From nursery into nature: A study on performance of cultivated varieties of native plants used in re-vegetation, their wild relatives and evolving wild×cultivar hybrids

Cultivated varieties may have life-history traits which are very different to those of their wild progenitors. Changes in life-history traits due to cultivation may not be desirable for plant material used for re-vegetation, as these plants may be adapted to constant human care and lack the finely tuned trade-off that allows wild plants to cope with the often harsh and heterogeneous environmental conditions outside of nurseries. Research is needed to identify differences in life-history traits between cultivated varieties used in re-vegetation and restoration and their wild relatives. If such traits are changed by cultivation, it is necessary to examine if they will persist also at the re-vegetation site and may be transferred to wild relatives by hybridization as that may reduce their survival or lead to undesirable changes on local ecosystems. In this study we examined whether cultivated varieties of Plantago lanceolata and Lotus corniculatus, two species frequently used in re-vegetation and restoration projects, differ from their wild relatives in morphology or flower phenology and whether differences could be transferred into wild relatives by hybridization. We tested if cultivated varieties are bred for high vegetative and generative yield in greenhouse studies. In common garden experiments we studied if the detected enhanced biomass production is persistent under the climatic conditions of the wild plant's natural habitat in Central Europe. Additionally, we tested if hybrids show effects of outbreeding depression or heterosis. The cultivated varieties of both species grew very vigorously and showed a more erect growth pattern than their wild relatives. The cultivated varieties seem to be selected toward high vegetative and generative yield. However, if exposed to local climatic conditions, cultivated varieties suffered a fitness loss with a complete mortality for the L. corniculatus cultivar and a reduced vegetative biomass production for P. lanceolata cultivars. On the other hand, we detected heterosis effects in hybrids for survival and generative biomass production in L. corniculatus and number of leaves in P. lanceolata. As it remains possible that the use of cultivated varieties may result in strongly competitive genotypes or reduced local adaptation of wild plant populations (via hybridization), large-scale use of cultivated varieties of native plants should be avoided in re-vegetation and restoration.