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  • Author or Editor: Allen V. Barker x
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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.

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Polyamine accumulation is a response of plants to various environmental stresses. Polyamine accumulation was assessed in relation to ammonium accumulation and ethylene evolution in tomato (Lycopersicon esculentum Mill.) under nutritional stress. Nutritional stresses were imparted on plants grown in quartz sand culture under greenhouse conditions with NH4-based modified Hoagland's solution or with NO3-based solutions without P, K, Ca, or Mg. The plants receiving NH4 nutrition were grown with or without 10-5 M (aminooxy)acetic acid (AOA) or 10-5 M silver thiosulfate (STS). Plants on nutrient deficient solution were grown with or without the AOA. When plants appeared with toxic or deficient symptoms, the new fully expanded leaves were collected and extracted by 5% perchloric acid for polyamine analyzes by HPLC. Plants receiving NH4-based nutrition had high putrescine and low spermidine concentrations. High spermidine and low putrescine concentrations occurred in plants receiving complete NO3-based nutrition. For plants receiving NH4-based nutrition, application of AOA suppressed accumulation of putrescine but had no effect on spermidine, and STS had no effect on polyamine accumulation. For plants receiving NO3-based nutrition without P, K, Ca, or Mg, the application of AOA restricted accumulation of putrescine and spermidine. High putrescine concentration was accompanied by high ammonium accumulation, high ethylene evolution, and stressinduced symptoms, indicating an association between polyamine accumulation and other stress-related phenomena.

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Polyamine accumulation in foliage was assessed in relation to ammonium accumulation and ethylene evolution in tomato (Lycopersicon esculentum Mill.) under nutritional stress. Nutritional stresses were induced in greenhouse-grown plants in quartz sand with an NH4-based solution or with NO3-based solutions without P, K, Ca, or Mg. Plants receiving NH4-based nutrition had higher putrescine and lower spermidine concentrations than plants receiving NO3-based nutrition. Adding AOA (10-5 m) to the nutrient solution of plants receiving NH4-based nutrition suppressed putrescine accumulation but had no effect on spermidine; silver thiosulfate (10-5 m) had no effect on polyamine accumulation. Deficiencies had no consistent effect on polyamine accumulation relative to its accumulation under full-nutrition conditions, but adding AOA restricted putrescine and spermidine accumulation in all nutrient-deficient regimes. Foliar spermine accumulation was not affected by nutritional regime. Ammonium-based nutrition resulted in enhanced putrescine and ammonium accumulation and accelerated ethylene evolution rates relative to plants receiving NO3-based nutrition. All nutrient-deficient plants had higher ammonium accumulation, and all but P-deficient plants had higher ethylene evolution than those receiving full NO3-based nutrition. Although some variability occurred among treatments, an association among putrescine accumulation, ammonium accumulation, ethylene evolution. and stress-induced symptoms was apparent. Chemical name used: (aminooxy) acetic acid (AOA).

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Many people want to use hydroponics in production of plants but often are hobbyists with limited access to the reagents necessary to formulate a nutrient solution. Several readily available commercial fertilizers and chemicals with tomato-(Lycopersicon esculentum Mill.) as the test plant were used to develop a nutrient solution. A 20-8.8-16.6 IN-P-K) general purpose fertilizer was added (1 g/liter) to deionized water to make a basic solution. This solution was fortified with slow-release fertilizer (approx. 17N-2.6P-8.5K with Ca, Hg, and minor elements) at 1 g/liter added directly to hydroponics vessels. Tomato developed severe foliar symptoms of Ca deficiency in this medium. Addition of CaSO4 or CaCO3 at 0.5 or 1 g/liter to give a solid phase of these chemicals in the vessels prevented development of symptoms of Ca deficiency; however, plants now showed symptoms of Mg deficiency. Addition of MgS0 at 0.25 g/liter to the basic solution prevented symptoms o Mg deficiency. Analyses confirmed that leaf N, P, K, Ca, and Mg were sufficient.

This solution was as good as Hoagland's No. 1 solution for growth of tomato, marigold, and cucumber and was better than Hoagland's solution for growth of corn and wheat.

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Urea fertilization of `Heinz 1350' tomato (Lycopersicon esculentum Mill.) in sand or soil culture did not enhance ethylene evolution or restrict growth relative to plants receiving \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{NO}_{\mathbf{3}}^{\mathbf{-}}\) \end{document} whereas \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{NO}_{\mathbf{4}}^{\mathbf{+}}\) \end{document} nutrition doubled the relative rates of ethylene evolution and restricted relative growth. Inhibitors of N transformations in media (nitrapyrin, Np; hydroquinone, HQ; and phenylphosphorodiamidate, PPD) had no apparent stimulator effects on ethylene evolution of plants grown on urea or \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{NO}_{\mathbf{3}}^{\mathbf{-}}\) \end{document} nutrition in sand or soil. Ethylene evolution was enhanced by PPD relative to that by Np or HQ for plants receiving \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{NO}_{\mathbf{4}}^{\mathbf{+}}\) \end{document} nutrition. Each inhibitor had toxic effects on plant growth. Increasing K+ supply from 0 to 8 mm in nutrient solutions decreased ethylene evolution and increased plant growth with urea fertilization. Urea had low phytotoxicity if its hydrolysis to \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathbf{NO}_{\mathbf{4}}^{\mathbf{+}}\) \end{document} was prevented in the media. Chemical names used: p-dihydroxybenzene (hydroquinone); benzenephosphorodiamide (phenylphosphorodiamidate); 2-chloro-6-(trichloromethyl)pyridine (nitrapyrin).

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Abstract

Bean, sweet corn, cucumber and pea plants were susceptible to ammonium toxicity when cultured on an ammonium source of N. Growth of plants was normal, however, when the pH of the nutrient solution was maintained near neutrality by the addition of CaCO3. The control of acidity was effective in altering the distribution of ammonium; ammonium accumulation in the shoot was lessened and accumulation of amides in roots was enhanced. A natural resistance to ammonium was exhibited by the onion plant since it did not accumulate ammonium in the leaves; however, the nonchlorophyllous bulb acted as an ammonium sink.

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The herbicidal action of foliar applications of glufosinate-ammonium (GLA) is due to toxic accumulation of unassimilated NH4 + in leaves; however, the effects of root-applied GLA on NH4 + accumulation and plant growth are unknown. In a dose-response hydroponics experiment, tomato (Lycopersicon esculentum Mill.) plants were grown in nitrate-based solutions with GLA added at 0, 6, 12, 25, or 50 mg·L-1. To observe plant responses to an exogenous NH4 + source with herbicide-induced responses, plants were grown in an NH4 +-based solution without GLA addition. At 6 days after treatment (DAT), GLA in solution at 25 mg·L-1 produced partial leaf wilting, chlorosis, and necrosis of foliage, and at 50 mg·L-1, plants were fully wilted and necrotic. Ammonium (NH4 +-N) concentration in shoots at 6 DAT increased from 0 to 6 mg·g-1 fresh weight with increasing GLA in the nutrient solution. Ethylene evolution doubled (from 4 to 8 nL·g-1·h-1, fresh weight) with increases in GLA from 0 to 25 mg·L-1 but declined with apparent plant death with GLA at 50 mg·L-1. Other treatments, including NH4 + nutrition, did not induce toxicity symptoms in leaves or give increases in NH4 + accumulation or ethylene evolution during the 6 days of the experiment. In a time-course experiment, tomato plants treated with GLA at 25 mg·L-1 were chlorotic at 4 DAT. Ethylene evolution (fresh weight basis) rose from an initial rate of 2.6 nL·g-1·h-1 to 8.3 nL·g-1·h-1 after 4 days. At 9 DAT, all plants receiving this treatment died. In the time-course experiment, an exogenous NH4 + treatment caused a slight inhibition in shoot fresh weight relative to NO3 - nutrition with no GLA but caused no visible symptoms and only slight enhancements in NH4 + accumulation and ethylene evolution over the 9-day period. Following GLA treatment, NH4 + accumulated in the shoots and increased sharply with time, whereas exogenous NH4 + led to NH4 + accumulation primarily in roots. Results suggest that GLA was absorbed by roots and translocated to shoots, where it initiated accumulation of NH4 + and ethylene evolution as indications of herbicidal action. Chemical name used: glufosinate-ammonium, GLA.

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Abstract

Tomato plants (Lycopersicon esculentum Mill. ‘Heinz 1350’, yellow-green-5, and neglecta-1) were grown in sand culture with 15 mm NH 4 + or NO 3 and with K+ varying from 0 to 8 mm. Other nutrients were provided at the concentrations of Hoagland's solution. The medium supplying NH 4 + was buffered with CaCO3 (pH 6.9) or was unbuffered (pH 3.4). Silver ions (0.01 μm) were incorporated in the nutrient solution in one experiment. Ammonium nutrition relative to NO 3 nutrition elevated rates of ethylene evolution from all genotypes, but yg-5 and neg-1 showed resistance to NH 4 + toxicity and exhibited relatively low ethylene evolution. Ethylene evolution declined as K+ supply increased. Accelerated rates of ethylene evolution did not occur at tissue K+ concentrations >10 g·kg−1 of the dry weights of shoots with NO 3 nutrition, but higher K+ levels were required with NH 4 + nutrition. Putrescine concentrations in leaves of ‘Heinz 1350’ supplied with NH 4 + were 2 to 5 times greater than in leaves of plants supplied with NO 3 . Potassium deficiency increased putrescine accumulation regardless of N form. Spermidine concentrations in leaves of plants supplied with NH 4 + were lower than in those supplied with NO 3 , whereas spermine concentrations were unaffected by treatments. ‘Heinz 1350’ grown in NH 4 + -based nutrient solutions with 0.01 μΜ Ag+ had low rates of ethylene evolution and developed few symptoms of NH 4 + toxicity. Quantities of ethylene and putrescine produced by tomato genotypes susceptible to the nutritional stresses were linked directly to the degree of stress imposed, and symptoms of NH 4 + toxicity were related to increased ethylene synthesis.

Open Access

Abstract

Studies of plant micronutrient uptake and translocation have indicated that excess Zn induces leaf chlorosis associated with Fe deficiency. Leaves from Spinacia oleracea L. and Lycoperiscon esculentum Mill, grown with Hoag-land's No. 1 and minor element nutrient solutions minus Fe or with additional Zn (0.17 mm) exhibited symptoms of Fe deficiency as interveinal chlorotic bleaching for spinach and interveinal chlorotic mottling for tomato. Similarly, the ultrastructure of spinach and tomato leaf chloroplasts from plants grown with additional Zn corresponded to the altered structural integrity representative of Fe-deficient chloroplasts for each plant species. Supplemental Fe (0.19 mm) added to the nutrient supply alleviated the effects of excess Zn as illustrated by a dark green leaf and an enhanced grana-fretwork system of mesophyll chloroplasts of spinach and tomato. These results constitute morphological evidence of Zn-induced Fe deficiency.

Open Access