Figure 2 Inhibitory effect of biuret for allantoinase activity. Crude extracts were prepared from shoots of 9-day-old rice seedlings hydroponically grown without biuret. Extracts were incubated at 30ÂșC with 10 mmol L-1 allantoin, 50 mmol L-1 Tricine-NaOH (pH8.0), 2mmol L-1MnSO4, and the desired concentration of biuret for 30min. The amount of allantoic acid produced from allantoin was colorimetorically determined. Same shape symbols indicate a same crude extract. Crossbars represent the mean value. The means were not significantly different among treatments at 5% level (One-way ANOVA with blocking, n = 4).