Department of Botany, Punjab University, 160014 Chandigarh, India.
*E-mail: daizybatish@yahoo.com
Plant Protection and Plant Health in Europe: Introduction and Spread of Invasive Species, held at Humboldt University Berlin, Germany, 9–11. June Pp.: 215–216, (2005).
A study was conducted to established the allelopathic effect of P. hysterophorus on 2 non-invasive naturalized species (Bidens pilosa and Cassia occidentalis) that seem to be adversely affected by its invasion. A P. hysterophorus-infested (PI) or P. hysterophorus-free (PF, control) area was selected. Compared with 39 plant types in the PF area, only 14 were present in the PI area, thereby indicating a sharp decline in vegetation diversity. Even vegetal biomass was drastically reduced in the PI areas (401 g/m2) compared with the PF areas (998 g1 m2). indicating that, upon invasion by P. hysterophorus, the diversity and biomass of the native species are drastically reduced. Early growth (seedling length and dry weight) of both B. pillosa and C. occidentalis was significantly reduced in the PI soil compared with the PF soil. Further, extracts prepared from debris also retarded growth of both weeds. The PI soil contained a significant amount of water-soluble phenolics (11.82 mg 1kg) compared with the PF soil (1.67 mg 1kg). Even the debris was rich in phenolics (11.87 mg/g).
