In laboratory condition phytotoxicity levels of aqueous extracts of leaves, stems and roots of Parthenium hysterophorus L. on the rate of seed germination, length of root and shoot, and Seed Vigour Index of Cajanus cajan was evaluated. The different concentrations used in the experiment were 15%, 25%, 50%, 75% and 100% of aquous extracts of leaves, stems and roots of P.hysterophorus. A control condition was maintained also. Ten seeds of C.cajan were placed in each petri dishes with ten replicates. The decrease in rate of seed germination in different concentrations of leaves ranged from 10.34 to 99.99%; in stem extract from 5 to 62% and in root extract from 1 to 22% only. Similarly root length value decreased from 1.02 to 70.41% in leaf extract; 25.62 to 63.33% in stem extract; and 57.61 to 87.12% in root extract. The decrease in most important parameter Seed Vigour Index ranged from 21.18 to 99.99% in leaf extract; 18.1 to 79.7% in stem extract; and 25.24 to 85.86% in root extract of Parthenium. Thus the effect of leaf extract was maximum followed by root extract and minimum in stem extract. The Tukey HSD and Post HOC Tests indicated effects of plant parts, treatments and interactions of plant parts and treatments were significantly different at p < 0.000. Thus the present study indicated that the leaves of Parthenium is more phytotoxic than root and stem for C.cajan.
