Effect of OsHAK5 expression level on rice growth and on the concentration of accumulated K under continuous supply of normal [K] (1 mm). Ten-day-old seedlings were grown in IRRI solution containing 1 mm  K continuously for 4 weeks. A, C, and E, OX lines and their wild types. B, D, and F, KO lines and their wild types. A and B, Accumulation of dry biomass (dry weight) per plant. C and D, Accumulation of K (K concentration and total K content per plant [insets]). E and F, Net K uptake rates in OX and KO lines during days 1 to 10 and 11 to 20 of growth in solution containing 1 mm  K. The abbreviated names of wild types and transgenic lines are as in Figure 4. Error bars indicate se (n = 5 plants). Significant differences from the wild type in each group (NB, DJ, or HY) are indicated by different letters (P < 0.05, one-way ANOVA).