Relative effectiveness of ethylenediurea, and constitutent amounts of ureaand phenylurea in ethylenediurea, in prevention of ozone injury to tobacco

The relative effectiveness of ethylene diurea (EDU:), and constituent amoun ts of urea (U) and phenylurea (PU) in EDU, in prevention of ozone injury to tobacco (Nicotiana tabacum) leaves was determined in greenhouse exposure c hambers. Four-leaf stage seedlings of tobacco cultivars Bel-W3 (ozone-sensi tive) and Bel-B (ozone-tolerant) were either sprayed with water (controls), EDU (300 mg/litre), U (70 mg/litre), or PU (159 mg/litre) 24 h before expo sure to charcoal-filtered (CF) air or CF plus ozone at 80+/-5 ppb for 7 h/d ay for 5 or 6 days. None of the treatments adversely affected Bel-W3 or Bel -B plants in CF air. Control or treated Bel-B plants in ozone were not affe cted. Ozone injury on Bel-W3 plants was evaluated daily, using the oldest t wo lower leaves (one and two). EDU was the most effective treatment, dimini shing slightly with length of ozone exposure. U-treated plants experienced as much or more ozone injury than the non-treated controls. PU reduced ozon e injury significantly, but was not as effective as EDU. When Bel-W3 plants were treated with 300 mg/litre EDU or PU and exposed to ozone, both compou nds were equally effective in preventing ozone injury. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.