To establish the relationship between ozone (O3) dose and foliar injury and yield in peanut (Arachis hypogaea L.), several approaches were employed. First, foliar sensitivity to O3 of 10 Spanish cultivars and lines, and eight Valencia cultivars and lines were assessed over a 3-yr period. Maximum percentage of the foliage affected by O3 rarely exceeded 10% for any Valencia cultivar, while foliar injury on Spanish cultivars in August frequently exceeded 25% and even 50% on some cultivars. In a second study, two Spanish and two Valencia cultivars were treated with the antioxidant, EDU, and compared to untreated controls. Neither Valencia cultivar exhibited relevant foliar injury or differences in yield because of EDU application. Untreated USDA PI 268661 (Spanish) exhibited consistently high levels of foliar injury and significant reductions in yield, while the Spanish line EM-12 exhibited less foliar injury and more variability in yield response. Thirdly, yield data of cultivar trials from 1975 to 1984 were used to determine if differences in yield between sensitive and insensitive cultivars could be regressed on seasonal ozone dose to attempt an estimation of a dose-response function. Over the 10-yr period regressions of yields of single cultivars on seasonal O3 dose were not significant for any cultivar. Regressions of the yield ratios (sensitive cultivar/insensitive cultivar) against O3 were also not significant. Even though yield varied greatly from year to year, yields of any two cultivars (sensitive or insensitive to O3) in any given year were highly correlated over the 10-yr period. It appears that yield data are not a sufficiently sensitive parameter to establish a dose-response function, and that other factors override any yield effects of O3 over the 10-yr period examined.Key words: Peanut, ozone sensitivity, ethylene diurea, cultivar differences, yield
Effects of tropospheric ozone on white clover plants exposed in open-top chambers or protected by the antioxidant ethylene-diurea (EDU)
