Foliar absorption and root translocation of nitrogen from different chemical forms in seedlings of two Mediterranean trees.
AuthorsUscola Fernández, María Mercedes; Oliet Palá, Juan Antonio; Villar Salvador, Pedro; Warren , Charles
IdentifiersPermanent link (URI): http://hdl.handle.net/10017/37386
Comunidad de Madrid
Australian Research Council
Environmental and Experimental Botany, 2014, v. 104, n. , p. 34-41
FPU-MEC AP2007-01397 to M.Uscola,AGL2006-12609-C02-01/FOR (ENCINUT),AGL2011-24296 ECOLPIN (MICIIN), REMEDINAL2 S2009/AMB/1783 (Comunidad de Madrid), Australian ResearchCouncil (Grant no. FT100100024).
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Along with root uptake, plants can also absorb N through leaves. There are few comparative studieson the foliar absorption of N from different chemical forms of N in forest tree species. We comparedthe foliar N absorption capacity in seedlings of two forest trees widespread in the Mediterranean basin,Quercus ilex and Pinus halepensis. Plants were sprayed with the following individual N forms at 40 mMN:15N-nitrate (NO3−),15N-ammonium (NH4+),15N-urea or13C and15N dual-labeled glycine. Cuticularconductance was used as a surrogate of cuticle permeability to water. Q. ilex had higher N foliar absorp-tion than P. hapelensis. Neither cuticular conductance nor shoot surface area explained N differences inabsorption rate between species, which were instead likely linked to differences in stomatal density andpresence of trichomes. In both species, foliar N absorption rate and N recovery differed among N forms:urea > NH4+≥ glycine ≥ NO3−. Differences in N absorption rate among N forms were correlated with theirphysico-chemical properties. The strong positive relationship between15N and13C uptake together withdetection in shoots of intact dual-labeled glycine (measured by gas chromatography&#-mass spectrome-try), indicated that a significant fraction of glycine was absorbed intact by the seedlings. In both species,higher cuticular conductance was related to faster N absorption from all forms except NO3&amp;amp;;8722#. Cuticularconductance had a stronger effect on N absorption from urea and NH4+than N absorption from glycine,and the effects were more intense in Q. ilex than in P. halepensis.
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