Assessing the allelopathy and autotoxicity effects of Parthenium hysterophorus L., Senna uniflora (Mill.) H.S. Irwin and Barneby and Hyptis suaveolens (L.) Poit.
In the current study laboratory experiments were conducted to elucidate the allelopathic and autotoxic effects of Parthenium hysterophorus, Senna uniflora and Hyptis suaveolens. The seed germination experiments were conducted using the leachates obtained from different organs of the three species. Ten grams, each of the plant materials were homogenized in 100 mL of quartz-distilled water for 24 hours, filtered and used as a stock solution of 100% concentration. From the stock solution, 25, 50 and 75% concentrations were prepared by diluting with quartz-distilled water. Three replicates with 30 seeds each for each plant species were maintained. Observations were made at regular intervals of 24 hours. The emergence of radicle was taken as the indicator of germination. Germination, root and shoot elongation was monitored for eight days. The study revealed inhibition of germination in both the species by the leaf leachates of P. hysterophorus of all concentrations. There was a strong and positive relationship between the concentration of the shoot and root leachates of H. suaveolens and their inhibitory effect on P. hysterophorus. The leachates of H. suaveolens, inhibited seed germination totally in P. hysterophorus in all concentrations. Allelopathic effect of leaf leachates of H. suaveolens on S. uniflora lasted longer than a week, inhibiting seed germination. The autotoxic effects of P. hysterophorus were much stronger than that of other two species. It is concluded that among the three species, H. suaveolens leaf leachates had the strongest inhibitory effect both on P. hysterophorus and S. uniflora and can be recommended as bio-herbicide.