian dwarf wheat genotypes based on nitrogen use efficiency (NUE) and nitrogen deficiency tolerance (NDT) traits and the associated miRNAs differentially expressed under N deficiency in selected genotypes. Eleven Indian dwarf wheat genotypes and a high NUE bread wheat genotype (for comparison) were evaluated for NUE under control and N deficit field conditions. Based on NUE, selected genotypes were further evaluated under hydroponics and miRNome was compared by miRNAseq under control and N deficit conditions. Among the identified, differentially expressed miRNAs in control and N starved seedlings, the target gene functions were associated with N metabolism, root development, secondary metabolism and cell-cycle associated pathways. The key findings on miRNA expression, changes in root architecture, root auxin abundance and changes in N metabolism reveal new information on the N deficiency response of Indian dwarf wheat and targets for genetic improvement of NUE.

Genome-Wide Urea Response in Rice Genotypes Contrasting for Nitrogen Use Efficiency.

Rice is an ideal crop for improvement of nitrogen use efficiency (NUE), especially with urea, its predominant fertilizer. There is a paucity of studies on rice genotypes contrasting for NUE. We compared low urea-responsive transcriptomes of contrasting rice genotypes, namely Nidhi (low NUE) and Panvel1 (high NUE). Transcriptomes of whole plants grown with media containing normal (15 mM) and low urea (1.5 mM) revealed 1497 and 2819 differentially expressed genes (DEGs) in Nidhi and Panvel1, respectively, of which 271 were common. Though 1226 DEGs were genotype-specific in Nidhi and 2548 in Panvel1, there was far higher commonality in underlying processes. High NUE is associated with the urea-responsive regulation of other nutrient transporters, miRNAs, transcription factors (TFs) and better photosynthesis, water use efficiency and post-translational modifications. Many of their genes co-localized to NUE-QTLs on chromosomes 1, 3 and 9. A field evaluation under different doses of urea revealed better agronomic performance including grain yield, transport/uptake efficiencies and NUE of Panvel1. Comparison of our urea-based transcriptomes with our previous nitrate-based transcriptomes revealed many common processes despite large differences in their expression profiles. Our model proposes that differential involvement of transporters and TFs, among others, contributes to better urea uptake, translocation, utilization, flower development and yield for high NUE.

Reduction in Nitrogen Rate and Improvement of Nitrogen Use Efficiency without Loss of Peanut Yield by Regional Mean Optimal Rate of Chemical Fertilizer Based on a Multi-Site Field Experiment in the North China Plain

It is important to quantify nutrient requirements and optimize fertilization to improve peanut yield and fertilizer use efficiency. In this study, a multi-site field trial was conducted from 2020 to 2021 in the North China Plain to estimate nitrogen (N), phosphorus (P), and potassium (K) uptake and requirements of peanuts, and to evaluate the effects of fertilization recommendations from the regional mean optimal rate (RMOR) on dry matter, pod yield, nutrient uptake, and fertilizer use efficiency. Results show that compared with farmer practice fertilization (FP), optimal fertilization (OPT) based on the RMOR increased peanut dry matter by 6.6% and pod yield by 10.9%. The average uptake rates of N, P, and K were 214.3, 23.3, and 78.4 kg/ha, respectively, with 76.0% N harvest index, 59.8% P harvest index, and 41.4% K harvest index. The OPT treatment increased N, P, and K uptake by 19.3%, 7.3%, and 11.0% compared with FP, respectively. However, the average of yield, nutrition uptake, and harvest indexes of N, P, and K were not significantly affected by fertilization. The peanut required 42.0 kg N, 4.6 kg P, and 15.3 kg K to produce 1000 kg of pods. The OPT treatment significantly improved the N partial factor productivity and N uptake efficiency but decreased the K partial factor productivity and K uptake efficiency. The present study demonstrates that fertilizer recommendations from RMOR improve N use efficiency, and reduce N and P fertilizer application without yield loss in regions with smallholder farmers, and the corresponding estimation of nutrient requirements helps to make peanut fertilization recommendations.

Reducing options of ammonia volatilization and improving nitrogen use efficiency via organic and inorganic amendments in wheat (Triticum aestivum L.).

This study investigates the effect of organic and inorganic supplements on the reduction of ammonia (NH3) volatilization, improvement in nitrogen use efficiency (NUE), and wheat yield. A field experiment was conducted following a randomized block design with 10 treatments i.e., T1-without nitrogen (control), T2-recommended dose of nitrogen (RDN), T3-(N-(n-butyl) thiophosphoric triamide) (NBPT @ 0.5% w/w of RDN), T4-hydroquinone (HQ @ 0.3% w/w of RDN), T5-calcium carbide (CaC2 @ 1% w/w of RDN), T6-vesicular arbuscular mycorrhiza (VAM @ 10 kg ha-1), T7-(azotobacter @ 50 g kg-1 seeds), T8-(garlic powder @ 0.8% w/w of RDN), T9-(linseed oil @ 0.06% w/w of RDN), T10-(pongamia oil @ 0.06% w/w of RDN). The highest NH3 volatilization losses were observed in T2 at about 20.4 kg ha-1 per season. Significant reduction in NH3 volatilization losses were observed in T3 by 40%, T4 by 27%, and T8 by 17% when compared to the control treatment. Soil urease activity was found to be decreased in plots receiving amendments, T3, T4, and T5. The highest grain yield was observed in the T7 treated plot with 5.09 t ha-1, and straw yield of 9.44 t ha-1 in T4. The shifting towards organic amendments is a feasible option to reduce NH3 volatilization from wheat cultivation and improves NUE.

Revealing the relationship between nitrogen use efficiency‐related QTLs and carbon and nitrogen metabolism regulation in poplar

AbstractPoplar provides a large amount of bioenergy and wood, but the lack of soil nitrogen in poplar plantations has seriously restricted its wood production. Using Populus deltoides ‘Danhong’, P. simonii ‘Tongliao1’, and their F1 populations as materials, nitrogen fertilizer and no nitrogen fertilizer were applied in the field. Under different nitrogen conditions, the wood yield of ‘Danhong’ was much higher than that of ‘Tongliao 1’, which indicated that ‘Danhong’ had excellent genetic resources related to nitrogen use efficiency (NUE). Based on a high‐density genetic map, we performed quantitative trait loci (QTL) analyses for ground diameter, plant height, stem biomass, and nitrogen response index. A total of 276 QTLs and 774 candidate genes were identified. We analysed the metabolites related to carbon and nitrogen metabolism and the transcriptome of the developing xylem in 10 clones under high‐ and low‐nitrogen conditions. Through weighted gene coexpression network analysis, it was found that the MEyellow module was closely related to biomass, carbon, and nitrogen metabolism, and a gene coexpression network was established. Finally, candidate genes NRT3.1, NPF5.1, NPF5.10, and NPF8.1 related to nitrogen transport; transcription factors NLP8.1, NLP8.2, and NLP2 regulating nitrogen transport; genes Potri.010G070900, GDH2, and SHM2 related to amino acid metabolism; and genes Necap2, Dscr3, trappc2l, Potri.013G072600, and LAX2 related to carbon metabolism were identified. This work provides abundant genetic resources for the genetic improvement of poplar NUE and provides new insights into the linkage mechanism between NUE and biomass yield.

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.

Effects of the timing of epibrassinolide spraying on yield and nitrogen use efficiency of wide-belt sowing wheat.

In this study, we investigated the effects of epibrassinolide spraying at different growth stages on grain yield and nitrogen use efficiency (NUE), and uptake efficiency (UPE) of wide-belt sowing wheat. The results showed that epibrassinolide spraying enhanced wheat grain yield by increasing the number of kernels per spike and (or) 1000-kernel weight, and improved NUE by promoting aboveground nitrogen accumulation and improving UPE. However, the magnitudes of such enhancements in yield and NUE differed among spraying times. Spraying epibrassinolide at the erecting and filling stages, jointing and filling stages, erecting, jointing, and filling stages, as well as erecting, flowering, and filling stages, produced the greatest increase in the number of kernels per spike and 1000-kernel weight, which led to substantial yield increases (12.8%-14.0%), and the greatest increase in aboveground nitrogen accumulation, which improved UPE by 16.4%-18.8%, and resulted in a significant improvement in NUE. Therefore, spraying epibrassinolide at the erecting and filling stage or jointing and filling stages could achieve high yield and NUE in wide-belt sowing wheat.

Quantify the effect of manure fertilizer addition and optimal nitrogen input on rainfed wheat yield and nitrogen requirement using nitrogen nutrition index

Combined manure fertilizer addition with optimal nitrogen (N) input reduces nitrogen demands for wheat while maintaining or increasing its yield and nitrogen productivity. However, the effect of manure addition has not been well explored for dryland wheat production on the Loess Plateau, especially in year with less precipitation. Therefore, a 4-year field experiment was performed: manure fertilizer (with and without) and N fertilization levels (0, 60, 120, 180 and 240 kg ha–1) under two precipitation years (normal and dry year). The target was to quantify the effect of manure addition on: i) wheat yield and nitrogen use efficiency (NUE), ii) crop growth and soil properties, and iii) wheat N status [N accumulation, N nutrition index (NNI)]. Compared with chemical N alone, manure addition increased topsoil organic matter, total nitrogen and the stability of macro-aggregate (R0.25). Manure addition increased grain yield by 12.5% in normal year and by 38.2% in dry year. The improved topsoil quality, root system, biomass (nitrogen) accumulation all occurred in NM120 or NM180 with manure addition, which brought an improvement of wheat yield and NUE with a suitable nitrogen nutrition status. NM180 (i.e., 150 kg N ha–1 +2000 kg ha–1 manure) and NM120 (i.e., 90 kg N ha–1 +2000 kg ha–1 manure) achieved the highest grain yield in normal and dry years, respectively. In summary, the optimal fertilization decision strategy based on precipitation and nitrogen nutrition index can be applied for dryland wheat production.

QTL analysis for nitrogen use efficiency in wheat (Triticum aestivum L.)

The genetic architecture of nitrogen use efficiency (NUE) and its two component traits i.e. NUpE (N uptake efficiency) and NUtE (N utilization efficiency) was studied using a bi-parental RIL mapping population derived from a cross HUW468 (high NUE)/C306 (low NUE). The mapping population, two parental genotypes and three check genotypes were evaluated under four different N levels (0, 60, 120, and 180 kg/ha) over three years. A genetic map containing 456 SNP markers (2571.38 cM length) was used for QTL analysis. Thirty six main effect QTLs (17 QTLs for NUE, 13 NUpE and 6 QTLs for NUtE) distributed on 12 chromosomes (1B, 1D, 2A, 2B, 3A, 4B, 5A, 5B, 5D, 6A, 6D, and 7A) were identified at 2.52–9.27 LOD scores. Individual QTLs explained 6.65–22.89% phenotypic variation. Multi-traits QTLs (Mt-QTLs) and epistatic QTLs involving first-order epistatic (QTL × QTL) interactions were also discovered. Candidate genes (CGs, as many as 737) were mined from QTL regions which were mainly involved in metabolic process, cellular process and catalytic activity, etc.; differential expression was observed for 49 CGs in roots and 34 in shoots. The CGs encoded important transcription factors, transporters, etc. having a role in NUE. QTLs and CGs reported in this study enriched the available knowledge. Seven QTLs (including three Mt-QTLs) and QTLs involved in six epistatic interactions are recommended for MAS for improvement of NUE in wheat.

Dietary protein oscillation: effects on digestibility, nutrient balance and estimated microbial protein synthesis in lactating dairy cows

Various studies with growing ruminants report increases in nitrogen use efficiency (NUE) when feeding oscillating (OS) dietary CP, whereas limited research with lactating dairy cows demonstrates a lack of improvement in NUE when feeding OS diets. We hypothesised that a total mixed ration (TMR) delivering OS CP (48-h phases of 134 and 171 g CP/kg DM, respectively) compared to a static CP TMR (ST; 152 g CP/kg DM) would result in similar or increased urinary purine derivative excretion (as a marker of microbial protein synthesis (MPS)) and greater urinary nitrogen excretion in lactating dairy cows. Responses in intake, production, apparent total tract digestibility (ATTD), nutrient balance, and estimated MPS were evaluated using faecal and urine collection in 12 multiparous cows (172 ± 39 d in milk) in a randomised complete block design, where total urinary output was estimated indirectly. All measurements were taken during d 8 (at 1700) to d 16 (at 1700) of the 16-d study that followed a 28-d period in which cows already received their respective treatments. Dry matter intake, yields of milk, protein, fat, lactose, and fat- and protein-corrected milk were similar for ST and OS. Milk composition, BW, and body condition score also did not differ between treatments, except for a tendency for increased milk urea concentration with OS (13.7 vs 12.4 mg/dL). Feed efficiency, NUE and ATTD of organic matter, NDF, CP and gross energy did not differ, but ATTD of crude fat (658 vs 627 g/kg) and starch (980 vs 975 g/kg) increased, and ATTD of DM (702 vs 691 g/kg) tended to increase with OS. Milk energy as a proportion of digested energy tended to decrease with OS (34.6 vs 37.1%), but other energy metabolism variables were not affected by treatment. Estimated urinary nitrogen excretion increased (165 vs 144 g/d), estimated urinary nitrogen as a proportion of nitrogen intake tended to increase (25.3 vs 22.7%), and milk nitrogen as a proportion of digested nitrogen decreased (47.3 vs 51.8%) in response to OS. Estimated urinary excretion of creatinine (184 vs 165 mmol/d), uric acid (29 vs 20 mmol/d) and urea (3.1 vs 2.5 mol/d) increased, but other nitrogen metabolism parameters were not affected by OS. Overall, oscillating dietary CP content did not affect lactational performance, milk NUE, or estimated MPS. However, ATTD of some nutrients increased, postabsorptive energy use for milk synthesis tended to decrease, and estimated urinary nitrogen losses increased with OS.

Tiller fertility is critical for improving grain yield, photosynthesis, and nitrogen efficiency in wheat

Genetic improvement has promoted wheat’s grain yield and nitrogen use efficiency (NUE) during the past decades. Therefore, the current wheat cultivars exhibit higher grain yield and NUE than previous cultivars in the Yangtze River Basin, China since the 2000s. However, the critical traits and mechanisms of the increased grain yield and NUE remain unknown. This study explores the mechanisms underlying these new cultivars’ increased grain yield and NUE by studying 21 local cultivars cultivated for three growing seasons from 2016 to 2019. Significantly positive correlations were observed between grain yield and NUE in the three years. The cultivars were grouped into high (HH), medium (MM), and low (LL) grain yield and NUE groups. The HH group exhibited significantly high grain yield and NUE. High grain yield was attributed to more effective ears by high tiller fertility and greater single-spike yield by increasing post-anthesis single-stem biomass. Compared to other groups, the HH group demonstrated a longer leaf stay-green ability and a greater flag leaf photosynthetic rate after anthesis. It also showed higher N accumulation at pre-anthesis, which contributed to increasing N accumulation per stem, including stem and leaf sheath, leaf blade, and unit leaf area at pre-anthesis, and promoting N uptake efficiency, the main contribution of high NUE. Moreover, tiller fertility was positively related to N accumulation per stem, N accumulation per unit leaf area, leaf stay-green ability, and flag leaf photosynthetic rate, which indicates that improving tiller fertility promoted N uptake, leaf N accumulation, and photosynthetic ability, thereby achieving synchronous improvements in grain yield and NUE. Therefore, tiller fertility is proposed as an important kernel indicator that can be used in the breeding and management of cultivars to improve agricultural efficiency and sustainability.

Transcriptome and Metabolome Studies on Pre-Harvest Nitrogen Impact on Fruit Yield and Quality of Peach (Prunus persica L.).

Pre-harvest nitrogen (N) application has been proven effective for improving fruit yield and quality. However, a full understanding of how differences in N availability/plant N status influence the transcriptome and metabolism underlying yield formation and quality remains elusive. Here, a combined analysis of the morpho-physiological qualities, transcriptome, and metabolite of peach plants was performed under different nitrogen levels at fruit pit hardening (PH) and fruit expansion (FE). Nitrogen fertilizer directly affected the yield, fruit quality, and metabolites of peach at different growth stages. RNA-Seq was used to analyze the influence of N levels at PH and FE in peach. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the differentially expressed genes (DEGs) focused on flavonoid biosynthesis and secondary metabolite biosynthetic processes. The differential metabolites among the different treatments were mainly involved in flavonoid metabolism. Transcriptome analysis showed that applying different nitrogen fertilizers at different growth stages of peach mainly affected the synthesis of flavonoids in fruit. Overall, these results suggest that the impacts of pre-harvest N application on fruit yield and quality differ between developmental stages. This research provides a full understanding of the metabolic processes underlying fruit growth and development in peach, providing a theoretical basis for the improvement of nitrogen use efficiency in peach trees.

Hole fertilization in the root zone facilitates maize yield and nitrogen utilization by mitigating potential N loss and improving mineral N accumulation

Reducing environmental impacts and improving N utilization are critical to ensuring food security in China. Although root-zone fertilization has been considered an effective strategy to improve nitrogen use efficiency (NUE), the effect of controlled-release urea (CRU) applied in conjunction with normal urea in this mode is unclear. Therefore, a 3-year field experiment was conducted using a no-N-added as a control and two fertilization modes (FF, furrow fertilization by manual trenching, i.e., farmer fertilizer practice; HF: root-zone hole fertilization by point broadcast manually) at 210 kg N ha–1 (controlled-release:normal fertilizer=5:5), along with a 1-year in-situ microplot experiment. Maize yield, NUE and N loss were investigated under different fertilization modes. The results showed that compared with FF, HF improved the average yield and N recovery efficiency by 8.5 and 22.3% over three years, respectively. HF had a greater potential for application than FF treatment, which led to increases in dry matter accumulation, total N uptake, SPAD value and LAI. In addition, HF remarkably enhanced the accumulation of 15N derived from fertilizer by 17.2% compared with FF, which in turn reduced the potential loss of 15N by 43.8%. HF increased the accumulation of N in the tillage layer of soils at harvest for potential use in the subsequent season relative to FF. Hence, HF could match the N requirement of summer maize, sustain yield, improve NUE and reduce environmental N loss simultaneously. Overall, root-zone hole fertilization with blended CRU and normal urea can represent an effective and promising practice to achieve environmental integrity and food security on the North China Plain, which deserves further application and investigation.

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.

Agricultural carbon footprint and food security: an assessment of multiple carbon mitigation strategies in China

PurposeTo achieve the dual goals of decarbonization and food security, this paper examines China's carbon footprint reduction in 2050 based on current mitigation strategies.Design/methodology/approachConsidering publications as featured evidence, this study develops an investigation of agricultural decarbonization in China. First, the authors summarize the mitigation strategies for agricultural greenhouse gas (GHG) emissions in the existing literature. Second, the authors demonstrate the domestic food production target in 2050 and the projection target's projected life-cycle-based GHG emissions at the commodity level. Lastly, the authors forecast China's emission removal in the agri-food sector in 2050 concerning current mitigation strategies and commodity productions. The authors highlight the extent to which each mitigation strategy contributes to decarbonization in China.FindingsPractices promoting sustainable development in the agri-food sector significantly contribute to GHG emission removal. The authors find mitigation strategies inhibiting future GHG emissions in the agri-food sector comprise improving nitrogen use efficiency in fertilizers, changing food consumption structure, manure management, cover crops, food waste reduction, dietary change of livestock and covered manure. A 10% improvement in nitrogen use efficiency contributes to 5.03% of GHG emission removal in the agri-food sector by 2050. Reducing food waste and food processing from 30% to 20% would inhibit 1.59% of the total GHG emissions in the agri-food sector.Originality/valueThis study contributes to policy discussions by accounting for agricultural direct and indirect emission components and assessing the dynamic changes in those related components. This study also extends existing research by forecasting to which extent the decarbonization effects implemented by current mitigation strategies can be achieved while meeting 2050 food security in China.

Nitrogen Fertilizers Technologies for Corn in Two Yield Environments in South Brazil.

Improvements in nitrogen use efficiency (NUE) in corn production systems are necessary, to decrease the economic and environmental losses caused by loss of ammonia volatilization (NH3-N). The objective was to study different nitrogen (N) fertilizer technologies through characterization of N sources, NH3-N volatilization losses, and their effects on the nutrient concentration and yield of corn grown in clayey and sandy soils in south Brazil. The treatments consisted of a control without N application as a topdressing, three conventional N sources (urea, ammonium sulfate, and ammonium nitrate + calcium sulfate), and three enhanced-efficiency fertilizers [urea treated with NBPT + Duromide, urea formaldehyde, and polymer-coated urea (PCU) + urea treated with NBPT and nitrification inhibitor (NI)]. The losses by NH3-N volatilization were up to 46% of the N applied with urea. However, NI addition to urea increased the N losses by NH3-N volatilization by 8.8 and 23.3%, in relation to urea alone for clayey and sandy soils, respectively. Clayey soil was 38.4% more responsive than sandy soil to N fertilization. Ammonium sulfate and ammonium nitrate + calcium sulfate showed the best results, because it increased the corn yield in clayey soil and contributed to reductions in NH3-N emissions of 84 and 80% in relation to urea, respectively.

Deciphering the Genetic Basis of Root and Biomass Traits in Rapeseed (Brassica napus L.) through the Integration of GWAS and RNA-Seq under Nitrogen Stress.

An excellent root system is responsible for crops with high nitrogen-use efficiency (NUE). The current study evaluated the natural variations in 13 root- and biomass-related traits under a low nitrogen (LN) treatment in a rapeseed association panel. The studied traits exhibited significant phenotypic differences with heritabilities ranging from 0.53 to 0.66, and most of the traits showed significant correlations with each other. The genome-wide association study (GWAS) found 51 significant and 30 suggestive trait–SNP associations that integrated into 14 valid quantitative trait loci (QTL) clusters and explained 5.7–21.2% phenotypic variance. In addition, RNA sequencing was performed at two time points to examine the differential expression of genes (DEGs) between high and low NUE lines. In total, 245, 540, and 399 DEGs were identified as LN stress-specific, high nitrogen (HN) condition-specific, and HNLN common DEGs, respectively. An integrated analysis of GWAS, weighted gene co-expression network, and DEGs revealed 16 genes involved in rapeseed root development under LN stress. Previous studies have reported that the homologs of seven out of sixteen potential genes control root growth and NUE. These findings revealed the genetic basis underlying nitrogen stress and provided worthwhile SNPs/genes information for the genetic improvement of NUE in rapeseed.