(A) Effects of NaB on pollen tube growth. Mean length of pollen tubes treated with 0, 0.05, 0.1, 0.2, 0.5, and 1 mM NaB, respectively. (B) Effects of NaB on pollen tube germination. Percent germination of pollen tubes treated with 0, 0.05, 0.1, 0.2, 0.5, and 1 mM NaB, respectively. (C) Pollen tubes cultured in standard medium for 24 h. (D) Pollen tubes cultured in medium containing 0.05 mM NaB for 24 h. (E) Pollen tubes cultured in medium containing 0.1 mM NaB for 24 h. (F) Pollen tubes cultured in medium containing 0.2 mM NaB for 24 h. (G) Pollen tubes cultured in medium containing 0.5 mM NaB for 24 h. (H) Pollen tubes cultured in medium containing 1 mM NaB for 24 h. One asterisk indicates a significant difference between the growth rates of the drug-treated and control groups at P<0.05. A double asterisk indicates a significant difference between the growth rates of the drug-treated and control groups at P<0.01. Three asterisks indicate a significant difference between the growth rates of the drug-treated and control groups at P<0.001. Bar = 150 μm.