POLLEN-TUBE GROWTH IN LILIUM-LONGIFLORUM FOLLOWING DIFFERENT POLLINATION TECHNIQUES AND FLOWER MANIPULATIONS

After cut-style pollination of Lilium longiflorum Thunb. using compati ble pollen, the percentage of ovules with a pollen tube in the micropy le was very low when compared with pollination at the stigma. Pollen t ube growth in the ovary, as observed with scanning electron microscopy , did not show any differences between these two pollination methods u ntil 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 mic ropyle. Grafting a stigma just above the ovary did not increase the pe netration percentage. Possible activation of the ovary, induced by pol lination or pollen tube growth in the style or even in the ovary itsel f, preceding intrastylar or placental pollination did not result in an increase of the penetration percentage. However, the percentage of ov ule 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 b uilt up during pollen tube growth through the style.