Stock William D, Evans John R
Department of Botany, University of Cape Town, Rondebosch 7701, South Africa.
Environmental Biology, Research School for Biological Sciences, The Australian National University, Canberra, ACT 0200, Australia.
Funct Plant Biol. 2006 Mar;33(3):219-227. doi: 10.1071/FP05188.
The relative effects of soil N, water supply and elevated atmospheric CO on foliar δN values were examined. Phalaris arundinacea L. (Holdfast) and Physalis peruviana L. (Cape Gooseberry) were grown for 80 d with three water availability treatments, two atmospheric CO concentrations and four N supply rates. Elevated CO increased total plant biomass and N for each treatment and decreased allocation to roots, leaf N concentrations and stomatal conductance. Leaves had less negative leaf δC values under low water supply associated with decreased stomatal conductance and increased leaf N concentration, which decreased the ratio of intercellular to ambient CO concentration. The δN value of the supplied nitrate (4.15‰) was similar to the value for Phalaris leaves (4.11‰), but Cape Gooseberry leaves were enriched (6.52‰). The effects of elevated CO on leaf δN values were small, with Phalaris showing no significant change, while Cape Gooseberry showed a significant (P < 0.05) decline of 0.42 ‰. Variation in δN values was unrelated to stomatal conductance, transpiration, differential use of N forms or denitrification. Plants with low foliar N concentrations tended to be depleted in N. We suggest that changes in N allocation alter foliar δN values under different CO and water treatments.
研究了土壤氮、水分供应和大气CO浓度升高对叶片δN值的相对影响。将虉草（Phalaris arundinacea L.，Holdfast）和灯笼果（Physalis peruviana L.，Cape Gooseberry）在三种水分有效性处理、两种大气CO浓度和四种氮供应速率条件下种植80天。CO浓度升高使各处理下的植物总生物量和氮含量增加，并减少了根系分配、叶片氮浓度和气孔导度。在水分供应较低的情况下，叶片的δC值负性较小，这与气孔导度降低和叶片氮浓度增加有关，从而降低了细胞间与外界CO浓度的比值。供应的硝酸盐的δN值（4.15‰）与虉草叶片的值（4.11‰）相似，但灯笼果叶片的δN值较高（6.52‰）。CO浓度升高对叶片δN值的影响较小，虉草无显著变化，而灯笼果则显著下降（P < 0.05），下降了0.42‰。δN值的变化与气孔导度、蒸腾作用、氮形态的差异利用或反硝化作用无关。叶片氮浓度低的植物往往氮含量较低。我们认为，在不同的CO和水分处理下，氮分配的变化会改变叶片的δN值。
