Fig. 5. Growth-inhibitory effect of the nutrient solution simulating chemical properties of infertile acid soils (LN + Al). Signalgrass and ruzigrass were grown in the greenhouse (left panel) and growth chamber (right panel). Growth was measured relative to the Al-free reference treatment containing adequate nutrient levels (i.e., [LN + Al]/AN). Values of growth parameters for plants from the AN treatment in the greenhouse were: 125.8 mg (shoot dry weight, SDW), 26.3 mg (root dry weight, RDW), 40.5 cm² (leaf area, LA), and 12.1 m (root length, RL) for signalgrass, and 139.3 mg (SDW), 40.5 mg (RDW), 52.5 cm² (LA), and 18.8 m (RL) for ruzigrass. Corresponding values in the growth chamber were: 47.5 mg (SDW), 5.3 mg (RDW), 23.4 cm² (LA), and 1.43 m (RL) for signalgrass, and 76.0 mg (SDW), 9.8 mg (RDW), 39.9 cm² (LA), and 2.81 m (RL) for ruzigrass. Error bars designate standard errors computed by weighted jackknifing, and asterisks indicate statistically significant differences between the grasses (P < 0.05).