2001～2002连续两年在大田生产条件下研究了10个烤烟基因型气孔密度和气孔导度的变异情况及其与抗臭氧伤害的关系；2002年在控制条件下采用低温加臭氧的方法处理烟草植株，研究分析了烟草叶片遭受臭氧伤害后抗氧化酶活性的变化及其与抗臭氧伤害的关系。结果表明：烤烟不同基因型对臭氧伤害的抗性存在显著的差异。烟草叶片下表皮气孔密度和气孔导度与臭氧伤害引起的气候斑点病具有相关关系，在烟株下部叶中，其相关性分别达到显著（R2001＝0.68，R2002＝0.65）和极显著水平（R2001＝0.87，R2002＝0.80）。因此，下部叶气孔密度和气孔导度可以作为抗病育种的选择指标。在控制条件下的试验结果表明：只有低温加臭氧复合因子才能诱发烟草叶片产生臭氧伤害症状。烟草叶片低温下遭遇臭氧伤害后，超氧化物歧化酶（SOD）活性升高，升幅与气候斑点病病情指数负相关，过氧化氢酶（CAT）活性略有升高，过氧化物酶（POD）活性急剧下降。抗性较差的烟草基因型抗氧化酶反应不敏感，臭氧伤害症状严重，抗性较强的烟草基因型抗氧化酶反应敏感，臭氧伤害症状较轻。低温和臭氧同时作用明显影响了活性氧清除系统，致使系统中酶活性比例失调，POD活性急剧下降,可能是烟草叶片产生臭氧伤害的原因之一，SOD和CAT活性升高对消除臭氧伤害具有一定的防御作用。
Changes in stoma density and stomatal conductance of 10 tobacco (Nicotiana tabacum) genotypes and its relationships to weather-fleck caused by ozone were studied in controlled field experiments in 2001 and 2002. Under controlled growing conditions in 2002, changes in the activities of 3 antioxidant enzymes in leaves of 5 genotypes were analyzed in relation to the degree of ozone injury following a combined treatment of ozone and low temperatures (10 ℃). The results showed that there were significant differences in leaf resistance to ozone injury among genotypes. Stoma density and stomatal conductance on the lower epidermis of tobacco leaves were related to weather-flecks caused by ozone. The lower leaves on the plants were especially sensitive to ozone injury. Correlation coefficients between stoma density and weather-flecks and between stomatal conductance and weather-flecks were 0.65 -0.68 and 0.80-0.87, respectively. Therefore, it is proposed that stoma density and stomatal conductance of the lower leaves on tobacco plant be used as a selection marker for disease-resistance breeding. The results of controlled experiments showed that ozone combined with low temperatures of 10 ℃ induced weather-flecks in leaves of 5 flue-cured tobacco genotypes. The activity of SOD increased in ozone-injured leaves and increasing SOD activity was negatively correlated to the weather-fleck index. Activity of CAT was slightly enhanced but activity of POD decreased remarkably. Activity of antioxidant enzymes was low and hence weather-fleck injury was great in tobacco genotypes with little resistance to ozone, whereas when the activity of antioxidant enzymes was high in genotypes, there was strong resistance to ozone injury. The results indicated that ozone combined with low temperatures of 10 ℃ markedly affected active oxygen-scavenging systems in tobacco leaves caused by an imbalance in activities of 3 antioxidant enzymes. Sharp decreases in POD activity might be one of the major reasons why leaves were injured by ozone, whereas increases in the activities both of SOD and CAT helped to protect against ozone injury.