Root regenerative ability of silverleaf nightshade (Solanum elaeagnifolium Cav.) in the glasshouse

Silverleaf nightshade is considered amongst the worst weeds of crop and pasture systems in Australia due to its extensive root system. Cultivation may exacerbate the problem due to the regenerative capacity of the root system. Glasshouse experiments were conducted to determine the importance of cultivation in the spread of silverleaf nightshade by investigating the regenerative abilities of various root fragment lengths (1, 2.5, 5 and 10 cm) buried at three soil depths of 2.5, 5 and 10 cm. Regeneration occurred from root fragments as short as 1 cm, with shoot production increasing with root fragment length. Optimum burial depth was 5 cm for 1 and 2.5 cm root fragments, while 5 and 10 cm root fragments were equally prolific at stem production from the 2.5 cm burial depth. High levels of fragment mortality occurred in 1 cm fragments, with mortality levels significantly declining as fragment length increased. This research suggests that minimum tillage techniques should be encouraged on areas with silverleaf nightshade infestations. Implements should be thoroughly cleaned before leaving the infested area, as even short root fragments adhered to machinery are capable of starting a new infestation in a clean field.