Nitrogen Fertilizer Utilization Research Articles

Assimilation of Nitrate into Asparagine for Transport in Soybeans

In this study, the systematic analysis of nitrate assimilation and transport in soybean roots was further improved by analyzing the concentrations of nitrate assimilates, asparagine and glutamine, in soybean roots and the related enzyme activities. This provided a theoretical basis for the efficient utilization of nitrogen fertilizer in soybean farming. A dual-root soybean system with both sides being nodulated was used to provide nitrate withdrawal and resupply in three phases on one side, while the other side received nutrients without nitrogen under sand culture conditions. Measurements were taken of the root’s nitrate reductase and glutamine synthetase activities, as well as the concentrations of asparagine. Measurements were also taken of the asparagine concentration in the basal root peeled skin (where the primary transport pathway is the phloem) and the woody parts (where the primary transport pathway is the xylem). Furthermore, the concentration of glutamine in the roots was also assessed. The findings indicated a positive correlation between the nitrate concentration in the roots and the activity of glutamine synthetase in the roots on both sides. The levels of asparagine in the roots, specifically those in the basal root peeled skin and woody part on both sides, rose when nitrate was added and declined when nitrate was removed. There was no significant change in glutamine concentration within the roots of soybeans. Hence, we deduced that the local provision of nitrate to the dual-root soybeans might enhance the absorption of nitrate into the roots on both sides. Additionally, the assimilated substances were predominantly carried as asparagine through the peeled skin and woody sections of the basal root, facilitating transportation in both directions within the soybean plants (from shoot to root and from root to shoot).

Application of information fusion technology in maize fertilizer utilization experiments

Abstract The article first utilizes the hyperspectral image grayscale, texture information, and reflectance spectral information at characteristic wavelengths to establish the corresponding quantitative analysis models of nutrient content in maize plants using three modeling methods, MLR, PCR, and PLS. Then from the basis of polarized reflection features, it was inferred that the polarization degree features at sensitive wavelengths were extracted using polarized spectra and combined with chemometric techniques to achieve a quantitative analysis of the degree of nutrient stress in maize. Finally, the feature variables extracted on the hyperspectral and polarized-reflection spectral measurement systems were fused with multiple information. A diagnostic evaluation model of fertilizer utilization with polarization-hyperspectral multidimensional light information was established. The results showed that for the new slow-release fertilizers, SF1 and YNPK had higher nitrogen utilization rates, 9.91% and 7.43% higher than N1PK, respectively. And the nitrogen fertilizer utilization rate was correspondingly higher by 6%-7% in 2020 than in 2019 for each fertilizer application treatment.

Effects of combined natural synergists and chemical inhibitors on yield, nitrogen utilization and balance in wheat/maize rotation system.

Urease inhibitors and nitrification inhibitors can enhance nitrogen (N) fertilizer utilization efficiency and reducing N losses through regulating urea-N transformation. Common urease or nitrification inhibitors, however, are predominantly chemically synthesized and high-cost. Furthermore, their inhibitory effects are mediated by soil pro-perties, climatic conditions, and crop systems. In this study, we conducted a field experiment using natural synergists humic acid/zeolite, along with chemical nitrification inhibitor dicyandiamide (DCD) and their combination to elucidate the impacts of natural synergists combined with chemical inhibitors on annual yield, nitrogen utilization efficiency, soil nitrate-N accumulation, and nitrogen balance within the wheat/maize rotation system. The treatments included no nitrogen fertilizer application (CK), single application of urea (N), urea +DCD (ND), urea + humic acid (NH), urea + zeolite (NP), urea + urease inhibitor N-butylthiophosphoric triamide + DCD (NUD), urea + humic acid + DCD (NHD), and urea + zeolite + DCD (NPD). The results showed that, compared to the treatments NH and NP, the integration of humic acid or zeolite with DCD (NHD and NPD) significantly increased maize yield (11268 and 11397 kg·hm-2) and total annual yield (20494 and 20582 kg·hm-2), which were comparable to those of combined chemical urease and nitrification inhibitors (NUD). The NHD and NPD treatments had higher nitrogen utilization efficiency and lower soil nitrate-N accumulation in 80-100 cm soil layer across all seasons relative to the N treatment, which had no significant difference compared to the NUD treatment. Furthermore, a decline in soil nitrogen surplus by 10.7% and 13.9% was observed when comparing the NHD and NPD treatments with the NH and NP treatments, respectively. These findings suggested that combined humic acid or zeolite and chemical nitrification inhibitors could effectively enhance crop yield and N utilization efficiency and meet the requirements of the green and environmental preservation of modern agriculture.

Transcriptome Analysis of Nitrogen-Deficiency-Responsive Genes in Two Potato Cultivars

The potato is the third largest food crop, and nitrogen fertilizer is important for increasing potato yields; however, the shallow root system of potatoes causes the nitrogen fertilizer utilization rate to be low, which results in waste and environmental pollution, meaning that high nitrogen efficiency breeding is highly significant for potatoes. In the high nitrogen efficiency breeding of potatoes, genes with a nitrogen-deficient response should first be identified, and RNA-seq is an efficient method for identifying nitrogen-deficiency-response genes. In this study, two potato cultivars, Dongnong 322 (DN322) and Dongnong 314 (DN314), were utilized, and two nitrogen fertilizer application rates (N0 and N1) were set for both cultivars. Through the determination of physiological indicators, we identified that DN314 is more sensitive to nitrogen fertilizer, while DN322 is relatively insensitive to nitrogen fertilizer. Samples were taken at the seedling and tuber formation stage. At the seedling stage, DN322 and DN314 had 573 and 150 differentially expressed genes (DEGs), while at the tuber formation stage, they had 59 and 1905 DEGs, respectively. A total of three genes related to a low-nitrogen response were obtained via the combined analysis of differentially expressed genes (DEGs) and weighted correlation network analysis (WGCNA), of which two genes were obtained at the tuber formation stage and one gene in the seedling stage, providing theoretical guidance for the high nitrogen efficiency breeding of potatoes.

Nitrate improves aluminium resistance through SLAH-mediated citrate exudation from roots.

Aluminium (Al) toxicity is one of the major constraint for crop production in acidic soil, and the inappropriate utilization of nitrogen fertilizer can accelerate soil acidification. Despite previous studies investigating the regulation of nitrogen forms in Al toxicity of plants, the underlying mechanism, particularly at the molecular level, remains unclear. This study aims to uncover the potentially regulatory mechanism of nitrate (NO3 - ) in the Al resistance of maize and Arabidopsis. NO3 - conservatively improves Al resistance in maize and Arabidopsis, with nitrate-elevated citrate synthesis and exudation potentially playing critical roles in excluding Al from the root symplast. ZmSLAH2 in maize and AtSLAH1 in Arabidopsis are essential for the regulation of citrate exudation and NO3 - -promoted Al resistance, with ZmMYB81 directly targeting the ZmSLAH2 promoter to activate its activity. Additionally, NO3 - transport is necessary for NO3 - -promoted Al resistance, with ZmNRT1.1A and AtNRT1.1 potentially playing vital roles. The suppression of NO3 - transport in roots by ammonium (NH4 + ) may inhibit NO3 - -promoted Al resistance. This study provides novel insights into the understanding of the crucial role of NO3 - -mediated signalling in the Al resistance of plants and offers guidance for nitrogen fertilization on acid soils.

Impact of Foliar Application of Nano Nitrogen and Nano Zinc on Soil Properties of Mustard (Brassica juncea L.) Crop

The utilization of nano-sized nitrogen (N) and zinc (Zn) fertilizers through foliar application has gained considerable attention in agricultural research. This study focuses on investigating the effects of such foliar applications on soil properties, including both chemical and biological aspects, after the harvest of mustard (Brassica juncea L.). The field experiment was carried out during October to March 2022 season at Instructional Farm, Rajasthan College of Agriculture, MPUAT, Udaipur which lies in agro-climatic zone IV-A of Rajasthan, India. The field was designed in a randomized block design having 10 treatments which were replicated thrice. The treatments include the various combination RDF and nano fertilizers of N and Zn. The application treatment T6 (100% NPK Zn +1st spray of Nano N and Zn at 30 DAS +2nd spray of Nano N and Zn at 45 DAS) has significantly increased the availability of macronutrients (N, P, K), micronutrients (Zn, Fe, Cu and Mn), microbial population (bacteria, fungi and actinomycetes) as well as the dehydrogenase and acid phosphatase enzyme activity in post-harvest soil of mustard over control.

Incorporation of spring maize into paddy fields increased nitrogen uptake in late rice by enhancing soil nitrogen supply: Field 15N tracer studies

To assess the impacts of the incorporation of spring maize into paddy fields on the utilization of nitrogen (N) fertilizer by late rice, a two-year microplot experiment was performed using labeled 15N-urea to trace the fate of N fertilizer in spring maize-late rice (SM-LR) and early rice-late rice (ER-LR) systems. Compared with ER-LR system, SM-LR system showed higher grain yields and total N use of late rice. However, no difference in fertilizer-N use in late rice between the two cropping systems, and the utilization of soil-N rather than fertilizer-N was responsible for the increased total N uptake by late rice. Further microplot experiments on the fate of soil residual 15N showed a greater amount of soil residual 15N in the spring maize season than in the early rice season (122 vs. 72 kg N ha−1). However, soil residual 15N from the first season had a negligible contribution to the utilization of N in late rice. We conclude that the improvement in the soil N supply accounts for the increased total N use in late rice under the incorporation of spring maize into paddy fields.

Changes in the diversity of pecan (Carya illinoinensis) rhizosphere microbial community with different nitrogen fertilization, a case study in Oklahoma pecan orchard

Pecan (Carya illinoinensis) is primarily native to North America and is known as the leading nut produced in Oklahoma. Since the prices of fertilizers have increased and the activity of soil microbes may greatly affect fertilizer utilization, it is important to investigate the effect of fertilization on microbes. Samples were collected from pecan trees receiving full nitrogen (70 lbs/acre), half nitrogen (35 lbs/acre), and no nitrogen (0 lbs/acre) fertilization in an orchard. Microbes were characterized by using the next generation sequencing and annotated into functional groups (trophic mode and nitrogen related) by FUNGuild and FAPROTAX. Our results showed the core fungal genera in this orchard were Tuber and Hymenoscyphus, while the core bacterial families were Chitinophagaceae, Xanthobacteraceae, and Chthoniobacteraceae. Among them, the pecan truffle Tuber lyonii was the dominant fungus. In association with an increase of nitrogen fertilization, the Simpson Index (SI) of fungi in roots was decreased, and the presence of pathotroph (such as Monographella cucumerina and Lectera longa) was increased, implying that the risk of plant infection by pathogens was increased. The pecan with half rate of nitrogen fertilizer had the highest colonization of symbiotrophic fungi, the lowest presence of pathotrophic fungi, and the highest relative abundance of Tuber. The relative abundances of bacteria related to nitrate reduction, nitrogen respiration, and nitrate respiration were found to be the highest in pecan with half rate of nitrogen fertilizer, which might imply the highest efficiency of nitrogen fertilizer utilization in this treatment. It revealed that applying half the recommended nitrogen rate of fertilizer could improve beneficial microbe presence, perhaps increasing nitrogen uptake and decreasing nitrogen needed for optimum production.

Effects of Urea Application on Soil Organic Nitrogen Mineralization and Nitrogen Fertilizer Availability in a Rice–Broad Bean Rotation System

Rice cultivation is facing a situation where rice production stagnates while nitrogen fertilizer (NF) application continues to increase. The effectiveness of the NF residues from the rice season on the growth of rotating broad beans is unclear. High NF use in rice cultivation also affects the nitrogen supply through soil organic nitrogen (SON) mineralization (SONM). However, the rules of SONM and the NF availability in the rice–broad bean rotation system (RBRS) are unknown. A field trial of the RBRS was conducted using 15N-labeled urea (CO(15NH2)2) as the partial NF source (15N accounted for 5.3% of the total pure nitrogen applied) for the rice and no NF for the broad bean. It was found that 33.0–38.1% of NF in the rice season was utilized. NF availability was low in the broad bean season (3.6–4.0%). SONM was the most important source, providing approximately 60% of the nitrogen for rice growth. The SONM into mineral nitrogen and the fixation of mineral nitrogen into SON occurred simultaneously, with SONM dominating in most cases. SON content decreased slowly in the rice season and dramatically in the broad bean’s podding stage with a 0.64 g kg−1 (24.1%) decrease. The high nitrogen application in rice season promoted SONM and aggravated groundwater pollution. Soil urease activity, rather than catalase, phosphatase, and invertase activities, can be the main monitoring object of SONM. Furthermore, fungal abundance (especially Aspergillaceae, Neuroceae, and unclassified_o__Helotiales), rather than bacteria, was the primary target for SONM monitoring. It is unreasonable to apply large amounts of NF in the rice season but not in the broad bean season in the RBRS. N1 (135 kg N ha−1) had the best comprehensive benefits regarding crop yield, nitrogen supply by SONM, NF utilization, and nitrogen loss on the environment in the RBRS.

Tillage with straw incorporation reduces the optimal nitrogen rate for maize production by affecting crop uptake, utility efficiency, and the soil balance of nitrogen

AbstractUnderstanding the combined effects of tillage and straw incorporation on grain yield and nitrogen (N) fertilizer utilization is vital for sustainable agriculture in northeastern China. How various tillage patterns with straw incorporation affect soil N balance and optimal N rate for crop production remains largely unknown. A four‐year (2015–2018) field experiment was conducted to assess the impact of rotary tillage with maize straw incorporation (RTS) and plough tillage with straw incorporation (PTS) combined with different N fertilizer rates (0, 112, 187, 262, and 337 kg N ha−1) on maize yield, N uptake, soil N balance, nitrogen use efficiency, and optimal N rate. In general, higher straw N uptake and lower N partial factor productivity, N use efficiency, and recovery of applied N in grains were obtained under PTS than under RTS. Moreover, grain yield and both straw and grain N uptake increased with the N application rate. However, no further increase in grain yield was observed when the applied N exceeded 187 kg N ha−1. PTS resulted in a higher level of unaccounted N from applied N fertilizer (38–81 kg N ha−1) than RTS. A high N fertilizer input (>262 kg N ha−1) combined with straw incorporation resulted in a high soil mineral N profit and substantially increased unaccounted N (614–715 kg N ha−1) over the four‐year field trial period. The optimal N input required for the highest maize yield could be reduced by 35.0%–44.6% using tillage with straw return. Nevertheless, PTS was more effective than RTS at lowering the optimal N application rate. Overall, the results of this short‐term maize field study conducted in northeastern China suggest that the amount of N fertilizer input required for maize production could be reduced by using tillage with continuous straw incorporation.

Dissecting the key genomic regions underlying high yield potential in common wheat variety ‘Kenong 9204’

The foundation parents play key roles in the genetic improvement of both yield potential and end-use quality in wheat. Characterizing the genetic basis that underlies certain beneficial traits in the foundation parents will provide theoretical reference for molecular breeding by a design approach. ‘Kenong 9204’ (KN9204) is a candidate foundation parent characterized by ideotype, high yield potential, and particularly high nitrogen fertilizer utilization. To better understand the genetic basis of its high yield potential, high throughput whole-genome re-sequencing (10×) was performed on KN9204, its parental lines and its derivatives. A high-resolution genetic composition map of KN9204 was constructed, which showed the parental origin of the favorable genomic segments based on the identification of excellent yield-related quantitative trait loci (QTL) from a bi-parental mapping population. Xiaoyan 693 (XY693), a wheat–Thinopyrum ponticum partial amphidiploid, contributed a great deal to the high yield potential of KN9204, and three major stable QTLs from XY693 were fine mapped. The transmissibility of key genomic segments from KN9204 to its derivatives were delineated, indicating that haplotype blocks containing beneficial gene combinations were conserved along with directional selection by breeders. Evidence for selection sweeps in the breeding programs was identified. This study provides a theoretical reference for the breeding of high-yield wheat varieties by a molecular design approach.

Effects of Organic Fertilizer Replacement Nitrogen Fertilizer on Nitrogen Utilization and Growth of Mung Bean: Evidence from 15N-Tracing Technology

To optimize a suitable fertilization method needed for high nitrogen utilization and growth of mung bean in the black soil of Northeast China, a field experiment was carried out with 10 treatments based on isotope-tracing technology. The nitrogen fertilizer utilization, residual, loss and dry-matter transportation, leaf area, photosynthetic potential, and wet-basis moisture content of mung bean were discussed. The results showed that the total utilization rate of nitrogen fertilizer under different treatments was 34.75~47.71%, while in the 0~15 cm soil layer, the total residual rate was 11.36~33.69%, and the loss rate was 21.03~53.89%. The T1 treatment had the lowest total nitrogen fertilizer utilization rate and the greatest loss rate. The leaf area and photosynthetic potential at the seedling stage in the T9 treatment, the branching stage in the T2 treatment, and the flowering stage in the T4 and T9 treatments were 5.11~31.82% higher than those in the CK treatment, and the values at the drumming and maturing stages were significantly lower than those in the CK treatment (p < 0.05). The total wet-basis water content of the root, stem, leaf, and pod in the whole stages compared with the CK treatment increased by 3.35~7.41% in T4, T5, T7, and T8. In the T6 and T9 treatments, the output rate of stem-sheath storage matter and the transformation rate were significantly higher than those in the T1 treatment (p < 0.05). The dry-matter accumulation in the T1 and T9 treatments was significantly different from that in the CK treatment, which increased by 27.72% and 5.10%, respectively. Thus, organic fertilizer coupled with nitrogen fertilizer can improve the nitrogen fertilizer utilization rate and the growth of mung beans.

Construction, Characterization, and Application of an Ammonium Transporter (AmtB) Deletion Mutant of the Nitrogen-Fixing Bacterium Kosakonia radicincitans GXGL-4A in Cucumis sativus L. Seedlings.

Nitrogen is an important factor affecting crop yield, but excessive use of chemical nitrogen fertilizer has caused decline in nitrogen utilization and soil and water pollution. Reducing the utilization of chemical nitrogen fertilizers by biological nitrogen fixation (BNF) is feasible for green production of crops. However, there are few reports on how to have more ammonium produced by nitrogen-fixing bacteria (NFB) flow outside the cell. In the present study, the amtB gene encoding an ammonium transporter (AmtB) in the genome of NFB strain Kosakonia radicincitans GXGL-4A was deleted and the △amtB mutant was characterized. The results showed that deletion of the amtB gene had no influence on the growth of bacterial cells. The extracellular ammonium nitrogen (NH4+) content of the △amtB mutant under nitrogen-free culture conditions was significantly higher than that of the wild-type strain GXGL-4A (WT-GXGL-4A), suggesting disruption of NH4+ transport. Meanwhile, the plant growth-promoting effect in cucumber seedlings was visualized after fertilization using cells of the △amtB mutant. NFB fertilization continuously increased the cucumber rhizosphere soil pH. The nitrate nitrogen (NO3-) content in soil in the △amtB treatment group was significantly higher than that in the WT-GXGL-4A treatment group in the short term but there was no difference in soil NH4+ contents between groups. Soil enzymatic activities varied during a 45-day assessment period, indicating that △amtB fertilization influenced soil nitrogen cycling in the cucumber rhizosphere. The results will provide a solid foundation for developing the NFB GXGL-4A into an efficient biofertilizer agent.

Effects of nitrogen reduction combined with organic fertilizer on growth and nitrogen fate in banana at seedling stage

Nitrogen reduction combined with organic fertilizer is of considerable significance for the sustainable development of agriculture. A pot experiment using nitrogen reduction combined with organic fertilizer was conducted to explore the effects of different treatments on matter accumulation, physiological resistance, and fertilizer nitrogen fate in banana seedlings. Compared with conventional fertilization, a 20% reduction of nitrogen did not affect the dry weight, chlorophyll content, physiological resistance, and fertilizer utilization rate of banana seedlings, but significantly reduced the nitrogen leaching loss and increased the nitrogen soil residue. Compared with conventional fertilization, organic nitrogen substituting 20% or 30% of the nitrogen reduced by 20% significantly promoted dry matter accumulation and physiological resistance. Organic nitrogen substituting 30% of the 20% reduction of nitrogen increased the dry matter of the whole plant by 24.94%, the nitrogen uptake in the root by 30.87%, the chlorophyll content by 6.05%, the soluble sugar content by 16.88%, Peroxidase (POD) activity by 26.35%, Catalase (CAT) activity by 27.48%, and Super Oxide Dismutase (SOD) activity by 22.97%. Compared with conventional fertilization, all organic substitution treatments significantly reduced fertilizer nitrogen leaching loss, apparent loss, and increased nitrogen soil residue. Compared with the 20% reduction of nitrogen, organic nitrogen substituting 30% of the 20% reduction of nitrogen significantly increased nitrogen utilization by 16.34% and soil residue rate by 13.26%, and reduced nitrogen leaching loss by 35.46%. The results of the present study revealed that a 20% reduction of nitrogen fertilizer with a 30% organic substitution application promoted matter accumulation, enhanced the physiological resistance of banana seedlings, increased the utilization and residue of nitrogen fertilizer, and reduced nitrogen pollution.

Regulation effects of carbonized apple branches on absorption, distribution, and utilization of 15N single-labeled ammonium nitrate (15NH4NO3 or NH415NO3) in Malus hupehensis

To improve the utilization of nitrogen fertilizer and orchard waste, the apple branches were separated and pyrolyzed into carbonized wood and carbonized bark, and then applied to root-zone soil of potted Malus hupehensis. The physiological characteristics of leaves and roots were detected, and the absorption, utilization, and distribution of 15NH4NO3 and NH415NO3 in plants were analyzed using the 15N isotope tracer technique. The results indicated that the net photosynthetic rate and water use efficiency of leaves, the root growth, and the activity of nitrate reductase and glutamine synthetase were greatest increased by 1.0% (w:w) carbonized bark and carbonized wood, and the effect of carbonized bark was more effective. The carbonized bark more effectively increased nitrogen derived from fertilizer (Ndff) value in all organs, the distribution of 15N in roots, and utilization of the 15NH4NO3 and NH415NO3 of Malus hupehensis compared with carbonized wood at the same application ratio, and 1.0% ratio performed better than other ratios in these terms. The Malus hupehensis treated with carbonized bark had the highest utilization ratio of 15NH4NO3 (10.54%) when the application ratio was 1.0%, and the corresponding parameter of NH415NO3 was 12.98%. The soil immobilization capacity of 15N was improved, and carbonized bark resulted in the greatest decrease in the loss ratios of 15NH4NO3 and NH415NO3 under 1.0% ratio, which decreased by 27.33% and 30.08%, respectively. For reducing nitrogen loss and improving nitrogen utilization, carbonized bark was more effective than carbonized wood, mainly because bark contained more cellulose and less lignin than wood.

Nitrogen-Reduction in Intensive Cultivation Improved Nitrogen Fertilizer Utilization Efficiency and Soil Nitrogen Mineralization of Double-Cropped Rice

Under the current rice cropping system, excessive nitrogen application has become a major issue that needs to be changed, and nitrogen reduction has become a hot research topic in recent years. The use of optimum planting density is becoming a common agronomic management system in addition to nitrogen reduction, especially under double cropping rice systems. In this paper, changes in rice yield, nitrogen-use efficiency (NUE) and net N mineralization under dense planting with a reduced nitrogen rate (DPRN) were studied. By comparing DPRN with high-nitrogen sparse planting (SPHN), we found that the population tiller number (tiller number per unit area) increased by 9–27% under DPRN cultivation. Nitrogen accumulation under DPRN treatment of double-cropped rice was basically stable. NUE under DPRN was significantly higher by 1.3–22.7% compared to SPHN. The partial factor productivity of applied N (PFPN) was significantly higher than that of SPHN, with an increase of 4.3–22.8%. The net N mineralized of double-cropped rice under DPRN increased at different stages, and the increase in late-season rice (LSR) was greater than that of early-season rice (ESR). The highest net N mineralized in double cropping rice at different stages was found in the dense planting treatment (DP) and N2 (120 kg N h−1). In conclusion, DPRN cultivation of double-cropped rice could be accepted as a proper management strategy for reducing nitrogen input, improving NUE and promoting soil nitrogen mineralization under given conditions.

Optimized Border Irrigation Improved Nitrogen Accumulation, Translocation of Winter Wheat and Reduce Soil Nitrate Nitrogen Residue

We aimed to optimize field border length in the Huang-Huai-Hai Plain of China (HPC) to reduce soil inorganic nitrogen residues and increase nitrogen absorption and utilization by wheat plants using a traditional border irrigation system. In a two-year experiment (2017–2019) conducted in the HPC, four border lengths were tested: 20 m (L20), 30 m (L30), 40 m (L40), and 50 m (L50). Supplementary irrigation was implemented during jointing and anthesis stages, and control fields received treatment without irrigation. The results showed that, compared with irrigation of other border lengths, L40 irrigation significantly increased nitrogen transport in stems and leaves. In addition, L40 irrigation had the highest rate of grain nitrogen accumulation after anthesis. The risk of nitrate leaching to deep layers increased with increasing border length; however, L40 irrigation improved the plants’ capacity to absorb soil nitrogen, and the soil inorganic nitrogen residue was significantly lower than that with irrigation of other border lengths. Therefore, the grain yield and nitrogen fertilizer utilization under L40 irrigation were significantly higher than those under irrigation of other border lengths, and L40 was considered as the best border irrigation length.

Rice yield, water productivity, and nitrogen use efficiency responses to nitrogen management strategies under supplementary irrigation for rain-fed rice cultivation

Rainfall-adapted irrigation (RAI) or supplementary irrigation for rain-fed rice cultivation consumes less amount of irrigation water by harvesting rainfall and thus is vital for sustainable rice (Oryza sativa L.) production in multi-rain areas, including the Jianghan Plain in China. However, nitrogen management strategies influence rice growth and water and nitrogen utilization under RAI remains unclear. Thus, we conducted a two-year (2016 and 2017) field experiment at Jingzhou City, central China to investigate the effects of nitrogen management strategies on grain yield, crop water productivity (CWP), and nitrogen use efficiency (NUE) of rice under conventional flooding irrigation (CF) and RAI. The nitrogen management strategies included local farmers’ nitrogen fertilization (CN), common urea (30% nitrogen) blended with controlled-release nitrogen fertilizer (70% nitrogen) (U+CRF), and optimized nitrogen fertilization (ON), at a nitrogen rate of 180, 180, and 150 kg ha−1, respectively. Compared to the CF condition, RAI down-regulated the numbers of irrigation (−3 in 2016 and −4 in 2017) and reduced the total amount of irrigation water (−41.6% in 2016 and −45.6% in 2017), suggesting that rainfall-adapted irrigation enhanced the rainwater storage capacity and usage. RAI also increased root length, root and shoot biomass, net photosynthetic rate, crop growth rate, nitrogen accumulation, percentage of productive tillers, harvest index, and nitrogen harvest index. The U+CRF and ON increased or maintained these parameters compared with the CN. Compared to the traditional irrigation and nitrogen fertilization pattern (CF interacted with CN), RAI combined with U+CRF or ON enhanced root length and root biomass, and had a relatively high spikelets number per panicle, grains filled percentage, and 1000-grain weight, and thus produced a high grain yield. Moreover, the new treatment reduced amount of irrigation water and improved utilization of nitrogen fertilizer, resulting in a greater CWP and NUE. The enhanced grain yield, CWP, and NUE were associated with the increased root biomass and root length. Therefore, rainfall-adapted irrigation combined with the new nitrogen management (U+CRF or ON) can synergistically increase grain yield and resource use efficiency by improving root growth in rice.

Can controlled-release urea replace the split application of normal urea in China? A meta-analysis based on crop grain yield and nitrogen use efficiency

Normal urea (NU) often requires multiple applications to increase crop yield and nitrogen (N) fertilizer utilization efficiency by improving the synchronization of crop N demand, which increases the labor input. Controlled-release urea (CRU) has excellent N release performance, and it can significantly increase crop productivity with only one application as a base fertilizer. However, there is still a lack of comprehensive evaluation of whether CRU can replace the split application of NU (split-NU) to increase crop yield and N fertilizer use efficiency, as this would reduce the necessary labor. Therefore, the aim of this study was to evaluate whether CRU can replace split-NU nationwide. To this end, we collected peer-reviewed articles on CRU and split-NU that were published in recent decades and performed a meta-analysis. The results showed that, compared with all NU as base fertilizer, CRU and split-NU increased crop yield by 10.08% and 8.11%, respectively, and N use efficiency by 47.55% and 45.21%, respectively. In general, CRU had a better substitution effect on split-NU nationwide. However, due to regional climate factors, soil physicochemical factors, and field management measures, the substitution effect of CRU on split-NU varied. In most cases, CRU had a good substitution effect on split-NU, but when the soil available N content (< 50 mg kg −1 ) and the N application rate (< 150 kg ha −1 ) are both low, the planted crop was wheat, CRU had a poor substitution effect on split-NU. In addition, we found that CRU had a good substitution effect on split-NU in reducing N loss (greenhouse gas emissions and nitrate leaching) and increasing economic benefits. Therefore, we highlighted the threefold benefits of CRU, as it can improve crop productivity, reduce N loss, and decrease labor input; thus, it can be widely applied nationwide. • Both CRU and split-application of NU can improve crop yield and NUE. • CRU had a good substitution effect for split-application of NU. • CRU can help reduce environment costs and the labor input.

Identification and characterization of apple MdNLP7 transcription factor in the nitrate response

Nitrogen is an essential nutrient for plant growth and development. Low utilization of nitrogen fertilizer during agricultural production causes a series of environmental problems, such as water eutrophication, soil acidity, and air pollution. Investigating the patterns and mechanisms of crop NO3− absorption and utilization therefore key to fully improving crop nitrogen utilization rates and promoting sustainable agricultural development. Apple is one of the most important horticultural crops in the world. Its nitrogen demand by apple during the growth period is very high, but few studies have been performed on apple genes, that regulate the NO3− response. Here, we found that the apple transcription factor MdNLP7 promoted nitrogen absorption and assimilation by activating the expression of MdNIA2 and MdNRT1.1. MdNLP7 also regulated H2O2 content by increasing catalase activity, which may also influence nitrate utilization. Our findings provide insight into the mechanisms by which MdNLP7 controls nitrate utilization in apple.