caa a22 4500 469096381 CHVBK 20180323133032.0 cr unu---uuuuu 170328e19921101xx s 000 0 eng 10.1007/BF00317361 doi (NATIONALLICENCE)springer-10.1007/BF00317361 Determinants of seed production in Geranium maculatum [Elektronische Daten] [Jon Ågren, Mary Willson] Summary: We experimentally examined factors limiting seed production in two populations of the perennial woodland herb Geranium maculatum in central Illinois, USA. To test the pollinator-limitation hypothesis, we compared the seed production of plants whose flowers were supplementarily pollinated with outcross pollen to that of control plants receiving natural pollination only. To test if fruit production by early flowers suppresses fruit and seed formation by late flowers, a third group of plants was prevented from producing seed from the first 50% of the flowers to open (stigmas were excised at flower opening). Finally, to test if seed maturation and flower initiation are correlated with photosynthetic capacity, we performed a defoliation experiment in which either the stem leaves within the inflorescence, the stem leaves below the inflorescence, or the rosette leaves were removed during late flowering. Plants that reccived supplemental pollination produced 1.5-1.6 times more seeds than control plants. We found no difference between hand-pollinated plants and controls in mortality, flowering frequency or number of flowers produced in the year following the experiment. In both control and hand-pollinated plants, the fruit set and total seed production of early flowers were more than twice as high as those of late flowers. In one of the two populations, plants whose early flowers were prevented from setting seed produced significantly more seeds from their late flowers than did control plants. Seed predation was low and did not differ between early and late flowers. Leaf removal did not affect seed number or size in the year of defoliation, nor did it reduce survival or flower production in the subsequent year. This suggests that the plants were able to compensate for a partial defoliation by using stored resources or by increasing photosynthetic rates in the remaining leaves. Taken together, the results demonstrate that both pollinator activity and resource levels influence patterns of seed production in G. maculatum. While seed production was pollinatorlimited in both populations, a seasonal decline in resource availability was apparently responsible for the low seed production by late flowers. Springer-Verlag, 1992 Geranium maculatum nationallicence Pollinator limitation nationallicence Resource limitation nationallicence Seed production nationallicence Temporal variability nationallicence Ågren Jon Department of Botany, University of Washington, KB-15, 98195, Seattle, WA, USA aut Willson Mary Forestry Sciences Laboratory, 2770 Sherwood Lane, 99801, Juneau, AK, USA aut Oecologia Springer-Verlag 92/2(1992-11-01), 177-182 0029-8549 92:2<177 1992 92 442 https://doi.org/10.1007/BF00317361 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317361 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ågren Jon Department of Botany, University of Washington, KB-15, 98195, Seattle, WA, USA aut NATIONALLICENCE 700 1- Willson Mary Forestry Sciences Laboratory, 2770 Sherwood Lane, 99801, Juneau, AK, USA aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 92/2(1992-11-01), 177-182 0029-8549 92:2<177 1992 92 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer