Growth and Physiology Response of Perennial Ryegrass to Cd~(2+)Stress

In order to examine the phytoremediation potentiality of perennial ryegrass to heavy metal Cd2 +,the accumulation characteristics,growth and physiology response of perennial ryegrass to Cd2 +stress were illustrated in this paper. The plants were treated with 0,5,10,20 mg·L- 1Cd2 +solution for 6 days,when 6 days after treatment( dat),the growth of perennial ryegrass was significant inhibition by Cd2 +,Cd content of leaf and root were significantly elevated with increasing Cd2 +concentration,perennial ryegrass represented hyper-accumulative ability for Cd. When 6dat exposed to 5mg·L- 1Cd2 +,the root,shoot biomass and the ratio of root to shoot were significantly decreased by36. 83%,12. 17%,27. 59% compared with control. The net photosynthesis rate( Pn) was significantly decreased by23. 38% compared with control when 6dat under 5 mg / L Cd2 +stress,whereas other gas exchange parameters,the photosynthetic pigment content and the maximum photochemical efficiency( Fv / Fm),potential photochemical efficiency( Fv/ Fo) were not affected significantly. When photosynthetically active radiation( PAR) exceeded 580μmol·m- 2·s- 1after 6 days treatment by 5 mg·L- 1Cd2 +concentration,the effective photochemical efficiency( ΦPSII) and relative electrons transport rate( r ETR) were lower than control,and the inhibition degree strengthened with the increasing PAR,when the PAR reached to the higest intensity( 1 465μmol·m- 2·s- 1),they were both significantly decreased by15. 46%.,whereas the regulatory energy dissipation [Y( NPQ) ] was significantly higher than control all the time,this would alleviate the damage of photosynthetic agency induced by the excess excitation energy. When 6dat exposed to 5mg·L- 1Cd2 +concentration,the activity of superoxide dismutase( SOD) and ascorbic acid peroxidase( APX) were both inhibited,the activity of catalase( CAT) was promoted,and the content of Malondialdehyde( MDA) was significantly increased. The Pn,r ETR,and SOD,APX activity could be taken as the physiological indexes to indicate the impair extent of perennial ryegrass by Cd2 +. The conclusions of this study would provide reference for remedy plants breeding on the heavy metal pollution.