BIOLOGY OF Solanum elaeagnifolium Cavi. (SOLANACEAE): GROWTH AND SURVIVAL

Solanum elaeagnifolium, an introduced creepingweed, is now established throughout Tunisia. Itsmanagement has been a significant challenge because oflarge rootstock and bud reserves in the soil. Thedevelopment of this weed has received little attention.Moreover the survival of this weed is not well understood.Experiments were conducted over two-year greenhousestudy investigating the effects of rhizome length, storage,burial and temperature on growth resumption andsurvival. Additionally, detailed studies were performedinvestigating the growth pattern. The emergence of S.elaeagnifolium occurs from March to July and thebiological cycle ends in November-December, fromDecember to early February, S. elaeagnifolium exhibitsgrowth rest. Growth resumption of S. elaeagnifoliumrhizomes exhibits mixed re-growth: base and summitgrowth.A correlative inhibition of among buds and shootsoccurred; the nitrogen increased bud sprouting, but didnot completely eliminate the bud or shoot dominanceeffect. The percent of buds that sprouted decreased as therhizome length increased. An inverse relationshipestablished between depth of burial and emergence. Adirect relationship established between the depth to whichrhizomes are buried in the soil and their retention ofviability. This study showed rhizomes to be sensitive todesiccation. These biological parameters should be takeninto account in any management strategy.