Abstract: Lower concentrations of CaCl2 show no obvious effects on growth of seed root and the formation and growth of root hair. Higher concentrations of CaCl2(0.1 mol/L) inhibit the growth of the seed root and the root hair, but has no effect on the formation of root hair. EGTA inhibits the growth of the seed root and the formation and growth of the root hair. Exogenous CaCl2 can eliminate the inhibition of EGTA. TFP and CPZ (CaM inhibitors) also show inhibitory effects on the growth of the seed root and the formation and growth of root hair which can be recovered with exogenous CaM.