Optimal Nitrogen Research Articles

Integrated Effects of Water and Nitrogen Coupling on Eggplant Productivity, Fruit Quality, and Resource Use Efficiency in a Cold and Arid Environment

In order to explore the water and fertilizer requirements of eggplants in the western oasis of the river, the experiment was conducted in Minle County of Gansu Province in 2022 and 2023 under three water stress gradients and three nitrogen application levels: (1) moderate water stress (W1, 50–60% in field water capacity [FC]), mild water stress (W2, 60–70% in FC), and full irrigation (W3, 70–80% in FC); (2) low nitrogen (N1, 215 kg·ha−1), medium nitrogen (N2, 270 kg·ha−1), and high nitrogen (N3, 325 kg·ha−1). Moderate and mild water stress were applied during eggplant flowering and fruiting while full irrigation was provided during the other growth stages; a control class (CK) was established with full irrigation throughout the whole plant growth without nitrogen application. This study investigated the effects of water-saving and nitrogen reduction on the yield, quality, and water-nitrogen use efficiency of eggplants in a cold and arid environment in the Hexi Oasis irrigation area of China. Using the EWM-TOPSIS model, we evaluated different water-nitrogen treatments and determined the optimal irrigation-nitrogen application model for eggplants in this region. The results showed that the W2N2 treatment had the highest yield, which was not significantly (p > 0.05) different from the W3N2 treatment while significantly (p < 0.05) 35.06% higher than CK in 2022 and 36.91% higher in 2023. In the W2N2 treatment, the transverse diameter of eggplants, as well as the contents of soluble protein, soluble sugar, soluble solids, and vitamin C, were all the highest. The W2N2 treatment had the maximum water use efficiency and irrigation water use efficiency, which were significantly higher than other water and nitrogen application treatments and CK by 14.79–42.51% in 2022 and 8.79–44.88% in 2023, and 15.86–45.55% in 2022 and 4.68–40.22% in 2023, respectively. By employing the EWM-TOPSIS model for comprehensive evaluation, the results indicated that mild water deficit (60–70% in FC) and moderate nitrogen application (270 kg·ha−1) at flowering and fruiting of eggplants was the optimal water and nitrogen application mode under mulched drip irrigation in the Hexi region of northwest China. The results will provide some theoretical basis for water-saving, productive, high-quality, and high-efficiency cultivation of eggplant in cold and arid environments.

Optimum Nitrogen and Density Allocation for Trade−Off Between Yield and Lodging Resistance of Winter Wheat

Increasing nitrogen and planting density can enhance crop yield, but it can reduce lodging resistance due to decreased lignin content. There is an urgent need to find feasible measures to balance these conflicting factors. We conducted a two-year field experiment in Tai’an, Shandong Province, China, evaluated SN23 (lodging resistant) and SN16 (lodging sensitive), under three nitrogen applications (120 kg/ha, N1; 240 kg/ha, N2; 360 kg/ha, N3) and four planting densities (75 plants/m2, D1; 225 plants/m2, D2; 375 plants/m2, D3; 525 plants/m2, D4), with N2D2 as the control, and measured lodging resistance related indexes and yield. N2D3 (SN23) increased internode length by 0.40 cm, reduced fresh weight by 0.09 g, resulting in a bending moment reduction of 0.39 g/cm. Lignin, cellulose, and hemicellulose decreased by 18.27, 16.48, and 16.22 mg/g DW, while S and G lignin subunits decreased by 118.09 and 127.34 μg/g DW, and H subunit increased by 23.59 μg/g DW. Eventually, the breaking strength was reduced by 1.74 g/cm resulting in a reduction of 0.09 in the lodging resistance index. The yield reached 10.17 t/ha due to an increase in spike number by 100.33 plants/m2, achieving an optimal balance between yield and lodging resistance in this experiment. This study provides a viable solution for balancing lodging resistance and yield in winter wheat.

Effect of Different Nitrogen Levels on Growth, Yield, and Nitrogen Use Efficiency (NUE) of Hardinath Hybrid Dhan-1 in Madhesh Province, Nepal

Determining the optimum dose of nitrogen fertilizer application for hybrid rice is vital for boosting production and productivity of rice. Therefore, this study examines the effect of different nitrogen levels on the growth, yield, and nitrogen use efficiency (NUE) of Hardinath Hybrid Dhan-1 in Madhesh Province, Nepal. A field experiment conducted in 2020 at the National Rice Research Program, Hardinath, Dhanusha tested six nitrogen levels (0, 75, 100, 125, 150, and 175 kg ha-1) with four replications under Randomized Complete Block Design during rainy season (June-September). The results showed that nitrogen application significantly improved plant growth and yield, with the highest grain yield (4.99 t ha-1) achieved at 150 kg N ha-1. Increasing nitrogen beyond this level did not further boost yield, indicating that excessive nitrogen does not improve productivity. Nitrogen use and agronomic efficiency were also highest at 150 kg N ha-1, marking it as the ideal rate for optimal rice performance. Soil health, in terms of organic matter and nutrient availability, improved with higher nitrogen levels, while the highest nitrogen uptake occurred at 175 kg N ha-1. In conclusion, 150 kg N ha-1 is recommended as the optimal nitrogen level to enhance hybrid rice yield and NUE, promoting sustainable rice production in the region. These findings highlight the need for optimal nitrogen management to improve crop yield and soil properties while minimizing environmental impact.

Optimum Nitrogen and Phosphorus Combination Improved Yield and Nutrient Use Efficiency of Sorghum in Saline Soil.

Two-year experiments were conducted to assess the responses of yield and nutrient use efficiency of sorghum to nitrogen and phosphorus under saline soils. Three nitrogen rates (0, 180, and 360 N kg ha-1) and three phosphorus rates (0, 60, and 120 P2O5 kg ha-1) were used in this study. Our results showed that nitrogen and phosphorus supply increased SPAD (leaf greenness, 5.0-29.1%), NSC (non-structural carbohydrates, 14.0-41.2%), nutrient accumulation (nitrogen: 14.1-50.0%, phosphorus: 11.8-41.5%, potassium: 13.7-28.2%), biomass (fresh: 10.8-29.3%, dry: 5.0-22.8%), yield (16.6-30.7%), and harvest index (2.0-9.8%) of sorghum at the maturity stage grown in saline soils but significantly decreased nutrient use efficiency. Combined application showed better performance on these attributes than sole nitrogen and sole phosphorus. The highest seed yield (5919 kg ha-1) was recorded at 180 N kg ha-1 and 60 P2O5 kg ha-1 treatment, while the largest value of dry biomass (18,401 kg ha-1) was obtained at 360 N kg ha-1 and 120 P2O5 kg ha-1 treatment. The Pearson analysis showed that seed yield had the highest correlation with aerial potassium accumulation, while dry biomass had the highest correlation with NSC as well as aerial nitrogen accumulation. A treatment of 180 N kg ha-1 and 60 P2O5 kg ha-1 was recommended to be used in sorghum production in saline soils based on harvest index and nutrient use efficiency.

Synergistic effects of heterogeneous mature compost and aeration rate on humification and nitrogen fixing during kitchen waste composting.

Sludge mature compost (SMC) is notable for its high production, easy accessibility, and stable supply. This study investigated the impact of the SMC addition and different aeration rates on the humification and nitrogen fixing process during kitchen waste composting. The results demonstrated that addition of SMC prolonged the thermophilic phase, as a comparison, increased aeration shortened this phase. The addition of SMC and increased aeration enhanced humus formation and nitrogen retention. SMC introduced more amide and polysaccharide compounds into the compost, promoting the Maillard humification pathway. Additionally, both SMC and high aeration inhibited denitrification: the SMC reduced the abundance of the nirK gene, while high aeration decreased the abundance of nosZ gene. Network analysis revealed that higher aeration enhanced fungal interactions but diminished bacterial interactions. Conversely, SMC addition bolstered both bacterial and fungal interactions. The final compost product with SMC addition showed a 11.56%-44.19% reduction in antibiotic resistance gene content compared with the control group, and heavy metal contents remained within safe application limits. The combination of high SMC addition and high aeration achieved optimal humification and nitrogen retention, underscoring its potential as a promising solution for kitchen waste composting.

Optimization of Irrigation and Fertilization in Maize–Soybean System Based on Coupled Water–Carbon–Nitrogen Interactions

Effective water and nitrogen management plays a pivotal role in enhancing crop yields while simultaneously reducing greenhouse gas emissions. This study differs from previous research by investigating the effects of water–nitrogen co-regulation involving organic carbon on the yield increase and emission mitigation in a soybean–maize system. A dryland experiment was conducted, employing 20 distinct combinations of water and nitrogen treatments that were meticulously designed for the maize–soybean system. The DSSAT crop model was employed to quantitatively elucidate the intricate interactions between water and nitrogen. A multi-objective optimization model, integrating experimental data and mechanistic insights, was constructed and refined using the NSGA-III genetic algorithm to identify the optimal water and nitrogen application ratios. An analysis of maize and soybean data from Acheng in Heilongjiang, China, indicates that optimized irrigation and nitrogen application regimes—152.2 mm and 247.1 kg·ha−1 for maize and 91.7 mm and 106.2 kg·ha−1 for soybean—substantially enhanced the net economic returns within the dryland ecosystem. There is a significant positive correlation between the yield (Y), soil nitrogen content, and soil organic carbon (SOC). Nitrate nitrogen has a significant positive correlation with CO2 gas emissions. Organic carbon changes the soil’s carbon to nitrogen ratio by participating in the water and nitrogen cycles, thereby affecting nitrogen and phosphorus loss and carbon emissions. This study presents a sustainable method for regulating water and nitrogen in the maize–soybean system.

Optimizing water‐nitrogen regulation for enhanced carbon absorption and reduced greenhouse gas emissions in greenhouse tomato cultivation

AbstractTo study the impact of different water‐nitrogen regulation modes on the carbon cycle of greenhouse tomatoes and determine optimal irrigation and nitrogen application levels to enhance carbon absorption and minimize greenhouse gas emissions. This study employed three irrigation levels (100%, 80%, and 60% of ET0) and three nitrogen application levels (240, 192, and 144 kg·ha−1), along with a control group (W1N1, i.e., 100% ET0‐240 kg·ha−1). Gas‐chromatography methods were used to monitor CH4 and soil CO2 emissions, while assessing dry matter, carbon content, and carbon fixation capacity of tomato organs throughout the growth period. Additionally, a system for evaluating the net ecosystem carbon budget of facility tomatoes was developed based on net primary productivity. Results indicated reduced CH4 and soil CO2 emissions with decreased irrigation and nitrogen application. Dry matter, carbon content, and carbon fixation of tomato organs initially increased with reduced nitrogen and irrigation but then declined. The W2N2 (80% ET0‐192 kg·ha−1) treatment showed maximal values for dry matter, carbon content, carbon fixation, net primary productivity (NPP), and gross primary productivity (GPP). Findings suggest a positive net ecosystem carbon budget under reduced water and nitrogen conditions, indicating carbon absorption. Specifically, the W2N2 treatment outperformed others in net carbon absorption, highlighting its potential as an effective mode for enhancing carbon sequestration in the region.

The Nitrogen Removal Characteristics of a Novel Salt-Tolerant Bacterium, Enterobacter quasihormaechei DGFC5, Isolated from Municipal Sludge.

A novel bacterial strain, Enterobacter quasihormaechei DGFC5, was isolated from a municipal sewage disposal system. It efficiently removed ammonium, nitrate, and nitrite under conditions of 5% salinity, without intermediate accumulation. Provided with a mixed nitrogen source, DGFC5 showed a higher utilization priority for NH4+-N. Whole-genome sequencing and nitrogen balance experiments revealed that DGFC5 can simultaneously consume NH4+-N in the liquid phase through assimilation and heterotrophic nitrification, and effectively remove nitrate via aerobic denitrification and dissimilatory reduction reactions. Single-factor experiments were conducted to determine the optimal nitrogen removal conditions, which were as follows: a carbon-to-nitrogen ratio of 15, a shaking speed of 200 rpm, a pH of 7, C4H4Na2O4 as the carbon source, and a temperature of 30 °C. DGFC5 showed efficient nitrogen purification capabilities under a wide range of environmental conditions, indicating its potential for disposing of nitrogenous wastewater with high salinity.

Hydrogen Release from Ammonia: Size and Support Effects in Heterogeneous Transition Metal Catalysis

Ammonia can serve as a promising renewable energy carrier based on its high hydrogen content and energy density as well as its full‐fledged transportation infrastructure. Renewable hydrogen can be converted in ammonia synthesis, stored and/or transported bound in ammonia and released on demand by ammonia decomposition. The most active catalysts for this reaction are Ru‐based due to its optimal nitrogen binding energy compared to other transition metals. However, the development of alternative non‐noble transition metal catalysts such as Fe, Ni or Co is attractive. For supported metal catalysts, size and support effects play important roles in many catalytic reactions resulting in a change of geometric and/or electronic properties. In this review, we first discuss existing studies of size and support effects on Ru, Fe, Ni, Co catalysts in ammonia decomposition from an experimental and theoretical viewpoint. Afterwards, we compare the available catalytic data in the form of TOFH2 and reaction rate for each metal catalyst supported on different supports and as a function of particle size, attempting to identify an optimum particle size and a trend for the different supports. Finally, we discuss the challenges and perspectives of future research on the size and support effect in ammonia decomposition.

Synthesis of diamond films with reduced roughness in microwave plasma

The work studies the effect of nitrogen additions on the secondary nucleation (nucleation) of diamond during its synthesis by chemical vapor deposition (CVD). A series of polycrystalline diamond (PCD) films 2 μm thick were grown on silicon substrates in methane-hydrogen-nitrogen gas mixtures with different nitrogen concentrations (0–1%). The structure and roughness of the grown films were studied using scanning electron microscopy (SEM) and optical profilometry. It has been shown that small additions of nitrogen play a key role in the processes of secondary nucleation of diamond, having a significant impact on the morphology of films. The comparison of the characteristics of grown PCD allowed us to find the optimal nitrogen concentration [N2] ≈ 0.2% for the formation of nanocrystalline diamond (NCD) films with low surface roughness and increased growth rate. The results obtained are expected to be used to optimize the parameters of CVD synthesis of PCD films for use as protective or friction-reducing layers, as well as for the manufacture of superhard cutting tools.

Morphological and agronomic features of potato cv. Gardena highly resistant to Phytophthora infestans (Mont.) de Bary depending on the nitrogen dose

In a 2-year field study, the impact of mineral nitrogen fertilization on the productivity of a new potato cultivar, promising due to the highest resistance to potato late blight among the registered ones, was compared to the proven, widely cultivated Denar cultivar. The study determined morphological features (size and weight of organs), physiological indicators (cover of soil by leaves – LAI. leaf greenness – SPAD) of potato plants during the growing season, yield and quality characteristics of tubers and optimal level of nitrogen fertilization. Tuber quality was assessed based on the share of tuber size and external defects in the yield structure. Optimal mineral nitrogen fertilization was determined based on the relationship between the increase in tuber yield and the increasing dose of this ingredient. The research took into account two factors: nitrogen dose (0, 50 kg‧ha–1, 100 kg‧ha–1, 150 kg‧ha–1) and cultivar (Gardena and Denar). The increase in the dose of mineral nitrogen fertilization to 150 kg‧ha–1 resulted in a significant increase in plant height, the weight of the root system, stems, leaves and the share of large tubers in the yield. It was shown that the Gardena cultivar was characterized by greater requirements for mineral nitrogen fertilization, low effectiveness of its use, a higher share of large tubers (diameter above 60 mm) and lower tuber yield than the Denar cultivar. In a year characterized by excess rainfall, plants produced a greater mass of the root system and the mass of the above-ground part, and in a year with an amount of rainfall close to optimal the final yield of tubers and the share of large tubers in the yield were higher.

Effects of Water and Nitrogen Regulation on Soil Environment and Crop Growth in a Lycium barbarum||Alfalfa System.

The increasing scarcity of water and soil resources, combined with inefficient water and fertilizer management, poses significant challenges to agriculture in arid regions. This study aimed to determine an optimal water and nitrogen regulation model to alleviate water shortages and improve agricultural productivity and quality. In this study, a two-year experiment was conducted to investigate the effects of varying irrigation and nitrogen levels on the soil environment and crop growth in a Lycium barbarum||alfalfa system (LB||AS). The experiment involved four moisture gradients and four nitrogen application levels (using urea as the nitrogen source). The results indicated that soil moisture decreased during crop development, followed by a slow increase, with significant variation across soil depths. Soil temperature peaked during the fruiting stage of Lycium barbarum in July, decreasing significantly with soil depth. Higher temperatures were recorded in N0 under the same irrigation level and in W3 under the same nitrogen level. Soil organic carbon (SOC) levels increased by 16.24% in W3N0 and by 18.05% in W2N1, compared to W0N3. Easily oxidizable organic carbon (EOC) and soluble organic carbon (DOC) levels exhibited significant variations depending on irrigation and nitrogen treatments. Irrigation and nitrogen had a stronger individual impact on alfalfa height and stem thickness than their combined effects. Water and nitrogen regulation significantly influenced Lycium barbarum yield, its 100-fruit weight, and economic efficiency (p < 0.05). The W0N2 treatment produced the highest yield (3238 kg·ha-1), exceeding other treatments by up to 29.52%. In conclusion, the optimal water-nitrogen regulation model for the LB||AS system is full irrigation (75-85% θfc) with a nitrogen application rate of 300 kg·ha-1. These findings offer critical insights for improving water and nitrogen management strategies in arid regions.

Optimization of superconducting niobium nitride thin films via high-power impulse magnetron sputtering

Abstract We report a systematic comparison of niobium nitride thin films deposited on oxidized silicon substrates by reactive DC magnetron sputtering and reactive high-power impulse magnetron sputtering (HiPIMS). After determining the nitrogen gas concentration that produces the highest superconducting critical temperature for each process, we characterize the dependence of the critical temperature on film thickness. The optimal nitrogen concentration is higher for HiPIMS than for DC sputtering, and HiPIMS produces higher critical temperatures for all thicknesses studied. We attribute this to the HiPIMS process enabling the films to get closer to optimal stoichiometry before beginning to form a hexagonal crystal phase that reduces the critical temperature, along with the extra kinetic energy in the HiPIMS process improving crystallinity. We also study the ability to increase the critical temperature of the HiPIMS films through the use of an aluminum nitride buffer layer and substrate heating.

Synthesis and characterization of titanium oxynitride catalyst via direct ammonia nitridation of titanium polyacrylate for oxygen reduction reaction

A titanium oxynitride catalyst for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells was synthesized through the direct ammonia nitridation of titanium complexes. Titanium polyacrylate was employed as the catalyst precursor, and the effect of the calcination temperature between 600 and 1000 °C on the catalyst structure was studied. The catalysts were characterized via X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, and powder electrical resistivity measurements. The formation of titanium oxynitride particles and deposited carbon was observed for all the samples; however, significant variations in the catalyst structure and catalytic activity were also observed. With an increase in the calcination temperature, nitridation of titanium oxynitride progressed, and the conductivity of the catalyst powder increased. The highest rest potential and ORR current density were achieved with calcination at 800 °C. Importantly, the results suggest that maintaining an optimal nitrogen doping level within the catalyst particles, along with ensuring the formation of electroconductive deposited carbon, is essential for achieving a high ORR current. This work introduces the direct ammonia nitridation of metal complexes as a promising process for designing metal oxynitride catalysts.

Impact of cellulolytic nitrogen-fixing composite inoculants on humification pathways and nitrogen cycling in kitchen waste composting

Low humification and nitrogen loss pose substantial challenges to the resource utilization in kitchen waste composting. This study investigated the effects of brown-rot fungi (BRF), cellulolytic nitrogen fixing bacteria (CNFB), and their composite microbial inoculants (CMI) during composting. Results indicated that microbial inoculants extended the thermophilic phase and enhanced cellulose degradation. Compared with the control, the degree of polymerization (HA/FA) in BRF, CNFB, and CMI was 2.28, 1.85, and 2.68 times higher, respectively, while increasing total nitrogen by 11.15%, 15.50%, and 19.73%. BRF and CMI primarily enhanced the Maillard humification pathway, while CNFB promoted the polyphenol humification pathway. Additionally, BRF enhanced nitrification and reduced denitrification, whereas CNFB and CMI improved nitrification, nitrogen fixation, and ammonification while reducing denitrification. Overall, BRF primarily promoted humification, while CNFB excelled in nitrogen retention. The CMI achieved optimal humification and nitrogen retention, indicating a potential sustainable solution for kitchen waste composting.

Optimal nitrogen management increased topsoil organic carbon stock and maintained whole soil inorganic carbon stock to increase soil carbon stock—A 15-year field evidence

Nitrogen application significantly impacts soil organic carbon (SOC) and soil inorganic carbon (SIC) stocks, both of which are crucial for soil carbon sequestration. However, the effects of nitrogen fertilizer on the dynamics of SOC and SIC stocks remain poorly understood. Over a 15-year wheat-maize rotation experiment conducted on calcareous alluvial soil in temperate continental monsoon climate, we quantitatively analyzed crop carbon return and dynamics of SOC and SIC stocks among soil layers. Compared to conventional nitrogen management (Con.N), optimal nitrogen management (Opt.N) increased crop carbon return by 130 kg C ha−1 yr−1. There was no significant difference in SOC stock between Opt.N and Con.N, despite Opt.N used 39.4 % less nitrogen input compared to Con.N. In the topsoil, Opt.N maintained SIC levels similar to those of the Control and significantly increased by 7.22 % compared to Con.N. The Con.N treatment reduced SIC stock by 10.1 % compared to the Control. Furthermore, Opt.N had no significant negative effect on SIC stock in subsoil, thereby maintaining the whole SIC stock. After 15 years, Opt.N achieved a soil carbon stock of 52.7 Mg C ha−1, outperforming Con.N. SOC dominated the topsoil carbon stock, while SIC played a more crucial role in the subsoil. Overall, Opt.N outperformed Con.N in terms of the combined SOC and SIC stocks. Our findings suggest that Opt.N can enhance soil carbon stock with lower resource consumption, thereby contributing to global warming mitigation and promoting sustainable low-carbon agriculture.

Influence of Different Nitrogen Concentrations on Growth, Yield, and Yield Attributes of Hydroponically Grown Cherry Tomato

This scientific study aimed to determine the optimal nitrogen concentration within a hydroponic solution for the Rosa variety of cherry tomato plants cultivated in a controlled greenhouse environment. The study was conducted over a period of October 2019 to April 2021. Various treatments were administered, each with distinct nitrogen concentrations, to evaluate their effects on plant growth, yield, and yield-attributing characteristics. The results unequivocally demonstrated that the application of 8 mmol/L of nitrogen (T3) emerged as the most efficacious treatment for optimizing the growth, yield, and yield-attributing characteristics of the cherry tomato plants. These findings hold significant implications for refining nitrogen management practices in horticultural crop production, particularly for the Rosa variety of cherry tomatoes, within controlled greenhouse settings.

Improvement of Transplanting Rice Yield and Nitrogen Use Efficiency by Increasing Planting Density in Northeast China Under the Optimal Nitrogen Split-Fertilizer Applications

There are few studies on how nitrogen (N) fertilizer application rates and transplanting densities impact rice yield, root distribution, and N use efficiency in the cold regions of Northeast China. This research involved a two-year field trial utilizing Jinongda 667 as the material. In 2021, three N split-fertilizer applications—T1 (6:3:1), T2 (5:3:2), T3 (4:3:3)—and two transplanting densities—D1 (30 cm × 13.3 cm) and D2 (30 cm × 20 cm)—were compared with the conventional cultivation mode (T0: 175 kg N hm−2, 6:3:1), whereby the N application mode most suitable for increasing density was explored. In 2022, four N application levels—0 (N0), 125 (N1), 150 (N2), and 175 (N3) kg N hm−2—were assessed under the same density treatment to analyze the yield, resource utilization efficiency, and root traits of Jinongda 667. The results indicated that when the transplanting density was 30 cm × 13.3 cm, the application of 5:3:2 fertilizer was more conducive to improving rice yield. Increasing planting density under reduced N input significantly enhanced both rice yield and N use efficiency. In contrast to the conventional cultivation method (D2N3), the treatment of increased planting density (D1N2) under reduced N input led to a 21.2% rise in the number of panicles per square meter and an 8.6% boost in rice yield. Furthermore, increasing planting density under reduced N input significantly enhanced the agronomic efficiency of N fertilizer, the apparent utilization rate, and the N harvest index. It also boosted the SPAD value, photosynthetic rate, and the utilization efficiency of light and N resources in rice. However, it was noted that root enzyme activity decreased. This study demonstrated that increasing planting density, combined with the N application mode of 5:3:2 and an N application rate of 150 kg hm−2, maximized resource utilization efficiency, optimized root absorption capacity, and resulted in higher yields.

Pathogenicity and Biological Characteristics of Botryosphaeria dothidea Causing Branch Blight of Salix babylonica

ABSTRACTSalix babylonica L. is a popular ornamental and ecological tree species. In this study, the results of pathogenicity tests showed that the Botryosphaeria dothidea isolates JXL1‐3, JXL1‐5, JXL1‐11, L1‐3, L2‐2, NFS1, NFS2, NFS5 and WLS1 were pathogens causing branch blight on S. babylonica. Meanwhile, the B. dothidea isolates JXL1‐11, L1‐3, NFS1 and WLS1 were found to be pathogenic to two other willows, S. chaenomeloides and S. suchowensis. The biological characteristics of B. dothidea isolates JXL1‐11, L1‐3, NFS1 and WLS1 were investigated under different conditions, including culture media, pH, temperatures, carbon/nitrogen sources and light. It was found that potato dextrose agar (PDA) medium was the most optimal medium for the B. dothidea isolates JXL1‐11, L1‐3, NFS1 and WLS1 mycelial growth, the suitable pH was 4, and the optimal temperatures were 25°C–30°C. The optimal carbon sources were glucose and sucrose, and the optimal nitrogen sources were ammonium sulfate and peptone. The optimal light condition for inducing sporulation was dark + ultraviolet light. This study provides a fundamental basis for the prevention and control the branch blight on willows and further studies.

Effects of Different Nitrogen and Phosphorus Doses on the Growth, Yield and Yield Components of Black Cumin (Nigella sativa L.)

ABSTRACT Proper adjustment of fertilizer dosage is necessary to achieve maximum yield. The use of too little or too much fertilizer can negatively affect plant growth. Nitrogen and phosphorus are two important nutrients in plant nutrition. Research on the combined effect of nitrogen and phosphorus on black cumin is very limited. Therefore, a field study was conducted to determine the effects of different nitrogen and phosphorus doses on the growth, yield and yield components of black cumin (Nigella sativa L.) under Mediterranean conditions during two growing seasons. Five doses (0 kg ha−1or control, 30 kg ha−1, 60 kg ha−1, 90 kg ha−1 and 120 kg ha−1) of nitrogen and four phosphorus doses (0 kg ha−1 or control, 20 kg ha−1, 40 kg ha−1 and 60 kg ha−1) were used as experimental factors. All the parameters except for capsule number were significantly affected by the growing season. Nitrogen dose significantly affected all the examined features except for seed number in capsule, seed weight in capsule and harvest index, while phosphorus dose significantly affected only SY and HI. In general, in the 2021–2022 growing season, black cumin had lower growth, yield and related traits. On the other hand, even though nitrogen fertilization, particularly at 90 kg ha−1 and 120 kg ha−1, had a positive effect on the yield and yield components of black cumin, the optimal nitrogen dose was 90 kg ha−1 for fewer input costs according to the results obtained from the present study. A phosphorus dose of 60 kg ha−1 was determined to be the appropriate dose in terms of seed yield, and this dose can be suggested for maximum seed yield of black cumin.