Quantitative analysis of 13C2 labelled FCs in rice treated with 0.1 mM [2,5-13C2]-4. The contents of labelled 1–4 in shoot and root of rice treated with 0.1 mM [2,5-13C2]-4 is described in left side and right side, respectively. The external standard method was used for quantification. Results are the mean ± S.D. (n = 3). FW: fresh weight.