Gram-positive and Gram-negative bacterial PLFAs were analyzed under different treatments at the three growth stages (Table VI). The PLFA concentrations of Gram-positive bacteria were lower than those of Gramnegative bacteria. Significant differences in Grampositive
and Gram-negative bacterial PLFAs were detected from paddy soils treated with different N levels under WLI and WCI. During the three growth stages, the N1, N2, and N3 treatments had significantly higher Gram-positive and Gram-negative bacteria than N0 through the irrigation patterns. However,there were no significant differences between N0 and N1 for both Gram-positive and Gram-negative PLFAs at the tillering stage under WCI condition. The Grampositive PLFAs under WLI were significantly higher
than those under WCI at the maturity stage (Table VI, P < 0.01). However, there were no significant differences between WLI and WCI for Gram-negative PLFAs at all the three growth stages. In addition,there were significant I × N interactions for the two
groups at the maturity stage (Table VI, P