Effects of defoliation on male and female reproductive traits of a perennial orchid, Dactylorhiza maculata

Abstract

1. The effects of defoliation on male reproductive traits of plants have received little attention. We conducted two field experiments with Dactylorhiza maculata (L.) Soó to examine the effects of defoliation on both male and female reproductive traits. We removed 0, 50 or 100% of leaves prior to flowering. The quality of pollen was tested by transferring pollen from the differently treated plants to untreated plants of the same population. 2. The non-defoliated plants did not differ from the defoliated plants in mass of pollinia. No differences were found in the weight of seed capsules or in the proportion of embryonic seeds raised by flowers receiving pollen from differently treated pollen donors. 3. The non-defoliated and partially defoliated plants produced relatively more and heavier capsules than the completely defoliated plants. 4. Defoliation decreased leaf area, corm mass and the probability of flowering in the following year. 5. These results demonstrate that defoliation has no acute effects on male traits in the long-living perennial orchid D. maculata. In this respect, D. maculata differs from the two other polycarpic species studied so far. Availability of resources appeared to be insufficient to prevent negative effects of defoliation on the later-occurring and more costly female functions.