K.W. Richards, K.R.D. Friesen
The genus Lotus is composed of about 115 species from mostly temperate regions. The World Conservation Union (IUCN) report (1994) on the conservation status of Lotus estimated 15% of the species are endangered, vulnerable or rare. The Plant Gene Resources of Canada (PGRC) collection consists of about 90 species with a high number of threatened and rare species. The pollination requirements are known for only about 1/4 of them. Thus, there is an urgent need to determine the pollination requirements in this genus to enhance seed production, maintain the genetic purity of accessions, assist plant development and improvement, and conservation efforts (ex situ and in situ) leading to a better understanding of the evolutionary mechanisms operating within the genus.
Pollination experiments were conducted on 5 species of Lotus. Six treatments representing self-fertility to cross-pollination were used to determine the pollination requirements for each species. Three annual species: Lotus unifoliolatus (Hook.) Benth., L. angustissimus L. and L. arabicus L. and two perennial species: L. arenarius Brot. and L. maroccanus Ball were selected. Plants were grown and all treatments were conducted under greenhouse conditions in the absence of insect pollinators.
L. unifoliolatus and L. angustissimus were self-fertile within flowers and produced no pods or seeds for crosses involving the same raceme or plant. Both species are small flowered with 1-2 flowers in leaf axils. Out-crossing between some plants occurred in L. unifoliolatus, but not between plants of L. angustissimus. L. arabicus, L. maroccanus, and L. arenarius are larger flowered species with 3-8 flowers per raceme. L. arabicus was partially self-fertile within flowers and racemes, but not between racemes on the same plant. Out-crossing between plants did not occur in this species. L. maroccanus and L. arenarius were completely self-incompatible within flowers, racemes and plants. Some out-crossing occurred between plants of L. maroccanus. L. arenarius did not successfully set pods with any treatment, thus further research involving environmental and/or pollinator interactions is required. This study suggests diverse and complex breeding systems operate within the genus Lotus. Further studies involving other species are planned.
Richards, K.W. and Friesen, K.R.D. (2001). BASIC POLLINATION REQUIREMENTS OF FIVE LOTUS SPECIES. Acta Hortic. 561, 333-337
DOI: 10.17660/ActaHortic.2001.561.51
Lotus, trefoil, pollination requirements, annual, perennial

Acta Horticulturae