Invasiveness of Solanum elaeagnifolium in Tunisia
Solanum elaeagnifolium (Solanaceae: EPPO A2 List) is a herbaceous perennial or a small shrub, native to the Americas and an invasive alien plant in parts of Asia, Africa and the EPPO region. It was first recorded in North Africa around 1940. S. elaeagnifolium can have negative impacts on the environment and can reduce yields in a number of crops (e.g. maize, wheat, cotton). In Tunisia, S. elaeagnifolium was first recorded in 1985 at Sbikha (central Tunisia). Since then, it has spread in the country and is now recorded in Sousse, Mahdia, Sidi Bouzid, Sfax, and Zaghouan. An experiment was conducted in the Chott Mariem region of Tunisia, a semi-arid region, to assess the growth phenology of S. elaeagnifolium under semi-arid environmental conditions. Two-hundred taproots were planted under controlled conditions and the plants were monitored over three growing seasons (2013, 2014, 2015). Five parameters were measured (1) vegetative regeneration rate, calculated as the number of regenerated new shoots from old stems; (2) vegetative propagation rate, calculated as the number of lateral offshoots emerged from rhizomes; (3) vegetative spread, estimated as the product of the number of lateral offshoots emerged from rhizomes per the average distance from the parent plants; (4) flowering potential, calculated as the total number of flowering shoots per month; and (5) fruiting potential, calculated as the total number of fruiting shoots per month. S. elaeagnifolium showed an active vegetative growth phase during the spring (March–May). It stopped its vegetative growth in June–August investing resources in flowering and fruiting. The vegetative growth resumed during September–October and declined in November, where it entered its dormant period. The vigorous growth of the rhizomatous system enabled offshoot growth with a radius of up to 1.5 m 30 months after its establishment. These findings could inform and improve dedicated management control options for S. elaeagnifolium. These results suggest that S. elaeagnifolium should be controlled before the full-flowering stage in spring and following the first autumnal rainfall to prevent vegetative propagation and fruiting.
Sources
Sayari N, Brundu G, Soilhi Z, Mekki M (2022) Solanum elaeagnifolium invasiveness under semi-arid environmental conditions in Tunisia. Earth 3, 1076–1086. https://doi.org/10.3390/earth3040062