Figure 1.

Effects of high concentration of a sole NH₄⁺ source on Arabidopsis growth and photosynthesis. A, Plants were treated with 5 mm NH₄NO₃ (Ctl) and with different sources of NH₄⁺ (10 mm) applied to rooting medium for 10 d. B to E, Relative fresh weight (B), relative biomass (C), photosynthetic rate (D), and chlorophyll concentration (E) of Col-0, chl1-1, and chl1-5 grown in 5 mm NH₄NO₃ (Ctl) and (NH₄)₂SO₄ for 10 d. Fresh weight (Fw) and dry weight were obtained from pooled samples of seven plants from each replicate, and data were calculated relative to the average value of Col-0 under control conditions. F, Grafted plants grown in 5 mm NH₄NO₃ (Ctl) and (NH₄)₂SO₄ for 10 d. Plant material names on the left indicate the genotypes of the shoot/root combination. G, Chlorophyll concentration of the grafted plants grown in 5 mm NH₄NO₃ (Ctl) and (NH₄)₂SO₄ for 10 d. H and I, Phenotypes and chlorophyll concentrations of Col-0 and chl1-9 grown in 5 mm NH₄NO₃ (Ctl) and (NH₄)₂SO₄ for 10 d. Data represent means ± se (n = 4). Bars with the same letter indicate no significant difference at P < 0.05 using the lsd method. Bars = 1 cm in A, F, and H.