Use of ethylene diurea (EDU) in assessing the impact of ozone on growth and productivity of five cultivars of Indian wheat (Triticum aestivum L.)

Increase in concentrations of tropospheric ozone (O-3) is one of the main factors affecting world agriculture production. Tropical countries including India are at greater risk due to their meteorological conditions (high solar radiation and temperature) being conducive to the formation of O-3. The most effective anti-ozonant chemical is N-[2-(2-oxo-1-imidazolidinyl) ethyl]-N-phenylurea or ethylene diurea (EDU). Due to its specific characteristics, EDU has been used in the field as a phytomonitoring agent to assess crop losses due to O-3. Field experiments were conducted on five local cultivars of wheat (Triticum aestivum L. cv HUW234, HUW468, HUW510, PBW343, and Sonalika) grown under natural field conditions in a suburban area of Varanasi, Uttar Pradesh, India during December 2006 to March 2007 to determine the impact of O-3 on their growth and yield characteristics. Mean monthly O-3 concentrations varied between 35.3 ppb and 54.2 ppb at the experimental site. EDU treatment positively affected various growth and yield parameters with difference between cultivars. EDU-treated plants showed increase in shoot and root length, leaf area, absolute growth rate, relative growth rate, and net primary productivity, indicating O-3 induced suppression in growth. EDU treatment was highly significant in different cultivars for total biomass and test weight but not for harvest index. Yield per plant was higher by 25.6%, 24%, 20.4%, 8.6%, and 1.9% in EDU-treated cultivars HUW468, Sonalika, HUW510, HUW234, and PBW343, respectively, than non-EDU-treated ones. These results clearly indicate the sensitivity of all the wheat cultivars to ambient levels of O-3 with cv HUW468 appearing to be most sensitive. The present study also supports the view that EDU has great potential in alleviating the unfavorable effects of O-3 and can be effectively used as a monitoring tool to assess growth and yield losses in areas experiencing elevated concentrations of O-3.