Pollen tube growth and seed set in stigmatic and cut-style pollinated Lilium longiflorum 'Georgia' flowers as influenced by pre pollination

Abstract

The present study was conducted to examine whether pre-pollination is effective in improving growth of pollen tubes and seed-sets of Lilium lingiflorum 'Georgia' by comparing cut-style pollination (CSP) and stigmatic pollination (SP). 1. Pollen tubes reached the basal end of the style by 48 hr in self-pollination of 'Georgia' and cross-pollination of 'Georgia' x 'Hinomoto' by CSP. Using the pre-pollination technique in CSP enhanced the growth of pollen tubes both in self- and cross-pollination. 2. Generative cell division of pollen tubes in the style was observed 24 hr after pollination. In cross-pollination by SP, 78% of the pollen tubes had 2 sperm nuclei and 1 vegetative nucleus ('2 S + V'), while only 15% of these appeared in the self-combination. Using CSP, pollen tubes with '2 S + V' were 32 % in cross- and 9% in self-pollination. The percentages increased to 54% and 35%, respectively, when pollen of 'Hinomoto' was used in the pre pollination treatment. 3. In SP, numerous pollen tubes which penetrated the style grow in a bunch between two rows of ovules in an ovary ; they reach the ovules near the mid-region of the loculi. In CSP, pollen tubes elongated poorly in the ovary ; only a few pollen tubes reached the ovules near the mid-region. 4. Penetration of pollen tubes to the micropyle occurred in about 35% of the ovules in cross-pollination by SP and in less than 10% of these by CSP. Pre-pollination in CSP effectively increased the percentage of ovules with a pollen tube in the micropyle. 5. Only 3 full-seeds per capsule in self and 6 in cross pollination were obtained by CSP, whereas 11 and 23 seeds per capsule, respectively, were obtained as the result of pre-pollination.