Tolerance and Susceptibility of Kentucky Bluegrass (Poa pratensis L.) Cultivars to Air Pollution: In the Field and in an Ozone Chamber

Abstract During late summer and autumn of 1970, differential injury, believed to be due to air pollution, was observed on five Kentucky bluegrass (Poa pratensis L.) cultivars: ‘Merion’, ‘Kenblue’, ‘Windsor’, ‘117‐27‐6’, and ‘Belturf’. Belturf was injured most, 117‐27‐6 least, and the other three cultivars were intermediate as to injury. Damage was less severe on parts of plots fertilized with N at 293 kg/ha than on parts of plots fertilized with 146.5 kg/ha of N. Subsequent tests of three of these cultivars in an ozone chamber (30 pphm 2 and 4 hours) showed cultivar injury ratings corresponding to field injury ratings. Belturf was most severely injured, Windsor next, and 117‐27‐6 least. Differences among cultivars were highly significant at both levels of ozonation. Injury was significantly greater when ozone was applied at 30 pphm for 4 hours, than at the same level for 2 hours. The 117‐27‐6 was unique in that it tolerated ozone considerably better than did previously investigated Kentucky bluegrass cultivars. The chance selection of this extremely tolerant cultivar was possibly related to its having been selected from M 3 progeny of irradiated Merion seed. This ozone experiment also indicated that bluegrass may build up some tolerance to repeated ozone treatments.