Impact of Hot-Water Treatment on Male–Female Fertility and Seed Production in Artemisia princeps

Hot-water emasculation is used to inactivate pollen during artificial pollination; however, its application is limited to few plant species. Thermal sensitivity of reproductive organs in the Asteraceae family remains unclear. We investigated the effects of hot-water treatment on floral development and seed production in Artemisia princeps. Inflorescences at the bud stage were treated with water at different temperatures (38–50 °C), and the effects on male and female fertility, floral morphology, seed yield, and germination rate were evaluated. Reproductive performance gradually declined with increasing treatment temperature and duration. Flowers treated <46 °C, regardless of duration, and those treated at 46 °C for <10 min retained the ability to produce achenes and viable seeds. However, treatment at 46 °C for 10 min or at 48 °C and above substantially reduced reproductive success, decreased pollen viability, and only shriveled, non-viable seeds were produced. Contrary to greater thermal sensitivity of male reproductive organs commonly reported in several plant species, our findings suggest that female reproductive function appeared to be more sensitive than pollen viability in A. princeps. These findings indicate that both male and female reproductive organs are highly sensitive to hot-water treatment, limiting the applicability of hot-water emasculation in A. princeps.