Research will focus on the causes of variation in the number of seeds that a plant produces by donating pollen to other individuals. Preliminary studies of rose mallow (Hibiscus moscheutos) showed that 1) pollen tubes, which carry paternal genes to the ovary, often compete for ovules within a flower, and 2) some individuals have faster growing pollen tubes than others. These differences among individuals are probably important in determining which plants sire the most seeds in natural populations. The investigators will examine the relative importance of genetic vs. environmental effects on pollen performance. They will also test the hypothesis that pollen tube growth rates are positively correlated with seedling growth rates. Results can be directly applied to agricultural problems by determining whether genetically superior seedlings can be artificially selected by hand-pollinating flowers with large amounts of pollen from a large group of donor plants. Fundamental questions will also be addressed about the reproductive ecology of wild plants, which should be conserved for their potential role as genetic "libraries". Useful genetic variation in this wild hibiscus could eventually be introduced into related species, such as cultivated hibiscus, cotton, okra, and kenaf, to improve their vigor and yield.
