抄録
Prosopis juliflora (Sw.) DC. (Mesquite) is one of 100 world’s worst invasive alien species, inducing a threat to human subsistence in arid regions. To control the invasion of Prosopis seedlings after episodic rainfall followed by immediate soil desiccation, we focus on the property of ‘seed gum’ (galactomannan (GM)). The purpose of the present study was to evaluate the ecological role of this saccharide for seed germination. Three germination tests were conducted under several osmotic potentials using poly-ethylene glycol (PEG) 6000 solutions. Intact seeds were incubated in eight PEG solutions (0, -1.0, -1.5, -1.6, -1.7, -1.8, -1.9 and -2.0 MPa). GM-present and GM-removed seeds were incubated in three PEG solutions (-1.5, -1.7, -1.9 MPa). GM-present and GM-removed seeds were desiccated in advance for one or two weeks, and incubated in the three PEG solutions. All intact seeds were germinated in 0 and -1.0 MPa. Germination rate in -1.5 MPa was slightly lower, and decreased as reducing osmotic potential. These results confirm that Prosopis seed is highly drought tolerant. GM-present seeds germinated more frequently than GM-removed seeds both in -1.5 and -1.7 MPa treatments, independent of desiccation periods. These results suggest that seed gum has important role to keep germination ability of Prosopis seeds through wet-dry cycle in rainy season of arid environments.
