Nitrogen Uptake Research Articles

Emergence delay effect on maize (Zea mays L.) nitrogen uptake

AbstractSpatial and temporal variability in plant emergence may cause differences in nitrogen (N) uptake by crops leading to a mismatch between plant nitrogen requirements and nitrogen supply, with negative environmental and economic impacts. We aimed to understand N uptake and concentration (%) in unevenly emerged plants by conducting experiments in pre‐determined yield stability zones (YSZs) in three farmers’ fields planted to maize (Zea mays L.). We found that maize emergence ranged from 64 to 124.1°C day, with significant variability between YSZ in two of three fields. Maize biomass plant‐to‐plant variation decreased from maize six leaves stage (V6) to maize silking stage (R1). At maize physiological maturity (R6), biomass ranged from 54 to 736 g plant−1 and was significantly affected by YSZ (p < 0.001). In the cases where late‐emerging plants accumulated less N than early emerging plants, this led to altered N partitioning within the plant (i.e., nitrogen harvest index decrease). Although N concentration in the grains remained unaffected by late emergence, the N concentration in the biomass increased. This was likely due to a reduced total biomass and the lack of a N sink (i.e., less yield per plant due to less grain per plant). The absence of variations in N utilization across emergence classes, coupled with the significant impact observed in the YSZ, reinforces the advantages of focusing on N management fitted to YSZ. Understanding the impact that the spatial and temporal variation of plant emergence has on maize N uptake is important in helping to improve N input prescription maps, N‐use efficiency, and reduce N losses to the environment.

Response of N uptake, N-total and yield of sweet corn (Zea mays saccharata Sturt) due to fertilization with granulated solid organic fertilizer and NPK in Inceptisol soil

Sweet corn productivity is greatly influenced by proper cultivation techniques, of which fertilization is one of the main factors. Effective fertilization not only supports plant growth but also affects nutrient uptake and yield. This study aimed to evaluate the effect of granulated solid organic fertilizer and NPK fertilizer on nitrogen (N) uptake, soil N-total content, and sweet corn yield in Inceptisol soil. The research was conducted from February to June 2024 at the Experimental Field, Faculty of Agriculture, Padjadjaran University with treatments including control, NPK fertilizer, and various combinations of granular organic fertilizer and NPK. The results showed that the combination of granule organic fertilizer and NPK significantly increased nitrogen uptake and N-total content in the soil compared to the single NPK application. In addition, sweet corn yield, as measured by cob weight per plant, per plot, and per hectare, also increased significantly with the fertilizer combination treatment. This study supports the use of fertilization strategies that integrate organic and inorganic fertilizers as an effective way to increase sweet corn productivity on soils with limited fertility, such as Inceptisol. The application of a combination of 1 NPK + 1 granulated organic fertilizer was the best combination in increasing N uptake, N-total and sweet corn yield.

Combined application of organic and inorganic fertilizers sustained rice yields and N accumulation and decreased soil-canopy system NH3 emission

Excessive inorganic fertilization created various environmental problems, and the combination of organic and inorganic fertilization not only maintains crop production but is also environmentally sustainable. A pot experiment was conducted in Yangzhou, China, to investigate the comprehensive effects of organic fertilization combined with inorganic fertilization on the yield and yield components, nitrogen (N) uptake of different organs, and soil-plant system ammonia (NH3) emissions of two rice cultivars, taking into account the interception of soil NH3 emissions by the rice canopy. The treatments included the conventional practice of inorganic N applied by local farmers (INO, 270 kg N ha−1), 30 % reduced INO (70 %-INO, 189 kg N ha−1), and organic fertilizer combined with 70 %-INO (ORG-INO). Compared to 70 %-INO, ORG-INO significantly increased grain yield by 38 %, mainly due to more panicles. Similarly, ORG-INO also significantly promoted N uptake in the two rice cultivars, especially in terms of grain N accumulation, relative to 70 %-INO. The increase in grain N accumulation caused by ORG-INO was mainly due to enhanced post-anthesis N uptake, rather than N remobilization of vegetative organs, which also suggested that organic fertilizer could modify the processes of N retention and release. There was no significant difference in rice yield and N accumulation between INO and ORG-INO treatments, which also indicated that ORG-INO was effective in maintaining grain yield while reducing inorganic fertilizer input. Moreover, ORG-INO significantly reduced soil-plant system NH3 emissions, while the rice canopy intercepted approximately 30 % of soil NH3 emissions throughout the entire growing season. In summary, ORG-INO treatment significantly reduced the yield-scaled NH3 emissions, and the partial substitution of organic fertilizers for inorganic fertilizers should be recommended to promote environmental sustainability while ensuring food security.

Microbial inoculants as a means of improving soil and crop yields

The article presented the results of studies of the influence of microbial inoculants Rhizobium japonicum and Azospirillum brasilense on the growth and development of soybean (Glycine max) at the initial stages of its development. The study was conducted on three experimental plots: a control plot without treatment, a plot with Rhizobium japonicum inoculum and a plot with Azospirillum brasilense inoculum. The main indicators were evaluated: plant height, number of leaves, root system development and total biomass at different stages of plant growth, as well as laboratory analysis of nitrogen content in plant tissues. The results of the study showed that the inoculants had a significant impact on all measured parameters compared to the control plot. In particular, the plants in the plot with Rhizobium japonicum showed 50% higher growth and development of the root system, which was confirmed by the formation of root nodules responsible for nitrogen fixation. Azospirillum brasilense also improved plant growth and root system development, but its effect was less pronounced compared to Rhizobium japonicum. Nitrogen content analysis showed that plants in the Rhizobium japonicum plot had 45% higher tissue nitrogen content compared to the control plot, indicating effective nitrogen fixation. In plants treated with Azospirillum brasilense, the nitrogen content was also 25% higher, but without nodule formation, the effect was less pronounced. The aim of the study was to evaluate the effectiveness of microbial inoculants in improving plant growth and development in the early stages of vegetation, to investigate their effect on root system productivity, nitrogen uptake and total plant biomass, and to determine the optimal conditions for maximising the impact of inoculants in agricultural conditions. The results emphasised the importance of using microbial inoculants to increase soybean productivity and resistance in the early stages of its development. The application of Rhizobium japonicum provided a greater increase in biomass, root system and nitrogen assimilation, which makes this inoculant more effective than Azospirillum brasilense

Nitrogen uptake, grain yield, and oil concentration of dwarf castor beans under nitrogen rates and inoculation of rhizobacteria in grasses-legumes rotation.

Plant growth-promoting bacteria (PGPB) have been primarily studied for atmospheric nitrogen (N) fixation but they also have the capacity to improve nutrition and yield of crop plants. Therefore, the objective of this research was to investigate the effects of inoculation with PGPB in association with different N rates on N uptake, grain yield, and oil concentration of dwarf castor beans in succession to legumes and grasses in Ilha Solteira, Brazil. The treatments consisted of N rates (0 to 180 kg ha-1 of N) and inoculation with three plant growth-promoting bacteria (Azospirillum brasiliense, Bacillus subtilis, and Pseudomonas fluorescens, applied by leaf) and a control with no-inoculation. The grain and oil yields of castor beans were increased by 20 and 40% at a rate of 103 kg ha-1 of N in succession to grasses as compared to without N application. In addition, the grain yield of castor bean after legumes was increased by 28, 64, and 40% with estimated rates of 97, 113, and 92 kg ha-1 of N in combination with inoculations of A. brasilense, B. subtilis, and P. fluorescens as compared to without N application, respectively. Shoot, grain, and total N uptake were improved with foliar inoculation of A. brasilense, B. subtilis, and P. fluorescens at the N rates of 45, 90, and 135 kg ha-1, respectively. Topdressing of N at the rate of 103 kg ha-1 and foliar inoculation in succession to grasses and 180 kg ha-1 of N without the effect of foliar inoculation in succession to legumes are recommended for higher grain and oil yield of castor beans. Foliar inoculations with A. brasilense, B. subtilis, and P. fluorescens increased grain yield under reduced use of N fertilizer by 44, 37, and 49% in dwarf castor cultivation in succession to legumes, potentially contributing to sustainable agriculture.

Nano Urea Fertilization in Sweet Corn Using Leaf Colour Chart and Its Effect on Nitrogen Use Efficiency

Broad based blanket recommendations of fertilizer nitrogen (N) in field may end up with lower N use efficiency because of large field-to field variability of soil N. At the identical time, crop should not suffer from the deficiency of N. Nitrogen fertilizer must be applied only when necessary and must be based on the crop’s nitrogen status. So, keeping in view the significance of N on productivity, a field experiment was conducted during summer seasons of 2022 and 2023 on medium black calcareous soil at Junagadh (Gujarat) to study nano urea fertilization in sweet corn using leaf colour chart (LCC) and its effect on nitrogen use efficiency. Ten treatments comprising 40 kg N as basal (through DAP and urea) + 40 kg N through urea at 25-30 DAS (days after sowing) + 40 kg N through urea at 40-45 DAS (T1), 40 kg N as basal + 40 kg N through urea at 25-30 DAS + two foliar spray of nano urea 0.4% (4 ml/l water) when LCC ≤ 4 (T2), 40 kg N as basal + 30 kg N through urea at 25-30 DAS + three foliar spray of nano urea 0.4% when LCC ≤ 4 (T3), 40 kg N as basal + 20 kg N through urea at 25-30 DAS + four foliar spray of nano urea 0.4% when LCC ≤ 4 (T4), 40 kg N as basal + 20 kg N through urea at 25-30 DAS + three foliar spray of nano urea 0.4% when LCC ≤ 4 (T5), 40 kg N as basal + 10 kg N through urea at 25-30 DAS + four foliar spray of nano urea 0.4% when LCC ≤ 4 (T6), 40 kg N as basal + 10 kg N through urea at 25-30 DAS + three foliar spray of nano urea 0.4% when LCC ≤ 4 (T7), 40 kg N as basal + four foliar spray of nano urea 0.4% when LCC ≤ 4 (T8), 40 kg N as basal + three foliar spray of nano urea 0.4% when LCC ≤ 4 (T9) and control (without N application) (T10) in Randomized Block Design with three replications. Recommended dose of 60 kg P2O5 and 60 kg K2O/ha were applied uniformly to all the plots as basal application. The experimental results revealed that 40 kg N as basal + 40 kg N through urea at 25-30 DAS + two foliar spray of nano urea 0.4% when LCC ≤ 4 recorded significantly the highest nitrogen, phosphorus and potassium uptake by cob and fodder and their total uptake by sweet corn, which remained at par with T3 and T1. Significantly maximum available nitrogen in soil after harvest of sweet corn was noted with T1, which remained at par with T2, T3 and T4. It can be concluded that nano urea fertilization in sweet corn using leaf colour chart ultimately resulted in improved nitrogen use efficiency, which also sustained the fertility of medium black calcareous soil.

Multi-nutrient and humic acid foliar applications enhance green gram growth and yield on alkaline soil by increasing nutrient use and physiological activity

Widespread multi-nutrient deficiency and water stress are the major yield-limiting factors in alkaline soil. Inorganic nutrient application in alkaline soil is ineffective for green gram due to the antagonistic interaction with alkalinity. In this setting, a balanced supply of foliar nutrients is a viable strategy to improve green gram nutrient utility and productivity in an alkaline environment. Field experiments were conducted for two consecutive years during Rabi 2019 and 2020. Water-soluble NPK (2%), 1% multi-micronutrient and 1% humic acid foliar nutrients in five combinations were applied at 30 and 45 days after sowing. The effect of multi-nutrient and humic acid foliar spray on green gram growth, physiology, nutrient accumulation, and yield were measured by adopting the standard protocol. Green gram seed yield increased by 20 per cent on the application of water soluble fertilizers 2% and liquid multi-micronutrients 1% with 1% humic acid. The same set of treatments augmented leaf area (428 cm2 plant−1), dry matter production (2087 kg ha−1), SPAD value (46.4), nitrogen (36.6 kg ha−1), phosphorous (4.9 kg ha−1), potassium (46.5 kg ha−1), and micronutrients uptake. Foliar application of multi-nutrients reduces nutrient stress and aids in the promotion of green gram crop growth and production in alkaline soil.

Nitrogen Uptake and Use Efficiency of Aerobic Rice as Affected by Different Nitrogen Management: A Review

Nitrogen Uptake and Use Efficiency of Aerobic Rice as Affected by Different Nitrogen Management: A Review

Deficit Irrigation and High Planting Density Improve Nitrogen Uptake and Use Efficiency of Cotton in Drip Irrigation

Deficit Irrigation and High Planting Density Improve Nitrogen Uptake and Use Efficiency of Cotton in Drip Irrigation

Assessing LDPE microplastics' impact on green gram (Vigna radiata L. Wilczek) cultivation: A greenhouse pot experiment

Plastic pollution, particularly from microplastics (MPs), poses a significant threat to agricultural ecosystems. This study investigates the impact of Low-Density Polyethylene (LDPE) microplastics on green gram (Vigna radiata) cultivation, focusing on growth, yield, and soil nutrient dynamics. A completely randomized design with nine treatments of varying LDPE concentrations was used in a controlled poly house environment. Soil analysis assessed mechanical and physico-chemical properties using established methods. Green gram variety Co (Gg) 8 was cultivated during the Rabi season, with comprehensive crop management including germination tests, pot culture preparations, precise fertilizer application, and essential cultural operations. Results indicated significant correlations between LDPE concentrations and green gram growth parameters, with higher concentrations having detrimental effects (correlation coefficient = −0.75, p < 0.05). LDPE treatments also influenced plant nutrient uptake, showing inverse correlations with nitrogen (N), phosphorus (P), and potassium (K) uptake (correlation coefficient = −0.82, p < 0.01). Post-harvest soil analysis revealed significant variations in available nutrients, with LDPE-treated soils exhibiting higher N, P, and K levels compared to control groups (correlation coefficient = 0.78, p < 0.01). Infrared spectroscopy confirmed the presence of LDPE microplastics in soil and plant samples, identified by characteristic (CO) and (C–H) stretching vibrations. These findings highlight the complex interactions between LDPE microplastics and agricultural systems, emphasizing the need for sustainable practices to mitigate the adverse effects of plastic pollution on agriculture. Statistical analysis using the CRD framework and correlation and regression analyses ensured robust interpretation of the data.

Enhancing drought resistance in Pinus tabuliformis seedlings through root symbiotic fungi inoculation.

Drought constitutes a major abiotic stress factor adversely affecting plant growth and productivity. Plant-microbe symbiotic associations have evolved regulatory mechanisms to adapt to environmental stress conditions. However, the interactive effects of different fungi on host growth and stress tolerance under drought conditions remain unclear. This study explored the effects of varying polyethylene glycol (PEG-6000) concentrations (0%, 15%, 25%, and 35%) on the growth and physiological responses of two ectomycorrhizal fungi (Suillus granulatus (Sg) and Pisolithus tinctorius (Pt)) and two dark septate endophytes (Pleotrichocladium opacum (Po) and Pseudopyrenochaeta sp. (Ps)) isolated from the root system of Pinus tabuliformis. Specifically, the study aimed to evaluate six inoculation treatments, including no inoculation (CK), single inoculations with Sg, Pt, Po, Ps, and a mixed inoculation (Sg: Pt : Po: Ps = 1:1:1:1), on the growth and physiological characteristics of P. tabuliformis seedlings under different water regimes: well-watered at 70% ± 5%, light drought at 50% ± 5%, and severe drought at 30% ± 5% of the maximum field water holding capacity. All four fungi exhibited the capacity to cope with drought stress by enhancing antioxidant activities and regulating osmotic balance. Upon successful root colonization, they increased plant height, shoot biomass, root biomass, total biomass, and mycorrhizal growth response in P. tabuliformis seedlings. Under drought stress conditions, fungal inoculation improved seedling drought resistance by increasing superoxide dismutase and catalase activities, free proline and soluble protein contents, and promoting nitrogen and phosphorus uptake. Notably, mixed inoculation treatments significantly enhanced antioxidant capacity, osmotic adjustment, and nutrient acquisition abilities, leading to superior growth promotion effects under drought stress compared to single inoculation treatments. All four fungi tolerated PEG-induced drought stress, with increased antioxidant enzyme activities and osmotic adjustment substances and they promoted the growth and enhanced drought resistance of P. tabuliformis seedlings.

Nitrogen and phosphorus uptake dynamics in anthropized and conserved Caatinga dry forests

Understanding human impacts on drylands is crucial in a global scenario of forest degradation and biodiversity loss. This study analyzed foliar concentrations of nitrogen (N) and phosphorous (P) in the Brazilian seasonally dry tropical forests (Caatinga). Foliar patterns of N, P, and the N/P ratio were assessed both within and among botanical families. To do this, 10 plots were established in an anthropized area and 10 in a conserved area. Within each plot, leaves from all tree species and soil samples from four random points were collected. Stoichiometric analyses were performed on the leaves of 136 trees from 14 botanical families. Significant differences were observed in soil P concentrations, organic matter content, and cation exchange capacity, with the highest values found in the conserved area. Foliar N and P concentrations and N/P were also higher in the conserved area for the F+ (nitrogen-fixing Fabaceae), F- (non-nitrogen-fixing Fabaceae), and NF (non-Fabaceae) groups, indicating greater efficiency in nutrient retention and cycling. When comparing species found in both areas, Aspidosperma pyrifolium (NF), Bauhinia forficata (F-), and Mimosa ophthalmocentra (F+) showed significant differences in foliar N concentrations and foliar P (for A. pyrifolium and B. forficata only). Degradation of the Caatinga directly impacts nutrient cycling.

Comparison of Growth and Metabolomic Profiles of Two Afforestation Cypress Species Cupressus chengiana and Platycladus orientalis Grown at Minjiang Valley in Southwest China.

In recent years, afforestation has been conducted in China's hot and dry valleys. However, there is still a paucity of knowledge regarding the performance of tree species in these semi-arid regions, particularly with regard to interspecies differences. The present study compares the growth and metabolome characteristics of two widely used cypress species, namely Cupressus chengiana and Platycladus orientalis, grown at two sites with distinct climate conditions in the hot and dry Minjiang Valley in southwestern China. The findings indicate that C. chengiana trees exhibit superior growth rates compared to P. orientalis trees at both study sites. In comparison to P. orientalis trees, C. chengiana trees demonstrated a greater tendency to close their stomata in order to prevent water loss at the hotter and drier site, Llianghekou (LHK). Additionally, C. chengiana trees exhibited significantly lower hydrogen peroxide levels than P. orientalis trees, either due to lower production and/or higher scavenging of reactive oxygen species. C. chengiana trees accumulated soluble sugars as well as sugar derivatives, particularly those involved in sucrose and galactose metabolisms under stressful conditions. The species-specific differences were also reflected in metabolites involved in the tricarboxylic acid cycle, nitrogen, and secondary metabolisms. The metabolome profiles of the two species appeared to be influenced by the prevailing climatic conditions. It appeared that the trees at the drier and hotter site, LHK, were capable of efficient nitrogen uptake from the soil despite the low soil nitrogen concentration. This study is the first to compare the growth performance and metabolic profiles of two widely used tree species with high resistance to adverse conditions. In addition to the species-specific differences and adaptations to different sites, the present study also provides insights into potential management strategies to alleviate abiotic stress, particularly with regard to nitrogen nutrients, in the context of climate change.

Machine learning and fluorosensing for estimation of maize nitrogen status at early growth-stages

Potential of mobile fluorescence sensor measurements have been in focus for quantifying plant nitrogen (N) variability early in the crop growing season. Real time estimation of such N status indicators at field scale would enable precision management of N fertilizers. In standard practice, linear regression analysis involves the use of several fluorescence channels and indices as predictive variables for estimating plant nitrogen content. Considering the multi-collinearity between these predictor variables, the conventional regression analysis (multiple linear regression) often fails to deliver a good range of prediction accuracies. Hence, machine learning regression techniques are utilized in this study to estimate N status indicators i.e., %N, above ground biomass, and N uptake at V6 and V9 growth stages of maize across three site-years in 2012 and 2013 crop growing seasons. The Multiplex®3 (FORCE-A) portable active fluorescence system was used to capture fluorescence information. Derived indices including four N balance indices (NBI_R, NBI_B, NBI_B, and NBI1), two chlorophyll indices (CHL and CHL1), and one flavonoid index (FLAV) were used as predictors. The independent site data were first utilized in a Support Vector Regression (SVR) model to assess the training and test accuracies in estimation of N status indicators considering a comparative analysis between V6 and V9 growth stages. The current research also involved assessing how well the machine learning-trained model could be applied to a different dataset and validated its performance in a cross-site experimental setting. Subsequently, cross-site comparisons of nitrogen status estimates were conducted to recommend the selection of machine learning strategies. These strategies include (1) Partial Least Square Regression, (2) Support Vector Regression, (3) Gaussian Process Regression, (4) Random Forest Regression, and (5) Artificial Neural Network. The comparative investigation demonstrated promising accuracy in estimating plant nitrogen content, above-ground biomass, and nitrogen uptake at the V6 stages of maize, with correlation coefficients in the moderate range (r = 0.72 ± 0.03) and Root Mean Square Error. Superior prediction accuracies were obtained at V9 growth stages than at V6. Among the various machine learning models assessed, Support Vector Regression consistently outperformed the others across the three site-year datasets, delivering error estimates well within acceptable ranges and demonstrating the lowest RMSE values for maize nitrogen indicators.

Impact of fertilization depth on sunflower yield and nitrogen utilization: a perspective on soil nutrient and root system compatibility.

The depth of fertilizer application significantly influences soil nitrate concentration (SNC), sunflower root length density (RLD), sunflower nitrogen uptake (SNU), and yield. However, current studies cannot precisely capture subtle nutrient variations between soil layers and their complex relationships with root growth. They also struggle to assess the impact of different fertilizer application depths on sunflower root development and distribution as well as their response to the spatial and temporal distribution of nutrients. The Agricultural Production Systems sIMulator (APSIM) model was employed to explore the spatial and temporal patterns of nitrogen distribution in the soil at three controlled-release fertilizer (CRF) placement depths: 5, 15, and 25 cm. This study investigated the characteristics of the root system regarding nitrogen absorption and utilization and analyzed their correlation with sunflower yield formation. Furthermore, this study introduced the modified Jaccard index (considering the compatibility between soil nitrate and root length density) to analyze soil-root interactions, providing a deeper insight into how changes in CRF placement depth affect crop growth and nitrogen uptake efficiency. The results indicated that a fertilization depth of 15 cm improved the modified Jaccard index by 6.60% and 7.34% compared to 5 cm and 25 cm depths, respectively, maximizing sunflower yield (an increase of 9.44%) and nitrogen absorption rate (an increase of 5.40%). This depth promoted a greater Root Length Density (RLD), with an increases of 11.95% and 16.42% compared those at 5 cm and 25 cm, respectively, enhancing deeper root growth and improving nitrogen uptake. In contrast, shallow fertilization led to higher nitrate concentrations in the topsoil, whereas deeper fertilization increased the nitrate concentrations in the deeper soil layers. These results provide valuable insights for precision agriculture and sustainable soil management, highlighting the importance of optimizing root nitrogen absorption through tailored fertilization strategies to enhance crop production efficiency and minimize environmental impact.

Starvation and re-feeding of Gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) co-cultured with glasswort (Salicornia europaea) in a polyculture aquaponic system.

The aim of this study was to evaluate the effect of starvation and refeeding on the growth and food intake of gilthead seabream (Sparus aurata) and seabass (Dicentrarchus labrax) and on the growth and nitrogen uptake of glasswort (Salicornia europaea) in a polyculture aquaponic system under 12 ppt salinity for 75 days. Nine small-scale autonomous aquaponic systems were used, each containing 10 gilthead seabreams (average weight of 6.33±0.73 g and average length of 5.73±0.72 cm) and 10 seabasses (5.82±0.77 g and 6.35±0.45 cm), as well as five glasswort plants. Three fish feeding treatments were performed, a control (A), in which fish were fed daily until satiation, and two fasting treatments for 4 (B) and 7 days (C). Fish growth performance was significantly lower (p<0.05) in the C treatment for both species compared to treatments A and B. Food consumption (FC) and feed conversion ratio (FCR) were significantly higher (p<0.05) in treatment C. Glasswort growth performance was significantly higher in treatment C (p<0.05). The results showed that the 4-day food-deprived fish were similar to the control fish by achieving partial compensatory growth. The more extended fasting period (7 days) resulted in significantly lower growth performance. The lipid and nitrogen retention levels in both species were significantly lower in food-deprived fish than in the control fish both before and during compensatory growth. The results suggest that a feeding schedule involving starvation-refeeding cycles is a promising feed management option for these species in polyculture aquaponic systems. The effect of food deprivation was also significantly beneficial (p<0.05) for the growth performance of glasswort compared to the control treatment.

EARLY FLOWERING3-1 represses Grain number, plant height, and heading date7 to promote ABC1 REPRESSOR1 and regulate nitrogen uptake in rice.

The extensive use of nitrogen fertilizer boosts rice (Oryza sativa) production but also harms ecosystems. Therefore, enhancing crop nitrogen use efficiency is crucial. Here, we performed map-based cloning and identified the EARLY FLOWERING3 (ELF3) like protein-encoding gene OsELF3-1, which confers enhanced nitrogen uptake in rice. OsELF3-1 forms a ternary complex (OsEC) with OsELF4s and OsLUX, the putative orthologs of ELF4 and LUX ARRHYTHMO (LUX) in Arabidopsis (Arabidopsis thaliana), respectively. OsEC directly binds to the promoter of Grain number, plant height, and heading date7 (Ghd7) and represses its expression. Ghd7 encodes a transcription factor that has major effects on multiple agronomic traits. Ghd7 is also a transcriptional repressor and directly suppresses the expression of ABC1 REPRESSOR1 (ARE1), a negative regulator of nitrogen use efficiency. Therefore, targeting the OsEC-Ghd7-ARE1 module offers an approach to enhance nitrogen uptake, presenting promising avenues for sustainable agriculture.

Determination of soluble solids content in tomatoes with different nitrogen levels based on hyperspectral imaging technique.

Tomato is sweet and sour with high nutritional value, and soluble solids content (SSC) is an important indicator of tomato flavor. Due to the different mechanisms of nitrogen uptake and assimilation in plants, exogenous supply of different forms of nitrogen will have different effects on the growth, development, and physiological metabolic processes of tomato, thus affecting the tomato flavor. In this paper, hyperspectral imaging (HSI) technique combined with neural network prediction model was used to predict SSC of tomato under different nitrogen treatments. Competitive adaptive reweighed sampling (CARS) and iterative retained information variable (IRIV) were used to extract the feature wavelengths. Based on the characteristic wavelength, the prediction models of tomato SSC are established by custom convolutional neural network (CNN) model that was constructed and optimized. The results showed that the SSC of tomato was negatively correlated with nitrogen fertilizer concentration. For tomatoes treated with different nitrogen concentrations, the residual predictive deviation (RPD) of CARS-CNN and IRIV-parallel convolutional neural networks (PCNN) reached 1.64 and 1.66, both more than 1.6, indicating good model prediction. This study provides technical support for future online nondestructive testing of tomato quality. PRACTICAL APPLICATION: The CARS-CNN and IRIV-PCNN were the best data processing model. Four customized convolutional neural networks were used for predictive modeling. The CNN model provides more accurate results than conventional methods.

Comparison of Organic and Inorganic Fertilization in Fenugreek Cultivation Using Nitrogen Indicators

Nitrogen indices could be used to evaluate organic and inorganic fertilization because they provide quantitative measures of nitrogen availability in the soil, allowing for a more accurate assessment of nutrient-management practices and optimization of crop yields. This study investigates the impact of different fertilization types and salinity on various soil parameters in fenugreek (Trigonella foenum-graecum L.) cultivation and nitrogen indices. A field experiment was established at the Agricultural University of Athens during the cropping period of 2018–2019 (CP I), 2019–2020 (CP II), and 2020–2021 (CP III) in a split-plot design with two main salinity treatments (high salinity, HS, and conventional salinity, CS) and five fertilization treatments (biocyclic–vegan humus soil (BHS), manure (FYM), compost (COMP), inorganic fertilization (11–15–15), and the control (C). The Nitrogen Balance Intensity (NBI) was statistically significantly affected by the factors of fertilization (p ≤ 0.01) and salinity (p ≤ 0.001) for CP I. The maximum NUEcrop value was recorded in the FYM treatment (0.83 ± 0.04) and the minimum in the COMP treatment (0.64 ± 0.04). Physiological efficiency (PE) was not significantly affected by any treatment for CP III. The fertilization factor significantly affected the NUEsoil index (p ≤ 0.001) for all three CPs. For CP I, the highest Nitrogen Uptake Efficiency (NUpE) value was recorded in the BHS treatment (27.08 ± 7.31) and the lowest in the C treatment (13.22 ± 7.31). There were no significant differences in CP I and CP II NUEbalance values among the NPK, BHS, and FYM treatments. These findings underscore the potential of organic fertilizers in addressing the global nitrogen challenge and promoting environmentally sustainable farming practices.

Full Density Powder Metallurgical Cold Work Tool Steel through Nitrogen Sintering and Capsule-Free Hot Isostatic Pressing

Vanadis 4E (V4E) is a powder metallurgical cold work tool steel predominantly used in application with demand for wear resistance, high hardness, and toughness. It is of interest to have a processing route that enables full density starting from clean gas-atomized powder allowing component shaping capabilities. This study presents a process involving freeze granulation of powder to facilitate compaction by means of cold isostatic pressing, followed by sintering to allow for capsule-free hot isostatic pressing (HIP) and subsequent heat treatments of fully densified specimens. The sintering stage has been studied in particular, and it is shown how sintering in pure nitrogen at 1150 °C results in predominantly closed porosity, while sintering at 1200 °C gives near full density. Microstructural investigation shows that vanadium-rich carbonitride (MX) is formed as a result of the nitrogen uptake during sintering, with coarser appearance for the higher temperature. Nearly complete densification, approximately 7.80 ± 0.01 g/cm3, was achieved after sintering at 1200 °C, and after sintering at 1150 °C, followed by capsule-free HIP, hardening, and tempering. Irrespective of processing once the MX is formed, the nitrogen is locked into this phase and the austenite is stabilised, which means any tempering tends to result in a mixture of austenite and tempered martensite, the former being predominate during the sequential tempering, whereas martensite formation during cooling from austenitization temperatures becomes limited.