Figure 4.

Comparison of control and L plants. A, Description of the three types of split-root systems. Hydroponically grown plants fed with either 1 mm KNO₃, 1 mm NH₄Cl, or fixing N₂ were subjected for 4 d to two N regimes. In control plants, this same regime was maintained on both sides of the root system (C roots). In L plants, the N source was removed to the treated side of the root system (−N roots) as described in Figure 1. C and L roots were continuously exposed to the same local environment during the treatment. B, NO₃⁻, NH₄⁺, and N₂ acquisition of the C and L roots. From the left to the right are: net NO₃⁻ intake of CNO₃⁻ and LNO₃⁻ roots, net NH₄⁺ intake of CNH₄⁺ and LNH₄⁺ roots, net N₂ intake of CN₂ and LN₂ roots. The values are the means of six replicates of one biological repeat. They are representative of three independent biological repeats. Vertical bars indicate sd. *Significant difference according to t test (P < 0.001).