Phytotoxicity of Salvia spp. exudates

A study on thirteen Salvia species about the phytotoxicity of their aerial part exudates is reported. The selected species were: Salvia namaensis Schinz (1), Salvia fallax Fernald (2), Salvia disermas L. (3), Salvia chamaedryoides Cav. (4), Salvia confertiflora Pohl. (5), S. x jamensis J.Compton (6), Salvia buchananii Hedge (7), S. wagneriana Polak (8), Salvia scabra Linn.fil. (9), Salvia miniata Fernald (10), Salvia cacaliaefolia Benth.(11), Salvia adenophora Fernald (12), Salvia rutilans Carrière (13). For each species the inhibitory potential against Papaver rhoeas L. and Avena sativa L. was evidenced by dose-response studies and growth experiments performed both in Petri dish and in pot and also evaluated by means of germination indices and growth parameters. New indices useful for describing the phytotoxic response by a reduced number of testing solutions are proposed. Principal Component Analysis (PCA) of the germination data revealed that the exudate concentrations most significant in explaining the data variability were 1 and 2 mg/mL in Petri dish and 10 and 20 mg/mL in pot experiments. Root length and seedling weight were more important with respect to the other growth parameters.