The Seasonal Semideciduous Forest (SSF) of SE Brazil is an extensively fragmented biome and continuously receives the deposition of heavy metals, such as cadmium (Cd). This metal, depending on its concentration, may cause oxidative stress in different plant species. In this study, we analyzed the effects of different Cd concentrations on the antioxidant activity and initial development of two SSF native species. Cedrela fissilis and Colubrina glandulosa seedlings were grown in different concentrations of Cd: 0 (control), 300, 700, and 1000 mg L⁻¹. After 10 days, the concentrations of Cd significantly reduced the length of both species and the dry mass in C. fissilis. The superoxide dismutase (SOD) and peroxidase (POD) activities of C. fissilis were reduced by Cd doses, while catalase (CAT) activity and proline concentration were increased. In C. glandulosa, the SOD activity showed a hormesis response and POD increase in 1000 mg L⁻¹ of Cd. The results showed that C. glandulosa had greater developmental plasticity and maintenance of biomass than C. fissilis, even when MDA values were high, suggesting that they were balanced by the higher efficiency of the enzymatic antioxidant system. In C. fissilis the mechanism of action against oxidative stress was partially enzymatic (CAT activity) and partially non-enzymatic (proline). These results showed that both species were sensitive to Cd exposure; however, they present different responses and tolerance levels under different concentrations of the metal. The parameters analyzed in these species can be used as suitable biomarkers for monitoring the toxicity of Cd in the SSF.

巴西东南部的季节性半落叶森林（SSF）是一个破碎的生物群落，并不断接受重金属（例如镉（Cd））的沉积。这种金属取决于其浓度，可能在不同的植物物种中引起氧化胁迫。在这项研究中，我们分析了不同Cd浓度对两种SSF天然物种的抗氧化活性和初始发育的影响。Cedrela fissilis和Colubrina glandulosa幼苗在不同浓度的Cd：0（对照），300、700和1000 mg L ^-1下生长。10天后，Cd的浓度显着降低了纤丝梭菌的两个物种的长度和干重。超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性镉剂量减少了C. fissilis，而过氧化氢酶（CAT）活性和脯氨酸浓度增加了。在C. glandulosa中，在1000 mg L ^-1的Cd中， SOD活性表现出兴奋反应，POD增加。结果表明，C.腺具有更大的发育可塑性和生物质比的维护C. fissilis，即使当MDA值分别为高，这表明它们是由酶促抗氧化系统的更高的效率平衡。在C. fissilis抗氧化应激的作用机制部分是酶促的（CAT活性）和部分是非酶促的（脯氨酸）。这些结果表明，这两种物种都对镉暴露敏感。但是，它们在不同浓度的金属下表现出不同的响应和耐受水平。在这些物种中分析的参数可用作监测SSF中Cd毒性的合适生物标记。