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1.
Peter R. Alefounder Stuart J. Ferguson 《Biochemical and biophysical research communications》1982,104(3):1149-1155
The nitrous oxide reductase activity of can be conveniently measured using an electrochemical method for determining N2O. Introduction of this procedure has shown that (i) N2O reductase activity is reversibly inhibited by oxygen; (ii) antimycin strongly inhibits electron flow to N2O and that the inhibition is bypassed by tetramethyl-p-phenylenediamine; (iii) ascorbate plus tetramethyl-p-phenylenediamine, presumably by donating electrons to cytochrome c, is an effective reductant for nitrous oxide reductase; (iv) in the presence of the nitrous oxide reductase inhibitor, acetylene, N2O is promptly produced from nitrite, consistent with the product of nitrite reductase being N2O. 相似文献
2.
冬玉米对氮肥的吸收利用和需求 总被引:2,自引:0,他引:2
在不同施氮量下 ,研究了冬玉米对氮肥的吸收利用 ,结果表明 :(1 )冬玉米地上各部分中氮的累积随着用氮量的增加而增加 ,花丝期前的吸收量均多于后期 ,但高氮区的前期吸氮比大于低氮区 ;(2 )营养体氮的转移率随施氮量的增加而降低 ,但绝对量依然是高氮处理大于低氮处理 ,其中雄穗的转移率最高 ,叶的转移量最大 ;(3 )氮肥利用率随施氮量的增加而提高 ,但氮的生产力下降。根据试验结果 ,在肥力好的土地上种植冬玉米以 1 80~ 2 70 kg N/hm2比较适宜 相似文献
3.
Summary Mobilization of soil-borne N, N fertilization and N removal by crops influence EUF-NO3-N contents as well as EUF-Norg contents in the course of a vegetation period. N mobilization alone (no N fertilization) increases the EUF-Norg contents only temporarily (mainly in May and July), while in December they are almost the same as in March (Table 1). The EUF-NO3 contents, on the contrary, increase during the vegetation period, so that an increment in NO3 is registered in unplanted pots in December. This increment is larger the higher the EUF-Norg contents are in March (Table 2).N fertilization increases the contents of both EUF-Norg and EUF-NO3, so that there is an increment in EUF-Norg as well as EUF-NO3 in December (Table 2). This finding also applies to field experiments under fallow (Figs. 4 and 5). However, in contrast to the pot experiment, the EUF-N contents in the field experiment were only temporarily increased by N mobilization alone. This means that N immobilization had taken place which had not been observed in the pot experiment under stable moisture conditions (Fig. 4 and Table 1).A close correlation between hot-water-soluble N contents and EUF-Norg is found only under uniform management conditions (uniform N-fertilizer rates). Depending on the time of sampling different regression equations are, however, obtained because of changes in EUF-Norg due to N mobilization, whereas the hot-water-soluble N contents hardly show any variations during the vegetation period (Fig. 6 and Table 3). 相似文献
4.
Partitioning of nitrogen by soybeans ( Glycine max L. Merr. cv. Hodgson) grown in natural conditions was studied by successive exposures of root systems to 15 N2 and periodical measurements of 15 N distribution. Nitrogen derived from the atmosphere was mainly found in the aerial parts of the plants, and the stage of development exerted a strong influence on the initial 15 N distribution (measured one week after incorporation). Until day 69 after sowing, leaf blades contained 47 to 57% of the fixed N. After that, reproductive structures attracted increasing proportions, 10 to 60% between days 69 and 92. Around day 82, stems and petioles stored up to 30% of the newly fixed N. During pod development and pod filling and until maturity, fixed N was remobilized from vegetative tissues and pod walls to seeds. These transfers first concerned the newly incorporated N, but at maturity 80 to 90% of the total was recovered in the seeds. The high mobility of N originating from the atmosphere as compared to that coming from the soil (vegetative tissues exported only 50% of their total N) seems to indicate that fixed N was at least partially integrated in a special pool. This was certainly the case at the later stage of N2 fixation, when a large portion of fixed N accumulated in the stems and petioles, probably in the form of storage compounds such as ureides for later transfer to the developing seeds. Further research is needed in order to investigate the nature and role of this pool in the nitrogen nutrition of soybeans. 相似文献
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A simple N balance model was used to calculate fertilizer requirement for a target N uptake by maize. Nitrogen uptake from soil sources and target uptake of N with fertilizer N additions were obtained from fertilizer trials in Africa and Latin America. Most experiments had data for only one cropping period, although some from Latin America had data for four to six crops. The transfer coefficient of fertilizer N to the crop was adjusted to realize maximum recovery of fertilizer N under best methods of fertilizer application. The time constants of transfer of soil N to the crop were allowed to vary and were affected mainly by soil texture. Where 4 to 6 cropping periods were available good agreement between actual and predicted fertilizer N requirements was obtained. With this approach long-term fertilizer N requirements for 14 sites were predicted using first cropping period N uptake. This study showed that pools of organic N in more coarse-textured soils were usually smaller and declined more rapidly than in fine-textured soils. Labile organic N pools declined with time under all simulations, but approached equilibrium within 10 croppings seasons. Equilibrium N uptake from the soil organic N pool was predicted to be 31 kg ha–1 for the more coarse-textured soils and 36 kg ha–1 for the fine-textured soils. Long-term projections of fertilizer requirements using input data of the field experiments were reasonable, and effects of legume green manures and other amendments could be clearly evaluated. 相似文献
8.
Tae-Hwan Kim Woo-Jin Jung Bok-Rye Lee Tadakatsu Yoneyama Hak-Yoon Kim Kil-Yong Kim 《Environmental and Experimental Botany》2003,50(3):233-242
The influence of P deficiency on the utilization of two sources of N, mineral N (exogenous N) and reserved N (endogenous N), for regrowth of Italian ryegrass (Lolium multiflorum) was studied. P-sufficient (+P) or P-free (−P) nutrition solution was applied from 7 days before defoliation to 24 days of regrowth and the N flows derived from two different N sources within the plant were quantified by 15N pulse-chase labeling. Shoot regrowth significantly reduced by 12 days of regrowth, while root growth was more in −P plants. Inorganic P (Pi) concentration was highly reduced by P deprivation more in the stubble and regrowing shoots and less in the roots. At defoliation, P deprivation had induced a higher accumulation for all N compounds in the stubble and for amino acids in the roots. The previously incorporated 15N in stubble and roots as nitrate and amino acids was much decreased in −P plants especially for the first 6 days of regrowth. Total N content in the regrowing leaves was not significantly different between +P and −P plants, but percentage contribution of remobilized N for total leaf N formation was significantly higher in −P plants (78%) than in +P plants (69%) at 6 days of regrowth. From day 12, the utilization of both endogenous and exogenous N was apparently inhibited in −P plants. 相似文献
9.
Assimilation of N by heterotrophic soil microbial biomass is associated with decomposition of organic matter in the soil. The form of N assimilated can be either low molecular weight organic N released from the breakdown of organic matter (direct assimilation), or NH+ 4 and NO− 3 from the soil inorganic N pool, into which mineralized organic N is released (mineralization immobilization turnover). The kinetics of C and N turnover in soil is quantifiable by means of computer simulation models. NCSOIL was constructed to represent the two assimilation schemes. The rate of N assimilation depends on the rate of C assimilation and microbial C/N ratio, thereby rendering it independent of the assimilation scheme. However, if any of the N forms is labeled, a different amount of labeled N assimilation will be simulated by the different schemes. Experimental data on inorganic N and 15 N and on organic 15 N dynamics in soils incubated with 15 N added as NH+ 4 or organic N were compared with data simulated by different model schemes. Direct assimilation could not account for the amount of 15 N assimilated in any of the experimental treatments. The best fit of the model to experimental data was obtained for the mineralization immobilization turnover scheme when both NH+ 4 and NO− 3 were assimilated, in proportion to their concentration in the soil. 相似文献
10.
S Gutteridge D B Winter W J Bruyninckx H S Mason 《Biochemical and biophysical research communications》1977,78(3):945-951
After mild dissociation of cytochrome oxidase protomers, and polyacrylamide gel electrophoresis, copper was found predominantly in polypeptides of Bands V (m.w. 12,100) and VII (m.w. 3,400), and heme a predominantly in polypeptides of Bands I (m.w. 35,300) and II (m.w. 21,000). Some copper was found in Band II – III, and heme a in Band V. 相似文献
11.
《Journal of morphology》2017,278(12):1619-1627
Contests between same‐sex opponents over resources necessary for reproduction, as well interactions used to discern mate quality, often involve exaggerated traits wherein large individuals have disproportionately larger traits. This positive allometric scaling of weapons or signals facilitates communication during social interactions by accentuating body size differences between individuals. Typically, males carry these exaggerated traits, as males must compete over limited female gametes. However, in Nicrophorus beetles both males and females engage in physical contests over the vertebrate carcasses they need to provision and raise offspring. Male and female Nicrophorus beetles have extended clypeal membranes directly above their mandibles, which could serve as signals. We investigated the scaling relationships between clypeal membrane size and shape and body size for five species of North American burying beetle to determine whether clypeal membranes contain exaggerated body size information. We found that clypeal membranes for both sexes of all species scaled positively with body size (slope > 1). Three of the five species also displayed sexual dimorphism in aspects of clypeal membrane size and shape allometry despite lack of dimorphism in body size. In two dimorphic species, small male clypeal membranes were statistically indistinguishable from the female form. We conclude that colored clypeal membranes in Nicrophorus beetles do contain exaggerated body size information. Observed patterns of dimorphism suggest that males sometimes experience stronger selection on marking size and shape, which might be explained by life history differences among species. 相似文献
12.
Alan E. S. Macklon Lucy J. Sheppard Allan Sim Ian D. Leith 《Trees - Structure and Function》1996,10(4):261-267
Cloned Sitka spruce grafts were subjected to NH4NO3 mist (1 mm day-1 equivalent) acidified with H2SO4, for 4 days a week, from April until November. Three N treatments at pH 5.0 used 0.01 mol m-3
15NH4
15NH3, 1.6 mol m-3
15NH4 NO3 or 1.6 mol m-3 NH4
15NO3. At pH 2.5, the treatments were15NH4
15NO3,15NH4NO3 and NH4
15NO3 all at 1.6 mol m-3. At the end of the growing season,15N was found in every part of the trees, even when NH4NO3 was supplied at 0.01 mol m-3. It was shown that both
and
could enter needles to a similar degree and be transported to the roots. No differences between pH treatments or clones could be demonstrated. Entry of labelled N via the roots, in those trees with unprotected compost, was reflected in higher fine root15N content, but no change in shoot15N levels. Per cent incorporation expressed as labelled N as a percentage of total N, was generally at its highest in bark, and in older needles in all treatments, values ranging from 5 to 11%. When15N content was expressed as total content for each tree part on a per tree basis, 25–36% was found in current year needles, with a further 12% in current year bark. The most reproducible data was that for dry weight of tree parts as per cent of the whole tree, where proportions compared closely between treatments and the two clones used. The implications of the results for cuticular transport mechanisms, N storage and internal cycling are discussed. 相似文献
13.
华北平原冬小麦/夏玉米轮作体系土壤硝态氮的适宜含量 总被引:19,自引:0,他引:19
采用冬小麦季不同施氮处理(夏玉米季不施氮)研究了华北平原冬小麦/夏玉米轮作体系夏玉米季土壤硝态氮的适宜含量.结果表明:在播前土壤无机氮含量较高的条件下,冬小麦季施用150kgN.hm-2即可满足冬小麦/夏玉米两季作物的氮素需求;各氮肥处理在冬小麦季的氮肥施用当季的利用率仅为11%~23%,在夏玉米季氮肥残效利用率则高达30%~52%.当夏玉米播前0~90cm土层硝态氮含量达到82kg.hm-2时,无需施氮即可保证夏玉米十叶期的生长,达到151kg.hm-2时,无需施氮即可保证整个生育期的生长.夏玉米十叶期和收获后0~90cm土层硝态氮含量低于46和65kg.hm-2时,则影响作物正常生长.综合考虑产量和环境效应,冬小麦/夏玉米轮作体系中0~90cm土层硝态氮含量应控制在65~151kg.hm-2之间. 相似文献
14.
Yield and crop parameters of wetland rice as influenced by soil and fertilizer nitrogen 总被引:2,自引:0,他引:2
Summary The behavior of soil N, fertilizer N and plant N was studied in a greenhouse experiment with 2 plant densities of rice (IR 36) under flooded conditions. Increasing plant density from 25 hills m2 to 50 hills m2 increased tiller number and panicle number but had no influence on grain yield. The yield of grain was linearly related to N content of the above ground dry matter at harvest (r2=.96) and thus the effect of manipulating the N supply on yield was directly related to N uptake.Mixing of (NH4)2SO4 with the soil volume before transplanting resulted in increases in N in the aboveground dry matter equal to 87% of the applied N. When (NH4)2SO4 was broadcast into the flood water at 4 stages of growth beginning 25 DAT, the corresponding increase was 77% of the applied N. When (NH4)2SO4 was split between shallow mixing before transplanting and a broadcast application of 32 DAT, the corresponding increase was 42%. Thus several applications of fertilizer N increased grain production per unit of applied N.Inorganic N extractable by KCl was a useful but not an infailible guide to the behavior of the soil and fertilizer inorganic N. 相似文献
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16.
B B Aggarwal Y Avi-Dor H M Tinberg L Packer 《Biochemical and biophysical research communications》1976,69(2):362-368
Exposure of mitochondria to visible light in the presence of riboflavin resulted in the initial release of respiratory control, followed by inhibition of electron transport and dissolution of structural integrity. Under these conditions, however, cytochrome c oxidase activity remained unchanged. ATPase activity was stimulated initially and remained in this activitated state even under continued illumination. In submitochondrial preparations, both electron transport and ATPase declined as a function of illumination time; cytochrome c oxidase was not sensitive to light. Enzyme inactivation also occurred to a lesser extent in the absence of riboflavin. 相似文献
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18.
The β-glucosides of 3-oxo-α-ionol and 5,6-epoxy-5,6-dihydro-3-hydroxy-β-ionol were isolated from fresh leaves of Nicotiana rustica. Two or more of the glucosides of 3-oxo-α-ionol, 5,6-epoxy-5,6-dihydro-3-hydroxy-β-ionol, 3-hydroxy-β-damascone, blumenol A, 4-(3-hydroxybutylidene)-3,5,5-trimethyl-2-cyclohexenl-one and blumenol C were shown to be present and the amounts measured in N. alata, N. repanda, N. rustica, N. undulata, N. accuminata, N. sylvestris and N. tabacum. No glucosides were detected in N. paniculata. 相似文献
19.
UTA FRIEDRICH KIRSTEN FALK ENNO BAHLMANN THORBEN MARQUARDT HARTMUT MEYER THOMAS NIEMEYER SIEGFRIED SCHEMMEL GODDERT von OHEIMB WERNER HÄRDTLE 《Global Change Biology》2011,17(4):1549-1559
In the present study, we analyze the fate of airborne nitrogen in heathland ecosystems (NW Germany) by means of a 15N tracer experiment. Our objective was to quantify N sequestration and N allocation patterns in an ecosystem that is naturally limited by N, but that has been exposed to airborne N inputs exceeding critical loads for more than 3 decades. We hypothesized that the system has a tendency towards N saturation, which should be indicated by low N sequestration and high N leaching. We analyzed 15N partitioning (aboveground biomass and soil horizons) and investigated 15N leaching over 2 years following a 15N tracer pulse addition. 15N tracer recovery was 90% and 76% in the first and second year, respectively. Contrary to our expectations, more than 99% of the tracer recovered was sequestered in the biomass and soil, while leaching losses were <0.05% after 2 years. Mosses were the most important short‐term sink for 15N (64% recovery in the first year), followed by the organic layer. In the second year, the moss layer developed from a sink to a source (23% losses), and soil compartments were the most important sink (gains of 11.2% in the second year). Low 15N recovery in the current year's shoots of Calluna vulgaris (<2%) indicated minor availability of 15N tracer sequestered in the organic layer. N partitioning patterns showed that the investigated heaths still have conservative N cycling, even after several decades of high N loads. This finding is mainly attributable to the high immobilization capacities for N of podzols in soil compartments. In the long term, the podzol A‐ and B‐horizons in particular may immobilize considerable amounts of incoming N. Since N compounds of these horizons are not readily bio‐available, podzols have a high potential to withdraw airborne N from the system's N cycle. 相似文献
20.
Nitrogen fertilization in citrus orchards 总被引:2,自引:0,他引:2
S. Dasberg 《Plant and Soil》1987,100(1-3):1-9
Summary The purpose of this review was to evaluate critically the results obtained in citrus nitrogen fertilization experiments in
Israel and in other parts of the world, in order to increase our understanding of the processes involved and to improve the
recommendations to growers. Mature citrus trees contain 1–2 kg N/tree, 30–60% of which is in the annual parts (leaves and
fruits). 30g N is deposited annually in the tree skeleton. Based on these results and on a review of long-term fertilization
experiments with citrus from various parts of the world, it was concluded that 200 kg N/ha applied annually is sufficient
to sustain good citrus yields and tree development, about half of which is incorporated in the fruits and one-tenth deposited
in the tree, the balance being made up by leaching and gaseous losses. Experiments with15N labeled fertilizer applications showed that the highest N-uptake rate occurred during fruit set and that in winter the uptake
was very low. N reserves in the older tissues played an important part in the development of new leaves and flowers in the
spring, when the uptake from the soil was still low. It was concluded that the nitrogen contained in the soil organic matter
(2 Mg/ha) and in the mature trees (1 Mg/ha) plays an important part in the regulation of N supply to the growing parts of
the tree. More N is derived from these parts with low N fertilization than with an abundant supply. The purpose of fertilization
is to ensure proper development of the tree, not the current fruit yield.
Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 1770-E. 1986 series. 相似文献