Review of Recent Work on Nitrogen Metabolism

McKee, H. S.

doi:10.1111/j.1469-8137.1949.tb05110.x

Cited by 33 publications

(10 citation statements)

References 193 publications

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Section: Introductionmentioning

confidence: 99%

“…Sunflower roots are less active in amide formation but transfer much of it, together with ammonia, into the shoots. Glutamine synthetase activity in leaves is 20-to 40-fold lower than in roots.Glucose-6-phosphate dehydrogenase activity appears to be correlated with the activity of the nitrate reducing system in roots, but not in leaves.Although it is well established that absorbed nitrate is converted to ammonium before assimilation into the organic form, it has long been recognized that ammonium and nitrate as sources of external nitrogen differ in their effects on the growth and chemical composition of plants (19). Recent In initial experiments sunflower seeds (Helianthus annuus L. var.…”

mentioning

confidence: 99%

“…Although it is well established that absorbed nitrate is converted to ammonium before assimilation into the organic form, it has long been recognized that ammonium and nitrate as sources of external nitrogen differ in their effects on the growth and chemical composition of plants (19). Recent studies have indicated that ammonium and nitrate nutrition exert contrasting effects on growth (2,24,33), enzyme activity (9,28), free amino acid composition of root exudate (30) and root tissue (25), and organic acid-mineral ion composition (13 (30).…”

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confidence: 99%

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Influence of Ammonium and Nitrate Nutrition on Enzymatic Activity in Soybean and Sunflower

Weissman

1972

Plant Physiol.

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Under conditions of controlled pH, nitrate and ammonium are equally effective in supporting the growth of young soybean (Glycine max var. Bansei) and sunflower (Helianthus annuus L. var., Mammoth Russian) plans. Soybean contains an active nitrate reductase in roots and leaves, but the low specific activity of this enzyme in sunflower leaves indicates a dependency upon the roots for nitrate reduction. Suppression of nitrate reductase activity in sunflower leaves may be due to high concentrations of ammonia received from the roots. Nitrate reductase activity in leaves of nitrate-supplied soybean and sunflower follows closely the distribution of nitrate reductase. For the roots of both species, glutamic acid dehydrogenase activity was greater with ammonium than with nitrate.The glutamic acid dehydrogenase of ammonium roots is wholly NADH-dependent, whereas that of nitrate roots is active with NADH and NADPH. In leaves, an NADPH-dependent glutamic acid dehydrogenase appears to be responsible for the assimilation of translocated ammonia and ammonia formed by nitrate reduction.In soybean roots ammonia is actively incorporated into amides, much of which remains in the roots. Sunflower roots are less active in amide formation but transfer much of it, together with ammonia, into the shoots. Glutamine synthetase activity in leaves is 20-to 40-fold lower than in roots.Glucose-6-phosphate dehydrogenase activity appears to be correlated with the activity of the nitrate reducing system in roots, but not in leaves.Although it is well established that absorbed nitrate is converted to ammonium before assimilation into the organic form, it has long been recognized that ammonium and nitrate as sources of external nitrogen differ in their effects on the growth and chemical composition of plants (19). Recent In initial experiments sunflower seeds (Helianthus annuus L. var. Mammoth Russian) and soybean (Glycine max var. Bansei) were germinated in filter-paper lined beakers and were transferred as 5-day-old seedlings to sand-filled paraffined cups as previously described (30). Culture solution lacking in nitrogen (29) was provided for the first 10 days of growth. The cotyledons were then removed, and culture solution containing either 10 mm NH4C1 or 10 mm KNO3 was added twice a day for the final 9 days of growth before harvest. Examination of the drippings passing through the glass wool covered perforations in the bottom of the cups on the final day of growth revealed that ammonium solutions, originally at pH 6.3, fell to pH 5.3 while nitrate solutions fell to pH 6.1. In order to minimize the effect of pH differences on the biochemical characteristics of ammonium-supplied and nitratesupplied plants, an Homogenates for the analysis of GDH activity were prepared by the method of Ritenour et al. (20). After the slurry was filtered through cheesecloth, the filtrate was centrifuged at 200g, the sediment was discarded, and the supernatant was centrifuged at 20,000g. Following the procedure described by Leech and Kirk (16), the p...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Influence of Ammonium and Nitrate Nutrition on Enzymatic Activity in Soybean and Sunflower

Weissman

1972

Plant Physiol.

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“…This result gives support to the hypothesis suggested by Hewitt, Jones, and Williams (1949) that manganese is not required for nitrate reduction, but may be required at a later stage in nitrogen metabolism. In the presence of urea, which is absorbed by the plant unchanged (McKee 1949), the same concentration of manganese (50 p.p.m.) had a toxic effect on the plants.…”

Section: C"'--mentioning

confidence: 99%

Relation Between Nitrogen Source and the Effects on Flax of an Excess of Manganese or Molybdenum in the Nutrient Solution

Cr¹

1950

Aust. Jnl. Of Bio. Sci.

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SummaryThe effects on flax of a given concentration of manganese or molybdenum in the nutrient solution were found to depend on the amount and form of nitrogen supplied. The interactions that occurred between either of these two elements on the one hand, and nitrogen source on the other, were highly significant but opposite in effect.Thus, with a given excess of manganese, symptoms were most severe in plants grown in solution supplied with nitrogen as nitrate or urea, and were absent in nitrogen-deficient solutions or those supplied with nitrogen as ammonium. In solutions supplied with ammonium nitrate, no manganese toxicity symptoms occurred or these were only slight. A concentration of 50 p.p.m. of manganese in the solution caused a very significant decrease in growth in the presence of nitrate, had no harmful effect on growth in the presence of· ammonium nitrate, and caused a significant increase in growth with ammonium. With urea, the reduction in growth was not as great as with nitrate. The presence of ammonium ions in the solution markedly reduced the manganese concentration in the plants when compared with that of plants receiving nitrate only.By contrast, at a given excess of molybdenum in the nutrient solution, toxicity symptoms in the test plants were affected by nitrogen source in the following order of decreasing severity: nitrogen deficiency> ammonium> ammonium nitrate> urea> nitrate. In solutions supplied with nitrate, a given concentration of molybdenum was significantly more toxic to growth when applied as ammonium molybdate than as sodium molybdate. In one experiment the addition to the nitrate solution of 10 p.p.m. of molybdenum as sodium molybdate resulted in a significant increase in the dry weight of the plants compared with the controls, even though such plants contained 400 p.p.m. of molybdenum on a dry basis. In the presence of ammonium or urea, no significant differences occurred between the effects of sodium molybdate or ammonium molybdate on plant growth.In the nitrate nutrient solutions less molybdenum was absorbed by the plants when a given excess of this element was added to the solution as sodium molybdate than when it was added as ammonium molybdate. It is concluded that the toxi~ity to flax of a given concentration of molybdenum in the nutrient solution is increased by the presence of ammonium (NH 4 +) ions.Where excess of manganese and molybdenum were added together to the nutrient solution, an interaction between the two elements occurred. Thus the severity of manganese-induced iron-deficiency chlorosis and lower leaf necrosis was reduced. However, a golden-yellow chlorosis, not typical of iron-deficiency chlorosis but similar to molybdenum toxicity symptoms, was induced in the " Plant Research Laboratory, Department of Agriculture, Burnley, Vic. NITROGEN SOURCE AND EXCESS MN OR Moplants in the presence of nitrate, ammonium nitrate, or urea, but not where ammonium was the sole source of nitrogen. The manganese-molybdenum interaction was facilitated by the presence of some ammon...

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“…Young roots with long and thick white tips absorbed more water than old roots of much greater length with highly suberized cortical tissues but with short and small diameter white tips. 4. Water requirements per plant per day were directly proportional to the quantities of newly formed tissues.…”

Section: Discussionmentioning

confidence: 99%

GROWTH OF ANANAS COMOSUS (L.) MERR. AT DIFFERENT LEVELS OF MINERAL NUTRITION UNDER GREENHOUSE AND FIELD CONDITIONS. I. PLANT AND FRUIT WEIGHTS AND ABSORPTION OF NITRATE AND POTASSIUM AT DIFFERENT GROWTH INTERVALS

Sideris¹,

Young²

1950

Plant Physiol.

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Review of Recent Work on Nitrogen Metabolism

Cited by 33 publications

References 193 publications

Influence of Ammonium and Nitrate Nutrition on Enzymatic Activity in Soybean and Sunflower

Influence of Ammonium and Nitrate Nutrition on Enzymatic Activity in Soybean and Sunflower

Relation Between Nitrogen Source and the Effects on Flax of an Excess of Manganese or Molybdenum in the Nutrient Solution

GROWTH OF ANANAS COMOSUS (L.) MERR. AT DIFFERENT LEVELS OF MINERAL NUTRITION UNDER GREENHOUSE AND FIELD CONDITIONS. I. PLANT AND FRUIT WEIGHTS AND ABSORPTION OF NITRATE AND POTASSIUM AT DIFFERENT GROWTH INTERVALS

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