JOURNAL OF AQUATIC PLANT MANAGEMENT(2009)--Physiological and Cellular Ultrastructure Responses for Three Grass Species under Submergence-河南省大气污染综合防治与生态安全重点实验室

To illustrate the tolerance mechanisms of different grass species to submergence, we examined the changes in biochemical and anatomical characteristics and leaf photosynthesis of three grass species. Vetivergrass (Vetiveria zizanioides), bahiagrass (Paspalum notatum), and carpetgrass (Axonopus compressus), the species selected for this study, are commonly used for erosion control under complete submergence in water-cultivation studies. After submergence, chlorophyll (a + b) and carotenoids of carpetgrass decreased by 10.4 and 32.2%, respectively, while those of vetivergrass increased by 39.8 and 39.5%, and bahiagrass increased by 35.9 and 27.8%, respectively, from 9 to 36 days. The PSII maximum photochemical efficiency and the quantum yield of carpetgrass decreased to a greater extent than that of vetiver-grass and bahiagrass. The malondialdehyde content of carpetgrass increased more than that of vetivergrass and bahiagrass, with increasing submergence time. The activity of superoxide dismutase and ascorbate peroxidase of carpetgrass decreased with submergence duration, whereas those of vetivergrass and bahiagrass remained stable or increased. When the stress duration was relatively short (<60 days), vetivergrass and bahiagrass had similar levels of tolerance with respect to photosynthetic features and biochemical response; however, the damage of submergence to the ultrastructure of some important organelles of bahiagrass was more severe than vetivergrass when the duration was longer than 60 days. The ultrastructure of vetivergrass was not damaged markedly unless it was exposed to 120 days of submergence, whereas that of carpetgrass was severely damaged by 32 days after submergence. Overall, vetivergrass was the most tolerant of the three species, while carpetgrass had the poorest tolerance.