caa a22 4500 397522258 CHVBK 20180308164636.0 cr unu---uuuuu 161202e199509 xx s 000 0 eng 10.1093/jxb/46.9.1103 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.9.1103 Nitrogen utilization by plant species from acid heathland soils [Elektronische Daten] I. Comparison between nitrate and ammonium nutrition at constant low pH1 [S.R. Troelstra, R. Wagenaar, W. Smant] Seven heathland species, four herbaceous plants and three dwarf shrubs, were tested for their capacity to utilize NH4+ or NO3− . When cultured in solution at pH 4.0 with 2mol m−3 N, all species showed similar growth responses with respect to N source. Nitrate was assimilated almost equally well as ammonium, with relative growth rate generally averaging 5-8% lower for NO3− grown plants, albeit not always significantly. However, N source was significantly and consistently correlated with biomass partitioning, as NH4+-fed plants allocated more dry matter to shoots and less to roots when compared to NO3− -fed plants. The strong difference in biomass partitioning may relate to the relative surplus of carbon per unit plant N (or, alternatively, the relatively suboptimal rate of N assimilation per unit plantC) in NO3−-fed plants Inherently slow-growing dwarf shrubs accumulated virtually no free nitrate in their tissues and reduction of nitrate was strictly root-based. Faster-growing herbaceous plants, however, partitioned the assimilation of nitrate over both shoots and roots, thereby accumulating relatively high tissue NO3− levels. Ion uptake rates depended clearly on the ‘relative shoot demand'. At similar shoot demands, especially in the herbaceous species, specific uptake rates for N and total inorganic (non-N) anions were higher in NH4+ -fed plants, whereas the uptake rate for total (non-N) cations was higher in NO3−-fed plants. Rate of P uptake was enhanced with increasing plant demand, but was independent of the N source. Net H+ extrusions ranged from 1.00 to 1.34 H+ per NH4+, and from −0.48 to −0.77 H+ per NO3− taken up. © Oxford University Press RESEARCH PAPERS nationallicence Ammonium, biomass partitioning nationallicence heathland plants nationallicence low pH nationallicence nitrate nationallicence nitrate reductase activity nationallicence relative shoot demand nationallicence specific absorption rate nationallicence Troelstra S.R. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut Wagenaar R. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut Smant W. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut Journal of Experimental Botany Oxford University Press 46/9(1995-09), 1103-1112 0022-0957 46:9<1103 1995 46 exbotj https://doi.org/10.1093/jxb/46.9.1103 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.9.1103 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Troelstra S.R. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut NATIONALLICENCE 700 1- Wagenaar R. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut NATIONALLICENCE 700 1- Smant W. Netherlands Institute of Ecology, Centre for Terrestrial Ecology, PO Box 40, NL-6666 ZG Heteren, The Netherlands aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/9(1995-09), 1103-1112 0022-0957 46:9<1103 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford