N Supply (n + supply)

Distribution by Scientific Domains
Distribution within Life Sciences

Selected Abstracts

Nitrogen utilization by Hylocomium splendens in a boreal forest fertilization experiment

Summary 1Nitrogen uptake in the terricolous bryophyte Hylocomium splendens (Hedw.) B.S.G. was studied in a boreal forest long-term N-treatment experiment including control plots, N-addition plots (50 kg N ha,1 year,1 for 8 years) and recovery plots (50 kg N ha,1 year,1 for 5 years and thereafter no N addition for 3 years). 2A main objective was to explore whether the N treatments changed bryophyte uptake of different inorganic and organic N forms. In addition, we estimated the contribution of N from throughfall precipitation to the bryophyte N supply. 3The results demonstrated that bryophyte N uptake was similar in all the long-term N-treatment plots. Hylocomium splendens took up more 15N labelled than or glycine when these N forms were applied in situ by the spraying of solutions with N concentrations similar to those in precipitation. 4Analysis of the precipitation collected beneath the closed tree canopy from late May to early October revealed that it contributed 2·0 kg N ha,1 during the period studied, distributed between (78%), amino acid N (17%) and (5%). 5The study highlights that, in addition to analyses of and (normally included in standard environmental monitoring of precipitation), analysis of amino acid N must be performed to account fully for the precipitation N input to bryophytes in boreal forest ecosystems. [source]

Ten years of free-air CO2 enrichment altered the mobilization of N from soil in Lolium perenne L. swards

Manuel K. Schneider
Abstract Effects of free-air carbon dioxide enrichment (FACE, 60 Pa pCO2) on plant growth as compared with ambient pCO2 (36 Pa) were studied in swards of Lolium perenne L. (perennial ryegrass) at two levels of N fertilization (14 and 56 g m,2 a,1) from 1993 to 2002. The objectives were to determine how plant growth responded to the availability of C and N in the long term and how the supply of N to the plant from the two sources of N in the soil, soil organic matter (SOM) and mineral fertilizer, varied over time. In three field experiments, 15N-labelled fertilizer was used to distinguish the sources of available N. In 1993, harvestable biomass under elevated pCO2 was 7% higher than under ambient pCO2. This relative pCO2 response increased to 32% in 2002 at high N, but remained low at low N. Between 1993 and 2002, the proportions and amounts of N in harvestable biomass derived from SOM (excluding remobilized fertilizer) were, at high N, increasingly higher at elevated pCO2 than at ambient pCO2. Two factorial experiments confirmed that at high N, but not at low N, a higher proportion of N in harvestable biomass was derived from soil (including remobilized fertilizer) following 7 and 9 years of elevated pCO2, when compared with ambient pCO2. It is suggested that N availability in the soil initially limited the pCO2 response of harvestable biomass. At high N, the limitation of plant growth decreased over time as a result of the stimulated mobilization of N from soil, especially from SOM. Consequently, harvestable biomass increasingly responded to elevated pCO2. The underlying mechanisms which contributed to the increased mobilization of N from SOM under elevated pCO2 are discussed. This study demonstrated that there are feedback mechanisms in the soil which are only revealed during long-term field experiments. Such investigations are thus, a prerequisite for understanding the responses of ecosystems to elevated pCO2 and N supply. [source]

A global study of relationships between leaf traits, climate and soil measures of nutrient fertility

GLOBAL ECOLOGY, Issue 2 2009
Jenny C. Ordoñez
ABSTRACT Aim This first global quantification of the relationship between leaf traits and soil nutrient fertility reflects the trade-off between growth and nutrient conservation. The power of soils versus climate in predicting leaf trait values is assessed in bivariate and multivariate analyses and is compared with the distribution of growth forms (as a discrete classification of vegetation) across gradients of soil fertility and climate. Location All continents except for Antarctica. Methods Data on specific leaf area (SLA), leaf N concentration (LNC), leaf P concentration (LPC) and leaf N:P were collected for 474 species distributed across 99 sites (809 records), together with abiotic information from each study site. Individual and combined effects of soils and climate on leaf traits were quantified using maximum likelihood methods. Differences in occurrence of growth form across soil fertility and climate were determined by one-way ANOVA. Results There was a consistent increase in SLA, LNC and LPC with increasing soil fertility. SLA was related to proxies of N supply, LNC to both soil total N and P and LPC was only related to proxies of P supply. Soil nutrient measures explained more variance in leaf traits among sites than climate in bivariate analysis. Multivariate analysis showed that climate interacted with soil nutrients for SLA and area-based LNC. Mass-based LNC and LPC were determined mostly by soil fertility, but soil P was highly correlated to precipitation. Relationships of leaf traits to soil nutrients were stronger than those of growth form versus soil nutrients. In contrast, climate determined distribution of growth form more strongly than it did leaf traits. Main conclusions We provide the first global quantification of the trade-off between traits associated with growth and resource conservation ,strategies' in relation to soil fertility. Precipitation but not temperature affected this trade-off. Continuous leaf traits might be better predictors of plant responses to nutrient supply than growth form, but growth forms reflect important aspects of plant species distribution with climate. [source]

Effect of N Fertilization Rate on Sugar Yield and Non-Sugar Impurities of Sugar Beets (Beta vulgaris) Grown Under Mediterranean Conditions

J. T. Tsialtas
Abstract For three successive growing seasons (1999,2001), a completely randomized block design experiment was established at the surrounding area of each of four sugar beet processing plants of Hellenic Sugar Industry SA, Greece (a total of 12 experiments). Nitrogen was applied at five rates (0, 60, 120, 180 and 240 kg N ha,1) and six replications per rate. Nitrogen fertilization had site-specific effects on quantitative (fresh root and sugar yields) and qualitative (sucrose content, K, Na, , -amino N) traits. When data were combined over years and sites, fresh root and sugar yields were maximized at high N rates (330.75 and 295 kg N ha,1 respectively), as derived from quadratic functions fitted to data. In three trials, increased N rates had negative effects on root and sugar yield. These sites were characterized by high yield in control plots, light soil texture (sand > 50 %) and low CEC values. When data were converted into relative values (the ratio of the trait values to the control mean of each experiment), root and sugar yield was found to be maximized at higher N rates (350 and 316 kg N ha,1, respectively). Sucrose content was strongly and linearly reduced by the increased N rates when data were combined but a significant reduction with increasing N rates was found in only two sites. Non-sugar impurities (K, Na, , -amino N) were positively related to the increased N rates when data were combined. Sodium and , -amino N showed to be most affected by N fertilization as positive relationships were found in six and eight of 12 locations, respectively. Increased N supply resulted in higher soil NO3 -N concentrations (0,90 cm depth) at harvest which were related with amino N contents in sugar beet roots (in 1999 and 2001). [source]

Effects of Salinity and Mixed Ammonium and Nitrate Nutrition on the Growth and Nitrogen Utilization of Barley

A. Ali
The absorption and utilization of nitrogen (N) by plants are affected by salinity and the form of N in the root medium. A hydroponic study was conducted under controlled conditions to investigate growth and N uptake by barley (Hordeum vulgare L.) supplied with five different NH4+ -N/NO3, -N ratios at electrical conductivity of 0 and 8 dS m,1. The five NH4+ -N/NO3 -N ratios were 0/100, 25/75, 50/50, 75/25 and 100/0, each giving a total N supply of 100 mg N l,1 in the root medium. A mixed N supply of NH4+ and NO3, resulted in greater accumulation of N in plants than either NO3, or NH4+ as the sole N source. Plants produced a significantly higher dry matter yield when grown with mixed N nutrition than with NH4+ or NO3, alone. Total dry matter production and root and shoot N contents decreased with increasing salinity in the root medium. The interaction between salinity and N nutrition was found to be significant for all the variables. A significant positive correlation (r=0.97) was found between nitrogen level in the plant shoot and its dry matter yield. Wachstum und Stickstoffausnutzung bei Gerste in Abhängigkeit von Versalzung und Michungen von Ammonium und Nitrat Aufnahme und Nutzung von N durch Pflanzen wird von der Versalzung und N-Form im Wurzelbereich bestimmt. Es wurde in Hydrokultur unter kontrollierten Bedingungen Wachstum und N-Aufnahme durch Gerste (Hordeum vulgare L.) bei Anwendung von fünf unterschiedlichen NH4+ -N/NO3, -N Verhältnissen bei einer elektrischen Konduktivität von 0 und 8 dS m,1 untersucht. Die Gesamtmenge von 100 mg N l,1 im Wurzelmedium wies NH4+ -N/NO3, -N Verhältnisse von 0/100, 25/75, 50/50, 75/25 und 100/0 auf. Mischungen von NH4+ und NO3, führten zu einer größeren Aufnahme durch die Pflanzen als bei alleiniger Anwendung von NO3, oder NH4+. Die Pflanzen produzierten signifikant mehr Gesamttrockenmasse mit Mischungen der beiden N-Formen im Vergleich zu alleiniger Anwendung von NH4+ oder NO3,. Die Gesamttrockenmasse sowie die N-Gehalte von Wurzel und Sproß nahmen mit steigender Versalzung ab. Versalzungs- und N-Versorgungs-Interaktion war signifikant in allen Versuchsbedingungen. Eine signifikante positive Korrelation (r=0,97) wurde zwischen Stickstoffkonzentration und der Trockenmasseproduktion der Pflanze gefunden. [source]

The use of endogenous nitrogen for microbial crude protein synthesis in the rumen of growing bulls

H. Kluth
Summary The objective of this study was to quantify endogenous nitrogen (N) recycled for microbial protein synthesis in the rumen. Four growing bulls (Schwarzbuntes Milchrind; bodyweight: 240,310 kg) with duodenal T-shaped cannulas were fed diets containing four levels of crude protein content (200, 156, 102 and 63 g/kg dry matter, respectively). The diets were based on wheat, barley, tapioca meal, soybean extracted meal, dried beet pulp, meadow hay and straw. The diets had an energy level of 11.1, 10.9, 10.2 and 9.6 MJ metabolizable energy/kg dry matter. Faeces and urine were collected in four 7-day balance periods. Duodenal flow rate was estimated by TiO2, pelleted with grain, as a marker. The relationship between urine N excretion, the amount of microbial N reaching the duodenum, ruminal N balance and N retention were examined and the amount of endogenous N available for microbial protein synthesis without negative effects on the N retention was determined. It can be concluded that up to 16% of the microbial N supply could be covered by recycled endogenous N, but N retention should not be decreased by more than 1.5 residual standard deviations of maximal N retention. [source]

Glutamine Nitrogen and Ammonium Nitrogen Supplied as a Nitrogen Source Is Not Converted into Nitrate Nitrogen of Plant Tissues of Hydroponically Grown Pak-Choi (Brassica chinensis L.)

H.-J. Wang
ABSTRACT:, Many vegetables, especially leafy vegetables, accumulate NO,3 -N in their edible portions. High nitrate levels in vegetables constitute a health hazard, such as cancers and blue baby syndrome. The aim of this study was to determine if (1) ammonium nitrogen (NH+4 -N) and glutamine-nitrogen (Gln-N) absorbed by plant roots is converted into nitrate-nitrogen of pak-choi (Brassica chinensis L.) tissues, and (2) if nitrate-nitrogen (NO,3 -N) accumulation and concentration of pak-choi tissues linearly increase with increasing NO,3 -N supply when grown in nutrient solution. In experiment 1, 4 different nitrogen treatments (no nitrogen, NH+4 -N, Gln-N, and NO,3 -N) with equal total N concentrations in treatments with added N were applied under sterile nutrient medium culture conditions. In experiment 2, 5 concentrations of N (from 0 to 48 mM), supplied as NO,3 -N in the nutrient solution, were tested. The results showed that Gln-N and NH+4 -N added to the nutrient media were not converted into nitrate-nitrogen of plant tissues. Also, NO,3 -N accumulation in the pak-choi tissues was the highest when plants were supplied 24 mM NO,3 -N in the media. The NO,3 -N concentration in plant tissues was quadratically correlated to the NO,3 -N concentration supplied in the nutrient solution. [source]

Nitrogen effects on total flavonoids, chlorogenic acid, and antioxidant activity of the medicinal plant Chrysanthemum morifolium

Dahui Liu
Abstract Chrysanthemum morifolium (Ramat.) has a long history of cultivation and use as a traditional medicine and tea plant in China. A greenhouse experiment with potted soil,quarz mixture studied the effects of nitrogen supply (0, 56, 112, 167, 224, 334, 501, 556, and 668 mg N,kg,1) on concentrations and ratios of total flavonoids and chlorogenic acid in the flowers of C. morifolium using spectrophotometric and HPLC methods. The antioxidant activity of the flowers was determined as the radical scavenging activities of hydroxyl, superoxide anion, and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radicals. A high N supply decreased the concentrations of total flavonoids by 18%,35% and that of chlorogenic acid by 8%,60% compared to a low N-supply rate. At the same time, increasing N supply significantly decreased the antioxidant activity of the flowers. The antioxidant activity of C. morifolium flowers was significantly positively correlated with the concentrations of total flavonoids and chlorogenic acid. We conclude that an N supply in excess of 300 mg (kg soil),1 will negatively affect the antioxidant activity and thereby reduce the quality of C. morifolium flowers. [source]

Effects of nitrogen supply on water-use efficiency of higher plants

Holger Brueck
Abstract The worldwide increase of food demand and reduced sweet-water availability in some important food-producing regions raised interest in more efficient water use, which has become one of the central research topics in agriculture. Improved irrigation management and reduced bare-soil evaporation have highest priority to increase agronomic water-use efficiency (WUE). Compared to these technical (irrigation) and basic (crop production) management options, effects of nutrient management on WUE were less frequently considered. Twenty-nine publications on nitrogen (N) effects on biomass WUE of container-grown plants are considered in this review. Most of them indicate positive N effects on WUE, and relevance of N effects on intrinsic WUE and unproductive water and carbon loss is discussed. A plot of 90 published data of percent decreases of WUE and dry mass under variable N supply is presented. Extrapolation of biomass WUE from leaf measurements of intrinsic WUE is critically reviewed. The positive correlation between WUE and dry-mass formation suggests that physiological rather than stomatal effects are more important in order to explain positive N effects on WUE. [source]

Sulfur and nitrogen supply influence growth, product appearance, and glucosinolate concentration of broccoli

Ilona Schonhof
Abstract The effects of insufficient and optimal sulfur (S) and nitrogen (N) supply on plant growth and glucosinolate formation were studied under controlled experimental conditions in broccoli "Monaco". Here, we report on the interaction between S and N supply, plant growth, and quality parameters and discuss the relevance of this interaction in relation to crop-management strategies. Broccoli plants supplied with insufficient amounts of S or N showed typical deficiency symptoms and yield decreases. In contrast, total glucosinolate concentrations were high at insufficient N supply, independent of the S level, and low at insufficient S supply in combination with an optimal N supply. This was mainly due to the presence of the alkyl glucosinolates glucoraphanin and glucoiberin. Furthermore, with S concentrations above 6 g (kg DM),1 and an N : S ratio lower than 10:1, the glucosinolate concentrations were on average around 0.33 g (kg fresh matter),1 and differed significantly from those plants characterized by an S concentration below 6 g (kg DM),1 and an N : S ratio above 10:1. In addition, N : S ratios between 7:1 and 10:1 promoted plant yield and enhanced overall appearance. Therefore, to produce broccoli (and potentially other Brassicaceae) with higher crop yields and enhanced product quality in the field, it is vital to establish the optimal S and N nutritional status of the plant and to integrate this information into crop-management strategy programs. [source]

Soil- and plant-based nitrogen-fertilizer recommendations in arable farming

Hans-Werner Olfs
Abstract Under- as well as overfertilization with nitrogen (N) will result in economic loss for the farmer due to reduced yields and quality of the products. Also from an ecological perspective, it is important that the grower makes the correct decision on how much and when to apply N for a certain crop to minimize impacts on the environment. To aggravate the situation, N is a substance that is present in many compartments in different forms (nitrate, ammonium, organic N, etc.) in the soil-plant environment and takes part in various processes (e.g., mineralization, immobilization, leaching, denitrification, etc.). Today, many N-recommendation systems are mainly based on yield expectation. However, yields are not stable from year to year for a given field. Also the processes that determine the N supply from other sources than fertilizer are not predictable at the start of the growing season. Different methodological approaches are reviewed that have been introduced to improve N-fertilizer recommendations for arable crops. Many soil-based methods have been developed to measure soil mineral N (SMN) that is available for plants at a given sampling date. Soil sampling at the start of the growing period and analyzing for the amount of NO -N (and NH -N) is a widespread approach in Europe and North America. Based on data from field calibrations, the SMN pool is filled up with fertilizer N to a recommended amount. Depending on pre-crop, use of organic manure, or soil characteristics, the recommendation might be modified (±10,50,kg N ha,1). Another set of soil methods has been established to estimate the amount of N that is mineralized from soil organic matter, plant residues, and/or organic manure. From the huge range of methods proposed so far, simple mild extraction procedures have gained most interest, but introduction into practical recommendation schemes has been rather limited. Plant-analytical procedures cover the whole range from quantitative laboratory analysis to semiquantitative "quick" tests carried out in the field. The main idea is that the plant itself is the best indicator for the N supply from any source within the growth period. In-field methods like the nitrate plant sap/petiole test and chlorophyll measurements with hand-held devices or via remote sensing are regarded as most promising, because with these methods an adequate adjustment of the N-fertilizer application strategy within the season is feasible. Prerequisite is a fertilization strategy that is based on several N applications and not on a one-go approach. Boden- und Pflanzenanalyse zur Stickstoff-Düngebedarfsprognose in Ackerkulturen Unter- und Überdüngung mit N führen zu deutlichen ökonomischen Verlusten für Landwirte, da sowohl der Ertrag als auch die Qualität der Erzeugnisse vermindert werden. Auch aus ökologischer Sicht ist die richtige Entscheidung des Anbauers über Höhe und Zeitpunkt der N-Düngung von Bedeutung, um die Auswirkungen auf die Umwelt so gering wie möglich zu halten. Erschwerend kommt hinzu, dass N in sehr vielen Umweltkompartimenten in verschiedenen Bindungsformen (Nitrat, Ammonium, organisch gebundener N) vorkommt und dass N in verschiedenste Umsetzungsprozesse involviert ist (Mineralisation, Immobilisation, Auswaschung, Denitrifikation). Auch heutzutage orientieren sich viele Systeme, die zur N-Düngebedarfsprognose eingesetzt werden, im Wesentlichen an der Ertragserwartung. Dabei ist jedoch zu bedenken, dass weder der Ertrag als von Jahr zu Jahr stabil angesehen werden kann, noch dass die Prozesse, die das bodenbürtige N-Angebot bestimmen, zu Beginn der Vegetationsperiode hinreichend gut vorausgesagt werden können. Daher werden im Folgenden verschiedene methodische Ansätze erläutert, die zur Verbesserung der N-Düngebedarfsprognose für Ackerkulturen geeignet erscheinen. Viele Bodenanalyse-Methoden zielen darauf ab, den mineralischen N-Vorrat des Bodens, der an einem bestimmten Beprobungstermin als pflanzenverfügbarer N vorliegt, zu erfassen. Die Bodenprobeentnahme zu Beginn der Vegetationsperiode und die Bestimmung der Menge an Nitrat (und Ammonium) ist ein in Europa und Nord-Amerika weitverbreiteter Ansatz. Anhand der Daten aus Kalibrierversuchen kann dann abgeleitet werden, wie viel Dünger-N zum Auffüllen des N-Vorrats eingesetzt werden soll. In Abhängigkeit von Vorfrucht, Einsatz von Wirtschaftsdüngern oder weiteren Bodeneigenschaften kann diese Empfehlung modifiziert werden (± 10 bis 50,kg N ha,1). Weitere Bodenuntersuchungsmethoden wurden entwickelt, um die Menge des während der Vegetationszeit aus der organischen Bodensubstanz, aus Ernteresten und/oder aus Wirtschaftsdüngern mineralisierten N zu bestimmen. Obwohl aus der Vielzahl der vorgeschlagenen Methoden einfache "milde" Extraktionsverfahren eine gewisse Bedeutung erlangt haben, werden diese in der Praxis bei der Ermittlung des N-Düngebedarfs als zusätzliche Information nur selten berücksichtigt. Verfahren der Pflanzenanalyse umfassen einen weiten Bereich von quantitativen Laboranalysen bis zu halbquantitativen Schnelltests, die direkt auf dem Acker eingesetzt werden können. Die wesentliche Idee beim Einsatz der Pflanzenanalyse ist die Vorstellung, dass die Pflanze an sich der beste Indikator ist, die N-Verfügbarkeit aus den verschiedenen Quellen gewissermaßen kumulativ innerhalb der Wachstumszeit anzuzeigen. Methoden, die auf dem Acker eingesetzt werden können, wie z.,B. der Nitrat-Pflanzensaft- (oder Blattstiel-)Test sowie die Chlorophyll-Messung mit Handgeräten oder berührungslose Messverfahren haben den klaren Vorteil, dass sie eine schnelle Anpassung der N-Düngestrategie während der Vegetation ermöglichen. Voraussetzung dazu ist allerdings, dass die N-Düngestrategie nicht auf einer Einmal-Applikation beruht, sondern dass die N-Düngermenge auf mehrere Teilgaben verteilt wird. [source]

Effects of nitrate-, ammonium-, and organic-nitrogen-based fertilizers on growth and yield of tomatoes

Anuschka Heeb
Abstract Mineral and organic fertilizers contain different forms and amounts of nitrogen (N), which can affect yield and product quality. The aim of this study was to determine appropriate amounts of N applied as nitrate (NO), ammonium (NH), and organic N (a mixture based on chicken manure) for optimal growth and quality of tomatoes. A pot experiment with sand as substrate was established in a greenhouse with six-week-old tomato plants (Lycopersicon esculentum Mill. cv. "Armada"). Nitrogen was applied in nutrient solutions at different NO : NH ratios combined with different chloride levels (NO -dominated, NO = NH at low Cl,, NO = NH at high Cl,, and NH -dominated, respectively) or as organic N at four N-application rates (250, 500, 750, 1000 mg N plant,1 week,1). No significant differences in shoot biomass and yields of red tomatoes were observed between NO - or NH -fed plants. Nitrogen rates above 750 mg N plant,1 week,1 did not significantly increase marketable fruit yield, but enhanced shoot-biomass production. The NH -N-dominated treatments (which also had high Cl, concentrations) showed increasing incidence of blossom-end-rot (BER)-infected fruits. In the organic-N treatments, shoot-biomass production and yields were lower than in the inorganic-N treatments, but fruit quality was good with few BER-infected fruits. The results show that with a total N supply below 750 mg N plant,1 week,1, NH can be used as equivalent N source to NO, resulting in equivalent yields of marketable fruit under the conditions in this experiment. Einfluss von Nitrat, Ammonium und organischem Stickstoff auf Wachstum und Ertrag von Tomaten Mineralische und organische Dünger enthalten verschiedene Formen von und Mengen an Stickstoff (N), welche den Ernteertrag und die Produktqualität beeinflussen können. Das Ziel dieser Arbeit war es, geeignete N-Mengen , appliziert als Nitrat, Ammonium oder organischer Stickstoff , für optimales Wachstum und Qualität von Tomaten zu bestimmen. Dazu wurde mit sechs Wochen alten Tomatenpflanzen (Lycopersicon esculentum Mill. cv. "Armada") unter Gewächshausbedingungen mit Sand als Substrat ein Gefäßversuch angelegt. Die Applikation von N erfolgte in Form von Nährlösungen mit verschiedenen NO:NH -Verhältnissen, kombiniert mit unterschiedlichen Chlorid (Cl)-Konzentrationen (NO -dominiert, NO = NH bei niedrigem Cl,, NO = NH bei hohem Cl, und NH -dominiert) bzw. als organischer N. Jede dieser Behandlungen wurde mit vier verschiedenen N-Mengen angelegt (250, 500, 750, 1000 mg N Pflanze,1 Woche,1). Zwischen den mit Nitrat und Ammonium gedüngten Pflanzen konnte kein signifikanter Unterschied in Sprosswachstum und Ertrag an erntereifen Tomaten festgestellt werden. Stickstoffmengen über 750 mg N Pflanze,1 Woche,1 steigerten den Ertrag verkaufsfähiger Tomaten nicht signifikant, obwohl die Produktion an Sprossbiomasse noch anstieg. In den NH -dominiert gedüngten Gefäßen mit gleichzeitig hohen Cl-Konzentrationen in den Nährlösungen wurden häufiger Tomaten mit Blütenendfäule beobachtet. In den Behandlungen mit organischem Stickstoff waren die Sprossbiomasseproduktion und der Ertrag geringer als in den mineralisch gedüngten Behandlungen, aber die Qualität der Früchte war gut, mit nur wenigen durch Blütenendfäule geschädigten Tomaten. Die Ergebnisse zeigen, dass bei einer Stickstoffversorgung unter 750 mg N Pflanze,1 Woche,1 Ammonium anstelle von Nitrat verwendet werden kann. Im vorliegenden Versuch wurden unter diesen Bedingungen vergleichbare Erträge verkaufsfähiger Früchte erzielt. [source]

Nitrogen fertilisation in coriander (Coriandrum sativum L.): a review and meta-analysis

Alessandra Carrubba
Abstract Nitrogen (N) fertilisation is one of the most important external inputs in assessing coriander seed yield and plant growth. Recent concerns related to the misuse of N fertilisers in agricultural environments, however, stress the opportunity for a fine-tuning of N management in order to optimise the use of this element, avoiding losses and reducing environmental hazards. In this study, some results from the literature concerning N fertilisation in coriander are reviewed and, by means of statistical analysis, an attempt is made to derive from them some general suggestions about practices of N fertilisation. In most cases examined, N fertilisation allowed a 10,70% increase in seed yields in comparison with each respective untreated control. The efficiency of use of this element, however, has proven to be greatly dependent on the overall fertility conditions of the growing site. The greatest yield advantages were actually found in more favourable environments, whereas in low-yielding environments plants reached their maximum yield with a comparatively reduced N supply. In low-yielding environments a careful risk/benefit assessment of this practice is therefore advisable. No definite conclusion could be drawn at this stage about essential oil yield and composition in relation to N fertilisation. Copyright © 2009 Society of Chemical Industry [source]

Long-term increase in nitrogen supply alters above- and below-ground ectomycorrhizal communities and increases the dominance of Russula spp. in a temperate oak savanna

Peter G. Avis
Summary ,,Here we examine the effects of increased nitrogen (N) supply on the ectomycorrhizal fungal communities of a temperate oak savanna. ,,In a 16-yr N-addition experiment in which replicate 1000 m2 plots received 0, 5.4 or 17 g N m,2 yr,1, ectomycorrhizal sporocarp production was measured in the 14th, 15th and 16th year of fertilization. Ectomycorrhizal fungi (EMF) colonizing roots were examined by morphotyping-PCR-RFLP and sequence analysis in the 14th and 15th year of fertilization. ,,Total sporocarp richness was reduced by > 50% in both fertilization treatments in all 3 yrs, whereas Russula spp. produced approx. five times more sporocarps with 17 g N m,2 yr,1. Below-ground, treatment-scale species richness and species area curves were lower with 17 g N m,2 yr,1 but richness, diversity indices and evenness at smaller spatial scales were not. Dominant fungi colonizing roots included Cenococcum geophilum, common in all treatments, Cortinarius spp., dominant in unfertilized plots, and Russula spp., dominant with 17 g N m,2 yr,1. ,,Communities of EMF in this temperate deciduous ecosystem responded to N addition similarly to those of coniferous ecosystems in that increased N supply altered EMF diversity and community composition but differently in that dominance of Russula spp. increased. [source]

How can we predict the effects of elevated CO2 on the balance between perennial C3 grass species competing for light?

F. Teyssonneyre
Summary ,,Changes in the balance between mixed plant species have been reported under elevated [CO2] compared with ambient atmospheric [CO2]. We hypothesized that species response to elevated CO2 in mixture can be explained by taking into account resource partitioning between mixed species. ,,This hypothesis was tested experimentally on three perennial C3 grass species (Lolium perenne, Festuca arundinacea and Holcus lanatus) grown in monocultures and in binary mixtures (Lolium,Festuca and Lolium,Holcus) under mild (frequent cuts) or severe (infrequent cuts) competition for light and at a high N supply (40 g N m,2). ,,Under mild competition for light, the dry matter yield response to elevated CO2 of the mixed grass species was similar to that observed in monocultures. By contrast, under severe light competition, the grass species that absorbed more light per unit leaf area (Holcus and Festuca), also had a greater response to elevated CO2 in mixture compared with monoculture. ,,Under our experimental conditions, we have shown that the dry matter yield response to CO2 in mixture can be predicted from both the species response in monoculture, and the light capture per unit leaf area in ambient CO2 of the mixed compared with the pure grasses. [source]

What are the effects of nitrogen deficiency on growth components of lettuce?

Relationships between nitrogen (N) content and growth are routinely measured in plants. This study determined the effects of N on the separate morphological and physiological components of plant growth, to assess how N-limited growth is effected through these components. Lettuce (Lactuca sativa) plants were grown hydroponically under contrasting N-supply regimes, with the external N supply either maintained continuously throughout the period of study, or withdrawn for up to 14 d. Richards' growth functions, selected using an objective curve-fitting technique, accounted for 99.0 and 99.1% of the variation in plant dry weight for control and N-limited plants respectively. Sublinear relationships occurred between N and relative growth rates under restricted N-supply conditions, consistent with previous observations. There were effects of treatment on morphological and physiological components of growth. Leaf weight ratio increased over time in control plants and decreased in N- limited plants. Shoot:root ratio followed a similar pattern. On a whole-plant basis, assimilation of carbon decreased in N-limited plants, a response paralleled by differences in stomatal conductance between treatments. Changes in C assimilation, expressed as a function of stomatal conductance to water vapour, suggest that the effects of N limitation on growth did not result directly from a lack of photosynthetic enzymes. Relationships between plant N content and components of growth will depend on the availability of different N pools for remobilization and use within the plant. [source]

Modification of Primary and Secondary Metabolism of Potato Plants by Nitrogen Application Differentially Affects Resistance to Phytophthora infestans and Alternaria solani

PLANT BIOLOGY, Issue 5 2006
K. Mittelstraß
Abstract: Potato plants (Solanum tuberosum L. cv. Indira) were grown at two levels of N supply in the greenhouse. Plants supplied with 0.8 g N per plant (high N variant) showed significantly increased biomass as compared to plants without additional N fertilisation (low N variant). C/N ratio was lower and protein content was higher in leaves of the high N variant. The concentration of chlorogenic acids and flavonols was significantly lower in leaves from the high N variant. Whereas resistance to Alternaria solani increased when plants were supplied with additional nitrogen, these plants were more susceptible to Phytophthora infestans. After infection with both pathogens, we found a strong induction of p-coumaroylnoradrenaline and p-coumaroyloctopamine, which are identified for the first time in potato leaves and are discussed as resistance factors of other solanaceous plants. [source]

Growth-Promoting Nitrogen Nutrition Affects Flavonoid Biosynthesis in Young Apple (Malus domestica Borkh.) Leaves

PLANT BIOLOGY, Issue 6 2005
T. Strissel
Abstract: Enhanced shoot growth and a decrease in flavonoid concentration in apple trees grown under high nitrogen (N) supply was observed in previous studies, along with increasing scab susceptibility of cultivar "Golden Delicious" after high N nutrition. Several hypotheses have suggested that there is a trade-off between primary and secondary metabolism because of competition for common substrates, but nothing is known about regulation at the enzyme level. In this study, a set of experiments was performed to elucidate the effect of N nutrition on the activities of key enzymes involved in flavonoid biosynthesis (phenylalanine ammonia-lyase [PAL], chalcone synthase/chalcone isomerase [CHS/CHI}, flavanone 3-hydroxylase [FHT], flavonol synthase [FLS], dihydroflavonol 4-reductase [DFR]) and the accumulation of different groups of phenylpropanoids. The inhibition of flavonoid accumulation by high N nutrition could be confirmed, but the influence of N supply on the flavonoid enzymes CHS/CHI, FHT, DFR, and FLS was not evident. However, PAL activity seems to be downregulated, thus forming a bottleneck resulting in a generally decreased flavonoid accumulation. Furthermore, the response of the scab-resistant cultivar "Rewena" to high N nutrition was not as strong as that of the susceptible cultivar "Golden Delicious". [source]

Control of Nitrate Uptake by Phloem-Translocated Glutamine in Zea mays L. Seedlings

PLANT BIOLOGY, Issue 4 2002
P. Pal'ove-Balang
Abstract: The putative role of glutamine, exported from leaves to roots, as a negative feedback signal for nitrate uptake was investigated in Zea mays L. seedlings. Glutamine (Gln) was supplied by immersion of the tip-cut leaves in a concentrated solution. Nitrate (NO3,) uptake was measured by its depletion in amino acid-free medium. The treatment with Gln resulted in a strong inhibition of nitrate uptake rate, accompanied by a significant enrichment of amino compounds in root tissue. The effect of N-availability on NO3, uptake was determined in split-root cultures. The plants were subjected to complete or localized N supply. Inducible NO3, uptake systems were also induced in N-deprived roots when the opposite side of the root system was supplied with KNO3. The inhibitory effect of Gln was unaffected by localized N supply on one side of the split-root. The potential role of Gln in the shoot-to-root control of NO3, uptake is discussed. [source]

Nitrogen uptake and utilization efficiency of European maize hybrids developed under conditions of low and high nitrogen input

PLANT BREEDING, Issue 6 2002
T. Presterl
Abstract Maize varieties with improved nitrogen(N)-use efficiency under low soil N conditions can contribute to sustainable agriculture. Tests were carried to see whether selection of European elite lines at low and high N supply would result in hybrids with differential adaptation to these contrasting N conditions. The objective was to analyze whether genotypic differences in N uptake and N-utilization efficiency existed in this material and to what extent these factors contributed to adaptation to low N supply. Twenty-four hybrids developed at low N supply (L × L) were compared with 25 hybrids developed at high N supply (H × H). The N uptake was determined as total above-ground N in whole plants, and N-utilization efficiency as the ratio between grain yield and N uptake in yield trials at four locations and at three N levels each. Highly significant variations as a result of hybrids and hybrids × N-level interaction were observed for grain yield as well as for N uptake and N-utilization efficiency in both hybrid types. Average yields of the L × L hybrids were higher than those of the H × H hybrids by 11.5% at low N supply and 5.4% at medium N level. There was no significant yield difference between the two hybrid types at high N supply. The L × L hybrids showed significantly higher N uptake at the low (12%) and medium (6%) N levels than the H × H hybrids. In contrast, no differences in N-utilization efficiency were observed between the hybrid types. These results indicate that adaptation of hybrids from European elite breeding material to conditions with reduced nitrogen input was possible and was mainly the result of an increase in N-uptake efficiency. [source]

Does soil nitrogen influence growth, water transport and survival of snow gum (Eucalyptus pauciflora Sieber ex Sprengel.) under CO2 enrichment?

ABSTRACT Eucalyptus pauciflora Sieber ex Sprengel. (snow gum) was grown under ambient (370 µL L,1) and elevated (700 µL L,1) atmospheric [CO2] in open-top chambers (OTCs) in the field and temperature-controlled glasshouses. Nitrogen applications to the soil ranged from 0.1 to 2.75 g N per plant. Trees in the field at high N levels grew rapidly during summer, particularly in CO2 -enriched atmosphere, but suffered high mortality during summer heatwaves. Generally, wider and more numerous secondary xylem vessels at the root,shoot junction in CO2 -enriched trees conferred fourfold higher below-ground hydraulic conductance. Enhanced hydraulic capacity was typical of plants at elevated [CO2] (in which root and shoot growth was accelerated), but did not result from high N supply. However, because high rates of N application consistently made trees prone to dehydration during heatwaves, glasshouse studies were required to identify the effect of N nutrition on root development and hydraulics. While the effects of elevated [CO2] were again predominantly on hydraulic conductivity, N nutrition acted specifically by constraining deep root penetration into soil. Specifically, 15,40% shallower root systems supported marginally larger shoot canopies. Independent changes to hydraulics and root penetration have implications for survival of fertilized trees under elevated atmospheric [CO2], particularly during water stress. [source]

Long-term influence of manure and mineral nitrogen applications on plant and soil 15N and 13C values from the Broadbalk Wheat Experiment,

Mehmet Senbayram
The Broadbalk Wheat Experiment at Rothamsted Research in the UK provides a unique opportunity to investigate the long-term impacts of environmental change and agronomic practices on plants and soils. We examined the influence of manure and mineral fertiliser applications on temporal trends in the stable N (15N) and C (13C) isotopes of wheat collected during 1968,1979 and 1996,2005, and of soil collected in 1966 and 2000. The soil ,15N values in 1966 and 2000 were higher in manure than the mineral N supplied soil; the latter had similar or higher ,15N values than non-fertilised soil. The straw ,15N values significantly decreased in all N treatments during 1968 to 1979, but not for 1996,2005. The straw ,15N values decreased under the highest mineral N supply (192,kg,N,ha,1,year,1) by 3, from 1968 to 1979. Mineral N supply significantly increased to straw ,13C values in dry years, but not in wet years. Significant correlations existed between wheat straw ,13C values with cumulative rainfall (March to June). The cultivar Hereward (grown 1996,2005) was less affected by changes in environmental conditions (i.e. water stress and fertiliser regime) than Cappelle Desprez (1968,1979). We conclude that, in addition to fertiliser type and application rates, water stress and, importantly, plant variety influenced plant ,13C and ,15N values. Hence, water stress and differential variety response should be considered in plant studies using plant ,13C and ,15N trends to delineate past or recent environmental or agronomic changes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Mitochondrial respiratory pathways modulate nitrate sensing and nitrogen-dependent regulation of plant architecture in Nicotiana sylvestris

Till K. Pellny
Summary Mitochondrial electron transport pathways exert effects on carbon,nitrogen (C/N) relationships. To examine whether mitochondria,N interactions also influence plant growth and development, we explored the responses of roots and shoots to external N supply in wild-type (WT) Nicotiana sylvestris and the cytoplasmic male sterile II (CMSII) mutant, which has a N-rich phenotype. Root architecture in N. sylvestris seedlings showed classic responses to nitrate and sucrose availability. In contrast, CMSII showed an altered ,nitrate-sensing' phenotype with decreased sensitivity to C and N metabolites. The WT growth phenotype was restored in CMSII seedling roots by high nitrate plus sugars and in shoots by gibberellic acid (GA). Genome-wide cDNA-amplified fragment length polymorphism (AFLP) analysis of leaves from mature plants revealed that only a small subset of transcripts was altered in CMSII. Tissue abscisic acid content was similar in CMSII and WT roots and shoots, and growth responses to zeatin were comparable. However, the abundance of key transcripts associated with GA synthesis was modified both by the availability of N and by the CMSII mutation. The CMSII mutant maintained a much higher shoot/root ratio at low N than WT, whereas no difference was observed at high N. Shoot/root ratios were strikingly correlated with root amines/nitrate ratios, values of <1 being characteristic of high N status. We propose a model in which the amine/nitrate ratio interacts with GA signalling and respiratory pathways to regulate the partitioning of biomass between shoots and roots. [source]

Seeking a sound index of competitive intensity: Application to the study of biomass production under elevated CO2 along a nitrogen gradient

Abstract The aim of this paper is to evaluate (i) the relevance of currently proposed measures of competitive intensity to elevated CO2 studies by means of an example analysis, hypothesizing that competitive intensity is increased under elevated CO2; and (ii) an alternative method for predicting species performance in mixtures from monocultures. Relative competition intensity (RCI), relative physiological performance and normalized ecological performance were used to characterize the competitive ability of two grasses (Danthonia riclwrdsonii Cashmore, Phalaris aquatica L.) and two legumes (Lotus pedunculatus Cav, Trifoliuni repens L.) grown in monocultures and mixtures of the four species along a N gradient under conditions of ambient and elevated CO2. Relative competition intensity could not be used to predict competitive outcomes in mixtures under conditions of elevated CO2 because it failed to account for changes in the size of interspecific differences along the N gradient and between CO2 concentrations. Relative physiological performance and relative ecological performance were more useful for investigating biomass production in mixtures and to predict species performance in mixtures from their performance in monocultures. Both indices of relative performance showed an increase in competitive intensity under elevated CO2 conditions. They also showed a decrease in competitive intensity with increasing N supply over most of the range of N supply, but a reversal of that trend at high levels of N supply. The merits and utility of these relative performance indices for elevated CO2 are discussed. [source]

Effects of timing and rate of N supply on leaf nitrogen status, grape yield and juice composition from Shiraz grapevines grafted to one of three different rootstocks

Abstract Yeast cells have a minimum N requirement to ferment a must through to dryness, so that grape N content (hence must N) becomes critical in meeting that prerequisite. Viticultural practices aimed at meeting that N requirement are of special relevance because interactions between rootstock and vineyard nitrogen supply strongly influence scion mineral nutrient status as well as shoot vigour, and via those processes, fruit composition. Such outcomes were investigated in a field trial involving Shiraz on three rootstocks viz. Teleki 5C, Schwarzmann and Ramsey. Five N supply regimes, varying from 0 to 80 kg/(haseason), were imposed through a drip-irrigation system during two periods (either flowering to veraison, or post-harvest to leaf-fall, or both) over three successive growing seasons. Post-harvest N supply increased scion leaf N and nitrate N concentrations at flowering for vines on Teleki 5C and Schwarzmann. By veraison, N recently applied in the flowering to veraison period elevated these indicators of N status in all vines on all rootstocks. Grape yields from vines on Teleki 5C and Schwarzmann were elevated by N supply after harvest, whereas juice soluble solids levels were lowered. Free amino acids in Shiraz juice were dominated by non-assimilable N, amounting to about 50% or more of the total free amino-N in the juice. Increasing N supply increased free amino acid concentrations in the juice of berries from vines on all rootstocks, but only vines on Schwarzmann derived any benefit from N supplied after harvest. The highest concentrations of free amino acids were measured in the berries from vines on Schwarzmann receiving 80 kg N/(ha.season). Of immediate practical relevance for N management of Shiraz grapevines on either Teleki 5C or Ramsey rootstocks, the minimum value for assimilable free amino-N concentration required to ferment a must through to dryness was not achieved if vineyard N application was limited to the post-harvest period. [source]

Biomass distribution and nitrate assimilation in response to N supply for Vitis vinifera L. cv. Cabernet Sauvignon on five Vitis rootstock genotypes

Abstract Effects of nitrogen (N) supply on biomass distribution as well as N effects on NO3"assimilation, were examined in two-year-old graftlings of Vitis vinifera L. cv. Cabernet Sauvignon on five rootstocks. Whole-plant biomass in all graftlings more than doubled with increased N supply in solution from 0.25 to 8 mM. Whole plant biomass was also affected by rootstock genotype, but to a lesser extent than by N supply. Biomass allocation to roots declined with increased N supply for all stock-scion combinations, but the magnitude of that response varied with rootstock genotype. Nitrate reductase activity (NRA) in leaves increased with increased N supply for all stock-scion combinations, whereas root NRA increased only up to 1 mM N supply, dropping markedly with additional N. NRA in leaves was one to two orders of magnitude higher than NRA in roots - a difference that increased steadily with increased N supply. By implication, grapevine leaves have a much higher capacity for NO3 - - reduction than do grapevine roots, and any contribution by roots to whole-vine NO3 - - assimilation declines even further as NO3 - - availability increases. [source]