Studies On Drought Resistance Of Plantago Asiatica L. And Viola Philippcia Cav.

Treated with different concentrations of PEG 6000 in 1/2 Hoagland nutrient solution for 3 days, the physiological indexes Pn, chlorophyll fluorescence parameters, cell membrane permeability, malondialdehyde and relative water contents of Plantago asiatica L. and Viola philippcia Cav. were studied. The Pn of P. asiatica and V. philippcia gradually decreased when water stress increased. Stomatal factor was the dominant factor of Pn decreasing of P. asiatica, while the Pn decreasing of V. philippcia was induced by both stomatal and non-stomatal factors. By the stress of ψw=-0.84MPa for 3 days, P. asiatica showed light water stress , while V. philippcia was moderate water stress, indicating both the plants have good drought resistance. Values of Fv/Fm and Fv/Fo in two plants gradually decreased with increasing water stress. Compared to the control, the cell membrane permeability of P. asiatica and V. philippcia increased by 54% and 126%, respectively, under 0.25Kg/L of PEG treatment. By the synthetic analyzing of all the indexes, it was concluded that P. asiatica be preferable to adapt to water stress, and net photosynthetic rate, cell membrane permeability and relative water content could be used for comparing the drought resistance of different species.Treated with PEG 6000 for 3 days, the increasing of cell membrane permeability of V. philippcia was not mostly induced by superoxide action. Malondialdehyde contents does not suit the qualifications for distinguish drought resistance of two species of plant.Fv/Fm didn't drop until the concentration was high enough. When plants is treated with low concentration PEG solutions, Fv/Fm is not a sensitive index.Treated with morn than 0.05Kg.L^-1 PEG 6000 solution for 5 days, the Pn of Plantago asiatica and Viola philippcia were both dropped. Non-stomatal factors affected the Pn of as soon as the concentration of PEG exceeds 0.20Kg.L-1. When water stress increased, the stomatal factors of Plantago asiatica increased gradually. Non-stomatal factors didn't affected the Pn of Plantago asiatica remarkably.As Fv'/Fm' decreasing, the qN of Plantago asiatica and Viola philippcia increased...