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The cultivation of drip-irrigated rice has resulted in lower yields. However, the decrease in rice yield under drip irrigation and its relationship with the existing water and N regime have not been fully explained. Research and development of optimized water and N-management techniques are crucial for increasing rice yield under drip irrigation. In this study, two irrigation treatments were set: conventional drip irrigation (DIO) and drip irrigation with water stress (DIS). Each irrigation treatment contained four N rates: urea N 240 kg ha−1 (LN), urea N 300 kg ha−1 (MN), urea N 360 kg ha−1 (HN), and ammonium sulfate N 300 kg ha−1 (AN). The soil's ammonium and nitrate contents were measured on the 2nd and 28th days after N application at panicle initiation stage. At anthesis, the aboveground and root biomass of rice were measured. In heading and maturity stage the N content of aboveground was measured and the yield, yield components, and NPFP were assessed at maturity stage. The results showed the following: (1) On the second day after N application, the contents of soil NO3−-N and NH4+-N in the 0–10 cm soil layer were highest for both the DIO and DIS. On the 28th day after N application, the soil NO3−-N content was highest at the 20–40 cm depth, while the soil NH4+-N content was still highest at the 0–10 cm depth. (2) The aboveground and root biomass in DIO treatment were significantly higher than in DIS. Furthermore, the root biomass at the 0–10 cm depth was significantly greater than at the 10–50 cm depth for both the DIO and DIS treatments. In the DIO treatment, the root biomass at the 10–50 cm depth was significantly higher with the HN and AN treatments compared to MN. However, in the DIS treatment, the root biomass at the 10–50 cm depth did not show significant differences between the MN, HN, and AN. (3) N accumulation in rice was significantly higher for the DIO treatment compared to the DIS treatment. Under the same irrigation treatment, the N accumulation in rice was highest in the AN and lowest in the LN. The PrNTA and PrNTC in DIS were significantly higher than in DIO, while the PoNAA and PoNAC were significantly lower in DIS. (4) The number of panicles, spikelets per panicle, seed-setting rate, 1000-grain weight, and grain yield were significantly lower in DIS. Under the DIS, these parameters were not significantly different among the MN, HN, and AN. In the DIO, the seed-setting rate, 1000-grain weight, and yield were not significantly different between the HN and AN, but were significantly higher than in the MN and LN. (5) NPFP was significantly higher in the DIO compared to the DIS. Among the different N rates, NPFP was highest with the AN treatment and lowest with the LN. In summary, under drip irrigation, there was a mismatch between soil mineral N and the distribution of rice roots, leading to reduced N accumulation and utilization in rice, ultimately impacting yield formation. Increasing N application and soil ammonium nutrition can improve rice yield under drip irrigation. However, optimizing N fertilizer management may not increase rice yield further when irrigation is further limited. [ABSTRACT FROM AUTHOR]

Frequent occurrence of drought in winter and spring, combined with soil P deficiency limits nitrogen absorption of winter wheat in southwest wheat. This study aims to investigate the effects of straw mulching from autumn fallow and phosphorus application on root NO3- uptake dynamic potential, nitrogen uptake and utilization, chlorophyll content, and grain yield in wheat, which provides the theoretical basis for high and stable yield of wheat as well as efficient use of nutrients. The experiment was carried out at Renshou in Sichuan province from 2020 to 2022. Two factors spilt-plot design was employed with main plot of maize straw mulching (SM) and no mulching (NSM), and three phosphorus levels 0 (P0), 75 (P75), and 120 (P120) kg hm-2 were set as sub-plot. Results showed that straw mulching and phosphorus application significantly increased above-ground phosphorus accumulation. Compared with NSM, SM increased root tip NO3- net absorption rate, grain nitrogen accumulation, nitrogen transport, nitrogen assimilation, nitrogen partial productivity and grain yield by 28.2%, 8.4%, 9.0%, 41.9%, 23.3%, and 21.9%, respectively. Compared with P0, P75 and P120 increased by 35.1%-37.6%, 12.6%-19.0%, 7.1%-9.3%, 35.7%-60.5%, 17.6%-23.8%, 17.2%-23.6%, respectively. Compared with NSM, SM increased the content of chlorophyll in flag leaf at grain filling stage, thus improving grain yield. In summary, straw mulching and phosphorus application can promote NO3- absorption in root tip of wheat and chlorophyll content, significantly increase post anthesis nitrogen absorption and reserved N remobilized to developing grains, and ultimately improve grain yield. Considering the economic benefits and yield returns, it is recommended to apply 75 kg hm-2 of phosphate fertilizer with straw mulching for high yield and efficiency cultivation of wheat in southwest China. [ABSTRACT FROM AUTHOR]

A field experiment of drip fertigated nitrogen reduction was set up in a typical Maize planting area in the Xiliao River Basin in 2018 and 2019. Different phased nitrogen reductions were set up under shallow buried drip irrigation during the growth period to explore ways to improve nitrogen use efficiency (NUE) by understanding the Maize regulation of nitrogen absorption and utilization. The recommended nitrogen application in the early stage (Nopt, total nitrogen 240 kg·hm−2) had the highest grain nitrogen uptake and total nitrogen uptake, followed by nitrogen reduction before the maximum canopy mulching (Nde-I, total nitrogen 180 kg·hm−2), nitrogen reduction after the maximum canopy mulching (Nde-II, total nitrogen 180 kg·hm−2) and no nitrogen application (N0). Without nitrogen application, the leaves were thin, green and yellow. The total nitrogen uptake was 38.54~41.31% lower than the recommended nitrogen application in the early stage. When nitrogen fertilizer was reduced in the maximum canopy mulching, grain nitrogen absorption was affected. Grain nitrogen absorption fell by 15.07% to 17.51% when nitrogen was reduced in the maximum canopy mulching compared to the recommended nitrogen application. The harvest index of nitrogen reduction before the maximum canopy coverage was 9.65~11.52% higher than that in the later stage, indicating that the nitrogen absorption between Maize grain, stem, and leaf was better regulated. Maize evapotranspiration water consumption was reduced throughout the growth cycle when nitrogen was reduced at various stages. Nitrogen reduction before maximum canopy mulching boosted water use efficiency (WUE) by 3.44% to 6.12% compared to the recommended nitrogen application in the early stage. The nitrogen fertilizer agronomic efficiency increased by 11.17% to 13.87%. The nitrogen use efficiency rose by 10.99~3.15% (5.24~6.60 percentage points). A total of 25% of nitrogen fertilizer was saved with the yield declining by only about 5%, resulting in increased NUE while maintaining the yield stability. Under shallow buried drip fertigated irrigation, the appropriate reduction in nitrogen fertilizer during the period from Maize sowing to the maximum canopy development ensured the nitrogen supply during tasseling–silking stage and filling stage, which can be used as a regulation method and a way to improve the Maize fertilizer use efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acid red soils are widely widespread in south China. The strong acidity and aluminum toxicity inhibit plant growth by decreasing soil fertility. Herein, we studied the potential effects of biochar on nitrogen absorption, photosynthesis, and plant-related enzyme activities in maize under different nitrogen fertilizer levels. We carried out a pot experiment with different peanut shell biochar levels (0, 0.5, 1, 2, and 3%) and two nitrogen fertilizer levels (0, 0.2 g kg−1) in the acid red soil. The results indicated that the application of biochar significantly improved the soil environment (pH, soil organic matter) and increased crop growth. Moreover, N accumulation was increased by 98–166% with biochar treatments. The application of 3% biochar to the soil under different N levels significantly increased nitrogen use efficiency (NUE) and physiological nitrogen use efficiency (PNUE). In addition, the functional components (amino acid, cellulose, and protein content) were significantly changed under nitrogen fertilizer treatment according to the results of Fourier transform infrared spectroscopy (FTIR). In particular, the treatments of 0.2 g kg−1 and 3% biochar had the highest photosynthesis parameters of maize. From the results of path analysis, maize growth and development were closely related to the physical and chemical properties of the soil. The study results revealed that biochar could be a green development way to reduce the input of chemical N fertilizer and effective use of resources. [ABSTRACT FROM AUTHOR]

The cultivation of drip-irrigated rice has resulted in lower yields. However, the decrease in rice yield under drip irrigation and its relationship with the existing water and N regime have not been fully explained. Research and development of optimized water and N-management techniques are crucial for increasing rice yield under drip irrigation. In this study, two irrigation treatments were set: conventional drip irrigation (DIO) and drip irrigation with water stress (DIS). Each irrigation treatment contained four N rates: urea N 240 kg ha−1 (LN), urea N 300 kg ha−1 (MN), urea N 360 kg ha−1 (HN), and ammonium sulfate N 300 kg ha−1 (AN). The soil’s ammonium and nitrate contents were measured on the 2nd and 28th days after N application at panicle initiation stage. At anthesis, the aboveground and root biomass of rice were measured. In heading and maturity stage the N content of aboveground was measured and the yield, yield components, and NPFP were assessed at maturity stage. The results showed the following: (1) On the second day after N application, the contents of soil NO3−-N and NH4+-N in the 0–10 cm soil layer were highest for both the DIO and DIS. On the 28th day after N application, the soil NO3−-N content was highest at the 20–40 cm depth, while the soil NH4+-N content was still highest at the 0–10 cm depth. (2) The aboveground and root biomass in DIO treatment were significantly higher than in DIS. Furthermore, the root biomass at the 0–10 cm depth was significantly greater than at the 10–50 cm depth for both the DIO and DIS treatments. In the DIO treatment, the root biomass at the 10–50 cm depth was significantly higher with the HN and AN treatments compared to MN. However, in the DIS treatment, the root biomass at the 10–50 cm depth did not show significant differences between the MN, HN, and AN. (3) N accumulation in rice was significantly higher for the DIO treatment compared to the DIS treatment. Under the same irrigation treatment, the N accumulation in rice was highest in the AN and lowest in the LN. The PrNTA and PrNTC in DIS were significantly higher than in DIO, while the PoNAA and PoNAC were significantly lower in DIS. (4) The number of panicles, spikelets per panicle, seed-setting rate, 1000-grain weight, and grain yield were significantly lower in DIS. Under the DIS, these parameters were not significantly different among the MN, HN, and AN. In the DIO, the seed-setting rate, 1000-grain weight, and yield were not significantly different between the HN and AN, but were significantly higher than in the MN and LN. (5) NPFP was significantly higher in the DIO compared to the DIS. Among the different N rates, NPFP was highest with the AN treatment and lowest with the LN. In summary, under drip irrigation, there was a mismatch between soil mineral N and the distribution of rice roots, leading to reduced N accumulation and utilization in rice, ultimately impacting yield formation. Increasing N application and soil ammonium nutrition can improve rice yield under drip irrigation. However, optimizing N fertilizer management may not increase rice yield further when irrigation is further limited.

Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by associating with ericoid mycorrhizal and endophytic fungi. However, the benefits of this association are both cultivar- and fungus-dependent. Our objective was to assess the effect of inoculation with three native fungal strains (Oidiodendron maius A, O. maius BP, and Acanthomyces lecanii BC) on plantlet growth, plantlet survival, and nitrogen (N) absorption of the southern highbush blueberry (SHB) cultivars Biloxi and Misty. The fungal strains were inoculated into the peat-based substrate for growing blueberry cultivars, and plantlets produced by micropropagation were transplanted and grown for four months. The three inoculated strains positively affected the survival percentage in at least one of the cultivars tested, whereas O. maius BP positively affected plant biomass, N derived from fertilizer absorption, N content, and plant N recovery (%) in both Biloxi and Misty. Our results show that the O. maius BP strain may prove useful as a bio-inoculant to improve blueberry production during the nursery stage. [ABSTRACT FROM AUTHOR]

A field experiment of drip fertigated nitrogen reduction was set up in a typical Maize planting area in the Xiliao River Basin in 2018 and 2019. Different phased nitrogen reductions were set up under shallow buried drip irrigation during the growth period to explore ways to improve nitrogen use efficiency (NUE) by understanding the Maize regulation of nitrogen absorption and utilization. The recommended nitrogen application in the early stage (Nopt, total nitrogen 240 kg·hm−2) had the highest grain nitrogen uptake and total nitrogen uptake, followed by nitrogen reduction before the maximum canopy mulching (Nde-I, total nitrogen 180 kg·hm−2), nitrogen reduction after the maximum canopy mulching (Nde-II, total nitrogen 180 kg·hm−2) and no nitrogen application (N0). Without nitrogen application, the leaves were thin, green and yellow. The total nitrogen uptake was 38.54~41.31% lower than the recommended nitrogen application in the early stage. When nitrogen fertilizer was reduced in the maximum canopy mulching, grain nitrogen absorption was affected. Grain nitrogen absorption fell by 15.07% to 17.51% when nitrogen was reduced in the maximum canopy mulching compared to the recommended nitrogen application. The harvest index of nitrogen reduction before the maximum canopy coverage was 9.65~11.52% higher than that in the later stage, indicating that the nitrogen absorption between Maize grain, stem, and leaf was better regulated. Maize evapotranspiration water consumption was reduced throughout the growth cycle when nitrogen was reduced at various stages. Nitrogen reduction before maximum canopy mulching boosted water use efficiency (WUE) by 3.44% to 6.12% compared to the recommended nitrogen application in the early stage. The nitrogen fertilizer agronomic efficiency increased by 11.17% to 13.87%. The nitrogen use efficiency rose by 10.99~3.15% (5.24~6.60 percentage points). A total of 25% of nitrogen fertilizer was saved with the yield declining by only about 5%, resulting in increased NUE while maintaining the yield stability. Under shallow buried drip fertigated irrigation, the appropriate reduction in nitrogen fertilizer during the period from Maize sowing to the maximum canopy development ensured the nitrogen supply during tasseling–silking stage and filling stage, which can be used as a regulation method and a way to improve the Maize fertilizer use efficiency.

In the old course of the Yellow River area, most orchards are over-applied with nitrogen (N) fertilizers. To improve N management in this area, a 15N tracing experiment was conducted to investigate the absorption, distribution and loss of spring-topdressing urea in pear orchards from March to August 2019. The 7-year-old Sucui 1 pear was used as the test material, and 277.5 g of ordinary urea and 15 g of 15N-urea N were evenly applied to each plant. The N absorption, distribution and utilization efficiency of different organs from the flowering stage to the post-harvest stage were analyzed, and the residual and loss of N in the soil were also discussed. The N fertilizer utilization rate increased with the advancement of the phenological period. The N fertilizer utilization rate in the full bloom period is 10.39%, which is the fastest growing period, and reached a maximum of 23.62% in the post-harvest stage. In the young fruit stage, the amount of N derived from labeled fertilizer (%Ndff) of the fruit was only 1.02%, and most of the new vegetative organs were above 1%. Residual amount in the 20–40 cm soil layer was significantly higher than that in other soil layers. Direction of N fertilizer is N fertilizer loss>soil residue>tree absorption. N loss in the fruit expansion stage and the harvest stage is higher, which are 3.76 g and 3.74 g, respectively. N utilization rate in this area is low throughout the year. There is nutrient competition between reproductive growth and vegetative growth, which can be effectively alleviated by spring top-dressing. The N loss during fruit expansion and harvesting is serious. Attention should be paid to split fertilizer application and the timely supplementation of an appropriate amount of N fertilizer to improve N use efficiency. [ABSTRACT FROM AUTHOR]

To address the issues related to the excessive use of nitrogen fertilizer and the low transplanting density in rice, the effects of reduced or increased nitrogen density on rice yield and nitrogen use efficiency were investigated, so as to provide a scientific basis for optimizing the production of rice in the cold region of northeast China. A field experiment was conducted during 2019 to 2020 to evaluate the effects of four cultivation management strategies on rice yield, shoot dry matter, nitrogen (N) accumulation and distribution, and N use efficiency at Hongguang farm, Qianguo County, Jilin Province. The strategies were as follows: no N fertilizer and transplanting density of 1.80×105 hole·hm-2 (N0), application of 235 kg·hm-2 N and transplanting density of 1.80×105 hole·hm- 2 (FP), application of 188 kg·hm-2 N and transplanting density of 2.40×105 hole·hm-2 (SNHD1), and application of 188 kg·hm-2 N and transplanting density of 3.00×105 hole· hm-2 (SNHD2). Compared with FP, SNHD1 and SNHD2 treatment led to significant increase in the number of effective panicles and the overall rice yield. In particular, SNHD1 led to an increase in yield by 7.8% on average over two years. Accumulation of dry matter and N in each growth stage of rice including after full heading were promoted by N reduction and transplanting densification. SNHD1 led to better results than SNHD2. Nonetheless, absorption efficiency, agronomic use efficiency, partial productivity, and nitrogen fertilizer use efficiency of N all increased significantly in both cases compared with the FP treatment. For SNHD1, in particular, increases by 0.3, 6.2, 14.4 kg·kg-1, and 16.4 percent points were evaluated, respectively. FP, SNHD1, and SNHD2 all led to a surplus in the apparent N balance in both years, with the lowest value evaluated for SNHD1. A significant positive correlation among dry matter and N accumulation before and after full heading and grain yield was observed. Moreover, the correlation between dry matter and N accumulation after full heading was higher than that before full heading. The use of reasonable N application rate and transplanting density led to an increase in dry matter and N accumulations during the entire growth period of rice, as well as to an increase in the accumulation ratio after full heading, enhanced yield, and N use efficiency. Overall consideration of rice yield, N uptake and N utilization, the use of 188 kg·hm-2 of N fertilizer and a 2.40×105 hole·hm-2 transplanting density represent the optimal cultivation conditions in the cold region of northeast China. [ABSTRACT FROM AUTHOR]

Excessive chemical fertilizer use leads to soil nitrogen leaching. Biogas slurry, which is rich in nitrogen, has been proposed as an organic substitute for chemical fertilizer via drip irrigation. However, the dynamics of nitrogen migration and potential threats to biogas slurry return remain unclear. Using a two-year field experiment and HYDRUS software, this study modeled soil moisture and nitrogen migration under biogas slurry drip irrigation. The validated model accurately simulates water and nitrogen migration, predicting nitrogen leaching dynamics. Compared to chemical fertilizer treatment, differences in soil hydraulic parameters under biogas slurry drip irrigation impact moisture and nitrate nitrogen distribution. Increasing biogas slurry proportion enhances nitrate nitrogen content in the root layer, promoting plant nitrogen absorption while reducing leaching by 49.66%. Optimizing the irrigation system involves high concentration substitution in early growth and low concentration in late growth, mitigating nitrogen leaching, and enhancing plant root absorption. [Display omitted] • HYDRUS simulates water/fertilizer migration under biogas drip irrigation. • Law of biogas slurry topdressing water and fertilizer migration. • Biogas slurry topdressing reduces nitrate leaching, increases nitrogen uptake. • Optimization strategy for biogas slurry topdressing under drip irrigation proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Saline–alkaline stress suppresses rice growth and threatens crop production. Despite substantial research on rice's tolerance to saline–alkaline stress, fewer studies have examined the impact of magnetic water treatments on saline–alkaline-stressed rice plants. We explored the physiological and molecular mechanisms involved in saline–alkaline stress tolerance enhancement via irrigation with magnetized water using Nipponbare. The growth of Nipponbare plants was inhibited by saline–alkaline stress, but this inhibition was alleviated by irrigating the plants with magnetized water, as evidenced by greater plant height, biomass, chlorophyll content, photosynthetic rates, and root system in plants irrigated with magnetized water compared to those irrigated with non-magnetized water. Plants that were irrigated with magnetized water were able to acquire more total nitrogen. In addition, we proved that rice seedlings irrigated with magnetized water had a greater root NO3−-nitrogen concentration and root NH4+-nitrogen concentration than plants irrigated with non-magnetized water. These findings suggest that treatment with magnetized water could increase nitrogen uptake. To test this hypothesis, we analyzed the expression levels of genes involved in nitrogen acquisition. The expression levels of OsNRT1;1, OsNRT1;2, OsNRT2;1, OsAMT1;2, OsAMT2;1, OsAMT2;2, OsAMT2;3, OsAMT3;1, OsAMT3;2, and OsAMT3;3 were higher in plants exposed to magnetized water medium compared to those exposed to non-magnetized water media. We further demonstrated that treatment with magnetized water increases available nitrogen, NO3−-nitrogen content, and NH4+-nitrogen content in soil under saline–alkaline stress. Our results revealed that the increased resistance of rice seedlings to saline–alkaline stress may be attributable to a very effective nitrogen acquisition system enhanced by magnetized water. [ABSTRACT FROM AUTHOR]

Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by associating with ericoid mycorrhizal and endophytic fungi. However, the benefits of this association are both cultivar- and fungus-dependent. Our objective was to assess the effect of inoculation with three native fungal strains (Oidiodendron maius A, O. maius BP, and Acanthomyces lecanii BC) on plantlet growth, plantlet survival, and nitrogen (N) absorption of the southern highbush blueberry (SHB) cultivars Biloxi and Misty. The fungal strains were inoculated into the peat-based substrate for growing blueberry cultivars, and plantlets produced by micropropagation were transplanted and grown for four months. The three inoculated strains positively affected the survival percentage in at least one of the cultivars tested, whereas O. maius BP positively affected plant biomass, N derived from fertilizer absorption, N content, and plant N recovery (%) in both Biloxi and Misty. Our results show that the O. maius BP strain may prove useful as a bio-inoculant to improve blueberry production during the nursery stage.

To better understand the mechanism of nitrogen (N) distribution, absorption, utilization and loss in fertilizer under different tillage practices, a study was conducted to quantitatively explore the fate of fertilizer N in the soil–plant–atmosphere using the 15N labelling technique under the long-term conservation tillage experiment in Northeast China. The test crop used was corn. This study compared the residual amount of 15N fertilizer in soil, the content of 15N fertilizer N in particle organic nitrogen (PON), light fraction organic matter nitrogen (LFOMN) and heavy fraction organic matter N (HFOMN) under different tillage practices. In addition, N uptake, utilization and distribution by corn, the emission of N2O and the gas loss of fertilizer N, and the fertilizer N utilization rate were also taken into account. The results showed that no tillage (NT) had a significantly lower amount of residual 15N fertilizer than a moldboard plow (MP) (p < 0.05). In general, the content under NT at the 0–30 cm soil layer was 7.85% lower than that of MP. NT led to significantly greater PON and LFOMN of soil organic N compared to MP (p < 0.05). 15N from N uptake, fertilizer absorption and utilization under NT were significantly higher than that under MP (p < 0.05), the soil N absorbed by plants under NT or MP was greater than 70%. The distribution of 15N from N fertilizer in each corn part increases in this order: seed > leave > sheath > stem > bract > ear; about 57.91–64.92% of 15N is distributed in the grain. NT resulted in significantly lower average and cumulative N2O emissions than those from MP based on the static closed chamber approach (p < 0.05). The average and cumulative emissions of soil fertilizer 15N-N2O under MP were also significantly greater than that of NT. Among the N2O emissions, 15.3% and 22.98% came from fertilizer N under NT and MP, respectively. On average, 0.1–0.16% of fertilizer N was lost in the form of N2O. There was a significant difference in fertilizer utilization between NT and MP, and NT was 4.23% larger than MP (p < 0.05). These one year findings suggest that NT plays a positive role in improving the N absorption and utilization of fertilizer in a Chinese mollisol and long-term effects need to be further studied. [ABSTRACT FROM AUTHOR]

Nitrate transporters (NRTs) play an important role in nitrate absorption and internal distribution in plant roots and other parts. Experiments were carried out to explore the sequences and expression characteristics of NRT genes, and their correlation with the N uptake in flowering Chinese cabbage. We have isolated three important BcNRTs (BcNRT1.1, BcNRT1.2, and BcNRT2.1) from flowering Chinese cabbage. Spatio-temporal expression analysis found that BcNRT1.1 and BcNRT2.1 were mainly expressed in roots, while BcNRT1.2 was more expressed in roots than in leaves during vegetative growth and was mainly expressed in leaves during reproductive growth. The NO3− uptake rate of the entire growth period was significantly correlated with BcNRT1.1 and BcNRT1.2 expression in roots. In addition, the total N content was increased with the increase in NO3− concentration in flowering Chinese cabbage. The NH4+ uptake was slightly induced by NH4+, but the total N content had no significant difference under the NH4+ concentration of 1–8 mmol/L. We also found that lower concentrations of NH4+ promoted the expression of BcNRT1.1 and BcNRT1.2 while inhibiting the expression of BcNRT2.1 in the roots of flowering Chinese cabbage. The amount of total N uptake in the treatment with 25/75 of NH4+/NO3− was significantly higher than that of the other two treatments (0/100 and 50/50). In the mixture of NH4+ and NO3−, total N uptake was significantly correlated with the BcNRT1.2 expression. We concluded that mixed nutrition with an NH4+/NO3− of 25/75 could significantly increase total nitrogen uptake in flowering Chinese cabbage, in which two members of the NRT1 subfamily (BcNRT1.1 and BcNRT1.2) might play a major regulatory role in it. This study is a beneficial attempt to dig deeper into the NRT genes resources and lays the foundation for the ultimate use of genetic improvement methods to increase the NUE with less nitrogen fertilizer in flowering Chinese cabbage. [ABSTRACT FROM AUTHOR]

Intensive pastoral farming has been linked to adverse environmental effects such as soil degradation and increased fluxes of nitrogen, phosphorus, sediments, and pathogens into waterways, resulting in their degradation. Stand-off pads are engineered structures covered with bedding materials, available for occupation by stock to minimise those adverse effects to soil and water bodies. Wood chips are ideal for bedding due to their low cost, high water holding capacity, and stock preference as resting areas. While they reduce the mobility of both nutrients and pathogens, their effectiveness depends on the type of wood, size of the chips, pH, pad design, and feeding management used. Dissolved organic carbon, present in wood residue, may slow nitrogen mineralisation thereby decreasing loss via leachate. This effect depends on plant tannins and nutrients already stored within the plant tissue. Poplar and willow have high concentrations of tannins in leaves and bark with potential nitrification-inhibiting properties. When grown on-farm, these deep-rooted trees also reduce nitrogen leaching and prevent soil erosion. This review addresses the use of temporary stand-off pads within poplar or willow silvopastoral systems. Harvested trees can provide suitable wood chips for constructing the stand-off pad, while the deep rooting systems of the trees will reduce the moisture content of the pad, preventing waterlogging. A key objective is to discuss the feasibility and establishment of multiple temporary stand-off pads that allow for stock rotation from pad to pad, and subsequent on-site composting of wood-wastes into fertiliser, reducing both nutrient inputs and losses in agricultural systems. The review highlights the potential suitability of poplar and willow tree species for such a system.

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the old course of the Yellow River area, most orchards are over-applied with nitrogen (N) fertilizers. To improve N management in this area, a 15N tracing experiment was conducted to investigate the absorption, distribution and loss of spring-topdressing urea in pear orchards from March to August 2019. The 7-year-old Sucui 1 pear was used as the test material, and 277.5 g of ordinary urea and 15 g of 15N-urea N were evenly applied to each plant. The N absorption, distribution and utilization efficiency of different organs from the flowering stage to the post-harvest stage were analyzed, and the residual and loss of N in the soil were also discussed. The N fertilizer utilization rate increased with the advancement of the phenological period. The N fertilizer utilization rate in the full bloom period is 10.39%, which is the fastest growing period, and reached a maximum of 23.62% in the post-harvest stage. In the young fruit stage, the amount of N derived from labeled fertilizer (%Ndff) of the fruit was only 1.02%, and most of the new vegetative organs were above 1%. Residual amount in the 20–40 cm soil layer was significantly higher than that in other soil layers. Direction of N fertilizer is N fertilizer loss>soil residue>tree absorption. N loss in the fruit expansion stage and the harvest stage is higher, which are 3.76 g and 3.74 g, respectively. N utilization rate in this area is low throughout the year. There is nutrient competition between reproductive growth and vegetative growth, which can be effectively alleviated by spring top-dressing. The N loss during fruit expansion and harvesting is serious. Attention should be paid to split fertilizer application and the timely supplementation of an appropriate amount of N fertilizer to improve N use efficiency.

Saline–alkaline stress suppresses rice growth and threatens crop production. Despite substantial research on rice’s tolerance to saline–alkaline stress, fewer studies have examined the impact of magnetic water treatments on saline–alkaline-stressed rice plants. We explored the physiological and molecular mechanisms involved in saline–alkaline stress tolerance enhancement via irrigation with magnetized water using Nipponbare. The growth of Nipponbare plants was inhibited by saline–alkaline stress, but this inhibition was alleviated by irrigating the plants with magnetized water, as evidenced by greater plant height, biomass, chlorophyll content, photosynthetic rates, and root system in plants irrigated with magnetized water compared to those irrigated with non-magnetized water. Plants that were irrigated with magnetized water were able to acquire more total nitrogen. In addition, we proved that rice seedlings irrigated with magnetized water had a greater root NO3−-nitrogen concentration and root NH4+-nitrogen concentration than plants irrigated with non-magnetized water. These findings suggest that treatment with magnetized water could increase nitrogen uptake. To test this hypothesis, we analyzed the expression levels of genes involved in nitrogen acquisition. The expression levels of OsNRT1;1, OsNRT1;2, OsNRT2;1, OsAMT1;2, OsAMT2;1, OsAMT2;2, OsAMT2;3, OsAMT3;1, OsAMT3;2, and OsAMT3;3 were higher in plants exposed to magnetized water medium compared to those exposed to non-magnetized water media. We further demonstrated that treatment with magnetized water increases available nitrogen, NO3−-nitrogen content, and NH4+-nitrogen content in soil under saline–alkaline stress. Our results revealed that the increased resistance of rice seedlings to saline–alkaline stress may be attributable to a very effective nitrogen acquisition system enhanced by magnetized water.

Feeding-derived amarula cake to growing pigs can overcome a narrow range of ingredients challenges and improve productivity. The objective of the current study was to determine the response in nitrogen (N) balance in slow-growing pigs fed on incremental levels of amarula nut cake (ANC). Thirty clinically healthy male growing Windsnyer (30.7 kg ± 6.57) (mean ± standard deviation) were individually assigned to separate pens in a completely randomized design, with six pigs per dietary treatment. Iso-energetic experimental diets were formulated to contain 0, 50, 100, 150, and 200 g/kg dry matter (DM) of ANC using the summit and dilution technique. Pigs were given 10 days of dietary adaptation and a collection period of 5 consecutive days after 31 days of feeding. Nitrogen intake increased linearly with incremental levels of ANC (P < 0.01). As ANC inclusion increased, the nitrogen (N) absorption, apparent N digestibility, and N retention in pigs increased until it reached a maximum, then started to decrease (P < 0.05). Nitrogen utilization increased at the rate of 0.63 g for each 1 g increase in ANC (P < 0.01). There was a linear decrease (P < 0.01) in total nitrogen excretion through urine and faeces with ANC inclusion. Urinary pH levels decreased quadratically in response to graded levels of ANC (P < 0.01). The relationship between urinary pH and ANC inclusion was Y = 0.0115x2 − 0.3491x + 4.872 (P < 0.01). The nitrogen balance responses were due to ANC inclusion in diets that were balanced for limiting amino acids. It can be concluded that ANC reduces N excretion, potentially minimizing ammonia volatilization, which makes it an alternative protein source for slow-growing pigs. [ABSTRACT FROM AUTHOR]

Sandy soil is typically poor in organic matter. When areas with sandy soil are used for pasture prior to soybean cultivation, the availability of nitrogen (N) for plants is limited even further. Our objective was to evaluate if inoculation combined with N fertilization increases N content in the soil and N supply to soybean plants in post-pasture and post-soybean areas. Four experiments were conducted in degraded post-pasture and post-soybean areas in a sandy soil (Rhodustult), between 2016 and 2018, in Brazil. Treatments used a combination of inoculant (zero, 4, 8 and 12 rates ha−1) and mineral N (0, 25, 50, and 100 kg ha−1) with four replicates. It was using the soybean cultivar TMG 7062 IPRO. The post-soybean area had higher N content in the soil than the post-pasture area; 33, 32, and 21% for total N, microbial biomass nitrogen (MBN), and inorganic nitrogen (IN), respectively. Soybean shoots from the post-soybean area also had greater accumulations of N (86 kg ha−1 of N). Increased N fertilization linearly raised levels of N in the soil (total N, MBN, and IN). In both areas, the effect of inoculation was restricted by the increase of total N in the soil. Inoculation combined with moderate rates of N in soybeans (50 kg ha−1) increased levels of N in the soil and N supply to plants in post-pasture areas. In post-soybean areas, inoculation alone fulfilled the N soybean need. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To better understand the mechanism of nitrogen (N) distribution, absorption, utilization and loss in fertilizer under different tillage practices, a study was conducted to quantitatively explore the fate of fertilizer N in the soil–plant–atmosphere using the 15N labelling technique under the long-term conservation tillage experiment in Northeast China. The test crop used was corn. This study compared the residual amount of 15N fertilizer in soil, the content of 15N fertilizer N in particle organic nitrogen (PON), light fraction organic matter nitrogen (LFOMN) and heavy fraction organic matter N (HFOMN) under different tillage practices. In addition, N uptake, utilization and distribution by corn, the emission of N2O and the gas loss of fertilizer N, and the fertilizer N utilization rate were also taken into account. The results showed that no tillage (NT) had a significantly lower amount of residual 15N fertilizer than a moldboard plow (MP) (p < 0.05). In general, the content under NT at the 0–30 cm soil layer was 7.85% lower than that of MP. NT led to significantly greater PON and LFOMN of soil organic N compared to MP (p < 0.05). 15N from N uptake, fertilizer absorption and utilization under NT were significantly higher than that under MP (p < 0.05), the soil N absorbed by plants under NT or MP was greater than 70%. The distribution of 15N from N fertilizer in each corn part increases in this order: seed > leave > sheath > stem > bract > ear; about 57.91–64.92% of 15N is distributed in the grain. NT resulted in significantly lower average and cumulative N2O emissions than those from MP based on the static closed chamber approach (p < 0.05). The average and cumulative emissions of soil fertilizer 15N-N2O under MP were also significantly greater than that of NT. Among the N2O emissions, 15.3% and 22.98% came from fertilizer N under NT and MP, respectively. On average, 0.1–0.16% of fertilizer N was lost in the form of N2O. There was a significant difference in fertilizer utilization between NT and MP, and NT was 4.23% larger than MP (p < 0.05). These one year findings suggest that NT plays a positive role in improving the N absorption and utilization of fertilizer in a Chinese mollisol and long-term effects need to be further studied.

Nitrate transporters (NRTs) play an important role in nitrate absorption and internal distribution in plant roots and other parts. Experiments were carried out to explore the sequences and expression characteristics of NRT genes, and their correlation with the N uptake in flowering Chinese cabbage. We have isolated three important BcNRTs (BcNRT1.1, BcNRT1.2, and BcNRT2.1) from flowering Chinese cabbage. Spatio-temporal expression analysis found that BcNRT1.1 and BcNRT2.1 were mainly expressed in roots, while BcNRT1.2 was more expressed in roots than in leaves during vegetative growth and was mainly expressed in leaves during reproductive growth. The NO3− uptake rate of the entire growth period was significantly correlated with BcNRT1.1 and BcNRT1.2 expression in roots. In addition, the total N content was increased with the increase in NO3− concentration in flowering Chinese cabbage. The NH4+ uptake was slightly induced by NH4+, but the total N content had no significant difference under the NH4+ concentration of 1–8 mmol/L. We also found that lower concentrations of NH4+ promoted the expression of BcNRT1.1 and BcNRT1.2 while inhibiting the expression of BcNRT2.1 in the roots of flowering Chinese cabbage. The amount of total N uptake in the treatment with 25/75 of NH4+/NO3− was significantly higher than that of the other two treatments (0/100 and 50/50). In the mixture of NH4+ and NO3−, total N uptake was significantly correlated with the BcNRT1.2 expression. We concluded that mixed nutrition with an NH4+/NO3− of 25/75 could significantly increase total nitrogen uptake in flowering Chinese cabbage, in which two members of the NRT1 subfamily (BcNRT1.1 and BcNRT1.2) might play a major regulatory role in it. This study is a beneficial attempt to dig deeper into the NRT genes resources and lays the foundation for the ultimate use of genetic improvement methods to increase the NUE with less nitrogen fertilizer in flowering Chinese cabbage.

Rice alternated with upland crops has become increasingly popular in recent years. To investigate the residual effects of nitrogen from the previous upland crop on rice growth, two cropping systems, garlic-rice and wheat-rice, were studied from 2014 to 2017 under field conditions and from 2016 to 2017 under pot conditions. The results showed that the total nitrogen content in the 0–0.2 m soil was higher for the garlic-rice cropping system than for the wheat-rice cropping system and the 15N isotope abundance of the soil after harvesting garlic was 63% higher than that after harvesting wheat. Residual nitrogen from the preceding crops was one of the main nitrogen sources for rice growth. The contribution of residual nitrogen accounted for 17% to 60% of the total nitrogen accumulation by rice plants during the vegetative stage, which gradually decreased after the rice jointing stage. Most of the residual nitrogen absorbed by rice plants was transported to the reproductive organs for grain growth. Therefore, the growth of vegetative organs, viz., tillers and leaves, was more vigorous under the garlic-rice cropping system than under the wheat-rice cropping system. This led to a significant increase in total nitrogen accumulation in rice plants and an increase in rice yield by 8% to 16%, even under identical management of rice under upland crop–paddy rice systems. Thus, under upland crop–paddy rice systems, high-yield and high-efficiency rice production can be achieved by utilizing residual nitrogen from the preceding crops and decreasing the application of base and tiller nitrogen. [ABSTRACT FROM AUTHOR]

The limited availability of nitrogen (N) is a fundamental challenge for many crop plants. We have hypothesized that the relative crop photosynthetic rate (P) is exponentially constrained by certain plant-specific enzyme activities, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-G3PDH), 3-phosphoglyceric acid (PGA) kinase, and chloroplast fructose-1,6-bisphosphatase (cpFBPase), in Triticum aestivum and Oryza sativa. We conducted a literature search to compile information from previous studies on C3 and C4 crop plants, to examine the photosynthetic rate responses to limited leaf [N] levels. We found that in Zea mays, NADP-malic enzyme (NADP-ME), PEP carboxykinase (PCK), and Rubisco activities were positively correlated with P. A positive correlation was also observed between both phosphoenolpyruvate carboxylase (PEPC) and Rubisco activity with leaf [N] in Sorghum bicolor. Key enzyme activities responded differently to P in C3 and C4 plants, suggesting that other factors, such as leaf [N] and the stage of leaf growth, also limited specific enzyme activities. The relationships followed the best fitting exponential relationships between key enzymes and the P rate in both C3 and C4 plants. It was found that C4 species absorbed less leaf [N] but had higher [N] assimilation rates (Arate) and higher maximum photosynthesis rates (Pmax), i.e., they were able to utilize and invest more [N] to sustain higher carbon gains. All C3 species studied herein had higher [N] storage (Nstore) and higher absorption of [N], when compared with the C4 species. Nstore was the main [N] source used for maintaining photosynthetic capacity and leaf expansion. Of the nine C3 species assessed, rice had the greatest Pmax, thereby absorbing more leaf [N]. Elevated CO2 (eCO2) was also found to reduce the leaf [N] and Pmax in rice but enhanced the leaf [N] and N use efficiency of photosynthesis in maize. We concluded that eCO2 affects [N] allocation, which directly or indirectly affects Pmax. These results highlight the need to further study these physiological and biochemical processes, to better predict how crops will respond to eCO2 concentrations and limited [N].

The limited availability of nitrogen (N) is a fundamental challenge for many crop plants. We have hypothesized that the relative crop photosynthetic rate (P) is exponentially constrained by certain plant-specific enzyme activities, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-G3PDH), 3-phosphoglyceric acid (PGA) kinase, and chloroplast fructose-1,6-bisphosphatase (cpFBPase), in Triticum aestivum and Oryza sativa. We conducted a literature search to compile information from previous studies on C3 and C4 crop plants, to examine the photosynthetic rate responses to limited leaf [N] levels. We found that in Zea may s, NADP-malic enzyme (NADP-ME), PEP carboxykinase (PCK), and Rubisco activities were positively correlated with P. A positive correlation was also observed between both phosphoenolpyruvate carboxylase (PEPC) and Rubisco activity with leaf [N] in Sorghum bicolor. Key enzyme activities responded differently to P in C3 and C4 plants, suggesting that other factors, such as leaf [N] and the stage of leaf growth, also limited specific enzyme activities. The relationships followed the best fitting exponential relationships between key enzymes and the P rate in both C3 and C4 plants. It was found that C4 species absorbed less leaf [N] but had higher [N] assimilation rates (A rate) and higher maximum photosynthesis rates (Pmax), i.e., they were able to utilize and invest more [N] to sustain higher carbon gains. All C3 species studied herein had higher [N] storage (Nstore) and higher absorption of [N], when compared with the C4 species. Nstore was the main [N] source used for maintaining photosynthetic capacity and leaf expansion. Of the nine C3 species assessed, rice had the greatest Pmax , thereby absorbing more leaf [N]. Elevated CO2 (eCO2) was also found to reduce the leaf [N] and Pmax in rice but enhanced the leaf [N] and N use efficiency of photosynthesis in maize. We concluded that eCO2 affects [N] allocation, which directly or indirectly affects Pmax. These results highlight the need to further study these physiological and biochemical processes, to better predict how crops will respond to eCO2 concentrations and limited [N]. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wheat is a staple crop worldwide, but yields may diminish as climate change causes increasingly unpredictable patterns of precipitation and soil nutrient availability. Farmers are thus challenged to maximize planting efficiency to increase yield, while also improving their resource use efficiency. In this study, sowing date and nitrogen uptake and planting density, and aspects of yield are assessed. The results show that proper and appropriate sowing is conducive to the coordination of the three elements of wheat production and can achieve high yield. The yield of wheat with the same fertilization amount increased with the increase of planting density, and the yield of wheat increased first and then decreased. There was a significant difference between different fertilization rates at the same density, and the yield of wheat treated with N2 was the highest. [ABSTRACT FROM AUTHOR]

Ideotype root system architecture is crucial for achieving high yields in maize by enhancing lodging resistance and nitrogen absorption, particularly under high planting densities. However, there is limited research on this topic in maize. The objectives of this study were to reveal the relative importance of different root system traits in root anchorage strength and nitrogen absorption, and to investigate their variations in response to increased plant density. To clarify this, a two-year field experiment was conducted in 2018 and 2019, involving four different lodging resistant maize genotypes and two plant densities. Root system traits including root crown architecture, root morphology per whorl, and root distribution in upper and lower soil layers were fully characterized. Root lodging resistance and nitrogen absorption capacity were quantified through artificial root lodging tests and 15N labeling, respectively, based on measuring root lodging rate and plant nitrogen content. In comparison to lodging susceptible genotypes XY335 and XD20, lodging resistant genotypes LS1 and FM985 exhibited stronger root anchorage strength and lower root lodging risk. These characteristics were primarily attributed to their wider root crown width, larger projected root area, larger root angle, thicker brace roots, and wider distribution of the root system in the upper soil layer. However, LS1 was unfavorable for nitrogen absorption due to the larger root skeleton increased metabolic costs of soil exploration, which led to reduced root elongation, shallower rooting depth, and thus limited nitrogen acquisition from the soil. FM985 demonstrated a comparable nitrogen absorption capacity to XY335 (slightly higher than LS1) mainly because of the larger growth angle of the outermost crown root and greater specific root length of embryonic roots. With increased plant density, LS1and FM985 had larger reductions in root system traits, but maintained a larger root crown architecture than that of XY335 and XD20, leading to a lower lodging risk. XY335 and XD20 exhibited a stronger capacity for nitrogen acquisition at high plant densities, attributed to the increased root surface area, root volume and root dry matter of embryonic roots and root dry matter in the subsoil. Taken together, maintaining an optimized root crown architecture, coupled with an increase in surface area, volume and dry matter of embryonic roots and root dry matter in the subsoil, appears to be a more feasible approach for reducing lodging incidents and enhancing nitrogen absorption at a dense population. [Display omitted] • Larger growth angle of outermost crown root is favorable for both root lodging resistance and nitrogen absorption. • Larger specific root length of embryonic roots is conductive to root lodging resistance and N absorption capacity. • Deep rooting is advantageous for accessing deeper nitrogen resources. • Increasing the surface area, volume and dry matter of embryonic roots able to reduce lodging and reinforce N absorption. [ABSTRACT FROM AUTHOR]

Modern rice cultivation relies heavily upon inorganic nitrogen fertilization. Effective fertilizer management is key to sustainable agricultural development. Field and pot trials were conducted in 2014–2016, including a 15N-labeled urea pot experiment (2014) to investigate mechanism by which optimized nitrogen fertilizer application (OFA) increases nitrogen utilization efficiency (NUE). Results showed that the applied nitrogen recovery efficiencies with OFA were 71.71%, 110.17%, and 51.38% higher than those obtained with traditional nitrogen fertilizer application (TFA) in 2014, 2015, and 2016, respectively. These improvements are attributed mainly to the high recovery efficiency rates derived from spikelet-developing and spikelet-promoting fertilizer applications at the jointing stage and 15–20 d after jointing. Under OFA, the amount of nitrogen fertilizer applied at the early stages was half that used in TFA, which not only promoted the absorption of soil nitrogen, but also reduced nitrogen loss to the environment, as the NUE of basal and tillering fertilizer was only about 22%. Nitrogen applied during the panicle differentiation stage increased the expression of ATM1;1, a NH4+ transporter in roots. This effect significantly improved the uptake of nitrogen derived from fertilizer from jointing to heading stage. Up-regulation of the expression and activity of GS and GOGAT at the panicle differentiation and grain-filling stages promoted nitrogen translocation from vegetative organs to reproductive organs. The uptake of nitrogen derived from fertilizer increased from 22.51% in TFA to 35.58% in OFA. Nevertheless, rice absorbs most of the nitrogen it requires from the soil. The OFA treatment could effectively utilize the environmental compensation effect, promote the absorption and transport of nitrogen, and ultimately lead to improvement in NUE. Future research should aim to understand the soil nitrogen supply capacity in order to apply nitrogenous fertilizer in such a way that it sustains the nitrogen balance.

The effects of two nitrogen (N) concentrations combining with three phosphorus (P) concentrations on Isochrysis zhangjiangensis growth and formation of fatty acid (FA) were investigated in this study. Biomass concentration, mass fraction, and productivity of FA in I. zhangjiangensis were low in N-deprived media. Under both N and P sufficiency conditions, the intake of P and N was 40 times and 4.7 times of the normal algal growth condition, respectively, indicating I. zhangjiangensis had the potential for removing P and N from high concentrated N and P salinity wastewater. This study also showed that P deficiency in N sufficient medium increased the FA content, however, the difference between P limitation and P deprivation was not significant (P > 0.05). In N sufficient and P limitation medium, FA productivity was the highest, with a composition suitable for biofuel, so, this condition was the optimal condition for biodiesel production from I. zhangjiangensis. [ABSTRACT FROM AUTHOR]

Mesoporous silica particles have been prepared with functionalized precursors, used either in situ co-condensation process or as post-synthesis grafting agents, in order to deliver surface functionalisation. Aminopropyl, mercaptopropyl, vinyl and hexyl organosilanes were used as funtionalized precursors, tetraethyl orthosilicate as the base silica precursor material, hexadecyl-trimethylammonium bromide (CTAB) as directing agent and water-ethanol mixture as solvent, with ammonia catalyst. The aim was to explore the effect of various recipes on the structural properties of the composite materials. The samples' microstructures have been evaluated using nitrogen sorption and small angle neutron scattering. Ordered mesoporous structures were obtained, for almost all synthesis conditions, after the solvent-extraction of the template agent. Only in one case, for the materials functionalized by mercaptopropyl groups in co-condensation route, disordered amorphous structure was obtained. All samples functionalized by post-grafting presented well-ordered mesoporous structures. The results have potential use for easy design of sorbent materials for drug loading or pollutant adsorption applications. [ABSTRACT FROM AUTHOR]

Modern rice cultivation relies heavily upon inorganic nitrogen fertilization. Effective fertilizer management is key to sustainable agricultural development. Field and pot trials were conducted in 2014–2016, including a 15N-labeled urea pot experiment (2014) to investigate mechanism by which optimized nitrogen fertilizer application (OFA) increases nitrogen utilization efficiency (NUE). Results showed that the applied nitrogen recovery efficiencies with OFA were 71.71%, 110.17%, and 51.38% higher than those obtained with traditional nitrogen fertilizer application (TFA) in 2014, 2015, and 2016, respectively. These improvements are attributed mainly to the high recovery efficiency rates derived from spikelet-developing and spikelet-promoting fertilizer applications at the jointing stage and 15–20 d after jointing. Under OFA, the amount of nitrogen fertilizer applied at the early stages was half that used in TFA, which not only promoted the absorption of soil nitrogen, but also reduced nitrogen loss to the environment, as the NUE of basal and tillering fertilizer was only about 22%. Nitrogen applied during the panicle differentiation stage increased the expression of ATM1;1 , a NH4+ transporter in roots. This effect significantly improved the uptake of nitrogen derived from fertilizer from jointing to heading stage. Up-regulation of the expression and activity of GS and GOGAT at the panicle differentiation and grain-filling stages promoted nitrogen translocation from vegetative organs to reproductive organs. The uptake of nitrogen derived from fertilizer increased from 22.51% in TFA to 35.58% in OFA. Nevertheless, rice absorbs most of the nitrogen it requires from the soil. The OFA treatment could effectively utilize the environmental compensation effect, promote the absorption and transport of nitrogen, and ultimately lead to improvement in NUE. Future research should aim to understand the soil nitrogen supply capacity in order to apply nitrogenous fertilizer in such a way that it sustains the nitrogen balance. [ABSTRACT FROM AUTHOR]

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【Objective】 In order to provide more theoretical support on application of chemical control technology in cassava cultivation, the effect of IAA on growth and nitrogen (N) absorption of cassava was investigated. 【Method】 The effects of IAA on morphology, dry matter quality, N content and N accumulation and the difference of endogenous IAA content in different parts of cassava (Southern China 205) under low N treatment for 94 days were analyzed by pot experiment. 【Result】 Compared with CK (Low N without IAA), the plant height, leaf area and the dry matters of cassava sprayed with IAA were increased. At the 94 days of planting, the leaf area, total root surface area and total root length of cassava sprayed with IAA increased by 8.26%, 20.48% and 20.67%, respectively. The treatment of sprayed with IAA on leaves induced the increase of the IAA contents in stem tip and leaf and the decrease of the root tip. 【Conclusion】 Under the low nitrogen condition, spraying IAA on the leaves could significantly increase the endogenous IAA content of the stem tip of cassava, maintain the growth advantage of stem tip and the metabolic intensity of leaves, promote the absorption and transport of cassava to nitrogen, and then promote the accumulation of dry matter and accelerate the growth of cassava. [ABSTRACT FROM AUTHOR]

Highlights • Image analysis is suitable for determining the specific surface area of fly ash. • Blaine air permeability test underestimates the specific surface area of fly ash. • Nitrogen absorption test overestimates the specific surface area of fly ash. • Laser diffraction test is affected by the material chemical composition. • Laser diffraction test underestimates the specific surface area of porous fly ash. Abstract The specific surface area (SSA) of fly ash has a significant effect on its pozzolanic reactivity and on the performance of fly ash-blended concrete. Because fly ash contains a considerable amount of irregularly shaped particles and unburned carbon, determination of an accurate SSA is analytically troublesome by conventional methods. Various methods for determining the SSA of fly ash are evaluated and compared in this study, including Blaine air permeability, nitrogen absorption testing, laser diffraction testing and image analysis. The experimental results show that Blaine air permeability and laser diffraction testing tend to underestimate the SSA of fly ash because they involve the assumption of perfectly spherical particle geometry. The SSA determined by nitrogen absorption testing is found to be associated with a significant overestimation induced by unburned carbon. Image analysis coupled with BSE appears to give consistent results and appears to be the most promising method of determining an accurate value for absolute SSA. [ABSTRACT FROM AUTHOR]

In the fabrication of 17-4 PH by laser powder bed fusion (L-PBF) the well-documented occurrence of large amounts of retained austenite can be attributed to an elevated concentration of nitrogen present in the material. While the effects of continuous wave (CW) laser processing on in-situ nitrogen absorption characteristics have been evaluated, power modulated pulsed wave (PW) laser processing effects have not. In this study the effects of PW L-PBF processing of 17-4 PH on nitrogen absorption, phase composition, and mechanical performance are explored using commercially available PW L-PBF equipment and compared to samples produced by CW L-PBF. PW L-PBF samples fabricated in cover gas conditions with varying amounts of nitrogen demonstrated reduced absorption levels compared to those produced by CW L-PBF with no effects on phase composition and minimal effects on mechanical performance.

Globally, nitrogen deposition increment has caused forest structural changes due to imbalanced plant nitrogen metabolism and subsequent carbon assimilation. Here, a 2 consecutive-year experiment was conducted to reveal the effects of canopy addition of nitrogen (CAN) on nitrogen absorption, assimilation, and allocation in leaves of three subtropical forest woody species ( Castanea henryi , Ardisia quinquegona , and Blastus cochinchinensis ). We hypothesized that CAN altered leaf nitrogen absorption, assimilation and partitioning of different plants in different ways in subtropical forest. It shows that CAN increased maximum photosynthetic rate (A max ), photosynthetic nitrogen use efficiency (PNUE), and metabolic protein content of the two understory species A. quinquegona and B. cochinchinensis . By contrary, for the overstory species, C. henryi , A max , PNUE, and metabolic protein content were significantly reduced in response to CAN. We found that changes in leaf nitrogen metabolism were mainly due to the differences in enzyme (e.g. Ribulose-1,5-bisphosphate carboxylase, nitrate reductase, nitrite reductase and glutamine synthetase) activities under CAN treatment. Our results indicated that C. henryi may be more susceptible to CAN treatment, and both A. quinquegona and B. cochinchinensis could better adapt to CAN treatment but in different ways. Our findings may partially explain the ongoing degradation of subtropical forest into a community dominated by small trees and shrubs in recent decades. It is possible that persistent high levels of atmospheric nitrogen deposition will lead to the steady replacement of dominant woody species in this subtropical forest. [ABSTRACT FROM AUTHOR]

Kinetics of nitrogen absorption and desorption by melts of the Fe-C system with surface and volumetric oxidation in a stream of oxygen containing 0.2% of nitrogen with an initial metal temperature of 1350-1600°С, [С] = 0.8-3.8%, oxygen flow 0.24-1.8 liter/(minŊkg), are studied. It is established that there is excess chemical potential of nitrogen in a boundary layer compared with the nitrogen content in a gas stream. [ABSTRACT FROM AUTHOR]

Background and aims: Nitrogen (N) is one of the most important limiting factors influencing plant growth and reproduction in alpine and tundra ecosystems. However, in situ observations of the effects of root traits on N absorption by alpine plant species are still lacking.Methods: We investigated the rates of N uptake and the effect of root characteristics in ten common herbaceous alpine plant species using a 15N isotope tracer technique and the root systems of plants growing in a semi-arid steppe environment on the Tibetan Plateau. Our objective was to determine the root traits (root biomass, volume, surface area, average diameter, length, specific root length and specific root area) that make the largest contribution to the total uptake of N (15N-NO3−, 15N-NH4+ or 15N-glycine) by alpine plant species.Results: Monocotyledonous species had higher absorption rates for 15N-NH4+, 15N-NO3−, 15N-glycine and total 15N than dicotyledonous species (P < 0.05). The root biomass, volume, surface area and average diameter were negatively correlated with the absorption capacity for 15N-NH4+, 15N-NO3− and total 15N across the ten alpine plant species. However, the specific root length and the specific root area had significantly positive effects on the uptake of N.Conclusions: In contrast with traditional views on the uptake of N, the N uptake rate was not improved by a larger root volume or root surface area for these alpine plant species in a high-altitude ecosystem. Root morphological traits had greater impacts on N absorption than traits related to the root system size in alpine herbaceous plants. [ABSTRACT FROM AUTHOR]

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Nitrogen (N) assimilation depends on nitrate reductase activity (NRA). Leaf sampling methods in field experimentation with sugarcane and analytical procedures are essential for the determination of the maximum activity (MA) of the enzyme. Thus, in five tests, it was possible to determine which period of the crop cycle should be used for leaf collection, the most adequate leaf for collection, the ideal number of leaves to be collected, the period of the day in which the enzyme has MA and which analytical procedures can be optimized. The evaluation of NRA in sugarcane should occur between 95 and 100 days after planting (DAP) and can be performed in any green leaf. In field experiments, it is recommended the collection of 15 leaves, which must occur between 12:00 and 12:30 h, with later incubation of the leaf tissues for 430 min, without vacuum application. [ABSTRACT FROM PUBLISHER]

Metal carbonitride powders and coatings are well known as superhard materials which are widely applied in many engineering products. Of this group of materials hafnium carbonitride properties are one of the least known due to difficulties with preparation. In this study, the electric discharge assisted mechanical milling (EDAMM) method involving a nitrogen plasma together with mechanical milling was used to synthetise hafnium carbonitride powders within minutes. It was found that difficulties in conventional manufacturing methods, resulting in the formation of only thin layers instead of bulk materials can be overcome by applying the new technique, and HfC x N y powder could be successfully engineered with controlled amount of nitrogen uptake. In this investigation we studied the effects of AC and DC discharges on nitrogen solubility in HfC powder. Microstructure and phase evolution were determined using XRD and SEM, while the nitrogen content in the grains was evaluated by EDS and bulk nitrogen content by CHN analysis. Maximum solubilities of 3.42 wt% and 2.95 wt%N under DC an AC discharge currents, respectively, were obtained. Reaction paths varied depending on processing conditions with HfC x N y formed under DC discharge processing and mixed products containing HfC, several HfC x N y phases and HfN like phase formed after AC processing. After nitrogenation the most highly nitrided powders were subjected to 1 min additional EDAMM processing using high power discharges to allow the formation of large, sintered particles of sufficient size to perform hardness measurements on. Vickers harnesses of fully sintered large particles after 5 and 10 min of EDAMM were 1808 and 2169HV, respectively. [ABSTRACT FROM AUTHOR]