Abstract: With sand culture in greenhouse, the responses of Fraxinus mandshurica seedlings growth, biomass, and N allocation to 2 levels of light intensity and 4 levels of N supply were studied. The results showed that under low light intensity, the seedlings shoot/root ratio (S/R) and net N uptake rate (NNUR) increased significantly (P<0.01), but their relative growth rate (RGR) and net assimilation rate (NAR) had a significant decrease (P<0.01). The biomass of root, stem, leaf, and total plant under low light was decreased by 36.8% (P<0.01), 1.7%, 12.7% (P<0.05), and 24.3% (P<0.01), respectively, and the N allocation to leaf increased but that to root was in adverse. At the two light levels, N supply had an obvious promotion effect on the seedlings growth, and the S/R and the N allocation to leaf were increased obviously with increasing N supply. Significant interactive effects of light and N supply were observed on the seedlings diameter, S/R, RGR, and biomass allocation.

Key words: purple soil, yellow soil, lettuce, pig manure, nitrate, yield, nutrient.