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Stable isotope analysis reveals differential effects of soil nitrogen and nitrogen dioxide on the water use efficiency in hybrid poplar leaves
Author(s) -
Siegwolf Rolf T. W.,
Matyssek Rainer,
Saurer Matthias,
Maurer Stephan,
GünthardtGoerg Madeleine S.,
Schmutz Paul,
Bucher Jürg B.
Publication year - 2001
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2001.00032.x
Subject(s) - water use efficiency , nitrogen , carbon dioxide , chemistry , biomass (ecology) , nitrate , agronomy , perennial plant , cutting , nitrogen cycle , soil water , shoot , nitrate reductase , horticulture , irrigation , biology , ecology , organic chemistry
• The effects of nitrogen dioxide (NO 2 ) exposure are reported on the physiology, morphology and carbon partitioning of hybrid poplar clone cuttings ( Populus × euramericana ) grown under high and low soil nitrogen supply. • Plants were exposed to filtered air or NO 2 ‐enriched air (80–135 nl l −1 ) over 12 wk growth in phytotrons. Stable isotope analysis, combined with CO 2 and H 2 O gas exchange measurements, biomass analysis and morphological development, was used to assess the integrated long‐term effects of NO 2 . • NO 2 had no toxic effects. A reduced 15 N‐isotope ratio indicated incorporation of NO 2 while nitrate reductase activity in leaves was stimulated. The two nitrogen sources had differential effects on water use efficiency (WUE): NO 2 exposure increased long‐term WUE; soil N supply decreased WUE; a result not detectable using growth and short‐term gas exchange experiments. Plants benefited from airborne NO 2 , increasing CO 2 assimilation rate and biomass; both N sources increased shoot production at the expense of root growth. NO 2 exposure induced leaf formation with reduced stomatal density and increased leaf area. • NO 2 exposure might be beneficial although the reduced root: shoot biomass could have a detrimental effect on nutrient balance and drought resistance.