Responses of invasive silverleaf nightshade (Solanum elaeagnifolium) populations to varying soil water availability

Aspects of the invasive potential of the noxious weed silverleaf nightshade (Solanum elaeagnifolium Cav.) were studied. Greenhouse experiments were conducted in order to assess several growth, production and fecundity traits of three silverleaf nightshade populations under differing levels of water availability and to correlate them with the invasive potential of each genotype. Our results showed that water availability certainly improves growth and fecundity of this serious invasive species. In ideal conditions, S. elaeagnifoilum shows a massive seed production which clearly promotes its invasiveness. However, the three populations show different phenotypic plasticity, which could explain their different adaptation and invasiveness in habitats with different water availability. Under low water availability, plants of the Etoloakarnania (ET) population allocate more than half of their total biomass to their roots (high R/S ratio), which serve as an important reproductive organ, while they maintain a relatively high seed production. These differences in phenotypic plasticity between weed populations mean that some of them (such as ET) would be more efficient in coping with changing water availability than others and therefore should be managed on high priority.