Effects of the N and Z treatments on rice seedling seminal root growth. (a) Phenotypic comparison of seminal roots of rice seedlings grown under different treatments. Scale bar is 5 cm. (b) Seminal root lengths under different treatments. In this experiment, germinated rice seeds were incubated in different solutions for four days, then photographs were taken, and the lengths of the seminal roots were measured. The data are the means ± SD calculated from 10 biological replicates. Significant differences (p < 0.05) are indicated by different letters (a, b, c, d, e, f). N, nitrogen; Z, zeatin.