Ozone Sensitivity of Green Ash Selections from Midwestern USA
Dennis R. Decoteau, Richard P. Marini, Donald D. Davis

Green ash seeds were collected from various sites in midwestern USA and shipped to The Pennsylvania State University for evaluation of resultant seedlings’ potential use as ozone bioindicators. Seeds were germinated in pots and seedlings maintained for one year in a greenhouse containing carbon-filtered-air (5 – 8 ppb ozone). Seedlings were then planted in the field within four open-top chambers. The air in two of the chambers was charcoal-filtered and contained 24 to 34% of ambient ozone (Filt), whereas two chambers received non-filtered ambient air (NF). After 2.5 years in the chambers, ozone injury symptoms were not observed on seedlings in the Filt treatment. In contrast, ozone-induced leaf injury (dark adaxial stipple) was observed in the NF treatment on seedlings from seed collected in Missouri (MO1 and MO3), Wisconsin (WI2 and WI2), Nebraska (NE) and North Dakota (ND). However, only seedlings from MO3 and ND had ozone injury levels that were significant for all foliar injury metrics, suggesting that seedlings from these two seed sources may serve as ozone-sensitive bioindicators. Seedlings from seed source WI13 exhibited significant reductions in ozone-induced growth effects, even though they exhibited no foliar injury.

Full Text: PDF DOI: 10.15640/jaes.v7n2a18