Effect of Parental Components and Pollination Frequency on the Setting and Germination of Chrysanthemum Seeds

The chrysanthemum is one of the most economically important ornamental plants in the <i>Asteraceae</i> family. Unfortunately, the efficacy of breeding through the traditional crossing in this species is highly limited due to inefficient seed setting. Therefore, this study aimed to investigate the effect of parental components and crossing frequency on the set and germination of chrysanthemum seeds. For this purpose, seven chrysanthemum cultivars were used as parental components in 10 crossing combinations. The crossing was performed either once or twice a week, for three successive weeks, starting from November. Next, the obtained chrysanthemum seeds were collected, sown in pots in a greenhouse, and seedling growth was observed. The efficacy of the seed set, germination rate, and plant development was evaluated. The plants of the F₁ generation were brought to flowering and evaluated phenotypically in the three successive vegetative propagation cycles. Both the arrangement of parental components and pollination frequency affected the production of seeds. More seeds were obtained if pollination was performed twice a week and if the ‘Wda’ cultivar was used as the maternal component. Approximately 50–100% of the seeds were able to germinate in the greenhouse, depending on the parental components, which also affected the developmental pace of the seedlings. Nearly all of the seedlings (80–100%) developed into properly growing plants. Out of 10 parental combinations tested, 7 produced the F₁ offspring. The obtained plants varied in the shape, size, and color of their flowers. A total of eight new phenotypes were found, among which six new cultivars granted plant breeders’ rights, so far. The present research expands knowledge on how effective crossing should be performed.