A COMPARISON OF SEED SETS IN SELF-, INTRASPECIFIC AND INTERSPECIFIC POLLINATION OF LILIUM SPECIES BY STIGMATIC AND CUT-STYLE POLLINATION METHODS

Growth and morphology of pollen tubes and formation of seeds were investigated in several Lilium species and cultivars after self-, intraspecific and interspecific pollination by two pollination methods: stigmatic and cut-style pollination. 1. The relative pollen tube length as a percentage of the style length from the stigma to the base of style was 100 % for 96 to 120 hr after stigmatic pollination between compatible mating partners; it was significantly less between incompatible partners because pollen tube growth was retarded. In the latter case, growth inhibition was evident 24 hr after pollination. Based on the relative tube length, L. longiflorum 'Hinomoto' and 'Georgia' had a stronger tendency for self-incompatible reaction than did L. x 'Enchantment'. 2. There was a possible relationship between the intensity of the self-incompatible reaction and the rate of deformed pollen tubes having bulbous or rugged tips. The deformed tubes made up 60 to 70% of the population after self-pollination of L. longiflorum 'Hinomoto' and 'Georgia'; they were 37% in L. x 'Enchantment' and less than 10% in other compatible matings. 3. Viable seeds were obtained in the compatible mating by cut-style pollination as well as by stigmatic pollination. The number of seeds produced by the former method was significantly smaller, ranging from 10 to 50% of the latter. In the self-incompatible mating viable seeds were also obtained in L. longiflorum, 'Georgia' and L. x 'Enchantment' by the cut-style pollination but not in L. longiflorum 'Hinomoto'. 4. After self- and intraspecific pollination of L, longiflorum 'Hinomoto' and 'Georgia' by cut-style pollination, pollen tubes were observed by a scanning electron microscopy. Pollen tubes of self-pollinated 'Hinomoto' passed by or stopped in front of the micropyles but did not enter them. In other matings, the pollen tubes entered the micropyles even though some had deformed, flat tips.