title: The effect of nitrogen nutrition on growth and biomass partitioning of annual plants originating from habitats of different nitrogen availability.
abstract: The hypothesis was tested that faster growth of nitrophilic plants at high nitrogen (N) nutrition is counterbalanced by faster growth of non-nitrophilic plants at low N-nutrition. Ten annual plant species were used which originated from habitats of different N-availability. The species' preference for N was quantified by the "N-number" of Ellenberg (1979), a relative measure of nitrophily. The plants were cultivated in a growth cabinet at five levels of ammonium-nitrate supply. At low N-supply, the relative growth rate (RGR) was independent of nitrophily. At high N-supply, RGR tended to be higher in nitrophilic than in non-nitrophilic species. However, the response of RGR to N-supply was strongly and positively correlated with the nitrophily of species. Increasing N-supply enhanced partitioning to leaf weight per total biomass (LWR) and increased plant leaf area per total biomass (LAR). Specific leaf weight (SLW) and LWR were both higher in non-nitrophilic than in nitrophilic species at all levels of N-nutrition. NAR (growth per leaf area or net assimilation rate) increased with nitrophily only under conditions of high N-supply. RGR correlated positively with LAR, irrespective of N-nutrition. Under conditions of high N-supply RGR correlated with SLW negatively and with NAR positively.
authors.affiliation: Lehrstuhl für Pflanzenökologie I, Universität Bayreuth, Postfach 101251, W-8580, Bayreuth, Federal Republic of Germany.
authors.forename: K
authors.initials: K
authors.lastname: Fichtner
authors.affiliation: Lehrstuhl für Pflanzenökologie I, Universität Bayreuth, Postfach 101251, W-8580, Bayreuth, Federal Republic of Germany.
authors.forename: E -D
authors.initials: E-
authors.lastname: Schulze
keywords: Annual plants; Biomass partitioning; Nitrogen nutrition; Relative growth rate