Effect of nitrogen supply on nitrogen and carbohydrate constituent accumulation in rhizomes and storage roots of Curcuma alismatifolia Gagnep.

Abstract

Curcuma (Curcuma alismatifolia cv. Gagnep.), a tropical flowering plant known as “Siam tulip”, were cultivated in a pot with vermiculite and supplied with different levels of nitrogen (N). Rhizomes with storage roots were harvested at 215 days after planting. Results indicated that a high level of N supply increased flower numbers and promoted continuous new rhizome formation, but storage root growth was depressed. The N supply to the plants increased the N concentrations both in the rhizomes and in the storage roots. The predominant nitrogenous compounds related to total N increase were proteins in the rhizomes. The N of the insoluble fraction of 80% ethanol or the N of the soluble fraction of 10% trichloroacetic acid was the predominant fraction of N that accumulated in the storage roots. A lack of N supply increased the starch concentration both in the rhizomes and in the storage roots. These results suggested that a high level of N supply to the curcuma plant increased new rhizome formation because of increased flower numbers, but depressed new storage root formation because of reduced starch accumulation.     

Immobilization of 15N in forest litter studied by 15N CPMAS NMR spectroscopy

Solutions labelled with ¹⁵N were applied as (¹⁵NH₄)₂SO₄ or K¹⁵NO₃ to isolated microplots in the floor of mountain beech forest (Nothofagus solandri var. cliffortioides) and incubated for 135 days under field conditions of moisture and temperature. Solid state ¹⁵N CPMAS NMR spectra of the forest litter layer showed that more than 80% of the total signal intensity was attributable to the secondary amide-peptide peak. The degree of ¹⁵N enrichment or form of N did not alter the relative intensity of signals attributable to ¹⁵N in peptides, nucleic acids and aliphatic amine groups (amino sugars and free NH₂ on amino acids). Combinations of ¹³C and ¹⁵N-NMR spectra, edited by a process that exploited differences in proton spin properties between distinct categories of organic matter, indicated incorporation of ¹⁵N in humified organic matter rather than partly degraded plant material. This application demonstrated that solid state ¹⁵N CPMAS NMR has potential for use in studies of N immobilization under field conditions and with materials containing little N and small ¹⁵N enrichment.     

15N示踪法研究弱光对不同穗型冬小麦氮素积累和转运的影响

在大田试验条件下,采用15N示踪法,设置不遮光(T0)、开花后1～10d遮光(T1)、开花后11～20 d遮光(T2)和开花后21～30 d遮光(T3)4个处理,每个处理设置15N尿素作底肥+普通尿素作追肥和普通尿素作底肥+ 15N尿素作追肥两个15N示踪的微区,研究灌浆期弱光条件下不同穗型小麦品种对不同来源氮素的吸收、分配、转运和氮素利用效率的影响.结果表明,灌浆期不同阶段遮光均不利于植株对氮素的吸收、积累和转运,品种间表现一致,呈T0 ＞T3 ＞T2 ＞T1规律;小麦植株吸收的氮素68.0 ％～71.39％来自土壤氮,对追施氮的吸收量大于底施氮,灌浆期遮光增加了土壤氮素在营养器官的分配比例,不利于营养器官中土壤氮素向籽粒中的转运;各处理籽粒产量、肥料氮吸收量、氮肥利用率和肥料偏生产力均表现为T0 ＞T3＞ T2 ＞T1.相同处理条件下,济麦22籽粒产量和对肥料的利用大于山农8355.小麦灌浆期阶段性遮光降低了植株对氮素的吸收、转运和籽粒产量,以灌浆前期遮光影响最大,中期次之,后期最小;相同遮光条件下济麦22的籽粒产量和氮素利用率较高.     

13C and 15N natural abundances of urban soils and herbaceous vegetation in Karlsruhe, Germany

We undertook what we believe to be a unique survey of the natural abundances of ¹³C and ¹⁵N in urban soils and plants in Karlsruhe (Germany), a European city of average size. We found broad patterns of these abundances in both soils and plants, which reflected geology and land use. In contrast with studies on smaller areas (showing the direct effect of human activities), our study first determined the extent to which the abundances correlated with land use or underlying geology and then assessed how we could further test such relationships. The spatial pattern of δ¹³C in surface soil correlated with that of the underlying parent material; construction activities superimposed a secondary signal. Maize cultivation was a source of less negative soil δ¹³C, whereas the C₃ vegetation is a source of more negative soil δ¹³C. There was a footprint of less negative plant δ¹³C in the industrial and port areas; plant δ¹³C downwind of the city was less negative than upwind, which might relate to atmospheric pollution from the port area or to differences in soil properties. There was no significant effect of wind direction or geology on soil or plant δ¹⁵N, which was correlated mainly with land use. The largest soil δ¹⁵N was under agriculture and the smallest under woodland. The abundance of ¹⁵N in inner-urban soil and plants was intermediate between those of agriculture and forests. This study represents a major advance in the use of stable isotope geochemistry in understanding urban environments.     

Gaseous nitrogen losses from soil under Sitka spruce following the application of fertilizer 15N urea

Gaseous N loss, through denitrification and NH₃⁻volatilization, was monitored throughout the growing season after spring application of ¹⁵N labelled urea fertilizer to peaty gley soils supporting N-deficient Sitka spruce. From the ¹⁵N data, it was calculated that only about 0.28% of applied N was lost through NH₃-volatilization, almost all within the first few days after fertilizer application. Approximately 0.05% of applied N was calculated to be lost through denitrification. Denitrification decreased slowly over a 4-month period after fertilizer application. Rates of NH₃-volatilization correlated with available NH₄⁺ in the litter layer, while for the early part of the study when N-losses were highest, denitrification rates correlated with available NO₃⁻ in the litter layer. Observations of gaseous N-loss are also discussed in relation to data from lysimetry, changes in soil pH, and the soil moisture regime.     

Following the decomposition of ryegrass labelled with 13C and 15N in soil by solid-state nuclear magnetic resonance spectroscopy

Investigating the biogeochemistry of plant material decomposition in soil has been restricted by difficulties extracting and identifying organic compounds. In this study the decomposition of ¹³C- and ¹⁵N-labelled Lolium perenne leaves mixed with mineral soil has been investigated over 224 days of incubation under laboratory conditions. Decomposition was followed using short-term rates of CO₂ evolution, the amounts of ¹³C and ¹⁵N remaining were determined by mass spectrometry, and ¹³C and ¹⁵N solid-state nuclear magnetic resonance (NMR) spectroscopy was used to characterize chemically the plant material as it decomposed. After 224 days 48% of the added ¹³C had been lost with a rapid period of C0₂ evolution over the first 56 days. The fraction of cross-polarization magic angle spinning (CP MAS) ¹³C NMR spectra represented by O-alkyl-C signal probably in carbohydrates (chemical shift, 60–90 p.p.m.) declined from 60 to 20% of the spectrum (chemical shift, 0–200 p.p.m.) over 224 days. The rate of decline of the total ¹³C exceeded that of the 60–90 p.p.m. signal during the first 56 days and was similar thereafter. The fraction of the CP MAS ¹³C NMR spectra represented by the alkyl- and methyl-C (chemical shift, 10–45 p.p.m.) signal increased from 5 to 14% over the first 14 days and was 19% after 224 days. CP MAS ¹³C NMR of ¹³C- and ¹⁵N-L. perenne contained in 100-μm aperture mesh bags incubated in the soil for 56 days indicated that the remaining material was mainly carbohydrate but there was an increase in the alkyl- and methyl-C associated with the bag's contents. After 224 days incubation of the labelled ¹³C- and ¹⁵N-L. perenne mixed with the soil, 40% of the added N had been lost. Throughout the incubation there was only one signal centred around 100 p.p.m. detectable in the CP MAS ¹⁵N NMR spectra. This signal corresponded to amide ¹⁵N in peptides and may have been of plant or microbial origin or both. Although there had been substantial interaction between the added ¹⁵N and the soil microorganisms, the associated redistribution of ¹⁵N from plant to microbial tissues occurred within the amide region. The feasibility of following some of the component processes of plant material decomposition in soil using NMR has been demonstrated in this study and evidence that microbial synthesis contributes to the increase in alkyl- and methyl-C content of soil during decomposition has been represented.     

Influence of pool substitution on the interpretation of fertilizer experiments with 15N

The uptake of labelled and unlabelled N by wheat was measured in pot and field experiments with ¹⁵N-labelled fertilizer. Soils from two sites on the same series were used in the pot experiment; one had been bare-fallowed for 22 years and contained 1.6% organic C, the other had been under grass for many years and contained 3.8% organic C. Fertilizer N increased the uptake of unlabelled soil N in both soils, i.e. there was a positive ‘added nitrogen interaction’ (ANI). There was no ANI in the field experiment. A simulation model is used to show how positive ANIs can arise as a result of ‘pool substitution’—labelled inorganic fertilizer N standing proxy for unlabelled inorganic soil N that would otherwise have been immobilized. In the low-organic fallow soil, pool substitution accounted for the whole of the observed ANI and fertilizer N did not enhance either gross or net mineralization of soil N. Pool substitution also operated in the high organic grassland soil, but here net mineralization of soil N increased with increasing additions of fertilizer, giving rise to a ‘real’ ANI in addition to the larger ‘apparent’ ANI caused by pool substitution. This increase in net mineralization is probably caused by a decrease in immobilization of N as fertilizer N additions increase, not by an increase in gross mineralization of soil N. For pool substitution to operate, fertilizer N and soil inorganic N must occupy the same pool. This occurred in the pot experiment but not in the field experiment, where fertilizer and soil inorganic N remained separate and there was no ANI. When pool substitution occurs, fertilizer use efficiency is predictably lower as measured by the isotopic method than as measured by the conventional non-isotopic procedure.     

应用~(15)N研究氮肥运筹对棉花氮素吸收利用及产量的影响

【目的】有关棉花适宜的施氮时期存在争议,国外有学者推荐最佳施氮时期为出苗后和现蕾期,也有研究认为播前和初花期各施一半较好。氮同位素示踪技术能区分作物吸收利用的肥料氮及土壤氮,并能深入细致研究施入氮肥的去向及在作物体内的分配。本文采用氮同位素示踪技术研究氮肥底追比例,施氮时期对棉花氮素吸收和产量的影响,以期为华北平原棉区氮肥管理提供理论依据。【方法】采用盆栽试验,以转Bt+Cp TI基因抗虫棉品种中棉所79(CCRI 79)、中棉所60(CCRI 60)为材料,设氮肥底施与初花期追施比例1∶1(N1)、1∶2(N2)、0∶1(N3)、氮肥底施与蕾期追施比例0∶1(N4)4个处理,研究氮肥运筹对棉花初花期、收获期15N吸收、15N回收率、生物量积累和籽棉产量的影响。【结果】初花期棉株不同器官的氮素吸收来自氮肥(Ndff)的比例随底肥氮施用量的增加而显著增加,增幅为25.88%42.45%。收获期不同处理棉花单株Ndff%随追施氮量的增加而显著增加,增幅为26.92%54.14%,N3、N4处理的棉花单株Ndff%显著高于N1和N2。N2处理的棉花单株籽棉产量高于其他处理,但与N1处理的差异不显著,N2处理单株生物量与N1、N3差异不显著。2个品种N3、N4处理的棉花收获期单株15N积累量均显著高于N1和N2处理,棉株收获期15N回收率均显著高于N1。N2处理的棉花收获期15N回收率高于N1处理,但差异未达到显著水平。棉花收获后N2处理土壤15N回收率低于N1,但差异不显著。【结论】本试验条件下,2个棉花品种氮素底追比为1∶2时的籽棉产量与15N回收率优于底追比为1∶1处理,底追比为0∶1的处理15N回收率在4个处理中最高,但未显示出产量优势,这些结果有待在大田试验中进一步验证。     

Real-time imaging of nitrogen fixation in an intact soybean plant with nodules using 13N-labeled nitrogen gas

Real-time images of nitrogen fixation in an intact nodule of hydroponically cultured soybean ( Glycine max [L] Merr.) were obtained. In the present study, we developed a rapid method to produce and purify ¹³N-labeled radioactive nitrogen gas (half life: 9.97 min). ¹³N was produced from a ¹⁶O (p, α) ¹³N nuclear reaction. The target chamber was filled with CO₂ and irradiated for 10 min with protons at an energy of 18.3 MeV and an electric current of 5 μA, which was delivered from a cyclotron. All CO₂ in the collected gas was absorbed and removed with powdered soda-lime in a syringe and replaced with helium gas. The resulting gas was injected into gas chromatography and separated and a 35 mL fraction, including the peak of [¹³N]-nitrogen gas, was collected by monitoring the chromatogram. The obtained gas was mixed with 10 mL of O₂ and 5 mL of N₂ and used in the tracer experiment. The tracer gas was fed into the underground part of intact nodulated soybean plants and serial images of the distribution of ¹³N were obtained non-invasively using a positron-emitting tracer imaging system (PETIS). The rates of nitrogen fixation of the six test plants were estimated to be 0.17 ± 0.10 μmol N₂ h⁻¹ from the PETIS image data. The decreasing rates of assimilated nitrogen were also estimated to be 0.012 ± 0.011 μmol N₂ h⁻¹. In conclusion, we successfully observed nitrogen fixation in soybean plants with nodules non-invasively and quantitatively using [¹³N]N₂ and PETIS.     

施氮量对嘎啦幼苗~(15)N、~(13)C分配利用特性影响

【目的】采用15N、13C同位素示踪技术,通过对不同施氮量下嘎啦幼苗生长状况及氮、碳分配、利用特性等的研究,以期为苹果生产合理施肥提供依据。【方法】将2年生盆栽嘎啦幼苗进行低、中、高三个氮水平处理,同时进行15N标记。在新梢旺长初始期、新梢旺长期、新梢缓长期分别进行整株13C标记,72小时后,整株解析为叶、梢、根三部分,进行15N、13C测定。样品全氮用凯氏定氮法测定,15N丰度用ZHT-03质谱计测定。13C丰度用DELTA V Advantage同位素比率质谱仪测定。【结果】1)中、高氮水平的施肥处理可在不同程度上提高整株及叶片干物质量和新梢长度。新梢旺长初始期和新梢缓长期嘎啦幼苗整株干物质量、新梢旺长期叶片干物质分配比率在中、高氮水平处理间差异不显著,中氮水平经济有效。新梢旺长期以后新梢长度以中氮高氮低氮,三者间差异性显著,中氮处理有利于新梢生长。2)在新梢旺长初始期,低氮处理植株叶片15N分配率达50%,比其他处理高出13个百分点左右,表明低氮处理更多的氮被叶片所利用,中氮和高氮处理间差异不显著,说明在本试验施氮条件下中氮供应水平已能满足氮素营养需求。3)新梢旺长期和新梢缓长期幼苗13C固定量均以中氮处理最高,新梢旺长初始期3个处理间根系13C分配率中氮高氮低氮,表明中氮处理有利于碳同化物在嘎啦幼苗中的分配。4)不同施氮量处理的嘎啦幼苗,15N利用率随施氮水平提高而降低,高氮处理对碳同化物分配没有显著贡献。【结论】低、中、高氮不同处理新梢缓长期碳同化物在各器官间的分配比较均衡,氮素水平不能影响碳同化物的分配。盆栽试验表明,中氮水平在保证营养供应的同时,能够促进新梢生长和树势健壮。     

Changes in the N Recovery Process from 15N-Labeled Swine Manure Compost and Rice Bran in Direct-Seeded Rice by Simultaneous Application of Cattle Manure Compost

The N recovery from ¹⁵N-labeled swine manure compost and rice bran with or without simultaneous application of unlabeled cattle manure compost was examined in a paddy field with direct-seeded rice during a 1-year period (1 crop season). In all the ¹⁵N-labeled materials including (¹⁵NH₄)₂SO₄, the processes of N recovery from the ¹⁵N materials by rice plants were different between the plots with and without application of cattle manure compost. At the tillering stage, the N recovery rates from the ¹⁵N materials in the plots with application of cattle manure compost were significantly lower than those in the plots without application of cattle manure compost. These recovery rates, however, became close and no significant differences were observed at the maturity stage. Thus, simultaneous application of cattle manure compost could impede the N recovery from swine manure compost, rice bran as well as (NH₄)₂SO₄.     

Uptake and translocation of nitrogen in patumma (Curcuma alismatifolia) by leaves or root

An adequate supply of nitrogen (N) is important for patumma growth and flower quality. This study aimed to compare the uptake and translocation of N by foliar and root application. Fertilization with ¹⁵ nitrate (NO₃)-N via roots or leaves was carried out at four stages, at the 1st to 4th fully expanded leaf (FEL) stages, and the plants were sampled at each successive stage. The uptake and translocation of ¹⁵N from foliar or root applications showed relatively similar patterns at all stages. Although the N fertilizer utilization rate by roots was higher than that via leaves, the foliar application stimulated reproductive growth by earlier flowering. The N supplied at the 1st FEL and the 2nd FEL was utilized mainly in leaves, whereas supplying N at the 3rd and 4th FEL promoted flower quality. Fertilizer application method and stage of application influence the utilization rate and translocation of N to the sink organs.