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Auteur Ørjan Totland (1968-) |
Documents disponibles écrits par cet auteur (2)
Affiner la rechercheBreeding system and effects of plant size and flowering time on reproductive success in the alpine herb Saxifraga stellaris L. / S.M. Sandvik in Arctic and alpine research, 31 (2) (05/1999)
Titre : Breeding system and effects of plant size and flowering time on reproductive success in the alpine herb Saxifraga stellaris L. Type de document : Imprimé Auteurs : S.M. Sandvik ; Ørjan Totland (1968-) ; J. Nylehn Année de publication : 1999 Article en page(s) : 96-201 Langues : Anglais (eng) Catégories : [LOTERRE-Biodiversité] Pollinisateur Mots-clés : Saxifraga sp. Saxifraga stellaris L. Résumé : The pollination and reproductive ecology of Saxifraga stellaris was investigated in alpine southwest Norway. A breeding system analysis, with performance of controlled crosses, revealed that S. stellaris is self-compatible and that reproductive success after cross- and self-pollination is equal. Relative autodeposition efficiency (i.e. mean seed:ovule ratio in caged, nonmanipulated plants relative to mean seed:ovule ratio of control plants) was, however, low (0.29), suggesting that S. stellaris depends on insect visitation for maximum seed set. Seed set is not restricted by pollen availability, as indicated by a supplemental hand-pollination experiment. Plant size had a strong positive impact on ovule number, which in turn was positively correlated with seed number. Plant size also had a positive influence on seed weight. Seed weight was lowest for late-flowering plants, suggesting that shorter time for seed maturation and lower temperatures late in the season restrict seed weight. No correlations between flowering date and seed number were found, perhaps because the pollinators are relatively insensitive to temperature conditions and thus their activity does not change through the flowering season of S. stellaris. Lien pérenne : DOI : 10.1080/15230430.1999.12003298 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137898
in Arctic and alpine research > 31 (2) (05/1999) . - 96-201Sandvik, S.M., Totland, Ørjan (1968-), Nylehn, J. 1999 Breeding system and effects of plant size and flowering time on reproductive success in the alpine herb Saxifraga stellaris L. Arctic and alpine research, 31(2): 96-201.Documents numériques
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Titre : Pollen limitation of reproductive success in two sympatic alpine willows (Salicaceae) with contrasting pollination strategies Type de document : Imprimé Auteurs : Ørjan Totland (1968-) ; Matteo Sottocornola Année de publication : 2001 Article en page(s) : 1011-1015 Langues : Anglais (eng) Catégories : [CBNPMP-Thématique] Biologie de la reproduction Mots-clés : Salix lapponum L. Résumé : We compared the extent of pollen limitation on female reproductive success of Salix lanata L., an entirely insect-pollinated willow, and S. lapponum L., which is 50 : 50% insect : wind pollinated (ambophilous). Supplemental hand-pollination significantly increased seed number per fruit by nearly 50% in the insect-pollinated willow, but had no significant impact on seed number in the dually pollinated species. Fruit set was not affected by the treatment in either of the species. These results demonstrate that pollen limitation on reproductive success is most pronounced in the species that depends entirely on insects for pollination. In general, pollinator visitation was highest to S. lapponum, but bumble bees were only observed on S. lanata, suggesting that the quantity and quality of pollinator visitation differed between the species. Our results empirically support the hypothesis that a dual pollination strategy is most effective in alpine environments with low and infrequent pollinator activity and high wind speeds. Lien pérenne : DOI : 10.2307/2657082 Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=137421
in American Journal of Botany > 88 (6) (2001) . - 1011-1015Totland, Ørjan (1968-), Sottocornola, Matteo 2001 Pollen limitation of reproductive success in two sympatic alpine willows (Salicaceae) with contrasting pollination strategies. American Journal of Botany, 88(6): 1011-1015.Documents numériques
article (2001)URL
