Effects Of Perchlorate On Alternanthera Philoxeroides And The Regulating Of Lanthanum

Perchlorate is a new emerging persistent pollutant. In order to explore the effects of 1⁵00mg/L perchlorate on aquatic plant and understand the regulating effect of exogenous lanthanum on the aquatic plant physiological response to perchlorate stress, Alternanthera philoxeroides was taken as experimental material under the controlled conditions. The results showed as follows:1.Effects of perchlorate on growth and differentiation of stem segmentsUnder perchlorate treatment, the growth of stem segments of A. philoxeroides and the germination of young leaves were inhibited with different degrees. Apical meristem of A. philoxeroides presented injury symptoms. And growth rhythm of root,root number didn't changed obviously, but the growth of root length of A. philoxeroides at high ClO₄^- concentration were inhibited significantly.2.Effects of perchlorate on growth physiology and ultrastructureThe sensitivity of different organs of A. philoxeroides to perchlorate was found to be: root>leaf>stem. Under perchlorate treatment for 40d, ETR-PAR curve, SPAD, Fv/Fm, Fv'/Fm',ΦPSâ…¡, ETR, and other indexes were inhibited with different degrees, but the proportion of stem biomass increased gradually. The observation of scanning electron microscope combining with energy spectrometer analysis and transmission electron microscope indicated that ClO₄^- can enter the root cell under perchlorate treatment, damage the root construction and function of A. philoxeroides, injure the nucleus and chloroplasts of leaf cell, in severe case, perchlorate treatment can disrupte chloroplast membrane and disintegrate organelles in cell.3.Effects of lanthanum on growth physiology and ultrastructure under perchlorate stressExogenous lanthanum (0.1⁰.5mg/L) application can alleviate the damage of nucleus, chloroplasts and oxidative stress under perchlorate stress. Compared with the ClO₄^- stress group, chlorophyll fluorescence, growth and other indexes of the treatment with appropriate lanthanum were increased in different degrees, but high concentration of lanthanum resulted in negative effect. Results from dark relaxations of non-photochemical quenching, the chlorophyll fluorescence induction kinetics and ETR-PAR curve showed that applying appropriate concentration of exogenous lanthanum to A. philoxeroides can efficiently ameliorate light energy between two photosystems equilibrium assignment, promote light energy conversion and photochemical reaction under the stress.