Improve Nitrogen Utilization Efficiency Research Articles

Epiberberine: a potential rumen microbial urease inhibitor to reduce ammonia release screened by targeting UreG

Rumen microbial urease inhibitors have been proposed for regulating nitrogen emission and improving nitrogen utilization efficiency in ruminant livestock industry. However, studies on plant-derived natural inhibitors of rumen microbial urease are limited. Urease accessory protein UreG, plays a crucial role in facilitating urease maturation, is a new target for design of urease inhibitor. The objective of this study was to select the potential effective inhibitor of rumen microbial urease from major protoberberine alkaloids in Rhizoma Coptidis by targeting UreG. Our results showed that berberine chloride and epiberberine exerted superior inhibition potential than other alkaloids based on GTPase activity study of UreG. Berberine chloride inhibition of UreG was mixed type, while inhibition kinetics type of epiberberine was uncompetitive. Furthermore, epiberberine was found to be more effective than berberine chloride in inhibiting the combination of nickel towards UreG and inducing changes in the second structure of UreG. Molecular modeling provided the rational structural basis for the higher inhibition potential of epiberberine, amino acid residues in G1 motif and G3 motif of UreG formed interactions with D ring of berberine chloride, while interacted with A ring and D ring of epiberberine. We further demonstrated the efficacy of epiberberine in the ruminal microbial fermentation with low ammonia release and urea degradation. In conclusion, our study clearly indicates that epiberberine is a promising candidate as a safe and effective inhibitor of rumen microbial urease and provides an optimal strategy and suitable feed additive for regulating nitrogen excretion in ruminants in the future.Key points• Epiberberine is the most effective inhibitor of rumen urease from Rhizoma Coptidis.• Urease accessory protein UreG is an effective target for design of urease inhibitor.• Epiberberine may be used as natural feed additive to reducing NH3 release in ruminants.

Plant Growth-Promoting Rhizobacteria Are Key to Promoting the Growth and Furanocoumarin Synthesis of Angelica dahurica var. formosana under Low-Nitrogen Conditions.

Microbiomes are the most important members involved in the regulation of soil nitrogen metabolism. Beneficial interactions between plants and microbiomes contribute to improving the nitrogen utilization efficiency. In this study, we investigated the Apiaceae medicinal plant Angelica dahurica var. formosana. We found that under a low-nitrogen treatment, the abundance of carbon metabolites in the rhizosphere secretions of A. dahurica var. formosana significantly increased, thereby promoting the ratio of C to N in rhizosphere and nonrhizosphere soils, increasing carbon sequestration, and shaping the microbial community composition, thus promoting a higher yield and furanocoumarin synthesis. Confirmation through the construction of a synthetic microbial community and feedback experiments indicated that beneficial plant growth-promoting rhizobacteria play a crucial role in improving nitrogen utilization efficiency and selectively regulating the synthesis of target furanocoumarins under low nitrogen conditions. These findings may contribute additional theoretical evidence for understanding the mechanisms of interaction between medicinal plants and rhizosphere microorganisms.

Effects of low-quality forage and starter protein content in starter diet of young calves on growth performance, rumen fermentation, and urinary purine derivatives.

Feeding low-quality forage (LQF) has been evaluated in mature ruminants and results show that it has been improved nitrogen utilization efficiency. The present study evaluated the interaction effect of feeding wheat straw as LQF (0 and 7.5%, DM basis) and starter protein level (20 vs. 24%, DM basis) on growth performance, ruminal fermentation, and microbial protein synthesis in Holstein dairy calves raised under moderate heat stress condition. Forty-eight 3-day old dairy calves (averaging 40.6 kg) were assigned in four experimental treatments as follow; 1) no LQF with 20% CP (NLQF-20CP), 2) no LQF with 24% CP (NLQF-24CP), 3) 7.5% LQF with 20% CP (LQF-20CP) and 4) 7.5% LQF and 24% CP (LQF-24CP). The calves were weaned on d 53 of age but the experiment extended until d 73 of age. Feeding LQF increased starter intake, average daily gain (tendency), ruminal acetate concentration, and improved fecal score of calves. The average daily gains before and after weaning were positively influenced with greater starter protein content. Hence, weaning and final BWs were improved when calves received greater CP content. In addition, greater starter CP content increased total ruminal volatile fatty acid concentration. With respect to the interaction effect between LQF feeding and starter protein content, the lower nitrogen excretion through urine was obtained for LQF-20CP diet among experimental treatments. The results of the current study showed that feeding LQF improved ruminal fermentation pattern and improved growth performance through increased starter intake. In addition, greater starter protein content is advisable during pre-weaning period for calves raised under mild heat stress condition. In conclusion, based on the results found in the current study, it can be suggested that feeding LQF for calves under heat stress condition can improve nitrogen utilization when dietary protein content is low. This can be opportunity to formulate starter diets with greater nitrogen utilization efficiency which is critical for accelerated growth programs at early stages of growth for young calves while calves raised under hot season condition.

Slow-release fertilizer deep placement increased rice yield and reduced the ecological and environmental impact in Southeast China: A life-cycle perspective

An unreasonable application of nitrogen fertilizer leads to increased agricultural greenhouse gas (GHG) emissions and carbon footprint (CF). To solve this issue, slow-release fertilizer and deep placement of nitrogen fertilizer are recommended, and have been proven effective in improving nitrogen utilization efficiency and reducing nitrogen loss. However, the deep placement of fertilizer increases the cost of mechanical fuel and labor, especially in the hilly and mountainous areas of southeast China and the comprehensive effects throughout the life cycle of crop production, including economic benefits, energy flow, and environmental and ecological advantages, resulting from different application strategies for nitrogen fertilizer, are still largely unknown. In this work, a two-year field trial was conducted in Fujian Province, China, from 2021 to 2022. The main objectives of the study were to investigate the yield and GHG emissions resulting from the deep placement of slow-release fertilizer (DSK) and to assess the carbon footprint, energy use efficiency, and net economic and ecological benefits from a life-cycle perspective. The results showed that compared with deep placement of urea (DCK), slow-release fertilizer broadcasting (SK), and the traditional fertilization mode practiced by farmers (CK), the average annual yield of rice under DSK treatment significantly increased by 8.78%, 15.18%, and 23.54% respectively. Compared with CK, the contents of indole-3-acetic acid (IAA) and trans-Zeatin Riboside (t-ZR) under DSK were significantly increased and the dry matter translocation amount, Non-Structural Carbohydrates (NSC) translocation amount and Nitrogen translocation amount were significantly increased by 22.79%, 49.60% and 41.47% respectively. GHG emissions were indirectly reduced by the transport of above-ground substances to grains. The average cumulative CH4 emissions were significantly reduced by 25.34% in the DSK treatment, compared to the CK treatment, primarily as a result of decreased methanogenic gene abundance of mcra gene. Additionally, N2O emissions decreased significantly by 48.97%, compared to the CK, mainly due to a decrease in nirK gene abundance and an increase in nosZ gene abundance in denitrifying bacteria. Furthermore, the carbon footprint of the DSK treatment significantly decreased by 38.74% compared to the CK treatment, while net energy income and net ecological and economic benefits increased by 43.83% and 76.43%, respectively. Comprehensive analysis showed that deep placement of slow-release fertilizer is a sustainable nitrogen fertilizer management mode that helps to balance grain yield, environmental footprint, and economic benefits in southeast China.

Controlled-Release Nitrogen Mixed with Common Nitrogen Fertilizer Can Maintain High Yield of Rapeseed and Improve Nitrogen Utilization Efficiency.

Field experiments were conducted to study the effects of different proportions of controlled-release nitrogen fertilizer mixed with quick-acting nitrogen fertilizer on the yield and nitrogen utilization efficiency of direct-seeding rapeseed. Using a conventional nitrogen application rate of 180 kg ha-1 as a control, a total of 5 types of available nitrogen fertilizers and different proportions of controlled-release nitrogen fertilizers were mixed for fertilizer treatment. The proportion of available nitrogen fertilizer used was 135 kg ha-1, and the addition ratios of the five types of controlled-release nitrogen fertilizers were 0%, 30%, 50%, 70%, and 100%, respectively (i.e., the proportion of controlled-release nitrogen to the total nitrogen application amount). These ratios were represented as N135R0, N135R1, N135R2, N135R3, and N135R4, respectively. The results showed that there was no significant difference in the number of pods per plant, the number of seeds per pod, or the grain yield under the treatment of controlled-release nitrogen fertilizer mixed with quick-acting nitrogen fertilizer for proportions of 30-50% (N135R1~R3) when compared with the control, and a stable yield was achieved. Mixing controlled-release nitrogen fertilizer under reduced nitrogen application can significantly improve the apparent utilization rate of rapeseed nitrogen fertilizer, but it first increases and then decreases with the increase of the controlled-release nitrogen mixing ratio, reaching its highest under the N135R2 treatment. The agronomic utilization efficiency and partial productivity of nitrogen fertilizer first increased and then decreased with the increased proportion of controlled-release nitrogen, and both reached their highest utilization with the N135R2 treatment. The mixed treatment of controlled-release nitrogen did not affect soil urease activity, but significantly increased soil sucrase activity. The mixed treatment of controlled-release nitrogen also increased soil microbial biomass nitrogen and carbon content. Especially in the flowering stage, the soil microbial biomass nitrogen and carbon content was significantly higher under a controlled-release nitrogen mixing ratio of 30-50%. At the same time, it had a similar effect on soil inorganic nitrogen content. Therefore, a controlled-release nitrogen mixing treatment provided sufficient nitrogen for the key growth period of rapeseed. Under the condition of reducing the amount of nitrogen fertilizer by 25% based on the amount of nitrogen fertilizer applied to conventional rapeseed, the application of controlled-release urea mixed with common nitrogen fertilizer mixed at a ratio of 30-50% can be an effective way to maintain grain yield levels and improve nitrogen utilization efficiency.

Novel coating of slow-release nitrogen fertilizers: Characterization and assessment

Developing novel fertilizers that reduce nitrogen release rate receives worldwide interest as a potential means for improving nitrogen utilization efficiency. Making these fertilizers sustainable, this work introduces various attempts to prepare slow-release nitrogen using different materials comprised of agro-industrial wastes such as sugarcane (SC) and beet filter cakes (mud) besides, sulfur, gypsum, and zeolite to cover two nitrogen sources. The prepared coated nitrogen fertilizers were characterized using SEM-EDX. Afterward, an incubation trial was conducted to appraise the produced slow-release fertilizers via mixing with three soils (from Egypt and Sudan) at various incubation periods. The tested coating process enhanced the surface morphology of the fertilizer grains, in which the surface became smoother and all the cracks and cavities were filled with the coating material, which is critical for the physical barrier property and preventing moisture penetration into the core. ANOVA analysis indicated that the released values of N were significantly varied according to the soil type, source of N, and the coating material. Zeolite was effective as a coating material for all nitrogen fertilizers. The coated granules by SC material provided a steady, adequate nitrogen supply throughout the incubation. Beet mud treatments showed the lowest N release among all coating materials, but the liberation of N gradually increased with time elapsed. The beet and sugarcane mud can be considered promising covering materials for developing environmentally friendly and cost-effective slow-release fertilizers. The results showed continuous release of N in the soils from all prepared coated fertilizers til the end of the incubation, enhancing the feasibility for agricultural application.

Integrated BSA-seq and RNA-seq analysis to identify candidate genes associated with nitrogen utilization efficiency (NUtE) in rapeseed (Brassica napus L.)

Rapeseed (Brassica napus L.) is one of the important oil crops, with a high demand for nitrogen (N). It is essential to explore the potential of rapeseed to improve nitrogen utilization efficiency (NUtE). Rapeseed is an allotetraploid crop with a relatively large and complex genome, and there are few studies on the mapping of genes related to NUtE regulation. In this study, we used the combination of bulk segregant analysis sequencing (BSA-Seq) and RNA sequencing (RNA-Seq) to analyze the N-efficient genotype ‘Zheyou 18’ and N-inefficient genotype ‘Sollux’, to identify the genetic regulatory mechanisms. Several candidate genes were screened, such as the high-affinity nitrate transporter gene NRT2.1 (BnaC08g43370D) and the abscisic acid (ABA) signal transduction-related genes (BnaC02g14540D, BnaA03g20760D, and BnaA05g01330D). BnaA05g01330D was annotated as ABA-INDUCIBLE bHLH-TYPE TRANSCRIPTION FACTOR (AIB/bHLH17), which was highly expressed in the root. The results showed that the primary root length of the ataib mutant was significantly longer than that of the wild type under low N conditions. Overexpression of BnaA5.AIB could reduce the NUtE under low N levels in Arabidopsis (Arabidopsis thaliana). Candidate genes identified in this study may be involved in the regulation of NUtE in rapeseed, and new functions of AIB in orchestrating N uptake and utilization have been revealed. It is indicated that BnaA5.AIB may be the key factor that links ABA to N signaling and a negative regulator of NUtE. It will provide a theoretical basis and application prospect for resource conservation, environmental protection, and sustainable agricultural development.

Challenges and opportunities for improving nitrogen utilization efficiency for more sustainable pork production

Pork is one of the most consumed animal-derived protein sources around the world, but less than 45% of dietary nitrogen (N) is converted into edible lean meat. This inefficiency contributes to the 80% of human-induced N emissions that have resulted in exceeding the planetary boundaries for N. Reducing this inefficiency requires using a multifaceted approach. Swine genetic selection programs have improved the rate of lean growth in recent decades, but further improvements may be difficult because of lack of genetic variation within the global pig population. Breeding programs to increase litter size have led to intrauterine growth restriction and an increased proportion of low-birth-weight piglets which do not utilize dietary protein as efficiently as normal birth weight pigs. Intact males have greater lean growth rate and N efficiency than castrates and gilts, and the use of immunocastration technology has been implemented in some countries to capture this benefit while minimizing boar taint in pig meat. Use of other metabolic modifiers including porcine somatotropin and ractopamine, alone or in combination with immunocastration, can further enhance lean growth and dietary N efficiency, but a general lack of consumer acceptance and potential food safety concerns have led to regulatory restrictions in many countries. Because feed production contributes about 70% of N emissions in pig production systems, use of precision feed formulation and feeding practices, selected dietary feed additives, feed processing, and minimizing feed wastage appear to offer the greatest opportunity to reduce N waste and environmental footprint to improve the sustainability of pork production.

Effect of Rural Sewage Irrigation Regime on Water-Nitrogen Utilization and Crop Growth of Paddy Rice in Southern China

Reclaimed water irrigation has become an effective mean to alleviate the contradiction between water availability and its consumption worldwide. In this study, three types of irrigation water sources (rural sewage’s primary treated water R1 and secondary treated water R2, and river water R3) meeting the requirements of water quality for farmland irrigation were selected, and three types of irrigation water levels (low water level W1 of 0–80 mm, medium water level W2 of 0–100 mm, and high water level W3 of 0–150 mm) were adopted to carry out research on the influence mechanismS of different irrigation water sources and water levels on water and nitrogen use and crop growth in paddy field. The water quantity indicators (irrigation times and irrigation volume), soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N), rice yield indicators (thousand-grain weight, the number of grains per spike, and the number of effective spikes), and quality indicators (the amount of protein, amylose, vitamin C, nitrate and nitrite content) of rice were measured. The results showed that, the average irrigation volume under W3 was 2.4 and 1.9 times of that under W1 and W2, respectively. Compared with R3, the peak consumption of rice was lagged behind under R1 and R2, and the nitrogen form in 0–40 cm soil layers under rural sewage irrigation was mainly NH4+-N. The changes of NO3−-N and NH4+-N in the 0–40 cm soil layer showed the trend of declining and then increasing. The water level control only had a significant effect on the change of NO3−-N in the 60–80 cm soil layer. Both irrigation water use efficiency and crop water use efficiency were gradually reduced with the increase of field water level control. The nitrogen utilization efficiency under rural sewage irrigation was significantly higher than that under R3. Compared with the R3, rural sewage irrigation could significantly increase the yield of rice, and as the field water level rose, the effect of yield promotion was more obvious. It was noteworthy that the grain of rice under R1 monitored the low nitrate and nitrite content, but no nitrate and nitrite was discovered under R2 and R3. Therefore, reasonable rural sewage irrigation (R2) and medium water level (W2) were beneficial to improve nitrogen utilization efficiency, crop yield and crop quality promotion.

Periphytic biofilms-mediated microbial interactions and their impact on the nitrogen cycle in rice paddies

Rice paddies are unique waterlogged wetlands artificially constructed for agricultural production. Periphytic biofilms (PBs) at the soil-water interface play an important role in rice paddies characterized by high nutrient input but low utilization efficiency. PBs are composed of microbial aggregates, including a wide variety of microorganisms (algae, bacteria, fungi, protozoa, and metazoa), extracellular polymeric substances and minerals (iron, aluminum, and calcium), which form an integrated food web and energy flux within a relatively stable micro-ecosystem. PBs are crucial to regulate and streamline the nitrogen cycle by neutralizing nitrogen losses and improving rice production since PBs can serve as both a sink by capturing surplus nitrogen and a source by slowly re-releasing this nitrogen for reutilization. Here the ecological advantages of PBs in regulating the nitrogen cycle in rice paddies are illustrated. We summarize the key functional importance of PBs, including the intricate and delicate community structure, microbial interactions among individual phylotypes, a wide diversity of self-produced organics, the active adaptation of PBs to constantly changing environments, and the intricate mechanisms by which PBs regulate the nitrogen cycle. We also identify the future challenges of microbial interspecific cooperation in PBs and their quantitative contributions to agricultural sustainability, optimizing nitrogen utilization and crop yields in rice paddies. ● Periphytic biofilms (PBs) are active microbial aggregates ubiquitously distributed in wetlands. ● PBs form a stable and intricate food web catalyzing biogeochemical cycling of soil nitrogen. ● PBs in rice paddies can improve nitrogen utilization efficiency by plants. ● PBs-mediated microbial interactions facilitate the nitrogen cycle cooperation among microorganisms, while self-produced organics and genomic adaptation are beneficial for the nitrogen cycle regulation by PBs.

Genome-Wide Identification of TaSAUR Gene Family Members in Hexaploid Wheat and Functional Characterization of TaSAUR66-5B in Improving Nitrogen Use Efficiency.

Excessive input of nitrogen fertilizer not only causes a great waste of resources but brings about a series of ecological and environmental problems. Although Small Auxin Up-regulated RNAs (SAURs) participate in diverse biological processes, the function of SAURs in the nitrogen starvation response has not been well-studied. Here, we identified 308 TaSAURs in wheat and divided them into 10 subfamilies. The promoter regions of most TaSAURs contain hormone responsive elements, and their expression levels change under the treatment of different hormones, such as IAA, MeJA, and ABA. Interestingly, overexpression of one of the TaSAUR family members, a nitrogen starvation responsive gene, TaSAUR66-5B, can promote the growth of Arabidopsis and wheat roots. In addition, overexpression of TaSAUR66-5B in Arabidopsis up-regulates the expression levels of auxin biosynthesis related genes, suggesting that overexpression TaSAUR66-5B may promote root growth by increasing the biosynthesis of auxin. Furthermore, overexpression of TaSAUR66-5B in wheat can increase the biomass and grain yields of transgenic plants, as well as the nitrogen concentration and accumulation of both shoots and grains, especially under low nitrogen conditions. This study provides important genomic information of the TaSAUR gene family and lays a foundation for elucidating the functions of TaSAURs in improving nitrogen utilization efficiency in wheat.

Coated, Stabilized Enhanced-Efficiency Nitrogen Fertilizers: Preparation and Effects on Maize Growth and Nitrogen Utilization.

Coated, slow/controlled release, or stabilized enhanced-efficiency nitrogen fertilizers (EENFs) are effective in improving nitrogen utilization efficiency (NUE) and crop yield. Better performance is expected from coated, stabilized EENFs where urease and nitrification inhibitors are treated in coated fertilizers. Firstly, five coated EENFs with different mass proportions of nature rubber (NR) in coating were prepared: CU0, CU1, CU2, CU3, CU4, and CU5 (0, 10, 20, 30, 40, and 50% of NR in coating). The controlled release performance of CU was tested by hydrostatic release test and the microstructure of controlled release urea, so as to screen the optimal addition ratio of NR (ER: NR = 7:3, CU3). Secondly, two coated, stabilized EENFs, CSU1 and CSU2, were prepared with natural rubber-modified epoxy resin (ER: NR = 7:3) as coating material. Seven treatments of different N fertilization were set up: CK (no N fertilization), urea, CU3, SU1, and SU2 (urease and nitrification inhibitors-treated urea fertilizers), CSU1 and CSU2 (urease and nitrification inhibitors-treated natural rubber-modified epoxy resin-coated urea fertilizers). Ammonia volatilization experiment and column leaching experiment showed that compared with conventional urea, NH3 volatilization loss was reduced by 20% and inorganic N leaching loss was reduced by 26% from CSU2, respectively. In the pot experiment, maize grain yield of 162.92 and 206.96 g/pot was achieved by CSU1 and CSU2, respectively, 41 and 79%, respectively, higher than that achieved by conventional urea. SUs treatments were more effective than conventional urea treatment in improving maize grain yield and NUE, but lower than in CSUs. The NUE, nitrogen fertilizer apparent utilization efficiency, partial factor productivity of applied N, and nitrogen utilization efficiency were 46, 30, 46, and 32%, respectively, higher in CSU1 and 58, 62, 58, and 29%, respectively, higher in CSU2 than in the conventional urea treatment. Compared with CSU1, CSU2 had better agronomic effectiveness with a higher NUE. It is recommended that urease and nitrification inhibitors be sandwiched between urea prill and the coating for preparation of novel, environmentally friendly coated, stabilized EENFs with high agronomic effectiveness, high NUE, and low N loss.

Research advance in the roles of water-nitrogen-oxygen factors in mediating rice growth, photosynthesis and nitrogen utilization in paddy soils.

Water and nitrogen are two important factors controlling rice growth and development. Suitable water-nitrogen interaction can alter nitrogen forms and oxygen environmental factors via regulating water content in the rhizosphere of paddy soil, promote the construction of root morphology, improve leaf photosynthesis and the allocation equilibrium of the photosynthetic products between the source and sink organs, and consequently increase rice population quality and grain yield. The microbial regulation mechanisms driven by the environmental factors (e.g. water, nitrogen and oxygen) also play an important role in improving nitrogen utilization efficiency in rice-soil system. Here, we reviewed the research progress in water-nitrogen interaction, and briefly discussed the effects of water, nitrogen form, and dissolved oxygen on rice growth, photosynthesis, carbon and nitrogen metabolism, nitrogen conversion and the underlying microbiological mechanism. We proposed several key directions for future researches: 1) to quantitatively investigate the spatial and temporal variations of dissolved oxygen in rhizosphere and their dominant environmental drivers under different water and nitrogen regimes; 2) to evaluate the responses of root-sourced signal to rhizosphere dissolved oxygen in different rice genotypes, and uncover its intrinsic mechanisms involved in rice growth and development; 3) to investigate the effects of key microbial process driven by the rhizosphere oxygen environment on the soil nitrogen conversion and rice nitrogen utilization.

Application of Bag-Controlled Release Fertilizer Facilitated New Root Formation, Delayed Leaf, and Root Senescence in Peach Trees and Improved Nitrogen Utilization Efficiency.

It is very important to promote root growth and delay root and leaf senescence, to improve nitrogen absorption and utilization efficiency, and to improve the storage nutrition level of the tree, so as to improve the fruit quality and yield of peach. In this experiment, we compared and analyzed the effects of traditional fertilization and bag-controlled release fertilizer (BCRF) on the growth of shoots and roots, senescence of leaves and roots, and fruit yield and quality. Moreover, the impacts of BCRF on ammonia volatilization, nitrogen utilization rate, fine root turnover, and plant storage nutrients were also investigated. Compared with conventional fertilizer use, the application of BCRF significantly promoted the shoot growth of young peach trees. Additionally, BCRF delayed leaf senescence and increased root activity in autumn. This increased the storage nutrients of the peach tree. Compared with traditional fertilizer, ammonia volatilization reduced to 54.36% under BCRF application situation. BCRF also promoted the occurrence of fine roots and decreased the annual turnover rate. A 15N tracer test showed that, compared with traditional fertilizer, BCRF nitrogen utilization efficiency increased by 37.73% in peach trees under BCRF treatment significantly. The results from 3 consecutive years showed that the application of BCRF increased the yield of individual plants by 21.35% on average compared to the yield from plants receiving equal amounts of fertilizer applied by spreading (FSA). Thus, BCRF can promote the occurrence of fine roots and decrease the root annual turnover rate in peach trees, and it also improves the utilization efficiency of fertilizer, reduces ammonia volatilization, delays leaf senescence, and enhances storage nutrition, fruit yield, and fruit quality in peach trees.

Effects of biochar on ammonia volatilization from farmland soil: A review.

Reducing soil ammonia volatilization is one of the key ways to reduce soil nitrogen loss and improve nitrogen utilization efficiency in farmlands. Biochar has unique physico-chemical pro-perties, which can change soil physical and chemical properties, affect soil nitrogen cycle, and affect ammonia volatilization in farmland soil. Firstly, we reviewed the ammonia volatilization process and its influencing factors (climatic condition, soil environment, and fertilization management, etc.) in paddy fields and upland fields. Then, research progress on the impacts of biochar on ammonia volatilization from farmland ecosystem was reviewed. Furthermore, the mechanisms underlying the responses of ammonia volatilization to biochar intervention were discussed from the aspects of physical adsorption, gas-liquid equilibrium, and biochemical progress regulation. The reduction of soil ammonia volatilization is mainly based on the adsorption of soil NH4+ and NH3 by oxygen-containing functional groups on the surface of biochar and the promotion of soil nitrification. How-ever, the increases of soil ammonia volatilization are mainly related to the increases of soil pH, air permeability, activities of microorganisms related with soil organic nitrogen mineralization. Finally, the research direction of reducing soil ammonia volatilization and improving nitrogen utilization efficiency by biochar was prospected.

The maize premature senesence2 encodes for PHYTOCHROME-DEPENDENT LATE-FLOWERING and its expression modulation improves agronomic traits under abiotic stresses.

Among the various abiotic stresses, water and nitrogen are major stress factors that limit crop productivity worldwide. Since leaf nutrients remobilization during leaf senescence might impact response to abiotic stress in crops, we undertook a forward screen of the Mutator‐active approach to identify premature senescence loci in maize. A mutant line isolated from a cross between a Pioneer Brand elite line and a public Mutator‐active material, designated premature senescence2 (pre2), expressed leaf senescence during flower initiation. The Pre2 gene encodes PHYTOCHROME‐DEPENDENT LATE‐FLOWERING (PHL) protein, a nuclear receptor coactivator. The pre2‐1 mutant allele was not a null mutation but produced a functional wild‐type transcript along with multiple mRNA species of varying lengths resulting from the alternate splicing of the Pre2 gene. The PHL accelerates flowering by suppressing the inhibitory effect of phyB on flowering in Arabidopsis (Endo et al., 2013). The ZmPRE2 polypeptide is highly conserved in plant species and has two identifiable motifs namely SPT20 and MED15. The Spt20 domain, which is a part of the SAGA (Spt‐Ada‐Gcn5 acetyltransferase) complex, is involved in histone deacetylation and MED15 proteins have nuclear functions in mediating DNA Pol II transcription. The differential spliced mature transcripts in both the pre2 alleles, as a result of transposon interference, were producing truncated proteins that lacked polyglutamine (Q) tract near the C‐terminus and might be causative of the premature senescence phenotype in maize. Endogenous gene suppression of ZmPre2 by RNAi improves maize agronomic performance under both water stress and suboptimal nitrogen conditions. The homozygous T‐DNA knockout of the pre2 homolog in Arabidopsis (At1G72390; the same insertional allele used by Endo et al., 2013) results in higher biomass, delayed maturity, enhanced tolerance to drought, and improved nitrogen utilization efficiency. The Arabidopsis mutant also showed hypersensitive response to 1 µM ABA (abscisic acid) concentration. These results indicate that the PHL protein plays a direct or indirect role in ABA‐dependent drought and N signaling pathways.

Reducing Ruminal Ammonia Production With Improvement in Feed Utilization Efficiency and Performance of Murrah Buffalo (Bubalus bubalis) Through Dietary Supplementation of Plant-Based Feed Additive Blend.

The study evaluated the potential of blends of eucalyptus oil and aqueous extract of mulethi (root of Glycyrrhiza glabra) to reduce rate of ruminal ammonia production without affecting feed digestion to improve nitrogen utilization efficiency and performance of Murrah buffalo (Bubalus bubalis). Based on preliminary independent studies with graded doses of eucalyptus oil and mulethi root aqueous extract in modulating in vitro rumen fermentation, four blends of feed additive comprising graded doses (5, 10, 15, and 25 μL) of eucalyptus oil and a fixed quantity (15 μL) of aqueous extract of mulethi roots were prepared and examined for their effects on in vitro rumen fermentation and on methane and gas production in 100-mL calibrated glass syringes by standard IVGP protocol. Rumen liquor was collected from four rumen fistulated Murrah buffaloes fed a total mixed ration. Out of four blends, blend-1 comprising 5 μL of eucalyptus oil and 15 μL of aqueous extract (233.6 g/L DW) of mulethi per 40 mL of in vitro medium was found to reduce ammonia production significantly (p < 0.001) without affecting feed digestibility. An equivalent dose of blend-1 (10.5 mL of eucalyptus oil and 7.35 g of mulethi root powder/h/day) fed to four rumen fistulated buffaloes for 24 days resulted in 50% reduction (p < 0.05) in rumen ammonia level with no inhibition in feed fermentation or short-chain fatty acid production. The total bacterial population including Ruminococcus albus, Fibrobacter succinogenes, Butyrivibrio fibrisolvens, and Megasphaera elsdenii as well as anaerobic fungi and methanogenic archaea remained unaffected (p > 0.05). Twelve buffalo calves (avg. BW 137.5 ± 9.2 kg, 8–12 months old) divided into two groups of six each and fed a total mixed ration (concentrate: roughage; 60:40) with or without supplementation of blend-1 for about 3 months demonstrated 14% increase (p < 0.05) in average daily gain in BW with a trend (p < 0.10) in improvement of feed or protein utilization efficiency (1.4 vs. 1.1 g crude protein/g average daily gain; 21.4% increase). Thus, supplementation of eucalyptus oil–mulethi root blend could reduce ruminal ammonia production and improve feed utilization efficiency in ruminants.

Giant milkweed (Calotropis gigantea): A new plant resource to inhibit protozoa and decrease ammoniagenesis of rumen microbiota in vitro without impairing fermentation

This study screened six different species of forest plants and then further evaluated the most promising plant, giant milkweed (Calotropis gigantea), for the potential to improve nitrogen utilization efficiency (NUE) through inhibiting rumen protozoa in vitro. Ground leaves of giant milkweed at 1.6 and 3.2 mg/mL decreased the counts of Entodinium cells by 41.30% and 58.89%, respectively, and damaged their cell surface structure. Dasytricha, Isotricha, Epidinium, Ophryoscolex, and Diplodinium were not affected, while total bacterial and archaeal populations did not decrease. Ammonia nitrogen (NH3-N) concentration decreased by 50.64% and 33.33% at 1.6 g/mL and 3.2 mg/mL, respectively. Volatile fatty acid (VFA) production and methane production remained unaffected, but butyrate production increased. The giant milkweed leaves contained (per gram of dry matter) 3636 μg phenolics including 205.9 μg of 3-hydroxybenzoic acid, 2079 μg flavonoids including 1197.5 μg of quercetin and 91.4 μg of myricetin, and 490 μg alkaloids including 219.8 μg of anthraquinone glycosides. The effective inhibition of Entodinium was accompanied by a decrease in NH3-N concentration, and methane production did not increase except for the dose of 1.6 mg/mL. Giant milkweed may be used as a new feed additive or an alternative to chemicals or antibiotics for sustainable animal husbandry enhancing NUE in ruminants.

Effects of different integration of water and fertilizer modes on the absorption and utilization of nitrogen fertilizer and fruit yield and quality of apple trees

We examined nitrogen use efficiency of 15N-urea of 15-year-old 'Gala' apple trees by broadcast fertilization (T1), nitrogen fertilization with drip irrigation (T2) and nitrogen fertilization with subsurface irrigation (T3), to further improve the water and fertilizer integration technology for apple orchard and to improve nitrogen utilization efficiency. The results showed that leaf area, chlorophyll, and leaf nitrogen content of leaves were significantly higher in T3 treatment than those in T1 and T2 treatments. Soil mineral nitrogen content (20-40 cm) in each period followed the order of T3>T2>T1, while that in 0-20 cm followed an order of T2>T3>T1. The Ndff value at organ level (the contribution rate of the 15N amount absorbed by various organs of the tree to the total nitrogen content of the organ) was the highest in T3 treatment in each period, followed by T2 and T1 treatments. The utilization rate of 15N in the fruit ripening period followed an order of T3>T2>T1. The 15N utilization rate of T3 reached 24.2%, being 1.19 and 1.65 times of T2 and T1, respectively. The 15N distribution rate in the fruits during the fruit maturity stage was the highest in T1 treatment, while that in the storage organs was the highest in T2 treatment and that in the reproduction organs was the highest in T3 treatment. The single fruit weight, yield, soluble solids, hardness, soluble sugar and sugar-acid ratio were the highest in T3 treatment, followed by T2 and T1 treatments. In summary, nitrogen application by percolation irrigation (subsurface application) significantly promoted leaf growth and nitrogen utilization of apple tree, and improved fruit yield and quality.

浅谈稻田种养系统氮素损失及提高系统氮素利用效率的方法

浅谈稻田种养系统氮素损失及提高系统氮素利用效率的方法