Genotypic differences in the responses of gas exchange, chlorophyll fluorescence, and antioxidant enzymes to aluminum stress in Festuca arundinacea

Abstract

In this study, the gas exchange, chlorophyll fluorescence, and antioxidant activity in eight tall fescue cultivars were investigated under aluminum stress. The results showed that the net photosynthetic rate (PN) and stomatal conductance (gs) were decreased, while the intercellular CO2 concentration (Ci) was stable or increased under Al stress conditions. The efficiency of excitation capture by open PSII reaction centers (F′v/F′m), the maximum quantum yield of PSII photochemistry (Fv/Fm), the quantum yield of PSII electron transport (ΦPSII), and the photochemical quenching (qP) were also decreased after Al stress, while the non-photochemical quenching (NPQ) was increased. Moreover, Al stress increased the antioxidant activities and MDA contents in each tall fescue cultivars. However, there was a lot genotype differences between the Al-tolerant and Al-sensitive cultivars. Cv. Barrington was the most sensitive cultivar and cv. Crossfire 2 was the most tolerant cultivar. The excessive excitation energy could not be dissipated efficiently by antenna pigments, and reactive oxygen species could not be scavenged efficiently, thereby resulting in membrane lipid peroxidation in cv. Barrington under Al stress conditions.