Figure 2.

ALA inhibits pollen tube growth of detached pear blossoms. Flower twigs were cultured with 10% sucrose, in a growth chamber at 25°C under a PPFD of 50 μmol·m⁻²·s⁻¹ in 12 h light/12 h dark cycles. (A,B) 100 mg/L ALA were sprayed to the flowers which were then hand pollinated 2, 8, 12, or 24 h later, respectively. Flowers that sprayed with distilled water and then hand pollinated 2, 8, 12, or 24 h later were set as controls. Because spraying water 2, 8, 12, and 24 h before pollination did not result in significant differences between pollen tube lengths, to make figure concise, only water application at 2 h before pollination was presented as Control. Fluorescence of the pollen tubes (A) at 48 h post-pollination was observed under a stereomicroscope (Olympus MVX10, Japan) and the pollen tube length (B) was determined. (C,D) flowers were hand pollinated and then sprayed 100 mg/L ALA 2, 8, 12, or 24 h later, respectively. Flowers that hand pollinated and then sprayed with distilled water 2, 8, 12, or 24 h later were set as controls. Because spraying water 2, 8, 12, and 24 h after pollination did not result in significant differences between pollen tube lengths, to make figure concise, only water application at 2 h after pollination was presented as Control. Fluorescence of the pollen tubes (C) at 48 h post-pollination was observed under a stereomicroscope (Olympus MVX10, Japan) and the pollen tube length (D) was determined. Scale bar: 50 μm. The white arrow points to the end of the pollen tubes. At least 15 styles from a population of three different plants were used for each treatment and experiments were repeated three times. Different small letters in (B) or (D) represent significant difference between treatments (P < 0.05).