Abstract

The present studies cover the phytotoxic effects of the crude methanolic extracts of different parts of 13 medicinal plants viz. Woodfordia fruiticosa, Adhatoda vasica,Chenopodium ambrosoides, Viburnum cotinifolium, Euphorbia hirta, Vitex negundo,Peganum harmala, Broussonetia papyrifera, Taraxacum officinale, Urtica dioica,Verbascum thapsus, Caryopteris grata and Mimosa rubicaulis collected from different localities of  Margalla Hills on the germination of radish seeds to study the germination %, growth inhibition %, root shoot length, velocity of germination, biomass fresh weight, dry weight and moisture content (%) at two concentration levels. Germination velocity was decreased by the application of the extracts, however more pronounced effect was seen at 10 mg/ml concentration. Maximum decrease in germination velocity of radish seed was exhibited by methanolic extract of W. fruticosa (25.23) and minimum by V. negundo (39.06). Maximum inhibition of radish seed germination was caused by B. papyrifera (53.33%), W. fruticosa (52%), V.thapsus  (48.89%) and minimum by M. rubicaulis (13.33%). At higher concentration that is, 10 mg/ml, the methanolic extract of W. fruticosa was most effective in decreasing the shoot fresh weight (0.15 gm), followed by B. papyrifera (0.29 gm),Caryopteris grata (0.39 gm), U. dioica (0.49 gm), V.thapsus (0.50 gm) and P. harmala(1.44 gm). The extract of W. fruticosa was more pronounced in decreasing the shoot dry weight (0.07 gm) followed by B. papyrifera (0.08 gm), V. thapsus (0.1 gm) and the least effective was the M. rubicaulis (0.21 gm). However at concentration 1 mg/ml, T. officinaleexhibited maximum decrease in germination velocity (35.65) and maximum inhibition of seed germination was caused by methanolic extract of U. dioica (42.22%), followed by V. thapsus (40%). Lower concentrations of V. negundo and T. officinale exhibited similar effects on germination velocity. The intensity of decrease in moisture content at concentration 1mg/ml was lower than that at 10 mg/ml. Maximum reduction in seedling moisture content was also recorded at concentration 1 mg/ ml for W. fruticosa (83.1%), followed by V. cotinifolium ( 84.51%) and B. papyrifera (86.42%) and minimum for that of V. thapsus  (90%). The P. harmala at low concentration (1 mg/ ml) promoted the growth rather showing the allelopathic effects.The phytotoxic activity of the selected medicinal plants on radish seed germination was dose dependent.

Key words: Medicinal plants, Margalla hills, phytotoxicity.