Levels Of Ammonium Nitrate Research Articles

Effect of Different Ammonium Nitrate Levels on the Performance of Cool-Climate Grass Species Grown in Çanakkale Conditions

This study was conducted to investigate effects of different levels of ammonium nitrate (33% N) dose (0, 50 and 100 g m-2) on morphological and quality traits of 3 different commonly cultivated turfgrass species (Lolium perenne ‘TOPGUN’, Festuca rubra ‘SERGEİ’ and Poa pratensis ‘AVALANCHE’) which are widely preferred in grass mixtures prepared for green areas in Çanakkale (Turkey). Fertilization treatments had positive effects on morphological parameters, except for germination power and germination rate parameters. In terms of landscape related aesthetic quality and growth percentage, 50 g m-2 and fertilization was found to be more suitable for Lolium perenne, while 100 g m-2 fertilization provided better performance for Festuca rubra. The 50 and 100 g m-2 fertilization rates yielded similar results for Poa pratensis in terms of general grass quality. It was observed that 50 g m-2 ammonium nitrate had a positive effect on root area and volume compared to other applications. In this application (50 g m-2 ammonium nitrate), the positive features of the root (high root area and volume) are the features that can prevent the grass plant from breaking off from the soil.

Shortening the Vegetative Growth Stage of Phalaenopsis Queen Beer ‘Mantefon’ by Controlling Light with Calcium Ammonium Nitrate Levels under Enriched CO2

The vegetative growth, photosynthetic, and stomatal characteristics were investigated in Phalaenopsis Queen Beer ‘Mantefon’ to determine light’s influence with calcium ammonium nitrate (CAN) levels under 800 μmol·mol−1 CO2. Two lights (150 ± 20 and 300 ± 20 μmol·m−2·s−1) and CAN levels were employed for 40 weeks: calcium, ammonium, and nitrate levels by 0.90, 0.55, and 2.97 mmol·L−1 (CAN1), 8.63, 1.11, and 6.05 mmol·L−1 (CAN2), 12.80, 1.72, and 9.13 mmol·L−1 (CAN3), and 18.80, 2.27, and 12.20 mmol·L−1 (CAN4), respectively. The number of leaves increased in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1 compared to control. Plants grown at 300 ± 20 μmol·m−2·s−1 with CAN4 had the lowest number of leaves among all plants. The time to the mature leaf span decreased in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1. The net CO2 uptake was higher in the plants grown at 300 ± 20 μmol·m−2·s−1 than those grown at 150 ± 20 μmol·m−2·s−1 with CAN1–3 conditions. The water-use efficiency is higher in the plants grown with CAN1 than those with CAN2–4 at 300 ± 20 μmol·m−2·s−1. The maximum stomatal aperture was the largest in the plants grown at 300 ± 20 μmol·m−2·s−1 with CAN1–2 among all plants. Consequently, light levels of 300 ± 20 μmol·m−2·s−1 in Phalaenopsis Queen Beer ‘Mantefon’ must be accompanied by nutrient CAN1 to improve photosynthesis and stomatal activity and promote leaf growth under 800 μmol·mol−1 CO2 conditions.

Effects of Acute Ammonium Nitrate Levels Caused by Agricultural Activities on Four Amphibian Species in The Eastern Black Sea Region

The tadpoles of four amphibian species, namely the Marsh Frog (Pelophylax ridibundus), the Iranian Long-Legged Frog (Rana macrocnemis), the Caucasian Parsley Frog (Pelodytes caucasicus) and the Variable Green Toad (Bufotes variabilis), were exposed to acute concentrations (0 to 500 mg/L) of ammonium nitrate to assess the lethal effects (larval growth, abnormalities, mortality, and LC50 values). Eggs of each species were obtained from clean and polluted habitats in the same region and the tadpoles for experiments were provided from those eggs in the laboratory conditions. Although there was some variability between different populations of the same species or between different species in the observed effects, acute levels of ammonium nitrate caused decreased growth rate and increased abnormalities and mortality in general. Among the 4 amphibian species, the Variable Green Toad was the most damaged one in terms of growth reduction (on average 77-83%), and abnormality rates, and the most damaged one in terms of mortality rates was the Marsh Frog (on average 61-72%). Additionally, the species with the lowest concentration of ammonium nitrate, which killed half of its population, was the Marsh Frog. LC50 values for two populations of Marsh Frog were 37 and 59 mg/L. As a result of our research, it was determined that the acute fertilizer levels caused by agricultural activities in the region had very important harmful effects for all the species we examined. In this context, it can be said that very important environmental and biodiversity problems may occur if certain precautions are not taken regarding the use of the fertilizers and if the awareness of the farmers using these fertilizers cannot be raised.

Effects of Environmentally Relevant Ammonium Nitrate Levels Caused by Agricultural Activities on Four Amphibian Species in The Eastern Black Sea Region

Within the scope of this research, the chronic effects of ammonium nitrate, which is the most widely used fertilizer worldwide, on the tadpoles of Marsh Frog (Pelophylax ridibundus), the Iranian Long-Legged Frog (Rana macrocnemis), the Caucasian Parsley Frog (Pelodytes caucasicus) and the Variable Green Toad (Bufotes variabilis) were examined. To assess the chronic effects of the fertilizer, the tadpoles of all the species were exposed to 0, 5, 10, 15, 20, 25 mg/L concentrations in same conditions. The chronic concentrations were applied from the 25th developmental stage to the 42nd developmental stage. It was defined at the end of the experiments that although there were some variability between different populations of the same species or between different species in the observed effects, chronic levels of ammonium nitrate caused decreased growth rate, prolonging in time to complete metamorphosis, increased abnormalities, and mortality in general. Among the 4 amphibian species, the Variable Green Toad was the most damaged one in terms of growth reduction (on average 31-41 %), abnormality rates (on average 50-75 %), prolonged time to complete metamorphose (14-21 days on average) and mortality rates (%54-100). The most adaptive species and the least damaged one was an Iranian long-legged frog for growth reduction (on average 0-15 %), prolonged time to complete metamorphose (7-9 days on average), and mortality rates (%9-15). All the harmful effects of chronic fertilizer levels caused by agricultural activities in the region had very important for examined species in our researches and it can be said that important environmental and biodiversity problems may occur if certain precautions are not taken regarding the use of the fertilizers and if the attitudes of the farmers on this issue cannot be changed.

Factors Affecting Foliar Oregonin and Condensed Tannin in Red Alder (Alnus rubra Bong.): Phytochemicals Implicated In Defense Against Western Tent Caterpillar (Malacosoma californicum Packard).

Past work shows a significant negative correlation between foliar oregonin concentration and western tent caterpillar (Malacosoma californicum Packard) feeding on red alder (Alnus rubra Bong.). Above an oregonin threshold of 20% leaf dry weight, little feeding by caterpillars is observed. Concentrations of defensive chemicals are influenced by plant genotype, environmental conditions, insect feeding, and the interactions of these factors. Our objective was to measure the effects of nitrogen (N) availability and wounding on foliar oregonin and condensed tannin concentrations in red alder genotypes. One-year-old seedlings from 100 half-sib red alder families were treated with two levels of ammonium nitrate (NH4NO3) for two growing seasons in a common garden. In the second year, leaves from 50 families from the fertilization experiment were used in a bioassay feeding experiment to determine the effects of N fertilization and genotype on WTC damage, and to identify a subset of 20 families with a range of damage to analyze for phytochemical composition. In separate experiments, wound-induction treatments were conducted outdoors and, in a greenhouse using the N treated trees in their third and fourth year, respectively. Foliar condensed tannin, oregonin and N concentrations were measured and ranked among the plant genotypes, and between the two N treatments and two wounding treatments. Results showed that oregonin and condensed tannin concentrations varied among the alder genotypes. Leaf N concentration was negatively correlated with concentration of oregonin. Neither of the measured phenolic compounds responded to wounding. The results suggest that red alder foliar oregonin and condensed tannin are likely constitutive defenses that are largely determined by genotype, and that the negative correlation of defense compounds with plant internal N status holds in this N-fixing tree.

Growth and Transcriptional Changes in Poplar Under Different Nitrogen Sources

Nitrogen greatly affects primary plant growth and development. The relationship between nitrogen availability and source and its effect on secondary growth is less well characterized. RNAseq has been used in various experiments to study changes in the plant transcriptome under experimental conditions. In this study, we first characterize the phenotypes of three tree species grown on varying nitrogen sources and levels. We then further characterize one of these three genotypes using RNAseq to identify differentially regulated genes under these varied conditions. Poplar trees were supplied with ammonium, nitrate, or ammonium nitrate. Ammonium nitrate was supplied under two concentrations. While there were few phenotypic changes in the three tree species assessed, each species had some changes in photosynthetic efficiency and biomass. Leaf weight was significantly different in two genotypes under high levels of ammonium nitrate. There was no change in height in any of the lines. Water use efficiency increased at higher N levels. Cell wall composition did not change across all genotypes for all treatments, with the exception of higher lignin in some high N conditions, contrary to previous studies. RNAseq revealed 8965 genes differentially regulated by a minimum of 1-fold with the largest changes seen in the nitrate and ammonium nitrate treatments. Assessment of the genes using MapMan showed that most genes belonged to stress response, nucleotide production, and photosynthesis reactions. The understanding of the relationship between nitrogen availability and secondary cell wall production is still limited. Here we show an unexpected result with increased lignin in high N treatments that may be development stage–specific. In addition, our results suggest that additional work in the area of understanding the impact of N on plant stress resistance is warranted.

Valorização agrícola de lamas de ETAR – disponibilidade de azoto

With the aim to study nitrogen availability from sewage sludge, a pot trial was installed under greenhouse conditions, using maize (Zea mays L.) as plant test. The experimental design was a completely randomized blocks with three replications and thirteen experimental treatments: control; four levels of N from sludge; four levels of N from a salt (NH4NO3) and four levels of N resulted of the sludge and salt mixture in equal quantities. Increasing amounts of sludge gave significantly increased yields (p=0.05) causing the larger response to the equivalent application level of 60 t ha‑1. The combined application of nitrogen in the mineral and sludge form proved to be a viable technique to supply the nitrogen needs of the crops, and led to the higher yields of the aerial part of the plant test and to larger amounts of removed nitrogen. The nitrogen recovery from the mixture of sludge and ammonium nitrate was statistically higher than the observed quantities when only sludge was applied and at the highest application level of ammonium nitrate.

Farklı Azotlu Gübre Form ve Dozlarının Narince (V. Vinifera) Üzüm Çeşidinde Salamuralık Taze Asma Yaprak Verimine Etkisi

Bu çalışmanın amacı, Narince üzüm çeşidine (Vitis Vinifera L) üç farklı form (amonyum nitrat, amonyum sülfat, üre) ve 4 farklı dozda (kontrol, 5, 10 ve 15 kg/da N) azot uygulamalarının taze asma yaprak verimine olan etkisi araştırılmıştır. 2012 vejetasyon periyodunda kordon şeklinde terbiye edilmiş asmalar bir veya iki göz üzerinden (24 göz/asma) dekara 5000 göz olacak şekilde şarj edilmiştir. Azotun dört farklı dozu bölünmüş parseller deneme desenine göre 4 tekerrürlü olarak asmalara uygulanmıştır. Salamuralık genç asma yaprakları beş dönemde hasat edilmiş ve taze yaprak verimi (kg/da) belirlenmiştir. Hasat edilen yaprak örneklerinde gübre formlarının yaprak verimi üzerine etkisi istatistiki olarak önemli bulunmuştur. Taze asma yaprak verimi 312,4 kg/da (Kontrol) ile 437,1 kg/da (Amonyum nitrat 10 kg N/da) arasında değişmiştir. Azot dozları arttıkça asma yaprağı verimi de artmıştır. Azot uygulaması taze yaprak verimini yaklaşık %30 artırmıştır. Deneme sonuçlarına göre, en yüksek asma yaprağı verimi 10 kg N/da uygulamasından alınmıştır. Amonyum nitrat uygulamaları ile diğer gübre formlarından daha yüksek yaprak verimi elde edildiği ortaya çıkmıştır.

Seed germination, vegetative growth and concentration of some elements in French marigold (Tageta patula) as influenced by salinity and ammonium nitrate

Marigold has special importance and application in landscape designing. Nowadays, various species and cultivars of this plant are grown in many climates, where different environmental stresses such as freezing, salinity and drought can lead to vegetative disorders. This study was carried out to investigate the interactions between salinity and ammonium nitrate on seed germination, vegetative growth and sodium and potassium concentrations in French marigold flowers (Tegeta patula). The experiment was conducted as a factorial arrangement based on a completely randomized design with two factors: salinity (0, 2, 4, 6 and 8 mmos cm-1) and ammonium nitrate (0, 15 and 30 g l-1) with four replications. Based on the obtained results, different salinity concentrations were negatively influenced all studied parameters except germination rate. The application of ammonium nitrate recovered the studied parameters to the same level as the control plants. Plant height was decreased by increasing salinity concentrations. The tallest plant was observed in the control treatments. Salinity levels negatively influenced shoot fresh weight. Different levels of ammonium nitrate had significant effects on root dry weight and potassium and sodium contents. Ammonium nitrate led to reductions in root dry weight and potassium content, and an enhancement in sodium content in the shoot. Sodium and potassium levels were increased and root dry weight was decreased by increasing salinity. Enhancement of potassium ions in the marigold following salinity stress can improve its tolerance to salinity stress.

Modified medium for micropropagation of recalcitrant potato cv. Kufri Jyoti

Experiments were conducted to devise an efficient micro-propagation medium for mass multiplication of a high yielding but recalcitrant potato cv. Kufri Jyoti using nodal explant with different concentrations and combinations of NHNOGAand NAA. Virus-indexed nodal cuttings established in full-strength Murashige and 43, 3 Skoog (1962) basal salts and vitamins, supplemented with 0.29 μM GA3 and 0.05 μM NAA was used as explants for the experiment. Among the various media tested, MS medium with increased level of ammonium nitrate (25.79 mM) supplemented with GA3 (0.58 μM) and NAA (0.1 μM) was found to be optimum as it significantly improved the shoot length, number of leaves, number of nodes and inter nodal length after 21 days of sub culturing. The next higher concentration of ammonium nitrate (30.94 mM) supplemented with GA3 (0.58 μM) and NAA (0.1 μM) also exhibited statistically at par response in most of the morphological characters but higher concentration (41.25 mM) retarded all the parameters studied.

Origins of extreme broadening mechanisms in near-edge x-ray spectra of nitrogen compounds

We demonstrate the observation of many-body lifetime effects in valence-band x-ray emission. A comparison of the N $K\ensuremath{\alpha}$ emission of crystalline ammonium nitrate to molecular-orbital calculations revealed an unexpected, extreme broadening of the NO $\ensuremath{\sigma}$ recombination---so extensively as to virtually disappear. GW calculations establish that this disappearance is due to a large imaginary component of the self-energy associated with the NO $\ensuremath{\sigma}$ orbitals. Building upon density-functional theory, we have calculated radiative transitions from the nitrogen $1s$ level of ammonium nitrate and ammonium chloride using a Bethe-Salpeter method to include electron-hole interactions. The absorption and emission spectra of both crystals evince large, orbital-dependent sensitivity to molecular dynamics. We demonstrate that many-body effects as well as thermal and zero-point motion are vital for understanding observed spectra. A computational approach using average atomic positions and uniform broadening to account for lifetime and phonon effects is unsatisfactory.

Carrot Yield and Quality as Influenced by Nitrogen Application in Cut-and-Peel Carrots

Root bulking, quality, and uniformity in cut-and-peel carrots (Daucus carota) are paramount for optimizing marketable yield and quality. Root bulking is an ecophysiological manifestation in response to inputs such as fertilizers. Understanding this ecophysioloical interaction will help to optimize yield, quality, and amount of inputs used. Three years of field trials were conducted in Kings County, Nova Scotia, to investigate the effects of varying levels of nitrogen (N) fertilizer on yield, recovery, and root and tissue N of two cut-and-peel varieties, Sugarsnax and TopCut. Seven levels of ammonium nitrate (34–0–0; 0, 50, 100, 150, 200, 300, and 400 kg N h−1) were hand broadcast in a split (60% pre-emergence and 40% 8 weeks after emergence) application. No significant interactive effects of N and variety in terms of gross yield or recovery were observed, though Sugarsnax total yields were 12.7% greater than those of TopCut. Overall, optimum yields were achieved at N rates of 150 kg N h−1 and further addition did not significantly improve yield or quality. Increased N significantly increased root and tissue N, but N concentration in both tissues peaked at the 300 kg N h−1 rate. However, neither root nor leaf tissue N had any effect on marketable or total yield. These results show that root bulking is not modulated by altering N applications, and the results also suggest that carrots may have high N-use efficiency or harness N from deeper zones.

Impact of Opened, Non Opened Pollination and Nitrogen Fertilizer on Sesame Production in the Reclaimed Lands, Ismailia Governorate, Egypt

Abstract The research was conducted at the Agriculture Research Farm, Faculty of Agriculture, University of Suez Canal, during the sesame growing seasons of 2011 and 2012. For studying the impact of insect pollination and nitrogen fertilization on sesame production, the experiment was divided to 13 treatments of open pollination and non open pollination, with three different levels of ammonium nitrate (NH4NO3) and one level of seryalin as biofertilizer. Non opened pollination treatments were covered before the start of flowering period with a perforated net bag, to allow the air to pass through and to prevent insects from approaching the plants. Quantitative and qualitative indicators, were measured as follows: rate of capsule per plant, capsule weight, rate of seeds in each capsule, weight of 1000 seeds, germination (%), seedlings vigour and oil content (%). Results clearly demonstrate that qualitative and quantitative indicators of sesame crop was significantly increased with opened pollination and with the increase of nitrogen fertilizer level up to 40 kg N/feedan-1 plus or minus seryalin, in reclaimed sandy soils, in Ismailia, Egypt.

Receptor model source attributions for Utah's Salt Lake City airshed and the impacts of wintertime secondary ammonium nitrate and ammonium chloride aerosol

Communities along Utah's Wasatch Front are currently developing strategies to reduce daily average PM2.5 levels to below National Ambient Air Quality Standards during wintertime persistent stable atmospheric conditions, or cold-air pools. Speciated PM2.5 data from the Wasatch Front airshed indicate that wintertime exceedances of the PM2.5 standard are mainly driven by high levels of ammonium nitrate. Stable wintertime conditions foster the formation of ammonium nitrate aerosol when sufficient sources of NOx, ammonia, and oxidative capacity exist. However, this work demonstrates that secondary ammonium chloride aerosol can also be a significant source of secondary wintertime PM2.5 if sufficient sources of atmospheric chlorine exist. Two factor analysis techniques, positive matrix factorization (PMF) and Unmix, were used to identify contributors to PM2.5 at three monitoring stations along Utah's Wasatch Front: Bountiful, Lindon, and Salt Lake City. The monitoring data included chemically speciated PM2.5 data for 227, 227, and 429 days at each location, respectively, during the period from May 2007 through May 2011. PMF identified 10–12 factors and Unmix identified 4–5 factors for each of the locations. The wintertime PMF and Unmix results showed large contributions from secondary PM2.5 when PM2.5 concentrations exceeded 20 μg/m3. PMF identified both ammonium nitrate and ammonium chloride aerosol as significant secondary contributors to PM2.5 (10–15% of total PM2.5 from ammonium chloride) during wintertime pollution episodes. Subsequent ion balance analysis of the monitoring data confirmed the presence of significant ammonium chloride aerosol on these highly polluted days at all three monitoring sites. The directly emitted primary PM2.5 portions of the source attribution results were further compared to county-level emissions inventories and showed generally good agreement for Salt Lake City and Lindon during wintertime except for wood smoke and fugitive dust, which have higher contributions in the receptor modeling results than in the emissions inventories. Implications: The study suggests that secondary ammonium chloride aerosol can be a significant source of wintertime PM2.5 in an ammonia-rich environment, like the Wasatch Front airshed, if sufficient sources of atmospheric chlorine exist. During wintertime, cold-air-pool events, the source attribution results generally agree with the county emission inventories with the exception of wood smoke and cooking sources. At the Salt Lake City monitoring station, the estimated contributions from wood smoke and cooking are nearly double those of the corresponding inventory, suggesting that they are nearly as important as gasoline emissions.

Gene expression patterns underlying changes in xylem structure and function in response to increased nitrogen availability in hybrid poplar

Nitrogen availability has a strong influence on plant growth and development. In this study, we examined the effect of nitrogen availability on xylogenesis in hybrid poplar (Populus trichocarpa x deltoides H11-11). Saplings of hybrid poplar were fertilized for 33 d with either high or adequate levels of ammonium nitrate. We observed enhanced radial growth, wider vessels and fibres and thinner fibre walls in the secondary xylem of high N relative to adequate N plants. These anatomical differences translated into altered hydraulic properties with xylem being more transport efficient but also more vulnerable to drought-induced cavitation in high N plants. The changes in xylem structure and function were associated with differences in gene expression as revealed by the transcriptome analysis of the developing xylem region. We found 388 genes differentially expressed (fold change ±1.5, P-value ≤ 0.05), including a number of genes putatively involved in nitrogen and carbohydrate metabolism and various aspects of xylem cell differentiation. Several genes encoding known transcriptional regulators of secondary cell wall deposition were down-regulated in high N plants, corresponding with thinner secondary cell walls in these plants. The results of this study provide us with gene candidates potentially affecting xylem hydraulic and structural traits.

Impact of pollination and fertilization on sesame production in the reclaimed lands, Ismailia governorate, Egypt

The research was conducted at the Agriculture Research Farm, Faculty of Agriculture, University of Suez Canal during the sesame growing seasons of 2011 and 2012. For the purpose of studying the impact of insect pollination and nitrogen fertilization on sesame production, the experiment was divided into 13 treatments of open pollination and non open pollination with three different levels of ammonium nitrate (N) and one level of seryalin as bio-fertilizer. Non open pollination treatments were covered before the start of flowering period with a perforated net bag to allow the air to pass through and to prevent insects from approaching the plants. Quantitative and qualitative parameters were measured as follows: number of capsules per plant, capsule weight, number of seeds per capsule, weight of 1000 seeds, germination rate, seedling vigour and oil content. Results clearly demonstrate that qualitative and quantitative parameters of sesame crop significantly increased with open pollination and with the increase of nitrogen fertilizer level up to 95 kg N/ha plus or minus seryalin in reclaimed sandy soils in Ismailia, Egypt.

Intraspecific Differences in Responses of Marsh Frog (Pelophylax ridibundus) Tadpoles Exposed to Environmentally Relevant and Acute Levels of Ammonium Nitrate Fertilizer

ABSTRACT Marsh frog (Pelophylax ridibundus) tadpoles from two different ponds in the same region were exposed to acute (0 to 500 mg/L) and chronic (0 to 25 mg/L) levels of ammonium nitrate to assess lethal and sublethal effects (growth, duration of larval development, occurrence and frequency of abnormalities, level of tadpole activity, and mortality). Both acute and chronic toxicity experiments indicated that there was a difference in the level of innate resistance of tadpoles taken from the two different sites. Elevated levels of ammonium nitrate caused prolonged larval development, decreased growth rate, increased number of abnormalities, decreased duration time for abnormalities to occur, increased mortality, and decreased activity. Our results suggest that different exposure regimes of ammonium nitrate in the natural habitats may drive adaptation mechanisms to increase resistance to ammonium nitrate, creating intraspecific variations among the populations of Pelophylax ridibundus

Simulating the fine and coarse inorganic particulate matter concentrations in a polluted megacity

A three dimensional chemical transport model (PMCAMx) is applied to the Mexico City Metropolitan Area (MCMA) in order to simulate the chemical composition and mass of the major PM 1 (fine) and PM 1–10 (coarse) inorganic components and determine the effect of mineral dust on their formation. The aerosol thermodynamic model ISORROPIA-II is used to explicitly simulate the effect of Ca, Mg, and K from dust on semi-volatile partitioning and water uptake. The hybrid approach is applied to simulate the inorganic components, assuming that the smallest particles are in thermodynamic equilibrium, while describing the mass transfer to and from the larger ones. The official MCMA 2004 emissions inventory with improved dust and NaCl emissions is used. The comparison between the model predictions and measurements during a week of April of 2003 at Centro Nacional de Investigacion y Capacitacion Ambiental (CENICA) “Supersite” shows that the model reproduces reasonably well the fine mode composition and its diurnal variation. Sulfate predicted levels are relatively uniform in the area (approximately 3 μg m −3), while ammonium nitrate peaks in Mexico City (approximately 7 μg m −3) and its concentration rapidly decreases due to dilution and evaporation away from the urban area. In areas of high dust concentrations, the associated alkalinity is predicted to increase the concentration of nitrate, chloride and ammonium in the coarse mode by up to 2 μg m −3 (a factor of 10), 0.4 μg m −3, and 0.6 μg m −3 (75%), respectively. The predicted ammonium nitrate levels inside Mexico City for this period are sensitive to the physical state (solid versus liquid) of the particles during periods with RH less than 50%.

Ammonium nitrate improves direct somatic embryogenesis and biolistic transformation of Triticum aestivum

Triticum aestivum is of major importance both nutritionally and economically. Introduction of new genes has been difficult to apply to elite wheat varieties mainly as a result of their recalcitrance to prerequisite tissue culture. We attempted to improve the frequency of wheat transformation by exposing plants to high level of ammonium nitrate. Our experiments showed that modification of the ammonium nitrate content in the direct somatic embryogenesis induction medium can increase the number of primary embryos produced over twofold in the elite hard red wheat cultivar Superb. The number of primary embryos that were capable of transitioning into shoot development also increased twofold. Biolistic transformation efficiency improved as much as sevenfold when targeted scutellar tissue was exposed to elevated ammonium nitrate levels. This simple approach could become extremely useful for increasing transformation efficiency in wheat.

Short-term effects of nitrogen availability on wood formation and fibre properties in hybrid poplar

The application of nitrogen-containing fertilisers is one approach used to increase growth rates and productivity of forest tree plantations. However, the effects of nitrogen fertilisation on wood properties have not been systematically assessed. The aim of this work was to document the impacts of nitrogen fertilisation on wood formation and secondary xylem fibre properties. We used three fertilisation treatments in which the level of ammonium nitrate was adjusted to 0, 1 and 10 mM in a complete nutrient solution applied daily over a period of 28 days in standardised greenhouse experiments with clonal material of Populus trichocarpa (Torr and Gray) × deltoides (Bartr. ex Marsh). We showed that there was a short-term and repeatable response in which xylem fibre morphology and secondary cell wall structure adapt to a shift in N availability. Under high-nitrogen exposure, xylem fibres were 17% wider and 18% shorter compared to the adequate nitrogen treatment. A very significant thickening of the fibre cell walls was also observed throughout the stem of trees receiving the high-N treatment. It appeared that cell wall structure was greatly affected by the high-N treatment as fibres developed a modified inner cell wall layer. Histological observations indicated that the internal cell wall layer was enriched in cellulose and chemical determinations showed that wood contained more holocellulose. Together, these results indicate that the response of poplar to nitrogen availability may involve marked effects on secondary xylem formation.