Nitrogen Treatments Research Articles

Optimising the PVS2 treatment duration for cryopreserving seeds of the endangered rheophytic orchid Epipactis flava Seidenf

ABSTRACT Epipactis flava Seidenf., an endangered Thai rheophytic orchid, urgently requires protection to prevent its extinction. This study aimed to develop an effective vitrification cryopreservation protocol for the long-term storage of E. flava seeds. Mature seeds were pretreated with a loading solution and dehydrated with plant vitrification solution 2 (PVS2) for 0, 30, 60, 90, and 120 min at 25 ± 2°C before immersion in liquid nitrogen for 24 hours. Post-cryopreservation, the seeds were germinated on BM-1 medium for 8 weeks, and then the protocorms were transferred to semi-solid MS medium for another 8 weeks. Seeds treated with PVS2 for 90 min and exposed to liquid nitrogen showed the highest viability (33.3%), while 120 min of dehydration yielded the highest germination rates (17.8%) and 5.8% of the protocorms reached advanced developmental stages (stage 4 and 5). The highest percentage of protocorms at stage 5 (3.3%) was also observed at 120 min of PVS2. No germination occurred in the cryopreserved seeds that had not been exposed to PVS2 prior to the liquid nitrogen treatment. Thus, our results showed that the optimal PVS2 exposure time for cryopreservation of E. flava seeds using the vitrification method was 120 min.

Full-scale simultaneous partial nitrification, anammox, and denitrification for the efficient treatment of carbon and nitrogen in low-C/N wastewater

A full-scale simultaneous partial nitrification, anaerobic ammonia oxidation (anammox), and denitrification (SNAD) reactor was initiated to address the problem of high energy consumption for the treatment of low C/N wastewater. The SNAD system achieved a nitrogen removal rate of 0.9 kg/(m3·d) at an influent NH₄+–N concentration of 500 mg/L after 450 days of stable operation. Partial nitrification was achieved by maintaining free ammonia levels at 0.8 ± 0.3 mg/L and dissolved oxygen concentrations between 0.3 mg/L and 1.2 mg/L, which resulted in synergistic nitrogen removal, with anammox contributing 61 % and denitrification contributing 39 %. Microbiological analyses indicated that the dominant microorganisms were Candidatus Brocadia, Thauera, Denitratisoma, and Nitrosomonas. In conclusion, study provides a solid foundation for the broader implementation of the SNAD process in wastewater treatment systems.

Spatial-spectral feature mining in hyperspectral corn leaf venation structure and its application in nitrogen content estimation

The growth of corn plants requires a significant amount of nitrogen nutrient supply to ensure the yield. Meanwhile, overfertilization could result in adverse environmental impacts, making it crucial to monitor the nitrogen supply condition in corn plants precisely. Hyperspectral imaging (HSI) could be the solution to this challenge, as HSI plant phenotyping technology has been widely utilized to nondestructively identify plant traits, such as mineral nutrient deficiencies in corn plants. However, limitations persist where the conventional HSI nitrogen prediction models mainly relied on the overall colors of the plant tissue extracted from the spectral domain but rarely included the spatially distributed information on the leaf level. This study aimed to examine if including new information from the spatial domain could potentially improve the performance of HSI models. Because the venation structure plays a crucial role in the distribution of various nutrients across the leaf, a series of physiological responses caused by nitrogen deficiency could result in non-uniform color patterns related to the veins. The recent advancement of HSI techniques such as LeafSpec, whose imaging quality and spatial-spectral resolution have been significantly improved, made it possible to extract the venation structure together with high-resolution spatial-spectral features. In this study, the hypothesis was that utilizing high-resolution spatial-spectral features extracted based on the venation structure could yield a better-performed nitrogen content prediction model compared to the averaged spectrum of the corn leaf. First, a venation structure segmentation algorithm was developed using the Local Binary Patterns (LBP) method for hyperspectral corn leaf images scanned with LeafSpec. Second, for every hyperspectral leaf image, 131 spectral index heatmaps were generated, and 30 leaf regions were picked based on the venation structure, resulting in 3930 spatial-spectral features. Third, the features were picked using the Least Absolute Shrinkage and Selection Operator (LASSO) regression. As the results tested with a field assay involving two different corn genotypes and two nitrogen treatments, the Partial Least Square Regression (PLS-R) model built with selected spatial-spectral features outperformed the model built with the averaged leaf spectra in terms of the Root Mean Squared Error (RMSE) of predictions. The results provided encouraging proof and guidance for the potential benefit of using high-resolution spatial-spectral features derived from hyperspectral leaf images to improve the accuracy and robustness of the nitrogen content prediction models for corn plants.

Light condition during grain-filling stage of main crop strongly influences ratooning ability of low-stubble ratoon rice

Compared with high-stubble ratoon rice (RR), low-stubble RR is superior in yield potential, grain quality, and economic benefit. However, the unstable ratooning ability limits the grain yield of low-stubble RR production. Light condition during the grain-filling stage of main crop (GFMC) may be important for rice ratooning. To elucidate the role of light condition during GFMC in affecting ratooning ability, the key response periods, and their underlying mechanisms, field experiments were conducted using two indica cultivars in 2021 and 2022. To create varied light conditions at the canopy base during GFMC, two planting density treatments combining three nitrogen (N) treatments were established in 2021, and three density treatments combining two N treatments and four shading treatments were established in 2022 for the main crop. Light intensity (LI), light quality as reflected by the ratio of red light/far red light (R/FR), and light transmission ratio (LTR) at the canopy base during GFMC and ratooning ability were dramatically altered by N fertilization but not by planting density. With increased N application, LTR, root bleeding rate, and maximum ratooning rate significantly decreased in 2021. In 2022, low N rate increased LI, R/FR, and maximum ratooning rate by 155.7-241.4%, 47.4-65.3%, and 15.6-27.5%, respectively, but reduced missing hill percentage (proportion of hills without regenerated tillers to the total number of hills) by 30.0-62.1% compared with high N rate. The missing hill percentage was negatively correlated with the indices of light condition, while the maximum ratooning rate was positively correlated with them for both cultivars. Root activity and the ratios of abscisic acid (ABA) to cytokinins (CTK), indole-3-acetic acid (IAA), and IAA+CTK could explain the effect of light condition during GFMC on ratooning ability. Shading experiment confirmed the effect of light condition on ratooning ability and further revealed that only shading during middle and late GFMC affected ratooning ability. These findings provide new insights into the regulation of ratooning ability, which are useful for developing management practices to increase the grain yield and yield stability of low-stubble RR.

Growth, Yield, and Photosynthetic Dry Matter Remobilization Response of Barley to Plant Growth Promoting Rhizobacteria (PGPR) and Nitrogen

A two-year factorial experiment based on a randomized complete block design with three replicates was carried out on barley cultivar LB-IRAN at the research farm of the Islamic Azad University, Ardabil, Iran, during the cropping years of 2019–2021, in order to survey the impact of plant growth-promoting rhizobacteria (PGPR) and nitrogen fertilizer on growth, yield, and remobilization of photosynthetic dry matter in barley. The first factor included five nitrogen levels: 0 (control), 25, 50, 75, 100 kg/ha net nitrogen; the second factor contained grain inoculations with four bacteria: no inoculation (control), Azotobacter chroococcum race 5, Azospirillum lipoferum race of, and a combination of the two mentioned bacteria. Fertilization was performed at the planting, tillering, and grain filling stages. Results revealed that the number of plant/m2, tiller per plant, 1000 grain weight, grain per spike, grain yield per unit area, biological yield, rate of dry matter remobilization from stem to the grain, contribution of dry matter remobilization from stem to the grain, rate of remobilization from whole of the plant to the grain, contribution of remobilization from whole of the plant to the grain, single grain weight, and harvest index significantly increased. Nitrogen rate increment resulted in the higher rates of the above-mentioned traits as 100 kg/ha nitrogen significantly showed the highest amounts while control showed the least. Combined treatment of the bacteria resulted in a higher rates as compared to the single bacteria, and the control showed the lowest amounts. It was also observed that application of 100 kg/ha nitrogen on Azotobacter chroococcum race 5 and Azospirillum lipoferum race of resulted in the lowest rate of dry matter remobilization from the stem and whole plant to the grain as well as the contribution of dry matter remobilization from the stem and whole plant to the grain, while control treatments of nitrogen and of PGPRs caused the highest rates. Difference between the highest and lowest rates of grain yield was observed by applying nitrogen (24%) and PGPRs (40%).

Boosting nitrogen removal efficiency of wastewater treatment plant tailwater through iron-rich tidal flow constructed wetland: Insights on the microbial removal mechanism

Iron-rich tidal flow constructed wetlands (ITCW) have emerged as effective and eco-friendly systems for achieving high-efficiency total nitrogen (TN) removal in tailwater. However, the microbial removal mechanism in ITCW, particularly the microbial assembly processes, remains unclear, which limits understanding of the relationship between micro-level microbial activities and macro-level performance of ITCW. In this study, ITCW was constructed to investigate its performance, microbial responses, and community assembly mechanisms using metagenomics and the neutral community model (NCM). Results demonstrated that total nitrogen removal in ITCW increased by 52.53 ± 9.03 % and 21.20 ± 6.26 %, respectively, compared to conventional constructed wetlands and iron-based constructed wetlands. The combination of tidal flow and iron substrate established an active iron cycle in ITCW. The iron cycle improved electron transfer capacity and supported the enrichment of nitrifiers (e.g., Nitrospira) and denitrifiers (e.g., Hydrogenophaga, Thauera), enhancing nitrogen removal efficiency in ITCW. Metagenomic analysis confirmed an increased relative abundance of functional genes associated with nitrogen metabolism (e.g., amoA, nirSKABD) and the iron cycle (e.g., korB). NCM analysis indicated that stochastic processes influenced community assembly in all three CWs. Nonetheless, tidal flow operations in ITCW reduced stochastic influences, fostering niche specialization of functional nitrogen microorganisms, which supported their growth while minimizing functional redundancy, thereby enhancing nitrogen treatment performance. These findings offer significant insights into microbial mechanisms for nitrogen removal and provide theoretical guidance for ITCW design and operation.

Research progress on solid-phase electron donors for the denitrification of wastewater: A review

Electron donor-mediated biological denitrification, the most extensively employed method for the treatment of nitrate nitrogen (NO3−-N), involves NO3−-N directly or indirectly by acquiring electrons provided by electron donors and converting them into N2. Currently, the most widely researched electron donors are gaseous, liquid, and solid forms. Owing to the difficulties in storing and transporting gaseous and liquid electron donors, and their potential for causing secondary pollution, solid-phase electron donors (SPEDs), which can be slowly utilized by microorganisms, have gradually gained attention. SPEDs not only serve as a carrier for microbial attachment, but most SPEDs are also low-cost and readily available, making them advantageous for practical applications. In this review, the different types of SPEDs are classified and their microbial utilization mechanisms in the biological denitrification process discussed based on their classification. Their denitrification performance, influencing factors, practical applications, and existing issues are summarized. This review provides a reference for future research on SPED and its applications. It also provides an outlook on SPED-mediated mixotrophic denitrification and SPED-coupled electrochemical technology for enhanced nitrogen removal processes, in view of this hot direction in SPED research.

Influence of nitrogen treatments on some nutrient concentration and bioactive compounds of broccoli.

Nitrogen fertilization in broccoli is very important for plant growth and productivity. However, it is known that the nitrogen source of the nitrogen fertilizer is also effective on quality parameters. In this study we investigated the effects of different nitrogen sources (ammonium sulphate and calcium nitrate) on bioactive compounds and leaf nutrients of broccoli cultivars (Monet, Italian and Karadede). The highest total phenolic content was 0.24 mg g- 1 fw in cultivar Monet. Nitrate-based fertilizer treatments provided higher total phenolic (0.28 mg g- 1 fw) and flavonoid (0.56 mg g1 fw) contents and FRAP (0.24 mmol g- 1 fw) values compared to ammonium-based fertilizer treatments. On the other hand, DPPH (0.77 mmol g- 1 fw) values were higher in the ammonium nitrogen treatments. Among the cultivars, Monet had the highest total phenolics, flavonoids and FRAP values. When leaf nutrient concentrations were analyzed, ammonium sulfate application resulted in higher sulfur (0.86%), zinc (20.72mg kg- 1) and manganese (28.80mg kg- 1) concentrations compared to calcium nitrate. Calcium nitrate treatment provided the highest calcium (2.09%) and iron (37.50mg kg- 1) concentration in Monet cultivar. Phosphorus (0.31-0.35%) and magnesium (0.073-0.084%) concentrations differed among cultivars. In conclusion, the choice of nitrogen source and cultivar in broccoli cultivation plays an important role in the bioactive compound profile and nutrient composition of the broccoli crop. The results provide useful information for the improvement of broccoli quality.

Microscopic Structure of Coal through Liquid Nitrogen Treatment Based on Micro-CT and 3D Visualization of Permeability Simulation

Microscopic Structure of Coal through Liquid Nitrogen Treatment Based on Micro-CT and 3D Visualization of Permeability Simulation

Enhanced photocatalytic activity of ZnS/TiO2 nanocomposite by nitrogen and tetrafluoromethane plasma treatments

In the present study, the photocatalytic performance of ZnS/TiO2 nanocomposite was investigated through the photodegradation of Acid Blue 113 (AB113) dye under ultraviolet light exposure. TiO2 and ZnS-based nanocomposites suffer from relatively wide bandgap energy and low adsorption capacity which limit their photocatalytic applications. These problems can be suppressed by modifying the surface of nanocomposite particles by the non-thermal plasma. Herein, surface modification of the ZnS/TiO2 nanocomposite was performed using a dielectric-barrier discharge plasma under nitrogen (N2) and tetrafluoromethane (CF4) gases. The characteristics of the plasma-treated nanocomposites were evaluated by XRD, FTIR, Raman, FESEM, EDS, BET, BJH, and DRS analyses. According to the results, by applying plasma treatment, cation and anion vacancies are produced that reduces the band gap energy of the photocatalyst hence improves its performance. The results indicate that the photocatalytic efficiency of the N2-plasma-treated nanocatalyst has been almost two times higher than that of the untreated ZnS/TiO2. It was found that after 25 min of UV irradiation, the AB113 was almost completely degraded in the presence of N2-plasma-treated ZnS/TiO2 nanocomposite (about 95%), whereas, it was degraded by 64% and 46% in the presence of CF4-plasma-treated ZnS/TiO2 and untreated ZnS/TiO2, respectively. This study presents a new approach to designing cost-effective plasma-treated photocatalysts to degrade organic contaminants in wastewater.

Effects of Nutrient Deficiency on Crop Yield and Soil Nutrients Under Winter Wheat–Summer Maize Rotation System in the North China Plain

The wheat–maize rotation system in the North China Plain (NCP) has a large amount of crop straw. However, improper crop straw management and blind fertilization lead to nutrient imbalance and accelerated nutrient loss from the soil, ultimately leading to nutrient deficiency affecting the wheat–maize rotation system. In order to explore the effects of nutrient deficiency on the yield and nutrient use efficiency of wheat and maize, the experiment was conducted in a randomized complete block design consisting of five treatments with three replicates for each treatment: (1) a potassium fertilizer deficiency and appropriate nitrogen and phosphate fertilizer treatment (NP); (2) a phosphate fertilizer deficiency and appropriate nitrogen and potassium fertilizer treatment (NK); (3) a nitrogen fertilizer deficiency and appropriate phosphate and potassium fertilizer treatment (PK); (4) an adequate nitrogen, phosphorus, and potassium fertilizer treatment (NPK); and (5) a no-fertilizer treatment (CK). The results showed that, compared with CK, the yields of wheat and maize treated with NPK were increased by 21.5% and 27.5%, respectively, and the accumulation of the dry matter of the wheat and maize was increased by 42.5% and 57.3%. In all the deficiency treatments, the NK treatment performed better in terms of yield compared to the NP and PK treatments, while the NP treatment demonstrated a greater increase in dry matter accumulation. The NPK treatment significantly improved the nitrogen use efficiency (NUE) and nitrogen harvest index (NHI) of the wheat and maize, which resulted in higher nitrogen accumulation in the NPK treatment, and the NP treatment was the best among the other nutrient deficiency treatments. The inorganic nitrogen content showed a similar trend. In conclusion, nutrient deficiency can severely restrict crop growth. Nitrogen deficiency can significantly reduce crop yields. Phosphorus deficiency had a greater impact than potassium deficiency in terms of nutrient absorption and accumulation. Therefore, nitrogen fertilizer application should be emphasized in crop rotation systems, with moderate increases in phosphorus fertilizer application. This practice can effectively improve the nutrient deficiency under the wheat and maize rotation system in the NCP and complete a rational fertilization system.

Combined transcriptomic, metabolomic and physiological analysis reveals the key role of nitrogen, but not phosphate and potassium in regulating anthocyanin biosynthesis induced by nutrient deficiency in Eucalyptus

Anthocyanin biosynthesis in Eucalyptus plants can be flexibly and rapidly modulated in response to hormones or environmental stimuli, including nutrient deprivation (ND). However, the underlying mechanism of ND in inducing anthocyanin biosynthesis in plants remains largely elusive. In this study, we discovered that anthocyanin levels in leaves and stems could well reflect nitrogen availability in Eucalyptus. Supplementation with nitrogen, but not with phosphate or potassium, effectively inhibited ND-induced anthocyanin biosynthesis. To further investigate how nitrogen regulates this process, comprehensive time-resolved transcriptomic and targeted metabolomic analyses were conducted. The results revealed that 3405, 2706, and 3153 genes were differentially regulated by nitrogen treatment at 1, 2, and 3 d, respectively. Pathway analysis indicated the majority of the enriched KEGG pathways were associated with cellular metabolism, such as amino acid and flavonoid biosynthesis. Moreover, metabolomic analysis showed that the most abundantly accumulated anthocyanins, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside, along with key intermediates in the flavonoid pathway, were downregulated by nitrogen treatment. Furthermore, nitrogen-responsive MYB-bHLH-WDR complex genes were identified, including six EgrMYB113 family members. Overexpression of one of the EgrMYB113-like genes induced anthocyanin biosynthesis in the transgenic hairy roots of Eucalyptus. Interestingly, mutation of AtMYB113 inhibited nitrogen deficiency-induced anthocyanin biosynthesis in Arabidopsis, suggesting that MYB113 is a novel N-responsive MYB transcriptional regulator of anthocyanin biosynthesis. Additionally, nitrogen treatment upregulated a few GA biosynthesis genes while simultaneously downregulated the expression of several GA2ox genes. Exogenous application of GA3 decreased ND-induced anthocyanin biosynthesis. Conclusively, this study provides novel insights into the molecular mechanism of nitrogen in the regulation of anthocyanin biosynthesis in Eucalyptus.

Combining UAV Multispectral and Thermal Infrared Data for Maize Growth Parameter Estimation

The leaf area index (LAI) and leaf chlorophyll content (LCC) are key indicators of crop photosynthetic efficiency and nitrogen status. This study explores the integration of UAV-based multispectral (MS) and thermal infrared (TIR) data to improve the estimation of maize LAI and LCC across different growth stages, aiming to enhance nitrogen (N) management. In field trials from 2022 to 2023, UAVs captured canopy images of maize under varied water and nitrogen treatments, while the LAI and LCC were measured. Estimation models, including partial least squares regression (PLS), convolutional neural networks (CNNs), and random forest (RF), were developed using spectral, thermal, and textural data. The results showed that MS data (spectral and textural features) had strong correlations with the LAI and LCC, and CNN models yielded accurate estimates (LAI: R2 = 0.61–0.79, RMSE = 0.02–0.38; LCC: R2 = 0.63–0.78, RMSE = 2.24–0.39 μg/cm2). Thermal data reflected maize growth but had limitations in estimating the LAI and LCC. Combining MS and TIR data significantly improved the estimation accuracy, increasing R2 values for the LAI and LCC by up to 23.06% and 19.01%, respectively. Nitrogen dilution curves using estimated LAIs effectively diagnosed crop N status. Deficit irrigation reduced the N uptake, intensifying the N deficiency, while proper water and N management enhanced the LAI and LCC.

Effect of Extracted Walnut Pomace Cake Edible Coating and Packaging Type on Quality Parameters of Walnut (Juglans regia L.) Kernels During Long Storage Periods

Walnuts are highly valued for their rich nutritional content, but their quality degrades during storage due to oxidation and other quality reducing processes. This study investigated the use of bioactive compounds extracted from walnut pomace, a by-product of walnut oil production, to develop an edible coating that extends the shelf life of ‘Milotai 10’ walnut kernels. Walnut kernels were stored for eight months in four different packaging materials (PE, PP, MPP, PLA) and three treatments were used (air or without treatment, nitrogen gas, and walnut pomace extract coating). The effects of these combinations on walnut quality parameters, including polyphenol content, vitamin E, fatty acids, peroxide value, and color, were analyzed. The results show that the combination of metallized polypropylene packaging under nitrogen treatment or with atmospheric air and walnut pomace extract (MPP-A-E+) best preserves walnut quality, making it a promising option for extending shelf-life.

Novel high-strength, recyclable, microbial-resistant, and freeze-thaw dual topological network hydrogel cooling media

The demand for multifunctional hydrogels, offering high mechanical strength, efficient cooling, and antimicrobial properties, is growing in food preservation. Here, a dual-network (DN) hydrogel PM@Cur, which includes curcumin, is fabricated through chemical crosslinking and hydrogen bonding interactions. The resulting hydrogels can withstand more than five freeze-thaw cycles at −80 °C, and resist brittleness after liquid nitrogen treatment. PM@Cur also exhibits surface hydrophobicity (contact angle >90°) for both water and organic solvents. These properties meet the mechanical, anti-fouling, and recyclable demands for hydrogel coolants. The antimicrobial assays in vitro confirmed that the inclusion of curcumin provided the PM@Cur with photodynamic antimicrobial capacity. Finally, the prepared PM@Cur hydrogel ice cubes have been confirmed to exhibit better anti-melting properties than traditional ice cubes, thus enabling the preservation of strawberries and shrimp. This study presents an innovative solution for producing advanced functional integrated hydrogels, offering a promising and safer option for food coolants.\\.

The Effect of Different Doses of Nitrogen and Seed Treatment with Biofertilizers on Growth, Yield and Seed Quality of Sunflower (Helianthus annus L.)

Aims: To study the effect of Different Doses of Nitrogen and Seed Treatment with Biofertilizers on Growth, Yield and Seed Quality of Sunflower. Study Design: The experiment was laid out in a randomized block design with eleven treatments replicated thrice. Place and Duration of Study: The field experiment was conducted during rabi season of 2019-20, 2020-21, 2021-22 and 2022-2023 in the Instructional Farm of Ramkrishna Ashram Krishi Vigyan Kendra, Nimpith, South 24 Parganas, West Bengal. Methodology: The experiment was carried out in randomized block design with eleven treatments and replicated thrice. The treatments were Control, 50% N, 100% N (90 kg N/ha), Azospirillum (seed treatment), Azatobacter (seed treatment), Azospirillum +Azatobacter (seed treatment), 50% N + Azospirillum (seed treatment), 50% N + Azatobacter (seed treatment), 50% N +Azospirillum + Azatobacter (seed treatment), 75% N + Azospirillum + Azatobacter (seed treatment) and 100% N + Azospirillum + Azatobacter (seed treatment). A common dose of Nitrogen@ 90kg/ha, phosphorus @90kg/ha and potash @40kg/ha were applied. Results: Higher head diameter (13.82 cm), 1000 seed weight (65.50 g), seed yield (1830 kg/ha), oil yield (628.80 kg/ha), gross return (Rs.48581), net return (Rs.26368) and B:C (2.19) than all other treatment followed by T10 (75% N + Azospirillum + Azotobacter) and T3 (100% N) which were statistically at par with each other. Conclusion: On the basis of all parameter as well as economics it can be concluded that treatment T10 (75% N + Azospirillum + Azotobacter) can be recommended for better benefit and sustainable production of sunflower. The results of this experiment showed that use of chemical fertilizers can be reduced by using a combination of bio-fertilizers and inorganic nitrogen fertilizer.

Transcriptome and metabolome reveal the role of different nitrogen treatments for volatile organic compounds accumulation in tomato leaf

Transcriptome and metabolome reveal the role of different nitrogen treatments for volatile organic compounds accumulation in tomato leaf

Coupling Image-Fusion Techniques with Machine Learning to Enhance Dynamic Monitoring of Nitrogen Content in Winter Wheat from UAV Multi-Source

Plant nitrogen concentration (PNC) is a key indicator reflecting the growth and development status of plants. The timely and accurate monitoring of plant PNC is of great significance for the refined management of crop nutrition in the field. The rapidly developing sensor technology provides a powerful means for monitoring crop PNC. Although RGB images have rich spatial information, they lack the spectral information of the red edge and near infrared bands, which are more sensitive to vegetation. Conversely, multispectral images offer superior spectral resolution but typically lag in spatial detail compared to RGB images. Therefore, the purpose of this study is to improve the accuracy and efficiency of crop PNC monitoring by combining the advantages of RGB images and multispectral images through image-fusion technology. This study was based on the booting, heading, and early-filling stages of winter wheat, synchronously acquiring UAV RGB and MS data, using Gram–Schmidt (GS) and principal component (PC) image-fusion methods to generate fused images and evaluate them with multiple image-quality indicators. Subsequently, models for predicting wheat PNC were constructed using machine-selection algorithms such as RF, GPR, and XGB. The results show that the RGB_B1 image contains richer image information and more image details compared to other bands. The GS image-fusion method is superior to the PC method, and the performance of fusing high-resolution RGB_B1 band images with MS images using the GS method is optimal. After image fusion, the correlation between vegetation indices (VIs) and wheat PNC has been enhanced to varying degrees in different growth periods, significantly enhancing the response ability of spectral information to wheat PNC. To comprehensively assess the potential of fused images in estimating wheat PNC, this study fully compared the performance of PNC models before and after fusion using machine learning algorithms such as Random Forest (RF), Gaussian Process Regression (GPR), and eXtreme Gradient Boosting (XGB). The results show that the model established by the fusion image has high stability and accuracy in a single growth period, multiple growth periods, different varieties, and different nitrogen treatments, making it significantly better than the MS image. The most significant enhancements were during the booting to early-filling stages, particularly with the RF algorithm, which achieved an 18.8% increase in R2, a 26.5% increase in RPD, and a 19.7% decrease in RMSE. This study provides an effective technical means for the dynamic monitoring of crop nutritional status and provides strong technical support for the precise management of crop nutrition.

High-yield rice with rich nutrition and low toxicity can be obtained under potato-rice cropping system.

Rice is often rotated with dryland crops to produce sufficient foodstuff, as rice is the main food crop of humans. In order to verify whether under the intensive rice-based cropping system, high yield and good quality of rice can be achieved simultaneously to ensure food security. Five long-term paddy-upland rotations - wheat-rice (WR), rapeseed-rice (RR), garlic-rice (GR), broad beans-rice (BR) and potato-rice (PR) - were conducted from 2014 to investigate rice yield, along with the profiling of 24 elements in rice grain. Mg, Zn, Cu, As, Mo and Sb concentrations were highest in the aleurone layer, and Ag and Cd concentrations showed little variation among different parts of the rice grain. Al, Ti, V, Si, Fe and Tl concentrations in the endosperm under GR were higher, while the Se concentration under PR was the highest. Furthermore, the yield of GR and PR were higher than the other three rotations with N supplementation, and the sustainable yield index of PR and WR were larger than 0.8. When we consider the concentration of toxic (As, Cd and Pb) and nutrient elements (Ca, Fe, Zn, Se, Cu and Mg) in the endosperm and grain yields, PR can simultaneously achieve high yield, high nutrition and low toxicity with different nitrogen treatments. Here we provide novel insights regarding the selection of rice-based cropping systems, focused on producing nutritious and safe rice with high grain yield. © 2024 Society of Chemical Industry.

Interactive effects of nitrogen and genotype on maize rough dwarf disease

AbstractNitrogen and genotype play vital roles in modulating plant disease resistance. Maize (Zea mays L.) rough dwarf disease (MRDD) is a global viral disease that has caused serious yield losses. However, it is not clear how nitrogen and genotype interact to affect MRDD. We conducted field experiments in 2011 and 2013 to investigate the MRDD incidence, yield, and yield loss rate of 59 maize hybrids under high nitrogen (HN) and low nitrogen (LN). Compared with HN, the MRDD incidence and yield loss rate of S‐sensitive hybrids (nitrogen significantly influenced MRDD incidence in susceptible genotypes) could be significantly reduced by 50.6% and 35.5%, respectively, in LN without compromising maize yield. In contrast, R‐insensitive types (resistant hybrids in which MRDD incidence was unresponsive to nitrogen treatment) could maintain high MRDD resistance and yield at HN. US hybrid 78599 and inbred line Dan340 were the main parental resources of the resistant genotypes, and inbred lines Huangzao4 and Ye478 were the main parental resources of the susceptible genotypes. The physiological mechanism leading to increased MRDD incidence was thought to be higher nitrogen concentrations in the stalks. This study provided theoretical support for using reasonable nitrogen management to control MRDD and breeding MRDD‐resistant maize hybrids.