Phytotoxicity of organic extracts of Turnera ulmifolia L. and Turnera diffusa Willd. ex Schult. in cucumber seeds

Abstract

We evaluated the phytotoxic effects that the hexane, ethyl acetate and methanol extracts from leaves and branches of the species Turnera ulmifolia L. and Turnera diffusa Willd. ex Schult. (Turneraceae), at concentrations of 1.25, 2.50, 3.75 and 5.00 mg ml −1 , have on seed germination and seedling development in cucumber (Cucumis sativus L.). None of the extracts tested prevented germination, although the ethyl acetate extracts of T. diffusa, at 3.75 and 5.00 mg ml −1 , reduced the mean germination speed and time to germination. Hexane extracts of both species reduced the main root length, number of secondary roots and hypocotyl length. In the ethyl acetate and methanol extracts, the number of secondary roots and hypocotyl length varied by species and concentration. Ethyl acetate extracts of T. ulmifolia at ≤ 2.50 mg ml −1 stimulated growth of the main root and hypocotyl, as did T. ulmifolia methanol extracts at 1.25 and 3.75 mg ml −1 ; all other extract/concentration combinations had an inhibitory effect on those parameters. The hexane and ethyl acetate extracts of T. diffusa inhibited the formation of secondary roots and of the main root, although significant inhibition of hypocotyl growth was observed only at ≥ 2.50 mg ml −1 . Comparatively, T. diffusa extracts inhibited development to a greater degree, thus presenting greater allelopathic potential, than did T. ulmifolia extracts.

Seasonality affects phytotoxic potential of five native species of Neotropical savanna

“…The decrease in germination ability and the speed of germination, and less synchronised germination indicate disruption of the chemical reactions in the germination process of these seeds (Santana et al 2006). However, in general, the phytotoxic effects were more pronounced on seedling growth than on germination, corroborating the results of other studies (Ferreira and Aquila 2000;Silvestre et al 2013).…”

“…The species selected for this study are abundant in the Cerrado and have biological activity (Barros et al 2006) or are used in popular medicine (Carvalho 2003;Stefanello et al 2006;Negrelle 2011;Santos et al 2012). Many medicinal plants have phytotoxic potential (Fujii et al 2003;Alves et al 2011;Silvestre et al 2013), indicating that these might be good candidates to be studied among the species that occur in the Cerrado. Thus, we investigated the phytotoxicity of leaf extracts of five Cerrado species and the effect of seasonality (dry and rainy season) on their phytotoxic potential.…”

Phytotoxic activity of differents plant parts of Drimys brasiliensis miers on germination and seedling development

“…When seeds of susceptible species are exposed to allelochemicals, germination can be inhibited; if this occurs, the seedlings may exhibit reductions in growth and development or abnormal metabolism. The most commonly observed effects are a delay in germination time, atrophy and thickened root, root growth reduction, primary or secondary root absence and hypocotyl growth reduction (GATTI et al, 2010;GUSMAN et al, 2011;GRISI et al, 2012;SILVESTRE et al, 2013 (EHRENDORFER et al, 1979;MELLO-SILVA, 2013). In folk medicine, the genus Drimys is used as a stimulant and as a tonic, as analgesic and antiinflammatory agents, and to treat ulcers, diarrhea, cancer and infections of the respiratory tract (TRINTA; SANTOS, 1997).…”