Table 1 Effects of different nitrogen supply levels on rice biomass (g), leaf area (cm²), leaf nitrogen content (N_L, g m^− 2), Rubisco content (g m^− 2), stomatal conductance (g_s, mol CO₂ m^− 2 s^− 1), mesophyll conductance (g_m, mol CO₂ m^− 2 s^− 1), chloroplast CO₂ concentration (C_c, μmol mol^− 1), photosynthesis rate (P_n, μmol m^− 2 s^− 1), and photosynthetic nitrogen use efficiency (PNUE, μmol CO₂ mmol^− 1 N s^− 1). Rice plants (“Zhendao 11”) were supplied with NH₄⁺ (AN) or NO₃⁻ (NN) under 3 different amounts, low N (0.71 mM, LAN and LNN), intermediate N (2.86 mM, MAN and MNN), and high N (7.14 mM, HAN and HNN). Data are presented as the means ± SD of four replications. Significant differences (P < 0.05) between treatments are indicated by different letters

From: Anatomically induced changes in rice leaf mesophyll conductance explain the variation in photosynthetic nitrogen use efficiency under contrasting nitrogen supply