POTENTIAL ROLE OF ALLELOPATHY IN THE SOIL AND THE DECOMPOSING ROOT OFCHINESE-FIR REPLANT WOODLAND

The role of allelopathy in the Chinese-fir (Cunninghamia lanceolata) r eplant problem was studied. The failure of Chinese-fir seedlings to gr ow normally in Chinese-fir replant woodland was not only caused by the depletion of nutrients and the deterioration of the structure of repl ant woodland soil, but also by biotic factors and allelopathy. Extract s of soils collected from replant woodlands significantly reduced the growth of Chinese-fir seedlings. Extracts and decomposing root residue s also significantly inhibited the growth of Chinese-fir seedlings. Ex tracts of the replant soil and of the decomposing roots from Chinese-f ir replant woodland were both toxic to other plants. The combination o f the decomposing root residues and the pathogenic fungi reduced the g rowth of Chinese-fir seedlings the most when compared to the decomposi ng root residue alone and the control. It appears that allelopathy is at least partly involved in the Chinese-fir replant problem.