Abstract: With decomposing pepper stalk as test material,this paper studied its allelopathy on the growth of pepper plants.The results showed that after 60 days of decomposition,the decomposed pepper stalk could decrease the plant height,stem diameter,dry weights of above-and underground biomass,leaf area,and chlorophyll content of pepper plants by 0.0374～0.0646,0.0020～0.0097,0.0050～0.0355 and 0.0916～0.3584,0.0016～0.0251,and 0.0043～0.0242 respectively.These inhibitory effects were enhanced after 120 days of decomposition,but the difference with CK was not significant.The root vigor and its SOD,POD and CAT activities of pepper plants were decreased,while the MDA content and relative conductivity were increased with the increasing concentration of decomposed pepper stalk and with the prolong of treating time.The allelopathic effects of decomposed pepper stalk on the physiological indices of pepper root activity ranged from 0.0163 to 0.6507,which was significantly higher than that of plant growth index.

Key words: priming effect, carbon isotope, soil layer, organic carbon mineralization, no-tillage., black soil