Varietal screening of ozone sensitivity in Mediterranean durum wheat (Triticum durum, Desf.)

This study investigated the ozone (O3) sensitivity of five cultivars of durum wheat (Triticum durum)\r\ngrown in Open-Top Chambers (OTC) during the 2013 growing season. Two levels of ozone were applied\r\nduring daylight hours: þ50% and 50% of ambient ozone concentration respectively in O3-enriched OTC\r\nand charcoal-filtered OTC. Results suggest that the significant differences observed in agronomic parameters,\r\nwere more cultivar-dependent rather than ozone-dependent. Two cultivars showed a significant\r\nreduction of aboveground biomass due to ozone ( 19.7% and 25%), however only one of them\r\nshowed also a significant reduction in grain yield ( 16%). Stomatal conductance was significantly\r\nreduced by ozone fumigation up to 33% in the afternoon measuring cycle. No significant effects on\r\nchlorophyll fluorescence were found, nor correlation was observed between ozone-like symptoms\r\nseverity (leaf chlorotic/necrotic spots) and yield reduction, suggesting that these parameters cannot be\r\nindicative of ozone sensitivity/tolerance. These results may be useful for the selection of durum wheat\r\ngenotypes more adapted for the cultivation in geographical areas where tropospheric ozone is particularly\r\nhigh, but also for the future definition of consistent doseeresponse relationships to be used in the\r\nozone risk assessment evaluation for the Mediterranean countries.