Titre :
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Fluxes of reserve-derived and currently assimilated carbon and nitrogen in perennial ryegrass recovering from defoliation. The regrowing tiller and its component functionally distinct zones
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Auteurs :
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H. Schnyder ;
R. Devisser
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Type de document :
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article/chapitre/communication
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Année de publication :
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1999
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Format :
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1423-1435
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Langues:
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= Anglais
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Résumé :
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The quantitative significance of reserves and current assimilates in regrowing tillers of severely defoliated plants of perennial ryegrass (Lolium perenne L.) was assessed by a new approach, comprising C-13/C-12 and N-15/N-14 steady-state labeling and separation of sink and source zones. The functionally distinct zones showed large differences in the kinetics of currently assimilated C and N. These are interpreted in terms of ''substrate'' and ''tissue'' flux among zones and C and N turnover within zones. Tillers refoliated rapidly, although C and N supply was initially decreased. Rapid refoliation was associated with (a) transient depletion of water-soluble carbohydrates and dilution of structural biomass in the immature zone of expanding leaves, (b) rapid transition to current assimilation-derived growth, and (c) rapid reestablishment of a balanced C:N ratio in growth substrate. This balance (C:N, approximately 8.9 [w/w] in new biomass) indicated coregulation of growth by C and N supply and resulted from complementary fluxes of reserve- and current assimilation-derived C and N. Reserves were the dominant N source until approximately 3 d after defoliation. Amino-C constituted approximately 60% of the net influx of reserve C during the first 2 d. Carbohydrate reserves were an insignificant source of C for tiller growth after d 1. We discuss the physiological mechanisms contributing to defoliation tolerance.
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Source :
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Plant Physiology - 0032-0889, vol. 119, n° 4
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