FIG 3.

Relative expression of nirK gene and norB gene of Bradyrhizobium sp. SUT-PR48 (A) and SUTN9-2 (B) in rice roots at 7 DAI in response to different nitrogen sources. The housekeeping gene atpD was used as an endogenous control. Letters indicate the N-amended treatments. Control, uninoculated control; KNO₃, KNO₃ supplementation; NH₄NO₃, NH₄NO₃ supplementation; urea, urea supplementation. The statistical analysis was separately calculated between nirK and norB genes. Means labeled with different letters are statistically different at a P value of ≤0.05 (n = 3).