OZONE TOLERANCES OF SOYBEAN CULTIVARS AND NEAR-ISOGENIC LINES IN A FUMIGATION CHAMBER

Ozone (O3) toxicity is a potential yield-limiting factor for soybean (Glycine max L. Merr.) in the United States and worldwide. The most economical solution to the problem is to use Os-tolerant cultivars. Thirty-four cultivars and 87 near-isogenic lines (NILS) of soybean were screened for O3 tolerance in a fumigation chamber (250 ppb for three hrs). Most tolerant cultivars tested were 'Cloud', 'T-276', 'T263', and 'Kindu'. Moderately tolerant cultivars included 'Davis', 'T-210', and 'Elton'. Most sensitive cultivars were 'Corsoy 79', 'Noir', and 'Midwest'. The original 'Clark' cultivar was not tested, but 'Clark 63' tended to be more tolerant than 'Harosoy'. The aluminum (All-tolerant 'Perry' cultivar also tended toward greater O3 tolerance than the Al-sensitive 'Chief', as observed earlier. Our rankings of 'Hark' as moderately sensitive and 'Davis' as moderately tolerant are also in agreement with earlier reports. Among NILS, the order of O3 tolerance was generally Williams>Clark>Harosoy, but differences were also observed within these parental groups. For example, L68-560 was more tolerant than some other NILS of 'Harosoy'. 'L76-1988' appeared more tolerant to O3 than other NILS of 'Williams', but all 'Williams' NILS were more tolerant than most NILS of 'Harosoy' and 'Clark'. Ozone-tolerant and -sensitive soybean cultivars or NILS identified in our study may be useful tools in studies on mechanisms of O3 tolerance and differential O3 tolerances in plants and in the development of ameliorative measures.