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20231227122918.0 |
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231222s2000 xx ||||| 00| ||eng c |
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|a pubmed24n1220.xml
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|a (DE-627)NLM10861493X
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|a (NLM)10938829
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|a DE-627
|b ger
|c DE-627
|e rakwb
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| 041 |
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|a eng
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| 100 |
1 |
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|a Walch-Liu, P
|e verfasserin
|4 aut
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| 245 |
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|a Rapid effects of nitrogen form on leaf morphogenesis in tobacco
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| 264 |
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|c 2000
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| 336 |
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|a Text
|b txt
|2 rdacontent
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| 337 |
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|a ohne Hilfsmittel zu benutzen
|b n
|2 rdamedia
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| 338 |
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|a Band
|b nc
|2 rdacarrier
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| 500 |
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|a Date Completed 25.08.2000
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|a Date Revised 13.12.2023
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|a published: Print
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|a Citation Status MEDLINE
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| 520 |
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|a Ammonium (NH4+) instead of nitrate (NO3-) as the nitrogen (N) source for tobacco (Nicotiana tabacum L.) cultivated in a pH-buffered nutrient solution resulted in decreased shoot and root biomass. Reduction of shoot fresh weight was mainly related to inhibition of leaf growth, which was already detectable after short-term NH4+ treatments of 24 h, and even at a moderate concentration level of 2 mM. Microscopic analysis of the epidermis of fully expanded leaves revealed a decrease in cell number (50%) and in cell size (30%) indicating that both cell division and cell elongation were affected by NH4+ application. Changes in various physiological parameters known to be associated with NH4(+)-induced growth depression were examined both in long-term and short-term experiments: the concentrations of total N, soluble sugars and starch as well as the osmotic potential, the apparent hydraulic conductivity and the rate of water uptake were not reduced by NH4+ treatments (duration 1-12 d), suggesting that leaf growth was neither limited by the availability of N and carbohydrates, nor by a lack of osmotica or water supply. Although the concentration of K+ in leaf press sap declined in expanding leaves by approximately 15% in response to NH4+ nutrition, limitation of mineral nutrients seems to be unlikely in view of the fast response of leaf growth at 24 h after the start of the NH4+ treatment. No inhibitory effects were observed when NH4+ and NO3- were applied simultaneously (each 1 mM) resulting in a NO3-/NH4+ net uptake ratio of 6:4. These findings suggest that the rapid inhibition of leaf growth was not primarily related to NH4+ toxicity, but to the lack of NO3(-)-supply. Growth inhibition of plants fed solely with NH4+ was associated with a 60% reduction of the zeatine + zeatine riboside (Z + ZR) cytokinin fraction in the xylem sap after 24 h. Furthermore Z + ZR levels declined to almost zero within the next 4 d after start of the NH4+ treatment. In contrast, the concentrations of the putative Z + ZR precursors isopentenyl-adenine and isopentenyl-adenosine (i-Ade + i-Ado) were not affected by NH4+ application. Since cytokinins are involved in the regulation of both cell division and cell elongation, it seems likely that the presence of NO3- is required to maintain biosynthesis and/or root to shoot transfer of cytokinins at a level that is sufficient to mediate normal leaf morphogenesis
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|a Journal Article
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| 650 |
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|a Research Support, Non-U.S. Gov't
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| 650 |
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7 |
|a Minerals
|2 NLM
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| 650 |
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7 |
|a Nitrogen
|2 NLM
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| 650 |
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7 |
|a N762921K75
|2 NLM
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| 700 |
1 |
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|a Neumann, G
|e verfasserin
|4 aut
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| 700 |
1 |
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|a Bangerth, F
|e verfasserin
|4 aut
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| 700 |
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|a Engels, C
|e verfasserin
|4 aut
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| 773 |
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|i Enthalten in
|t Journal of experimental botany
|d 1985
|g 51(2000), 343 vom: 28. Feb., Seite 227-37
|w (DE-627)NLM098182706
|x 1460-2431
|7 nnns
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| 773 |
1 |
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|g volume:51
|g year:2000
|g number:343
|g day:28
|g month:02
|g pages:227-37
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|a AR
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| 952 |
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|d 51
|j 2000
|e 343
|b 28
|c 02
|h 227-37
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