POSITIVE EFFECTS OF POLLINATION ON SUBSEQUENT SIZE, REPRODUCTION, ANDSURVIVAL OF PRIMULA-VERIS

We conducted three experiments in which we applied additional hand pol lination, flower removal, and leaf removal treatments in Various combi nations to Primula veris, a perennial spring-flowering rosette species . The purpose of the study was to determine whether the seed set of Pr imula veris was limited by pollen availability or by other resources, and whether there were measurable costs of reproduction. Hand pollinat ion in the beginning of experiments significantly increased current se ed set in only one of the three experiments. It also increased the nex t-year fruiting probability in that first experiment. In the second ex periment, hand pollination did not significantly affect current seed s et, but we nevertheless observed enhanced leaf growth in the treatment year and the two following years, and increased flowering frequency, fruiting frequency, and survival in the two following years. In the th ird experiment, after hand pollination we observed a higher net photos ynthetic capacity of the leaves and, again, increased leaf growth in t he treatment year and a higher flowering probability in the following year. The positive effect of hand pollination was even clearer when th e leaves of the plants were removed at the beginning of the experiment . However, the treatment in which all the flowers were removed had eff ects on subsequent performance similar to those of the hand-pollinatio n treatment, suggesting trade-offs. Thus, we did not observe any costs associated with reproduction after supplemental hand pollination; on the contrary, hand pollination resulted in increased survival, size, a nd reproduction of the plants in the subsequent years.