Three wheat (Triticum aestivum L.) cultivars [HD 2987 (ozone (O₃) sensitive), PBW 502 (intermediately sensitive) and Kharchiya 65 (O₃ tolerant)] with known sensitivity to O₃ were re-evaluated using ethylenediurea (EDU; 400 ppm) to ascertain the use of EDU in determiningO₃ sensitivity under highly O₃-polluted tropical environments. EDU treatment helped in improving the growth, biomass, photosynthetic pigments and the antioxidative defense system of all the wheat cultivars. Under EDU treatment, PBW 502 retained more biomass, while HD 2987 showed better performance and ultimately the greatest increment in yield. Cultivar Kharchiya 65 also showed a positive response to EDU as manifested with an increase in pigment contents, total biomass and enzymatic antioxidants; however, this increment was comparatively lower compared to the other two cultivars. The results indicated that EDU did not have many physiological effects on cultivars but helped in counteracting O₃ primarily by scavenging reactive oxygen species and enhancing the antioxidative defense system where superoxide dismutase emerged as the major responsive biochemical parameter against ambient O₃. The observed results clearly indicated that differential O₃ sensitivity in three wheat cultivars established by the previous study is in accordance with the present study using EDU as a sensitivity tool, which is an easy and efficient technology in comparison to chamber and Free-Air Carbon dioxide Enrichment (FACE) experiments although its mechanistic understanding needs to be further validated.
Keywords: antioxidants; biomass; ethylenediurea; ozone sensitivity; yield.