Comparison of growth and chlorophyll fluorescence characteristics between Plantago virginica and P. asiatica under aluminum stress.
The present study is aimed at comparing the differences in growth responses and chlorophyll fluorescence characteristics between exotic invasive species Plantago virginica and native species P. asiatica under various concentrations of Al3+ stress (100, 500, 800 and 2 000 mg . L-1) along with different durations (0, 10, 20 and 30 d). The results showed that root/shoot ratio increased slightly under low concentration of aluminum (100 mg . L-1) and began to decrease significantly at over moderate concentration (500 mg . L-1); leaf chlorophyll a and chlorophyll b showed less change under low concentration of aluminum, but decreased obviously with the increases in Al3+ concentration and treatment duration. Measurements of chlorophyll fluorescence parameters revealed that Fv/Fm, ΦPS II and Fv/Fo increased slightly under low concentration of aluminum, and decreased obviously with the increases in Al3+ concentration and duration. The decreases in root/shoot ratio, chlorophyll a and chloraphyll b, Fv/Fm, ΦPS II and Fv/Fo of P. virginica was less than those of P. asiatica, indicating that the exotic invasive P. virginica had greater potential to alleviate aluminum stress through the mechanism of physiological defense, compared with the native P. virginica.