Premium
THE CONSEQUENCES OF SELF‐POLLINATION IN ASCLEPIAS EXALTATA, A SELF‐INCOMPATIBLE MILKWEED
Author(s) -
Broyles Steven B.,
Wyatt Robert
Publication year - 1993
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1993.tb13765.x
Subject(s) - pollination , biology , pollen , hand pollination , botany , ovule , self pollination , horticulture , pollinator
We investigated the effect of self‐pollination on fruit‐ and seed‐set in Asclepias exaltata , a self‐incompatible milkweed. A total of 1,380 hand‐pollinations were performed on 138 flowers in each of five treatments. In each treatment, two pollinia were placed in adjacent stigmatic chambers, which transmitted pollen tubes to the same ovary. Treatments 1 and 2 involved simultaneous placement of two self‐pollinia (treatment 1) or two cross‐pollinia (treatment 2) into adjacent stigmatic chambers. No fruits were produced after self‐pollinations, but 23% of the cross‐pollinated flowers matured fruits. The three remaining experimental pollination treatments were self‐pollination preceding cross‐pollination by 24 hr (treatment 3), simultaneous self‐ and cross‐pollination (treatment 4), and cross‐pollination preceding self‐pollination by 24 hr (treatment 5). Compared with that in flowers receiving only cross‐pollen, fruit‐set in treatments 3–5 was reduced 81%, 49%, and 29%, respectively. Seed‐set was also significantly reduced in flowers receiving self‐pollen 24 hr in advance of the cross‐pollen. Using genetic markers, we observed that only 0.6% of seeds resulted from self‐pollination. Our data strongly suggest that self‐pollination in milkweeds not only wastes pollen but also greatly reduces the number of ovules and ovaries that might otherwise mature fruits and seeds after cross‐pollination.