Fig. 1.

Accumulation pattern of cytokinins in rice roots and shoots in response to nitrate and ammonium. Rice seedlings were hydroponically grown in tap water for 11 d after sowing and transferred to nitrogen-free culture medium for 3 d. Then, the roots were dipped into culture media containing 1 mM NH₄Cl, 1 mM KNO₃ or 1 mM KCl. After the time indicated, roots and shoots were separately harvested in triplicate, and the cytokinin contents were quantified. The value in each block indicates the concentration (mean values) as pmol g⁻¹ FW. The relative accumulation level of each compound compared with the accumulation in the KCl treatment is color-coded. BQ, below the quantification limit. *P < 0.05; **P < 0.01 (Student’s t-test, comparison with the KCl treatment). The complete data set is presented in Supplementary Tables S1 and S2.