Division of Environmental Physiology and Biotechnology, G.B. Pant Institute of Himalayan Environment and Development, Kosi- Katarmal, Almora-263 643.
Parthenium (Parthenium hysterophorus L.) flower residue (FR) was inhibitory at 0.50% (w/v) and lethal at and above 0.75% to lemna (Lemna pausicostata Hegelm.). The leaf residue (LR) was inhibitory at 0.50% and lethal at and above 1.00%. The stem residue (SR) was inhibitory at 1% but non-lethal even at 1.25%, and root residue (RR) was inhibitory at 1.25%. The lethal dose caused desiccation of fronds, and the roots became flaccid resulting in death and decay. At lower doses the symptoms appeared and disappeared depending on the residue types, concentration and duration of the treatments. The lethal dose caused massive loss of electrolytes and UV absorbing substances from the roots and loss of chlorophyll a, b and total chlorophyll and carotenoids.
