Abstract: 【Objective】The purpose of this paper is to clarify the protective effects of exogenous silicon and CoQ10 on the biophysical characters and respiration of mitochondria in vitro from the salt-stressed cucumber (Cucumis sativus L.) roots. 【Method】The treatments with K2SiO3 (1.0 mmol·L-1) were divided into three groups: CK group, NaCl group, NaCl＋K2SiO3 group; and the isolated mitochondria were treated with 10 mmol·L-1 CoQ10.【Result】The results showed that additional silicon in nutrient solution could significantly decrease H2O2 and MDA contents, increase membrane fluidity and membrane electronic potential (ΔΦM) in mitochondria from salt-stressed cucumber roots, decrease membrane swelling, increase the rate of respiration by prominently increasing respiratory control ratio（RCR）and oxidative phosphorilation ratio (P/O). The addition of CoQ10 in isolated mitochondria also decreased membrane swelling, increased membrane micro-viscosity and electronic potential, decreased the contents of H2O2 and MDA in the meantime, especially under salt stress. 【Conclusion】The above results suggests that exogenous silicon and CoQ10 may effectively antagonize the afor ementioned changes in mitochondria induced by salt stress, increase its ability of protection against lipid peroxidation and membrane integrity, which leads to the increase of respiratory rate.

Key words: Cucumber (Cucumis sativus L.), CoQ10, Exogenous silicon, Mitochondria, Salt stress