High doses of ethylene diurea (EDU) are not toxic to willow and act as nitrogen fertilizer.
Ethylene diurea (EDU) is synthetic chemical which protects plants against damage caused by ground level O3 and is used experimentally as a biomonitoring tool at doses usually ranging from 200 to 400mgL(-1) a.i. Although several studies have investigated the protective action of EDU, this mechanism remains unclear. Important uncertainties in EDU action are whether EDU acts as a source of nitrogen (N) to plants and whether high doses are phytotoxic. In order to answer these questions, we conducted an open-field experiment where potted willow (Salix sachalinensis Fr. Schm) plants were exposed to ambient O3 conditions and treated with 0, 800 or 1600mgL(-1) EDU as a soil drench, every nine days, for about 2.5months. We examined approximately 50 response variables. Based on N content in different plant organs, we found that (a) all EDU was transferred to the leaves and (b) high doses of EDU increased the leaf N content. However, EDU did not affect the C content and distribution within the plant body. Still, even at the highest dose, EDU was not toxic to this fast-growing species (however such a high dose should not be applied in uncontrolled environments); and there was no EDU persistence in the soil, as indicated by soil N content. Notably, our soil was free from organic matter and N-poor.


CONCLUSIONS
EDU per se does not cause toxicity to willow plants when applied as drench to a soil with no organic matter, rather, high EDU doses may act as nitrogen fertilizer in a nitrogen-poor soil.
Silviculture & Forest Ecological Studies, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan. Electronic address: evgenios_ag@hotmail.com.
Evgenios
E
Agathokleous
Institute of Sustainable Plant Protection, National Council of Research, Via Madonna del Piano 10, Sesto Fiorentino, Florence 50019, Italy. Electronic address: elena.paoletti@cnr.it.
Elena
E
Paoletti
Lab of Ecology and Environmental Science, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece. Electronic address: saitanis@aua.gr.
Costas J
CJ
Saitanis
Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA, USA. Electronic address: wmanning@microbio.umass.edu.
William J
WJ
Manning
Silviculture & Forest Ecological Studies, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
Cong
C
Shi
Silviculture & Forest Ecological Studies, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan. Electronic address: tkoike@for.agr.hokudai.ac.jp.
Takayoshi
T
Koike
D000393:Air Pollutants / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D005308:Fertilizers; D009584:Nitrogen / Q000008:administration & dosage / Q000494:pharmacology*; D010126:Ozone / Q000737:chemistry; D010671:Phenylurea Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D020011:Protective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D032108:Salix / Q000187:drug effects*
D000393:Air Pollutants; D005308:Fertilizers; D010671:Phenylurea Compounds; D020011:Protective Agents; C032766:ethylene diurea; D010126:Ozone; D009584:Nitrogen
Air pollution; Antiozonant; C4H10N4O2; Ethylenediurea; N-[−2-(2-oxo-1-imidazolidinyl) ethyl]-N′-phenylurea]; Ozone