Abstract: A pot experiment was conducted to study the effects of drought stress on the dry matter partitioning of young Robinia pseudoacacia at its early, vigorous, and late growth stages under five soil moisture regimes (40%, 52.2%, 70%, 87.8%, and 100% of field water-holding capacity). At any given growth stage, soil moisture regime had no significant effects on the dry matter partitioning ratio of branch and stem. Short-term (15 d), medium- and light drought stress (70% and 87.8% of field water-holding capacity) had less effects on the dry matter partitioning ratio of leaf and shoot, while long-term (45-60 d) severe drought stress (40% of field water-holding capacity) decreased this partitioning ratio significantly, and increased the course root dry matter partitioning ratio and root/shoot ratio. As affected by the inherited growth characteristics of R. pseudoacacia itself and the variation of weather conditions among seasons, drought stress had different extents of effects on the dry matter partitioning of young R. pseudoacacia at its different growth stages, with the most significant effect occurred at early growth stage and the least at late growth stage.

Key words: Degrading bacterium, Methyl parathion, Pesticide residue, Degrading rate