Supply Of NH4 Research Articles

Low Root Temperature Retardation of the Mineral Nitrogen Induced Decline in N2 Fixation by a Northern Ecotype of White Clover

Abstract Nodulated white clover plants ( Trifolium repens L.) of a Norwegian ecotype from Pasvik (70°N) were grown in flowing solution culture. Root temperature was 17°C until 51d after sowing, when it was lowered decrementally over 5d to 7°C in four of the eight plant culture units. After a further 24h, mineral N was supplied automatically at 20μ M NH 4 NO 3 in three culture units at each root temperature (7 and 17°C) over 17d. The remaining two units provided control plants solely dependent on N 2 fixation at 7 and 17°C. The supply of NH 4 NO 3 greatly reduced the nodule biomass per plant at 17°C over 17d compared with control plants, but had little effect at 7°C. The nodule decline at 17°C accompanied an acute and progressive decrease in specific rate of N 2 fixation, from 9mmolN d -1 g -1 nodule d.wt on day 0 to zero by day 10. Whilst initial rates of N 2 fixation were lower at 7°C, the mineral N-induced decrease in fixation rates was also less severe than at 17°C and specific fixation rates recovered after reaching a minimum on day 11. N 2 fixation accounted for 36% of the total uptake of N by +min.N plants during the treatment period at 7°C as opposed to only 13% at 17°C. The total N 2 fixed at 7°C was 86% of that fixed at 17°C, although the specific growth rate (d.wt) at 7°C was only 55% of that at 17°C. Addition of NH 4 NO 3 at 7°C had little effect on the gross amount of N 2 fixed subsequently. In contrast, total N 2 fixation by +min.N plants at 17°C was only 24% of that fixed by the corresponding controls. The possible mechanisms by which mineral N affects N 2 fixation are discussed.

Transpiration and drought resistance of Douglas-fir seedlings exposed to excess ammonium

In a pot trial growth and transpiration of 3-year-old Douglas-fir seedlings on an acid, sandy soil was examined at a deficient (30 kg N ha-1 year-1) and an excessive level (120 kg N ha-1 year-1 of NH4 application. Dissolved ammonium sulphate was applied to the pots weekly for two growing seasons. In half of the pots a complete set of other nutrients was applied in optimal proportions to the applied nitrogen. Water supply was optimal and transpiration was recorded. At the end of the second treatment season irrigation was stopped for 2 weeks during dry and sunny weather. Both high application of NH4 and additional nutrients increased shoot growth and transpiration demand in the first treatment year. The root system was smaller at higher N level and this reduced water uptake accordingly. In the second year the combination of high NH4+ and additional nutrients affected root functioning predominantly due to salinity effects and this seriously decreased water uptake capacity and shoot water potentials, finally resulting in tree death. Without addition of other nutrients the high NH4+ application resulted in a high degree of soil acidification, which damaged the roots, that showed a decrease in water uptake capacity. At the low NH4 supply level soil acidification was lower, and root functioning was not affected, and the trees recovered quickly from the imposed drought. Higher needle K and P status depressed transpiration rates at the low NH4 application rate.

Estimation of Nitrification and Denitrification from Microprofiles of Oxygen and Nitrate in Model Sediment Systems

The coupling between nitrification and denitrification and the regulation of these processes by oxygen were studied in freshwater sediment microcosms with O(2) and NO(3) microsensors. Depth profiles of nitrification (indicated as NO(3) production), denitrification (indicated as NO(3) consumption), and O(2) consumption activities within the sediment were calculated from the measured concentration profiles. From the concentration profiles, it was furthermore possible to distinguish between the rate of denitrification based on the diffusional supply of NO(3) from the overlying water and the rate based on NO(3) supplied by benthic nitrification (D(w) and D(n), respectively). An increase in O(2) concentration caused a deeper O(2) penetration while a decrease in D(w) and an increase in D(n) were observed. The relative importance for total denitrification of NO(3) produced by nitrification thus increased compared with NO(3) supplied from the water phase. The decrease in D(w) at high oxygen was due to an increase in diffusion path for NO(3) from the overlying water to the denitrifying layers in the anoxic sediment. At high O(2) concentrations, nitrifying activity was restricted to the lower part of the oxic zone where there was a continuous diffusional supply of NH(4) from deeper mineralization processes, and the long diffusion path from the nitrification zone to the overlying water compared with the path to the denitrifying layers led to a stimulation in D(n).

MINERAL NUTRITION OF RED SPRUCE SEEDLINGS IN AN ACIDIC FOREST SOIL

Coniferous forest trees showing chlorosis and dieback appear to be deficient in Ca and Mg. These deficiencies may be induced by nitrogenous nutrients borne in the atmosphere. This study assessed the roles of nitrogen nutrition and soil on nutrient accumulation by red spruce (Picea rubens, Sarg.) and radishes (Raphanus sativus, L.). Plants were grown in the greenhouse in acid O or A horizons (Typic Haplorthod) collected from a red spruce forest. Plants were grown with a complete nutrient solution with 15 mM N of which NH4 was 0, 3.75, 7.5, 11.25, or 15 mM with the remainder being NO3-. After 120 days, the spruce needles became chlorotic with 11.25 or 15 mM NH4. Radishes exhibited NH4-toxicity after 28 days. Radishes were larger in the O horizon than in the A horizon. As NH4 was increased, radishes had lesser dry weights and accumulated less foliar Ca. Foliar Ca also was lower in spruce with the higher NH4. Magnesium concentrations in leaves of red spruce and radishes were not affected significantly by increasing NH4 supply. Radishes are suitable indicator plants to study the effect of nitrogen form on mineral nutrition of spruce because each species responded similarly to the treatments.

Effects of Exogenously Supplied Ammonium on Root Development of Scots Pine ( Pinus sylvestris L.) Seedlings

The effect of potentially toxic concentrations of ammonium on root development of Scots pine seedlings raised on Perlite was investigated during growth periods of 3 or 10 weeks after sowing. It was shown that imbalanced ammonium nutrition led to conspicuous changes of root morphology provided the pH value in the medium was allowed to decrease to 3.9 due to the NH+4-dependent proton excretion into the rhizosphere. Ammonium toxicity could not be observed with seedlings treated either with ammonium nitrate or with ammonium chloride at pH 5.3 − 6.8. While the supply of NH+4 considerably inhibited root development the biomass production of the shoot was increased. Determination of the endogenous level of ammonium in roots and the leaf whorl exclude a simple causal correlation between ammonium toxicity and accumulated ammonium as has been postulated for herbaceous plants.

Growth Responses to N Forms in Rabbiteye and Highbush Blueberries.

Effects of different NH4+/NO3- ratios in the nutrient solutions on the plant growth and the concentrations of free NH4+ in the leaves were compared between rabbiteye and highbush blueberries. One-year-old rooted cuttings of both blueberry species were grown in sand culture and supplied with 56mg•liter-1 of N at NH4+/NO3- ratios of 0/56, 42/14, 28/28, 14/42 and 0/56. The pH of the nutrient solutions was maintained at 5.5 in each treatment.Dry weight of plant tops was greatest at 28/28 of NH4+/NO3- ratio for both species. At 42/14 or the 0/56, plants of both blueberry species showed leaf scorch. The reduction in growth caused by excessive NH4+ supply at concentrations higher than 42mg•liter-1 was more noticeable in highbush blueberries than it was in rabbiteye blueberries. Highbush blueberries grew equally well at 28/28 and 14/42 of NH4+/NO3- ratio, whereas rabbiteye blueberries grew poorly at 14/42.For both blueberry species, the concentration of free NH4+ in the leaves increased as NH4+/NO3- ratio of nutrient solution increased. When NH4+/NO3- ratio was 56/0, highbush blueberries had lower concentrations of free NH4+ in leaves than rabbiteye blueberries did.Hence, highbush blueberries are seemingly less tolerant to the excessive supply of NH4+ than do rabbiteye blueberries, although NH4+ was assimilated more efficiently in highbush blueberries.

Spring Wheat Response to Enhanced Ammonium Supply: I. Dry Matter and Nitrogen Content

AbstractSpring wheat (Triticum aestivum L.) grain dry matter (DM) has been increased in previous greenhouse experiments through the use of a nitrification inhibitor (NI), which provides an enhanced ammonium supply (EAS). The objective of this research was to determine, under greenhouse conditions, the effect of EAS on the accumulation and partitioning of DM and N at several stages of plant development and on the yield components (heads plant−1, kernels head−1, and kernel weight). Enhanced NH4 supply increased plant DM at 18 d after plant emergence, boot stage, 7 d after anthesis, and maturity. Enhanced NH4 supply did not alter the relative partitioning of DM among leaf, stem, and grain at any stage of development. Effects of EAS on plant and grain DM at maturity increased with increasing N rate. At the highest N rates, grain DM was increased 18 and 6% in two experiments. Nitrogen and moisture stress appeared to alter grain DM response to EAS. Increased grain DM was associated with an increased number of heads plant−1. Kernels head−1 were decreased with EAS, but kernel weight was not affected. Consequently, EAS increased heads plant−1 more than grain DM. At growth stages prior to maturity, EAS increased plant N uptake. At maturity, plant N uptake was slightly and inconsistently affected by EAS; however, the proportion of plant N in the grain was increased by EAS. This indicated a greater translocation of N from the stem to the grain with EAS. In general, increased spring wheat grain DM is associated with proportional increases in plant DM throughout plant development, but not necessarily with proportional increases in plant N uptake. Heads plant−1 is the only yield component increased positively by EAS and thus warrants further research.

Effect of Nitrate, Ammonium and Some Amino Acids on Growth and Nitrate Reductase Activity in Suspension Cultures of Atropa belladonna

Our aim was to determine whether the precursor amino acids of the tropane skeleton affect nitrate reductase activity in Atropa belladonna and whether the simultaneous supply of NH 4 + ions leads to its repression. The interrelationship between nitrate reductase activity, growth and utilization of NO 3 − and NH 4 + were also studied

Effect of NO3:NH4ratio and light intensity on nitrogen partitioning in pepper plants

Abstract Pepper plants were hydroponically grown in a growth chamber with two levels of light intensity (300 and 240 w/m2) and two NO3:NH4 ratios (100:0 and 80:20). Plants grown with both N forms (80:20) under high light regime displayed greater concentrations of free NH4, organic soluble N and insoluble N than NO3, treated plants, this effect was more pronounced for stem, petioles and root. By contrast, nitrate‐ammonium fed plants with light reduced over 25% presented similar concentrations of organic N (soluble and insoluble) as compared to plants supplied with NO3 as sole source of N, however, the amount of free NH4 in stem and root was increased. Results indicat that NH4 supplied at low concentration was more deletereous for pepper plants grown under high light conditions, when light was reduced, plants presented an alleviation of toxic effect of NH4 supply. Finally, nitrogen use efficiency is related to form of N nutrition and the light supplied to crop.

Inorganic carbon and ammonium uptake by phytoplankton in nitrogen depleted waters in Lake Suwa.

Inorganic carbon and NH4+ uptake by phytoplankton was studied during a period of nitrogen depletion in early fall of 1985 in Lake Suwa to investigate a possible effect of NH4+ supply from the bottom sediments on phytoplankton production. Phytoplankton samples from the experimental enclosures were, after being size-fractionated using 40 μm netting, incubated with the simultaneous addition of 13C inorganic carbon at tracer level (6.515.6% in excess of ambient DIC) and 15NH4+ in substrate saturated concentration (541330% in excess of ambient NH4+) under saturation light intensity for 34 hr. The 40 μm fraction, exclusively composed of large colonial blue-green algae Microcystis spp. There was little difference in specific carbon uptake rates and no difference in photosynthetic activity between the two size fractions. It was suggested that during a period of nitrogen depletion in Lake Suwa a large supply of NH4+ from the bottom sediments could more favorably affect the small-sized phytoplankton than the large colonial Microcystis.

Aluminum tolerance is independent of rhizosphere pH intriticum aestivmL.

Abstract Cultivars of Triticum aestivum (wheat) differ in their ability to grow under conditions of aluminum (Al) stress, a phenomenon aptly called differential tolerance to Al. The physiological basis of differential tolerance to Al may be the result of differences among cultivars in patterns of nitrogen (N) assimilation. If cultivars differ in their relative preference for NH4 + and NO3 ‐ in mixed N substrates, this could affect plant‐induced pH of the growth solution, the solubility and speciation of Al and, hence, the expression of Al tolerance. To further test this hypothesis, an Al‐tolerant cultivar (Atlas‐66) and an Al‐sensitive cultivar (Scout‐66) were grown in solution cultures where the relative supply of NH4 + and NO3 ‐ was varied. Plant‐induced pH changes in the growth solutions varied among N treatments and between cultivars. As the supply of NH4 + was increased, both cultivars induced a more acidic pH in the growth solution. Despite differences in plant‐induced pH among treatments, the relat...

Nitrogen Mineralization, Immobilization, and Nitrification Following Urea Fertilization of a Forest Soil Under Field and Laboratory Conditions

AbstractFollowing a 200‐kg urea‐N/ha fertilization in a loblolly pine stand (Pinus taeda), soil mineral N levels (almost entirely NH4+) declined from 200 ppm 20 days after fertilization to < 10 ppm within 161 days. Similar patterns had been previously observed following urea fertilization in a Douglas‐fir stand. After the decline in soil mineral N, 20% (40 ppm) of fertilizer N was mineralized within 4 weeks of aerobic incubation in the laboratory at 25°C. Nitrogen mineralization in control soils did not occur after 7 weeks incubation.In contrast to field results, urea additions to control soils in the laboratory resulted in rapid net N mineralization. The difference between laboratory and field fertilization results is thought to be due principally to differences in available C supplies, i.e., large (> 2 mm) litter and roots were excluded from laboratory tests.The maximum rate of nitrification during incubation was related to the supply of NH4+ substrate, whereas the delay period was probably related to the initial populations of nitrifiers.Additions of 100 kg P/ha as triple superphosphate in the field and equivalent additions of NaH2PO4 in the laboratory had little or no effect on results.

Transport and Distribution of 14CO2 Assimilate in Lolium perenne in Response to Varying Nitrogen Supply to Halves of a Divided Root System

AbstractThe movement of 14C assimilate from shoots to roots and its subsequent metabolism in the root of Lolium perenne L. was studied using variable N nutrition supplied to halves of a divided root system. Half of the N‐deficient root system was supplied with either high NO3‐N or high NH4‐N for 16 hours or 6 days before 14CO2 labeling of the shoots.The distribution of 14C in sugars, ethanol‐soluble nitrogen and organic acids in roots appeared to be related to the N content of the tissue. Supply of high NO3‐N for 6 days resulted in significant internal translocation of N into the low N supplied root half. Both root halves also had similar patterns of 14C distribution among soluble and insoluble metabolites. However, NH4‐N supply for 6 days did not result in a significant increase of N in the low N supplied roots, thus only the high NH4‐N supplied roots displayed stimulated sugar metabolism, similar to that in both root halves in the high NO3‐N supply treatment.Percent transport of 14C assimilates from shoot to root was influenced by form and level of N supplied to root halves. Root halves supplied with either high N source for 6 days accumulated greater amounts of 14C assimilate than the corresponding low N root half. However NH4‐N supply appeared to make roots stronger sinks since NH4 supply resulted in significantly greater 14C accumulation in both the high NH4 supplied and the low N root halves than did NO3‐N supply in corresponding root halves.The data suggest that factors other than root metabolism, such as N mediated metabolism in the shoot, may also influence the percent transport of assimilates to the root. Internal distribution of the incoming assimilate within the root system could be regulated by the metabolic activity or assimilate demand of the roots.

Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 4. Role of the water regime.

[116.17.012:145.911].Available N in a flooded soil under rice was assessed by measuring N uptake by the plants. During flooding the supply of NH4 was unchanged but NO3 rapidly denitrified. When applied to a dry soil NH4 was nitrified but flooding caused the denitrification of NO3 to occur and the supply of N was roughly halved. A change in soil pH towards acidity (to pH 4.5) was sufficient to check nitrification and the loss of N from NH4 applied before flooding. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Nitrogen fixation by cell-free extracts of Klebsiella penumoniae.

A cell-free system which permits nitrogen fixation by extracts of Klebsiella pneumoniae M5al (formerly Aerobacter aerogenes) has been developed. It is, essentially, that system described by Bulen and associates for Azotobacter vinelandii, utilizing ATP as a source of energy and dithionite as a source of electrons. The Michaelis constant for fixation has been estimated to be 0.12 atm. The extracts possessed an ATP-dependent hydrogen evolving system. Hydrogen evolution from these extracts was less under nitrogen than under helium in the presence of ATP. Nitrogen gas appears to be the inducer of nitrogen fixation. In the absence of N2, no induction of nitrogenase occurs. Nitrogenase is absent in cells grown on NH4+-N. There is a lag of about 13 h after the introduction of N2 gas into a culture which has depleted its supply of NH4+-N before nitrogenase can be detected. For reasons discussed in the text, this conclusion must be regarded as tentative at this time. Ammonium ion appears to prevent the synthesis of new molecules of nitrogenase without affecting the activity of those already formed.

Studies on the sodium chloride injury of vegetable crops in relation to the form of nitrogen in sand culture. II

Spinach, Chinese cabbage, celery, turnip, and carrot were grown in sand culture under glass and were supplied with NO3 (a mixture of nitrates of K, Ca, and Mg), NH4+NO3 (ammonium nitrate), or NH4 (ammonium sulfate) in the absence and presence of NaCl, to study the sodium chloride injury of these crops in relation to the form of nitrogen supplied. The nitrogen concentration of any nutrient solution was equally 10m.e./l (140ppm), and the concentration of NaCl added to the solution was 8000ppm for spinach and Chinese cabbage, 6000ppm for celery, 2500ppm for turnip, and 4000 ppm for carrot. The pH of the solutions was adjusted to 6.2-6.4 in all cases.1. Both in the absence and presence of NaCl, plant growth was much better with NO3 than with NH4. And NH4+NO3 plants showed growth similar to or less than that shown by NO3 plants. Effect of NaCl on the yield of crops was not always constant with each nitrogen form.2. The dry weight percentage of plants generally incresed with the increasing supply of NH4-N.3. In the absence of NaCl, plants supplied with NO3 developed no specific symptoms; but NH4+NO3 plants produced darker green foliage than NO3 plants in some crops, and produced uneven or leathery leaves in Chinese cabbage. The supply of NH4 alone generally caused various specific symptoms, such as entire or interveinal chlorosis, burn, or withering of leaves. The rate of dead leaves increased as the amount of NH4-N increased. Some crops supplied with NH4 alone had brownish or purplish rootlets.In the presence of NaCl, the supply of NH4-N crops caused serious symptoms of malnutrition more markedly than in the absence of NaCl with NH4 alone chlorosis was developed markedly in general, and leaves of some crops were fragile. In Chinese cabbage, NH4+NO3 caused marginal rot of younger leaves, symptom of Ca deficiency, more markedly than NO3; and plants supplied with NH4 alone were severely stunted in growth showing entire chlorosis, marginal rot, and burn of leaves. In carrot, branched roots occurred to a high degree with NH4+NO3 or NH4.4. In the absence of NaCl, as the proportion fo NH4-N in the solution increased, N content of both leaves and roots tended to increase; and P content of leaves similarly increased, while that of roots showed an irregular tendency. Content of K, Ca, or Mg of both leaves and roots generally decreased with the increasing supply of NH4-N.In the presence of NaCl, similar tendencies as mentioned above were obtained for each element, except for N in leaves which mostly decreased with the supply of NH4-N, and the content of any essential cation was generally depressed by the interaction with Na. Moreover, Cl or Na content of leaves increased with the increasing supply of NH4-N, while that of roots showed a variable tendency with crop species.5. It is concluded that NO3-N is much more favourable than NH4-N as the nitrogen source for the crops tested, especially in the presence of excess NaCl. Application of NH4-N in the presence of excess NaCl may cause marked interference in absorption of essential cations, especially of Ca, and increased accumlation of Cl or Na in leaves.

Influence of the forms of nitrogen supplied on the growth of vege-table crops. (II)

Experiments were carried out to clarify the influ-ences of the forms of nitrogen supplied with vary-ing concentrations on the growth, yields and chemical compositions of turnip in sand culture under glass. In the first experiment, mixed nitrates (KNO3: Ca (NO3)2, ; Mg(NO3)2=5:5:4), NaNO3, NH2NO3, (NH4)2SO4 and (NH2)2 CO were used as nitrogen sources and nitrogen concentrations supplied were 5, 10, 20, 40, 80 and 120 m. e. for each nitrogen source, respectively. In the second experiment, nitrogen sources were NaNO3, NH4NO3 and (NH4)2SO4, and nitrogen concentrations supplied were 1, 3, 5, 10, 20, 40, 60, 80 and 120m. e. All known nutrients were provided for each treatment. Results of both experiments were summarized as follows. (1) In the mixed nitrates and NaNO3 treatments, leaves were light green and even-surfaced. On the contrary NH4NO3 plants produced deep green foliage, and with increased nitrogen concentration their leaves became darker green and uneven-surfaced. Further, in the later stage of growth, they developed symptoms similar to that of potassium deficiency. In the (NH4)2SO4 series, leaves were darker green at the lower concentrations, but at the higher concen-trations became dull to yellow green and developed injuries due to excessive ammoniacal nitrogen. Leaves of the (NH2)2CO plants were chlorotic. And leaf color was proportional to the chlorophyll contents in the leaves. (2) Among mixed nitrates, NaNO3 and NH4NO3 treatments, there was no great difference of their top growth up to 40m. e. (560ppm) nitrogen level. But beyond 40m. e., the decreasing of growth was most remarkable in the NH4NO3, and least in the mixed nitrates. The growth of plants supplied with (NH2)2CO, especially with (NH4)2SO4 were markedly inferior to the above 3 nitrogen forms at every concentration. And at higher concentrations of (NH4)2SO4 and of NH4NO2, the decreasing of fleshy root growth was more remarkable than other nitro-gen forms, and their fibrous roots were also injured. (3) Total nitrogen content of both leaves and roots increased with increment of nitrogen supplied, irrespective of nitrogen forms. And in the higher nitrogen concentrations supplied (beyond 40m. e.), increment of nitrogen content was remarkable for (NH4)2SO4 and NH4NO3 treatments, but gradual for mixed nitrates and NaNO3. (NH2)2CO plants at lower concentrations contained less nitrogen than other nitrogen forms, but at higher concentrati-ons absorbed fairly much nitrogen. And generally NaNO3 plants accumulated much of nitrate nitro-gen, but (NH4)2SO4 plants contained only trace, and NH4NO3 was intermediate. As to ammonium nitrogen, the relation of (NH4)2S04>NH4NO3>NaNO3 was found, but accumulation of ammonium nitrogen was much less compared with nitrate nitrogen. (4) In the NH4NO3, especially in the (NH4)2SO4 treatment, phosphorus content of leaves was higher and increased with increment of ammoniacal nitrogen supplied. As to potassium, plants supplied with mix-ed nitrates or (NH2)2CO contained much. Plants supplied with NaNO3, NH4NO3 or (NH4)2SO4, had less potassium than the above 2 nitrogen forms, and potassium content decreased against increased Na or NH4 supply