Pollen tube growth in Lilium longiflorum following different pollination techniques and flower manipulations

After cut-style pollination of Lilium longiflorum Thunb. using compatible pollen, the percentage of ovules with a pollen tube in the micropyle was very low when compared with pollination at the stigma. Pollen tube growth in the ovary, as observed with scanning electron microscopy, did not show any differences between these two pollination methods until the arrival of the pollen tube at the inner integument. After cut-style pollination, the majority of the pollen tubes either grew past the inner integument and ignored it, or grew over but not into the micropyle. Grafting a stigma just above the ovary did not increase the penetration percentage. Possible activation of the ovary, induced by pollination or pollen tube growth in the style or even in the ovary itself, preceding intrastylar or placental pollination did not result in an increase of the penetration percentage. However, the percentage of ovule penetration after cut-style pollination did increase when a longer part of the style was left at the ovary. The basis of the interaction between pollen tube and pistil, which led to ovule penetration, was built up during pollen tube growth through the style.