Abstract: A field experiment was conducted to study the biomass accumulation and nitrogen (N) storage in different parts of eucalypt in the current year (2007) and next year (2008) of N topdressing. Compared with the control, N topdressing increased the eucalypt biomass, and the increment was much higher in 2008 than in 2007, suggesting that N topdressing had definite positive and cumulative effect on eucalypt growth. Nitrogen topdressing also increased the N storage in eucalypt, with the increment in 2007 and 2008 being 30.2% and 73.5%, respectively. Compared with that in 2007, the eucalypt biomass and N storage in the control in 2008 was increased by 35.9% and decreased by 13.1%, respectively, while those under N topdressing in 2008 were increased by one-fold and 15.7%, respectively. The main reason for these was the foliage yield reduction in 2008. Among the organs of eucalypt, leaf had the most obvious decrease in N storage. In 2008, the leaf N storage in the control and under N topdressing was decreased by 46.5% and 36.9%, respectively, compared with that in 2007.

Key words: Greenhouse, Cucumber, Bagging, Ecological effect