Carbon-nitrogen Balance Research Articles

OsSTP1 mediates sucrose allocation to regulate rice responses to different nitrogen supply levels

Improving the nitrogen use efficiency is an effective way to increase the yield of rice, and maintaining carbon-nitrogen balance is essential for the normal growth and development of rice. To investigate the impact of the sucrose transporter protein OsSTP1 on nitrogen absorption in rice, in this study, we constructed transgenic lines overexpressing the sucrose transporter gene OsSTP1 (OsSTP1-OE1, OsSTP1-OE2) and mutant transgenic lines (osstp1-1, osstp1-2) from the wild type TB309. Further, we conducted a hydroponic experiment with four nitrogen supply levels of free nitrogen (FN, 0 mg/L), low nitrogen (LN, 10 mg/L), normal nitrogen (NN, 40 mg/L), and high nitrogen (HN, 80 mg/L) to study the responses of each line to different nitrogen supply levels during the seedling stage. The results showed that compared with the wild type and mutant lines in the LN group, the OsSTP1-overexpressing lines exhibited significantly increased biomass, root length, and plant height, decreased soluble sugar content in the leaves, and increased soluble sugar content in the roots. The results indicate that the soluble sugars produced by leaf photosynthesis are transported to the roots through the phloem to promote root growth and nitrogen uptake, thus increasing the aboveground biomass. This study has identified that OsSTP1 can affect the long-distance transport of carbohydrates from source to sink to promote root growth, ultimately influencing rice's absorption and accumulation of nitrogen, improving nitrogen use efficiency and providing reference for reducing nitrogen fertilizer application.

Melatonin mitigates root growth inhibition and carbon-nitrogen metabolism imbalance in apple rootstock M9T337 under high nitrogen stress.

Nitrogen (N) is an essential element for plant growth, development, and metabolism. In apple production, the excessive use of N fertilizer may cause high N stress. Whether high N stress can be alleviated by regulating melatonin supply is unclear. The effects of melatonin on root morphology, antioxidant enzyme activity and 13C and 15N accumulation in apple rootstock M9T337 treated with high N were studied by soil culture. The results showed that correctly raising the melatonin supply level is helpful to root development of M9T337 rootstock under severe N stress. Compared with HN treatment, HN+MT treatment increased root and leaf growth by 11.38%, and 28.01%, respectively. Under high N conditions, appropriately increasing melatonin level can activate antioxidant enzyme activity, reduce lipid peroxidation in roots, protect root structural integrity, promote the transport of sorbitol and sucrose to roots, and promote further degradation and utilization of sorbitol and sucrose in roots, which is conducive to the accumulation of photosynthetic products, thereby reducing the inhibitory effect of high N treatment on root growth. Based on the above research results, we found that under high N stress, melatonin significantly promotes nitrate absorption, enhances N metabolism enzyme activity, and upregulates related gene expression, and regulate N uptake and utilization in the M9T337 rootstock. These results presented a fresh notion for improving N application and preserving carbon-nitrogen balance.

Insights into CO2 and N2O emissions driven by applying biochar and nitrogen fertilizers in upland soil

Biochar and soil carbon sequestration hold promise in mitigating global warming by storing carbon in the soil. However, the interaction between biochar properties, soil carbon-nitrogen cycling, and nitrogen fertilizer application's impact on soil carbon-nitrogen balance remained unclear. Herein, we conducted batch experiments to study the effects and mechanisms of rice straw biochar application (produced at 300, 500, and 700 °C) on net greenhouse gas emissions (CO2, N2O, CH4) in upland soils under different forms of nitrogen fertilizers. The findings revealed that (NH4)2SO4 and urea significantly elevated soil carbon dioxide equivalent emissions, ranging from 28 to 61.7 kg CO2e/ha and 8.2 to 37.7 kg CO2e/ha, respectively. Conversely, KNO3 reduced soil CO2e emissions, ranging from 2.2 to 13.6 kg CO2e/ha. However, none of these three nitrogen forms exhibited a significant effect on CH4 emissions. The pyrolysis temperature of biochar was found negatively correlated with soil CO2 and N2O emissions. The alkaline substances presented in biochar pyrolyzed at 500–700 °C raised soil pH, increased the ratio of Gram-negative to Gram-positive bacteria, and enhanced the relative abundance of Sphingomonadaceae. Moreover, the co-application of KNO3 based nitrogen fertilizer and biochar increased the total carbon/inorganic nitrogen ratio and reduces the relative abundance of Nitrospirae. This series of reactions led to a significant increase in soil DOC content, meanwhile reduced soil CO2 emissions, and inhibited the nitrification process and decreased the emission of soil N2O. This study provided a scientific basis for the rational application of biochar in soil.

Regulating Effect of Exogenous α-Ketoglutarate on Ammonium Assimilation in Poplar.

Extensive industrial activities and anthropogenic agricultural practices have led to substantial ammonia release to the environment. Although croplands can act as ammonia sinks, reduced crop production under high concentrations of ammonium has been documented. Alpha-ketoglutarate (AKG) is a critical carbon source, displaying pleiotropic physiological functions. The objective of the present study is to disclose the potential of AKG to enhance ammonium assimilation in poplars. It showed that AKG application substantially boosted the height, biomass, and photosynthesis activity of poplars exposed to excessive ammonium. AKG also enhanced the activities of key enzymes involved in nitrogen assimilation: glutamine synthetase (GS) and glutamate synthase (GOGAT), elevating the content of amino acids, sucrose, and the tricarboxylic acid cycle (TCA) metabolites. Furthermore, AKG positively modulated key genes tied to glucose metabolism and ATP synthesis, while suppressing ATP-depleting genes. Correspondingly, both H+-ATPase activity and ATP content increased. These findings demonstrate that exogenously applying AKG improves poplar growth under a high level of ammonium treatment. AKG might function through sufficient carbon investment, which enhances the carbon-nitrogen balance and energy stability in poplars, promoting ammonium assimilation at high doses of ammonium. Our study provides novel insight into AKG's role in improving poplar growth in response to excess ammonia exposure.

Weakened relationship between tree growth and nitrogen availability due to global CO2 increase and warming in the Taibai Mountain timberline, central China

Abstract Climate warming, rising atmospheric CO2 concentration (Ca), and nitrogen (N) availability are exerting profound impacts on global forest ecosystems, particularly in high-altitude mountains. This study investigated the tree-growth dynamics of timberline Larix chinensis in the Taibai Mountain, central China, and explored its ecophysiological responses to environmental stresses by combining tree growth and stable isotopes. The results showed that the growth rate of L. chinensis has significantly increased since the 1960s, and that tree growth in this timberline was particularly sensitive to temperature in spring. Moreover, the continuously rising intrinsic water-use efficiency (iWUE), linked to higher Ca and warmer environment, promoted the growth of L. chinensis. Before the 1960s, tree-ring δ15N gradually increased, then shifted to an insignificant decline with the acceleration of tree growth, and broke the preexisting carbon–nitrogen balance. Meanwhile, climate warming and increased iWUE have replaced N as the principal drivers of tree growth since the 1960s. It is believed that L. chinensis may gradually suffer a decline in N availability as it continues to grow rapidly. The insightful understanding of the biochemical mechanisms of plant responses to growth-related environmental conditions will improve our ability to predict the evolution of high-elevation mountain ecosystems in the future.

Comparing the Grain Yields and Other Properties of Old and New Wheat Cultivars

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems’ C dynamics.

CO2 enhances low-nitrogen adaption by promoting amino acid metabolism in Brassica napus

Increasing concentrations of atmospheric CO2 are driving climate change and negatively impacting the carbon-nitrogen (C/N) balance in crops, which in turn alters fertilizer use efficiency. In this study, Brassica napus was cultivated under different CO2 and NO3−-N concentrations to study the impact of C/N ratio on plant growth. Elevated CO2 enhanced biomass and nitrogen assimilation efficiency under low NO3−-N conditions, indicating an adaptation by Brassica napus. Transcriptome and metabolome analyses revealed that elevated CO2 promoted amino acid catabolism under low NO3−-N conditions. This study provides new insights into how Brassica napus adapts to environmental change.

Divergence of functions and expression patterns of soybean bZIP transcription factors.

Soybean (Glycine max) is a major protein and oil crop. Soybean basic region/leucine zipper (bZIP) transcription factors are involved in many regulatory pathways, including yield, stress responses, environmental signaling, and carbon-nitrogen balance. Here, we discuss the members of the soybean bZIP family and their classification: 161 members have been identified and clustered into 13 groups. Our review of the transcriptional regulation and functions of soybean bZIP members provides important information for future study of bZIP transcription factors and genetic resources for soybean breeding.

Development of a Mobile Open-Circuit Respiration Head Hood System for Measuring Gas Exchange in Camelids in the Andean Plateau.

Peru has the largest inventory of alpacas worldwide. Despite their importance as a source of net income for rural communities living at the Andean Plateau, data on energy requirements and methane (CH4) emissions for alpacas are particularly lacking. In 2019, the International Panel on Climate Change (IPCC; 2006, and Refinement 2019) outlined methods for estimating CH4 emissions from enteric fermentation and no methane (CH4) conversion factors were reported for camelids. IPCC has since updated its guidelines for estimating CH4 emissions from the enteric fermentation of livestock at a national scale. For greenhouse gas (GHG) inventory purposes, conversion factors were developed for ruminants but not for domestic South American camelids (SAC), with this category including alpacas. A mobile open-circuit respirometry system (head hood) for the rapid determination of CH4 and CO2 production, O2 consumption, and thereafter, heat production (HP) for camelids was built and validated. In addition, an experimental test with eight alpacas was conducted for validation purposes. The average HP measured by indirect calorimetry (respiratory quotient (RQ) method) was close to the average HP determined from the carbon-nitrogen balance (CN method); 402 kJ/kg BW0.75 and 398 kJ/kg BW0.75, respectively. Fasting HP was determined by the RQ method and 250 kJ/kg BW0.75 was obtained. The metabolizable energy requirement for maintenance (MEm) was calculated to be 323 kJ/kg BW0.75 with an efficiency of energy utilization of 77%. When intake was adjusted to zero energy retention by linear regression, the MEm requirement increased to 369 kJ/kg BW0.75 and the efficiency decreased up to 68%. The CH4 conversion factor (Ym) was 5.5% on average. Further research is required to gain a better understanding of the energy requirements and CH4 emissions of alpacas in conditions of the Andean Plateau and to quantify them with greater accuracy.

Rice circadian clock regulator Nhd1 controls the expression of the sucrose transporter gene OsSUT1 and impacts carbon-nitrogen balance.

Interdependent metabolic and transport processes of carbon (C) and nitrogen (N) regulate plant growth and development, while the regulatory pathways remain poorly defined. We previously reported that rice circadian clock N-mediated heading date-1 (Nhd1) regulates growth duration-dependent N use efficiency. Here, we report that knockout of Nhd1 in rice reduced the rate of photosynthesis and the sucrose ratio of sheaths to blades, but increased the total C to N ratio and free amino acids. Leaf RNA-seq analysis indicated that mutation of Nhd1 dramatically altered expression of the genes linked to starch and sucrose metabolism, circadian rhythm, and amino acid metabolic pathways. We identified that Nhd1 can directly activate the transcriptional expression of sucrose transporter-1 (OsSUT1). Knockout of Nhd1 suppressed OsSUT1 expression, and both nhd1 and ossut1 mutants showed similar shorter height, and lower shoot biomass and sucrose concentration in comparison with the wild type, while overexpression of OsSUT1 can restore the defective sucrose transport and partially ameliorate the reduced growth of nhd1 mutants. The Nhd1-binding site of the OsSUT1 promoter is conserved in all known rice genomes. The positively related variation of Nhd1 and OsSUT1 expression among randomly selected indica and japonica varieties suggests a common regulatory module of Nhd1-OsSUT1-mediated C and N balance in rice.

Genome-wide identification of glutamate synthase gene family and expression patterns analysis in response to carbon and nitrogen treatment in Populus

Glutamate synthase (GOGAT) is a key enzyme in glutamine synthetase (GS)/GOGAT cycle and at the hub of carbon and nitrogen metabolism, catalyzing the formation of glutamate from α-oxoglutarate and glutamine. In this study, members of GOGAT family in Populus trichocarpa were identified and analyzed by bioinformatics. The four PtGOGATs were divided into two subgroups: subgroup A (Fd-GOGAT1 and Fd-GOGAT2) and subgroup B (NADH-GOGAT1 and NADH-GOGAT2). Many important elements have been identified in the promoters of different PtGOGATs, including hormone- and light-responsive elements. Meanwhile, the transcript levels of PxGOGATs were affected by light and diurnal cycle. Quantitative real-time PCR showed PxFd-GOGATs and PxNADH-GOGATs were mainly expressed in leaves and roots in Populus × xiaohei T. S. Hwang et Liang, respectively. Under elevated CO2, PxGOGATs were suppressed in all tissues except the stem. And PxFd-GOGATs and PxNADH-GOGATs were strongly induced by nitrogen in leaves and roots, respectively. In addition, PxGOGATs were stimulated significantly in roots in response to NH4+and glutamine directly. Our results provide new insights about GOGATs in poplar and their expression patterns under exogenous substances, to lay molecular basis for studying gene function and provide a reference for exploring putative roles of GOGATs in carbon–nitrogen balance.

Light: a crucial factor for rhizobium-induced root nodulation.

Wang et al. recently showed that, in soybean (Glycine max), root nodule formation is induced by a light-triggered signal that moves from the upper part of the plant to the roots. This novel signaling process opens a new area of research aimed to optimize the carbon-nitrogen balance in plant-rhizobium symbiosis.

Аэробная твердофазная ферментация отходов птицефабрик как элемент функционирования устойчивой продовольственной системы

Within the framework of the study, the possibility of accelerated processing poultry waste and packaging material (cellulose) was studied, the operating parameters of technological processes were determined, and the safety indicators for the products obtained were substantiated. The physicochemical composition of the poultry manure was studied: the mass of dry fraction 26.98 ± 0.30%; pH 7.4 ±0.30; organic carbon content 38.0 ± 0.80%; mass fraction of total nitrogen 2.37 ± 0.24%; ammonium nitrogen 0.87 ± 0.10%, total phosphorus 1.31 ± 0.13%, and total potassium 0.56 ± 0.06%; their discrepancy with the recommended values of the basic parameters for the successful biothermal processes was established. The study of the indicators for microbiological and parasitic purity established the excess of the indices of coliforms (1000) and enterococcus (1000) in the original material, as well as the presence of Proteus mirabilis. Salmonella, staphylococcus, enteropathogenic types of E. coli, larvae and pupae of synanthropic flies, eggs and larvae of helminths, intestinal pathogenic protozoa cysts were not found. To equalize the physico-chemical composition of the fermented material, crushed corrugated cardboard was added in the ratio (4.5:1). The resulting mixture corresponds to a humidity of 64 ± 0.36%, a pH of 7.2 ± 0.25, a carbon-nitrogen balance of 21:1, and a density of 700 ± 0.70 kg/m3. As a result of experimental studies, a steady course of mesophilic biothermic processes was recorded: 34 ± 3°C, the maximum temperature of 36 ± 1°C was reached on the 5th day of fermentation. After 7 days, the experimental substrate was unloaded. A decrease in the coliforms index to acceptable limits (1–9) and a tenfold decrease in the enterococcus index (100) were found, however, exceeding this indicator and the presence of Proteus mirabilis does not allow us to assert the safety of the obtained substrate for use as an organic fertilizer.

Integration of physiological and metabolomic profiles to elucidate the regulatory mechanisms underlying the stimulatory effect of melatonin on astaxanthin and lipids coproduction in Haematococcus pluvialis under inductive stress conditions

The effect of melatonin (MT) on the coproduction of astaxanthin and lipids was studied in Haematococcus pluvialis under inductive stress conditions. The contents of astaxanthin and lipids were enhanced by 1.78- and 1.3-fold, respectively. MT treatment upregulated the transcription levels of carotenogenic, lipogenic and antioxidant system-related genes and decreased the levels of abiotic stress-induced reactive oxidative species (ROS). Further metabolomic analysis suggested that the intermediates in glycolysis and TCA cycle facilitate the accumulation of astaxanthin and lipids in algae treated with MT. Meanwhile, MT treatment upregulated the metabolite levels of the γ-aminobutyric acid (GABA) shunt, which might regulate the carbon-nitrogen balance and the antioxidant system. After MT treatment, exogenous linoleic acid, succinate, and GABA further increased the astaxanthin content. This study may help to elucidate the specific responses to MT induction in H. pluvialis and to identify novel biomarkers that may be employed to further promote astaxanthin and lipids coproduction.

Responses of GABA shunt coupled with carbon and nitrogen metabolism in poplar under NaCl and CdCl2 stresses.

The γ-aminobutyric acid (GABA) shunt is closely associated with plant tolerance; however, little is known about its mechanism. This study aimed to decipher the responses of the GABA shunt and related carbon-nitrogen metabolism in poplar seedlings (Populus alba×Populus glandulosa) treated with different NaCl and CdCl2 concentrations for 30h. The results showed that the activities of glutamate decarboxylase (GAD) and GABA-transaminase (GABA-T) were activated, as well as α-ketoglutarate dehydrogenase (α-KGDH) and succinate dehydrogenase (SDH) activities were enhanced by NaCl and CdCl2 stresses, except for SDH under CdCl2 stress. Meanwhile, the expression levels of GADs, GABA-Ts SDHs, succinyl-CoA ligases (SCSs), and succinic acid aldehyde dehydrogenases (SSADHs) were also increased. Notably, significant increases in the key components of GABA shunt, Glu and GABA, were observed under both stresses. Soluble sugars and free amino acids were enhanced, whereas citrate, malate and succinate were almost inhibited by both NaCl and CdCl2 stresses except that citrate was not changed or just increased by 50-mM NaCl stress. Thus, these results suggested that the carbon-nitrogen balance could be altered by activating the GABA shunt when main TCA-cycle intermediates were inhibited under NaCl and CdCl2 stresses. This study can enhance the understanding about the functions of the GABA shunt in woody plants under abiotic stresses and may be applied to the genetic improvement of trees for phytoremediation.

TOR inhibition interrupts the metabolic homeostasis by shifting the carbon–nitrogen balance in Chlamydomonas reinhardtii

ABSTRACTThe allocation of nutrient resources to growth and metabolism is an essential function for controlling biomass accumulation in photoautotrophic organisms. One essential protein complex involved in this process is the target of rapamycin (TOR) kinase. It has been shown that the inhibition of TOR leads to a considerable upsurge in the amino acid levels. This molecular phenotype relies mainly on the availability of light, carbon (C) and nitrogen (N). To validate the time-resolved response of C and N metabolites, we used a targeted gas chromatography mass spectrometery (GC-MS)-based metabolomic approach, where we examined the response of Chlamydomonas reinhardtii upon TOR inhibition under C-limited condition, namely extended darkness. Contrary to C-supplemented conditions, the rapid increase in the amino acid levels is suppressed almost completely 4 h after TOR inhibition, confirming that C supply is essential to raise the amino acid levels mediated by their de novo synthesis. An exception to this observation was the levels of aspartate, which is presumably synthesized via the anaplerotic pathway. In agreement with previous reports, TOR repression, under these C-limited conditions, leads to a significant reduction in the C/N ratio, corroborating with the crucial role of the pathway in maintaining the metabolic balance of the cells and consequently propelling growth.

Aggregation of Nontuberculous Mycobacteria Is Regulated by Carbon-Nitrogen Balance.

Nontuberculous mycobacteria (NTM) are emerging opportunistic pathogens that colonize household water systems and cause chronic lung infections in susceptible patients. The ability of NTM to form surface-attached biofilms in the nonhost environment and corded aggregates in vivo is important to their ability to persist in both contexts. Underlying the development of these multicellular structures is the capacity of mycobacterial cells to adhere to one another. Unlike most other bacteria, NTM spontaneously and constitutively aggregate in vitro, hindering our ability to understand the transition between planktonic and aggregated cells. While culturing a model NTM, Mycobacterium smegmatis, in rich medium, we fortuitously discovered that planktonic cells accumulate after ∼3 days of growth. By providing selective pressure for bacteria that disperse earlier, we isolated a strain with two mutations in the oligopeptide permease operon (opp). A mutant lacking the opp operon (Δopp) disperses earlier than wild type (WT) due to a defect in nutrient uptake. Experiments with WT M. smegmatis revealed that growth as aggregates is favored when carbon is replete, but under conditions of low available carbon relative to available nitrogen, M. smegmatis grows as planktonic cells. By adjusting carbon and nitrogen sources in defined medium, we tuned the cellular C/N ratio such that M. smegmatis grows either as aggregates or as planktonic cells. C/N-mediated aggregation regulation is widespread among NTM with the possible exception of rough-colony Mycobacterium abscessus isolates. Altogether, we show that NTM aggregation is a controlled process that is governed by the relative availability of carbon and nitrogen for metabolism.IMPORTANCE Free-living bacteria can assemble into multicellular structures called biofilms. Biofilms help bacteria tolerate multiple stresses, including antibiotics and the host immune system. Nontuberculous mycobacteria are a group of emerging opportunistic pathogens that utilize biofilms to adhere to household plumbing and showerheads and to avoid phagocytosis by host immune cells. Typically, bacteria regulate biofilm formation by controlling expression of adhesive structures to attach to surfaces and other bacterial cells. Mycobacteria harbor a unique cell wall built chiefly of long-chain mycolic acids that confers hydrophobicity and has been thought to cause constitutive aggregation in liquid media. Here we show that aggregation is instead a regulated process dictated by the balance of available carbon and nitrogen. Understanding that mycobacteria utilize metabolic cues to regulate the transition between planktonic and aggregated cells reveals an inroad to controlling biofilm formation through targeted therapeutics.

An Open-Circuit Indirect Calorimetry Head Hood System for Measuring Methane Emission and Energy Metabolism in Small Ruminants.

Simple SummaryAn open-circuit indirect calorimetry system for small ruminants was updated. Calibration factors for CH4, CO2 and O2 close to 1 confirmed the absence of leaks in the indirect calorimetry system and the accurate performance of this device. An experimental test quantified the gas exchange and the repeatability for CH4 and heat production measurements, which were 79% and 61%, respectively. The heat production obtained by indirect calorimetry was close to the heat production obtained by carbon and nitrogen balance. Discrepancies between the two methods averaged 1.92% when expressed as a percentage of the intake of metabolizable energy, a rather satisfactory value considering the substantial amount of technical and analytical work involved. The close agreement found between them can be considered as an indicative of the absence of systematic error. When diets with different forages were compared, the daily CH4 production was 1.54 and 1.25 L/h for diets-based in alfalfa hay and alfalfa silage, respectively.Methane (CH4) is a natural by-product of microbial fermentation in the rumen and is a powerful greenhouse gas. An open-circuit indirect calorimetry system for continuous determination of CH4 and CO2 production and O2 consumption and, thereafter, heat production (HP) calculation for small ruminants was described and validated. The system consisted of a computerized control, data acquisition and recording system for gases and air flux. The average value ± standard deviation for the calibration factors in the system were 1.005 ± 0.0007 (n = 6), 1.013 ± 0.0012 (n = 6) and 0.988 ± 0.0035 (n = 6) for O2, CO2 and CH4, respectively. Calibration factors close to 1 confirmed the absence of leaks in the indirect calorimetry system. In addition, an experimental test with 8 goats at mid lactation was conducted to validate the system. The repeatability for CH4 and heat production measured with the open-circuit indirect calorimetry system was 79% and 61%, respectively. Daily average HP measured by indirect calorimetry (Respiration Quotient method) was close to the average HP determined from Carbon-Nitrogen balance (CN method), accounting for 685 and 667 kJ per kg metabolic body weight, respectively. Therefore, discrepancies averaged 1.92%, a rather satisfactory value considering the substantial amount of technical and analytical work involved. The close agreement found between both methods can be considered as being indicative of the absence of systematic error. Two diets with different forage were tested: 40% was either alfalfa hay (HAY) or alfalfa silage (SIL), and the proportion of concentrate was the same in both groups (60%). The experimental trial shown that HP and CH4 were higher in HAY than SIL diet (differences between treatments of 28 kJ of HP per kg of metabolic body weight and 7.1 L CH4/day were found). The data acquisition and recording device developed improved the accuracy of the indirect calorimetry system by reducing the work involved in managing output data and refining the functionality for measuring gas exchange and energy metabolism in small ruminants.

Nitrogen deficiency induced a decrease in grain yield related to photosynthetic characteristics, carbon–nitrogen balance and nitrogen use efficiency in proso millet (Panicum miliaceum L.)

ABSTRACTField experiments involving proso millet (Panicum miliaceum L.) cultivar under four nitrogen (N) levels (N0, N60, N105 and N150) were conducted in 2015 and 2016 to explore the decrease in grain yield under N deficiency related to the changes in leaf photosynthetic characteristics, carbon (C)–N balance and N use efficiency. Results showed that N deficiency decreased the net photosynthesis rate, stomatal conductance, transpiration rate and chlorophyll content and increased the intercellular CO2 concentration of proso millet flag leaves from flowering to maturity. N deficiency negatively regulated the C–N balance and increased the C/N ratio by reducing the total N, soluble protein and soluble sugar contents, resulting in high starch content. N uptake and utilisation were significantly reduced because of less available N. Significantly positive correlations were observed between the grain yield and photosynthetic characteristics or N use efficiency, whereas a negative correlation was found between the grain yield and the C/N ratio. The yields generated by N0, N60 and N105 were lower than that of N150 in both years. The N fertiliser regression formulae developed in the study would provide useful information about the N fertiliser rate of proso millet.

氮素水平对茶树叶片氮代谢关键酶活性及非结构性碳水化合物的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 氮素水平对茶树叶片氮代谢关键酶活性及非结构性碳水化合物的影响 DOI: 10.5846/stxb201810112203 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 湖南农业科技创新资金项目（2017JC17）；2018年度湖南省重点研发计划项目（2018NK2032）；湖南省自然科学基金（2017JJ3167） Effects of nitrogen levels on key enzyme activities and non-structural carbohydrates in nitrogen metabolism in tea leaves Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以福鼎大白茶（FD）、保靖黄金茶1号（HJ1）、白毫早（BHZ）为材料，设置不施氮N0（0 g）、低氮N1（11 g）、中氮N2（22 g）和高氮N3（33 g）4个氮素水平的盆栽实验，研究了铵态氮对3个品种茶树的根系活力、氮代谢关键酶及非结构性碳水化合物（NSC）的影响。结果表明：随着施氮水平的提高，N2、N3处理的茶树根系活力较对照N0显著增加（P<0.05），但二者间无显著差异；叶片谷氨酰胺合成酶（GS）、谷氨酸合成酶（GOGAT）活性总体呈上升趋势；与对照比较，茶树叶片全氮和可溶性蛋白含量增加，其中HJ1在N2和N3处理后显著增加（P<0.05）；在3个茶树品种中，非结构性碳水化合物中可溶性总糖含量均呈上升趋势，淀粉含量具有品种特异性，施氮处理后3个茶树品种氮代谢关键酶活性及NSC含量变化存在差异，以HJ1的氮同化关键酶GS、GOGAT酶活性较高、根系活力较强，氮代谢产物显著增加，表明其具有较高的氮同化速率。施氮后HJ1的总NSC的含量及碳氮比的变化幅度较另外2个品种小，能够更好的保持碳氮平衡，游离氨基酸含量增幅较高，品质更优。因此，通过茶树氮代谢关键酶活性及非结构性化合物的研究能为茶树品种的品质评价以及提高茶树的品质和氮素利用效率提供依据。 Abstract:We investigated the effects of nitrogen on root activity, key enzyme activities of nitrogen metabolism, and non-structural carbohydrates (NSC) in 3 tea varieties (Fuding dabai tea (FD),Baojing huangjin tea 1# (HJ1) and Baihaozao (BHZ)) with 4 ammonium nitrogen (N) treatments:without N deposition:N0 (0 g), low N deposition:N1 (11 g), medium N deposition:N2 (22 g), and high N deposition:N3 (33 g). The results showed that root activity increased significantly in N2 and N3 compared with the control, however, there were no differences between these two treatments. The GS and GOGAT activities in tea leaves increased after N treatment. Compared with the control, the total nitrogen content and soluble protein content in tea leaves generally increased following nitrogen treatment, significantly in the case of N2 and N3 in HJ1 (P<0.05). As the mass of N in the treatment increased, the NSC and total soluble sugars presented a tendency of increasing. However, the changes in starch content displayed varietal specificities in FD, HJ1 and BHZ. Changes in key enzymes involved in nitrogen metabolism and NSC content were observed after nitrogen treatment, which were different in the 3 tea varieties. Following N treatment, HJ1 showed higher GS and GOGAT activities, higher root activity, and a significant increase of nitrogen metabolites compares to FD and BHZ, which indicates a higher rate of nitrogen assimilation. The total NSC content and C/N changed less in HJ1, which had a better quality of higher free amino acid content, implying that HJ1 better maintain a carbon-nitrogen balance. Therefore, research on the activities of key enzymes involved in nitrogen metabolism and NSC in tea plants can provide a basis for evaluating the quality of tea varieties and improving the quality and nitrogen use efficiency of tea plants. 参考文献 相似文献 引证文献