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Titolo:
Assimilate transport in the xylem sap of pedunculate oak (Quercus robur) saplings
Autore:
Heizmann, U; Kreuzwieser, J; Schnitzler, JP; Bruggemann, N; Rennenberg, H;
Indirizzi:
Univ Freiburg, Inst Forstbot & Baumphysiol, D-79110 Freiburg, Germany UnivFreiburg Freiburg Germany D-79110 hysiol, D-79110 Freiburg, Germany Fraunhofer Inst Atmosphar Umweltforsch, D-8100 Garmisch Partenkirchen, Germany Fraunhofer Inst Atmosphar Umweltforsch Garmisch Partenkirchen Germany D-8100
Titolo Testata:
PLANT BIOLOGY
fascicolo: 2, volume: 3, anno: 2001,
pagine: 132 - 138
SICI:
1435-8603(200103)3:2<132:ATITXS>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
SPRUCE PICEA-ABIES; SOLUBLE N-COMPOUNDS; HIGH LOADS; PHLOEM TRANSPORT; FIELD CONDITIONS; TREES; PLANTS; SUCROSE; STORAGE; GROWTH;
Keywords:
organic carbon; carbon cycling; photosynthesis; transpiration; Quercus robur;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
35
Recensione:
Indirizzi per estratti:
Indirizzo: Rennenberg, H Univ Freiburg, Inst Forstbot & Baumphysiol, Georges Kohler Allee,Geb 053-054, D-79110 Freiburg, Germany Univ Freiburg Georges Kohler Allee,Geb 053-054 Freiburg Germany D-79110
Citazione:
U. Heizmann et al., "Assimilate transport in the xylem sap of pedunculate oak (Quercus robur) saplings", PLANT BIO, 3(2), 2001, pp. 132-138

Abstract

The rates of photosynthesis and transpiration, as well as the concentrations of organic compounds (total soluble nonprotein N compounds [TSNN], soluble carbohydrates), in the xylem sap were determined during two growth seasons in one-year-old Quercus robur saplings. From the data, the total C gain bf the leaves, by both photosynthesis and the transpiration stream, was calculated. Large amounts of C were allocated to the leaves by the transpiration stream; depending on the time of day and the environmental conditions the portion of C originating from xylem transport amounted to 8 to 91% of total C delivery to the leaves. Particularly under conditions of reduced photosynthesis, e.g., during midday depression of photosynthesis, a high percentage of the total C delivery was provided to the leaves by the transpirationstream (83 to 91%). Apparently, attack by phloem-feeding aphids lowered the assimilate transport from roots to shoots; as a consequence the portion of C available to the leaves from xylem transport amounted to only 12 to 16%. The most abundant organic compounds transported in the xylem sap were sugars (sucrose, glucose, fructose) with concentrations of co. 50 to 500 mu mol C ml(-1), whereas C from N compounds was of minor significance (3 to 20 mu mol ml(-1) C). The results indicate a significant cycling of C in the plants because the daily transport of C with the transpiration stream exceededthe daily photosynthetic CO2 fixation in several cases. This cycling pool of C may sustain delivery of photosynthate to heterotrophic tissues, independent of short time fluctuations in photosynthetic CO2 fixation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 14/07/20 alle ore 19:12:06