Allelopathic potential of well water fromPluchea lanceolata-infested cultivated fields.

Pluchea lanceolata, an allelopathic perennial weed, has an extensive deep root and rhizome system. The objective of the present study was to determine the allelopathic potential of well water collected from weed-infested cultivated fields. Results indicate that well water recovered fromP. lanceolata-infested cultivated fields inhibited the shoot growth of pea, chick pea, mustard, and wheat under greenhouse conditions. Two phenolic compounds, phenol and phloroglucinol, were isolated and identified from collected well water using UV spectroscopy. The allelopathic potential of the aqueous extract of the two compounds was determined by growth experiments with 10(4) M solutions of the compounds. As a consequence of repeated irrigation with well water fromP. lanceolata-infested fields, higher levels of phenolics can accumulate in the soil, which may contribue to increased interference to crop plants. The present study is of significance since it cautions on the use of well water for irrigating cultivated fields infested with the perennial allelopathic weed (P. lanceolata) with dense subterranean systems and emphasizes the importance of controlling such weeds in cultivated fields.