Maize Nitrogen Use Research Articles

Root plasticity improves maize nitrogen use when nitrogen is limiting: an analysis using 3D plant modelling.

Plant phenotypic plasticity plays an important role in nitrogen (N) acquisition and use under nitrogen-limited conditions. However, this role has never been quantified as a function of N availability, leaving it unclear whether plastic responses should be considered as potential targets for selection. A combined modelling and experimentation approach was adopted to quantify the role of plasticity in N uptake and plant yield. Based on a greenhouse experiment we considered plasticity in two maize (Zea mays) traits: root-to-leaf biomass allocation ratio and emergence rate of axial roots. In a simulation experiment we individually enabled or disabled both plastic responses for maize stands grown across six N levels. Both plastic responses contributed to maintaining a higher N uptake, and plant productivity as N availability declined compared with stands in which plastic responses were disabled. We conclude that plastic responses quantified in this study may be a potential target trait in breeding programs for greater N uptake across N levels while it may only be important for the internal use of N under N-limited conditions in maize. Given the complexity of breeding for plastic responses, an a priori model analysis is useful to identify which plastic traits to target for enhanced plant performance.

Long-term excessive nitrogen application decreases spring maize nitrogen use efficiency via suppressing root physiological characteristics

Long-term excessive nitrogen application decreases spring maize nitrogen use efficiency via suppressing root physiological characteristics

Effect of Glycolipids Application Combined with Nitrogen Fertilizer Reduction on Maize Nitrogen Use Efficiency and Yield.

Microbial-driven N turnover is important in regulating N fertilizer use efficiency through the secretion of metabolites like glycolipids. Currently, our understanding of the potential of glycolipids to partially reduce N fertilizer use and the effects of glycolipids on crop yield and N use efficiency is still limited. Here, a three-year in situ field experiment was conducted with seven treatments: no fertilization (CK); chemical N, phosphorus and potassium (NPK); NPK plus glycolipids (N+PKT); and PK plus glycolipids with 10% (0.9 N+PKT), 20% (0.8 N+PKT), 30% (0.7 N+PKT), and 100% (PKT) N reduction. Compared with NPK, glycolipids with 0-20% N reduction did not significantly reduce maize yields, and also increased N uptake by 6.26-11.07%, but no significant changes in grain or straw N uptake. The N resorption efficiency under 0.9 N+PKT was significantly greater than that under NPK, while the apparent utilization rates of N fertilizer and partial factor productivity of N under 0.9 N+PKT were significantly greater than those under NPK. Although 0.9 N+PKT led to additional labor and input costs, compared with NPK, it had a greater net economic benefit. Our study demonstrates the potential for using glycolipids in agroecosystem management and provides theoretical support for optimizing fertilization strategies.

Nitrogen fertilization promoted microbial growth and N2O emissions by increasing the abundance of nirS and nosZ denitrifiers in semiarid maize field.

Nitrous oxide (N2O) emissions are a major source of gaseous nitrogen loss, causing environmental pollution. The low organic content in the Loess Plateau region, coupled with the high fertilizer demand of maize, further exacerbates these N losses. N fertilizers play a primary role in N2O emissions by influencing soil denitrifying bacteria, however, the underlying microbial mechanisms that contribute to N2O emissions have not been fully explored. Therefore, the research aimed to gain insights into the intricate relationships between N fertilization, soil denitrification, N2O emissions, potential denitrification activity (PDA), and maize nitrogen use efficiency (NUE) in semi-arid regions. Four nitrogen (N) fertilizer rates, namely N0, N1, N2, and N3 (representing 0, 100, 200, and 300 kg ha-1 yr.-1, respectively) were applied to maize field. The cumulative N2O emissions were 32 and 33% higher under N2 and 37 and 39% higher under N3 in the 2020 and 2021, respectively, than the N0 treatment. N fertilization rates impacted the abundance, composition, and network of soil denitrifying communities (nirS and nosZ) in the bulk and rhizosphere soil. Additionally, within the nirS community, the genera Cupriavidus and Rhodanobacter were associated with N2O emissions. Conversely, in the nosZ denitrifier, the genera Azospirillum, Mesorhizobium, and Microvirga in the bulk and rhizosphere soil reduced N2O emissions. Further analysis using both random forest and structural equation model (SEM) revealed that specific soil properties (pH, NO3--N, SOC, SWC, and DON), and the presence of nirS-harboring denitrification, were positively associated with PDA activities, respectively, and exhibited a significant association to N2O emissions and PDA activities but expressed a negative effect on maize NUE. However, nosZ-harboring denitrification showed an opposite trend, suggesting different effects on these variables. Our findings suggest that N fertilization promoted microbial growth and N2O emissions by increasing the abundance of nirS and nosZ denitrifiers and altering the composition of their communities. This study provides new insights into the relationships among soil microbiome, maize productivity, NUE, and soil N2O emissions in semi-arid regions.

Genetic control of agronomic efficiency of nitrogen use in maize

Genetic control of agronomic efficiency of nitrogen use in maize

The Effect of Nitrogen Fertilizer and Faba Bean Density in Rotation, on Maize Nitrogen Use Efficiency under No-till System

دستیابی همزمان به امنیت غذایی و پایداری محیط‌زیست یک چالش بزرگ جهانی است. بنابراین، استفاده از سیستم‌های کشاورزی حفاظتی برای دستیابی به این هدف ضروری به نظر می‌رسد. از این‌رو یک آزمایش مزرعه‌ای طی دو سال زراعی (1397-1396 و 1398-1397) به‌صورت فاکتوریل دو عاملی بر پایه طرح بلوک کامل تصادفی با سه تکرار در مزرعه دانشکده کشاورزی دانشگاه محقق اردبیلی اجرا شد. تیمارهای آزمایشی شامل تراکم‌های مختلف بوته در باقلا (25، 35، 40 و 80 بوته در متر مربع) و مقادیر مختلف نیتروژن معدنی بر پایه کود اوره در ذرت علوفه‌ای (0، 100، 200 و 300 کیلوگرم در هکتار) بود. نتایج نشان داد که تراکم بوته باقلا بر تلاش زادآوری، عملکرد تر و خشک دانه، درصد نیتروژن و پروتئین خام موجود در دانه، عملکرد پروتئین و شاخص برداشت پروتئین دانه باقلا معنی‌دار P<(0.01) بود. بیشترین عملکرد دانه باقلا از تراکم‌های 80 و 40 بوته در مترمربع به‌ترتیب با میانگین 76/3 و 65/3 تن در هکتار به‌دست آمد. همچنین اثرات متقابل مقادیر مختلف کاربرد نیتروژن معدنی و تراکم‌های مختلف بوته باقلا بر تولید ماده‌ی خشک، کارایی مصرف نیتروژن و کارایی تولید ذرت علوفه‌ای تاثیر معنی‌داریP<(0.01) داشت. بیشترین میزان ماده‌ی خشک در ذرت علوفه‌ای با میانگین 6/15 تن در هکتار از تیمار 200 کیلوگرم نیتروژن معدنی در هکتار و تراکم 40 بوته در مترمربع باقلا حاصل شد. به‌طور کلی نتایج حاصل از این آزمایش نشان داد که قرارگیری باقلا در تناوب با ذرت می‌تواند یک روش جایگزینی مناسب برای سیستم تک کشتی ذرت با مقادیر بالای مصرف کود نیتروژنه باشد.

Function analysis of nitrogen-responsive transcription factor ZmNLP5 affecting root growth in maize

<p indent=0mm>Improving nitrogen (N) use efficiency of crops is crucial for minimizing N loss and reducing environmental pollution, which is a requirement for the sustainable agriculture. Our previous study found that the transcription factor ZmNLP5 directly regulated the expression of <italic>ZmNIR1</italic>.<italic>1</italic> and promoted nitrogen uptake and assimilation in maize, however, its underlying regulation mechanism is unclear. Here, we performed further phenotype analysis of <italic>zmnlp5 </italic>and wild type (W22) plants in hydroponic culture on sufficient nitrogen (SN) solution and deficient nitrogen (DN) solution. Compared with WT plants, the root length of <italic>zmnlp5</italic> mutant plants was significantly decreased under DN condition. Compared with upper and middle regions of roots, ZmNLP5 was predominantly expressed in root tip regions. Then, we examined the relationship between root length and nitrite content in root tips under a series of nitrite concentrations. The results showed that there was no significant differences in root length between WT and <italic>zmnlp5</italic> until the nitrite concentration reached <sc>2 mmol L^–1</sc> and higher; however, when the concentration of nitrite was higher than <sc>2 mmol L^–1,</sc> the root length of <italic>zmnlp5</italic> was significantly shorter than WT, and the accumulation of nitrite in the root tips of <italic>zmnlp5</italic> was significantly higher than WT. Interestingly, <italic>zmnlp5 </italic>plants also accumulated significantly more nitrite in the root tips than WT under DN condition. The study showed that the transcription factor ZmNLP5 played an important role in the root growth of maize in response to deficient nitrogen condition, and provided the candidate genes for breeding of maize nitrogen use efficiency in the future.

Maize nitrogen use efficiency improved due to density tolerance increase since the 1950s

AbstractMeeting maize (Zea mays L.) production targets of high grain yields and nitrogen use efficiency (NUE) requires the development of stress‐tolerant cultivars and corresponding cultivation practices that maximize efficiency. Therefore, our objectives were to (i) determine the impacts of N application rate, planting density, and maize cultivar (which have improved with each successive release date) on the N partial productivity factor (PFPN) and N agronomic efficiency (AEN), and to (ii) characterize the responses of maize cultivars indexes to different cultivation conditions. We found that maize PFPN and AEN values were affected by N application, planting density, and cultivar. The PFPN and AEN declined with increasing N but increased with increasing planting density or genetic improvement (i.e. later year of release). The responses of PFPN and AEN to planting density and N application, taken either as single factors or as interacting factors, were greater for recently released cultivars than for older cultivars. The PFPN and AEN values were not automatically associated with maize yields, indicating that the genetic improvements that led to increases in PFPN and AEN were due to unconscious selection. Thus, improvements in NUE resulted from improvements in cultivars’ tolerance to planting density stresses and from cultivation practices that employed higher planting densities from the 1950s to 2010.

Nitrogen rate impacts on tropical maize nitrogen use efficiency and soil nitrogen depletion in eastern and southern Africa

Sub-Saharan Africa is facing food security challenges due, in part, to decades of soil nitrogen (N) depletion. Applying N fertilizer could increase crop yields and replenish soil N pools. From 2010 to 2015, field experiments conducted in Embu and Kiboko, Kenya and Harare, Zimbabwe investigated yield and N uptake response of six maize (Zea mays L.) hybrids to four N fertilizer rates (0 to 160 kg N ha−1) in continuous maize production systems. The N recovery efficiency (NRE), cumulative N balance, and soil N content in the upper 0.9 m of soil following the final harvest were determined at each N rate. Plant and soil responses to N fertilizer applications did not differ amongst hybrids. Across locations and N rates, NRE ranged from 0.4 to 1.8 kg kg−1. Higher NRE values in Kiboko and Harare occurred at lower post-harvest soil inorganic N levels. The excessively high NRE value of 1.8 kg kg−1 at 40 kg N ha−1 in Harare suggested that maize hybrids deplete soil inorganic N most at low N rates. Still, negative cumulative N balances indicated that inorganic soil N depletion occurred at all N rates in Embu and Harare (up to − 193 and − 167 kg N ha−1, respectively) and at the 40 kg N ha−1 rate in Kiboko (− 72 kg N ha−1). Overall, maize N uptake exceeded fertilizer N applied and so, while yields increased, soil N pools were not replenished, especially at low total soil N levels (< 10,000 kg N ha−1 in top 0.9 m).

Mechanisms of Nitrogen Use in Maize

Nitrogen (N) fertilizers are needed to enhance maize (Zea mays L.) production. Maize plays a major role in the livestock industry, biofuels, and human nutrition. Globally, less than one-half of applied N is recovered by maize. Although the application of N fertilizer can improve maize yield, excess N application due to low knowledge of the mechanisms of nitrogen use efficiency (NUE) poses serious threats to environmental sustainability. Increased environmental consciousness and an ever-increasing human population necessitate improved N utilization strategies in maize production. Enhanced understanding of the relationship between maize growth and productivity and the dynamics of maize N recovery are of major significance. A better understanding of the metabolic and genetic control of N acquisition and remobilization during vegetative and reproductive phases are important to improve maize productivity and to avoid excessive use of N fertilizers. Synchronizing the N supply with maize N demand throughout the growing season is key to improving NUE and reducing N loss to the environment. This review examines the mechanisms of N use in maize to provide a basis for driving innovations to improve NUE and reduce risks of negative environmental impacts.

Conversion to No-Till Improves Maize Nitrogen Use Efficiency in a Continuous Cover Cropping System.

A two-year experiment was conducted in the field to measure the combined impact of tilling and N fertilization on various agronomic traits related to nitrogen (N) use efficiency and to grain yield in maize cultivated in the presence of a cover crop. Four years after conversion to no-till, a significant increase in N use efficiency N harvest index, N remobilization and N remobilization efficiency was observed both under no and high N fertilization conditions. Moreover, we observed that grain yield and grain N content were higher under no-till conditions only when N fertilizers were applied. Thus, agronomic practices based on continuous no-till appear to be a promising for increasing N use efficiency in maize.

Anhydrous Ammonia Timing and Rate Effects on Maize Nitrogen Use Efficiencies

Current guidance and equipment technologies permit anhydrous ammonia (NH3) to be confidently placed parallel to crop rows in both before‐ and after‐planting situations at shallower depths than traditional applications. Field studies from 2010 to 2012 investigated the effects of pre‐plant vs. side‐dress NH3 at four N rates (0, 90, 145, and 202 kg N ha−1) on maize (Zea mays L.) grain yield (GY), N recovery efficiency (NRE), and N use efficiency (NUE). All NH3 was injected to a 12‐cm depth; pre‐plant NH3 was banded parallel to, but approximately 15 cm offset from, intended rows a few days before planting. Side‐dress NH3 was applied to mid‐row positions at the V6–V7 growth stage. Whole‐plant N uptake at maturity was consistently higher with pre‐plant application. Highest GY was observed at the highest N rate with side‐dress timing in 2011 but with the pre‐plant timing in 2012. Relative to side‐dress, pre‐plant application improved average NRE across N rates from 0.53 to 0.72 kg plant N kg−1 applied N during the 3‐yr period. Overall NUE levels in 2012 were 50% lower than in 2010 and 40% lower than in 2011 due to drought, yet NRE doubled and NUE more than tripled with pre‐plant relative to side‐dress application. This 3‐yr study highlights the inability of either one‐time NH3 application strategy investigated to consistently have the highest GY and NUE as well as the dominating year‐specific influences of both N timing and N rates on NRE.

Above‐ and Belowground Growth, Biomass, and Nitrogen Use in Maize and Reconstructed Prairie Cropping Systems

ABSTRACTWe studied temporal dynamics of above‐ and belowground growth and N use in three production systems: maize (C4 annual), reconstructed prairie (a mixture of perennial C3 and C4 species) and fertilized reconstructed prairie. Our objectives were to fill knowledge gaps about temporal patterns of growth (especially for roots), inform further experimental research, and provide quantitative datasets for modeling. A 2‐yr field study was conducted near Boone, IA, in which above‐ and belowground plant tissues were sampled repeatedly during each growing season (n = 15 aboveground, n = 4 belowground). Dry weight and tissue N concentration were measured, and growth rates and N productivity were estimated. We found that maize produced more aboveground biomass (18.4 Mg/ha) with higher growth rates that peaked later in the season compared with the two prairie treatments (9.4–14.9 Mg/ha/year). Maize allocated a smaller proportion of its biomass belowground (10%) than both prairie treatments did (20–40%). Overall the N productivity ranged from 11 to 135 kg biomass kg–1 thermal unit–1 for maize and 34 to 344 kg biomass kg–1 thermal unit–1 for both prairie treatments. Our findings provide new, quantitative data that will be useful for predicting system‐level processes of annual and perennial crops evaluated for food and biofuel production.

Effects of urea types and irrigation on crop uptake, soil residual, and loss of nitrogen in maize field on the North China Plain

Water and nitrogen managements are both very important to increase crop yield. An experiment was carried out in split plot design to study the effects of urea types (normal urea and coated urea) and irrigation on soil and fertilizer nitrogen use in maize (Zea mays L.) field in 2006 and 2007. Irrigation was used as main plot, and urea types were used as split-plot. Two irrigation levels, no irrigation in the whole growth duration and 85 mm irrigation at the blister stage, were designed. There were five nitrogen treatments, which were no nitrogen used as control (N0), normal urea 75 kg N/ha (N1), normal urea 150 kg N/ha (N2), coated urea 75 kg N/ha (C1) and coated urea 150 kg N/ha (C2). The results showed that, at the same level of irrigation and nitrogen, the soil nitrogen contents of the treatments with coated urea (CU) applied were higher in 0~40 cm soil layers, but lower in deeper soil layers, than those with normal urea (NU) applied. Irrigation increased the nitrate losing, but the nitrate loss of CU was lower than those of NU. Using CU with irrigation could increase the nitrogen uptake by maize, and more nitrogen was transfered to grain. At the same nitrogen level, CU had higher N recovery efficiency but lower soil N dependent rate than NU. When applied with CU, the nitrogen release rate was lower and the nitrogen was quickly absorbed by maize, which reduced the risk of nitrogen loss and increased the use efficiency of soil and fertilizer nitrogen. These results suggest that coated urea combined with deficit irrigation should be applied for high yield and nitrogen use efficiency of maize on the North China Plain.

Differential global gene expression changes in response to low nitrogen stress in two maize inbred lines with contrasting low nitrogen tolerance

The global gene expression changes in response to low nitrogen stress in leaf tissues of two maize inbred lines(Mo17 and Hz4) with contrasting low nitrogen tolerance was analyzed using the Affymetrix maize genome array. Our results showed 887 genes involved in a variety of biological processes were responsive to low nitrogen treatment in Mo17, out of which 384 were up-regulated and 503 were down-regulated. In Hz4 the expression of 1108 genes was changed, of which 696 were up-regulated and 412 genes were down-regulated. The gene expression profiles also revealed 1799 genes differentially expressed (910 and 889 genes with higher level of expression in Hz4 and Mo17, respectively) between the two lines under low nitrogen conditions. These results explain at the transcript level why Mo17 is more sensitive than Hz4 under low nitrogen stress. In addition to previously reported nitrogen response genes (nitrate transporter, nitrite reductase, nitrate reductase, ferredoxin) we found many new nitrogen response genes (early light-inducible protein, uroporphyrinogen methyltransferas e, phosphoenolpyruvate carboxylase, tonoplast intrinsic protein, sesquiterpene cyclase). Our results not only provide new insights on the molecular mechanisms of nitrogen stress, but also serve as a valuable resource to researchers who aim to improve the efficiency of maize nitrogen use.

Stem‐infused nitrogen‐15 enrichment for evaluation of nitrogen use in maize

Nitrogen use efficiency (NUE) of N fertilizer can be accurately estimated by tracing the fate of soil applied 15N‐labeling. However, the quantity of N remobilization from non‐kernel components into kernels in maize (Zea mays L.) plants is difficult to determine. A field experiment involving stem infusion with four levels of enriched 15N solution plus non‐infusion or infusion with water was conducted at Ottawa (45°22'N, 75°43'W), Canada to determine the effect of 15N atom % enrichment (a.e.) on physiological processes associated with NUE. At anthesis, 30 mL of 35.7 mmol N solution as 15NH4 15NO3 at 5.0 (N05), 33.0 (N33), 66.0 (N66) and 99.2 (N99) 15N% a.e. was infused into the internode below the primary cob. The control plants were infused with distilled water. Photosynthesis was measured at 2, 4, 6, 24 h and 1 wk after infusion. Plants were sampled and separated into components at 4 d after anthesis (D4A) and at physiological maturity (PM). Dry weight, total N concentration, NH4‐ and NO3‐N, and 15N% a.e. of each component were determined. At D4A, the N33 and N66 treatments resulted in component 15N enrichment similar to that of N99 treatment. At PM, however, only N66 treatment produced results similar to that of N99. None of the infused 15N treatments interfered with ear‐leaf photosynthesis or component NH4‐ and NO3‐N concentrations. Infused 15N was easily moved out of the internode where it was infused, into most components, with the majority in the dominant sinks (cob, husk, and kernels). Nitrogen remobilization in both N66 and N99 treatments accounted for 62% of kernel N. These findings indicate that stem infusion is an appropriate approach to study N remobilization. Based on the concentrations investigated in this study, 66% or higher 15N% a.e. is required for accurate labeling when soil available N is high.