Allelopathic effects of an invasive alien weed Parthenium hysterophorus L. compost on lettuce germination and growth

The present study was conducted to determine allelopathic effects of parthenium compost and to investigate whether ratio of parthenium composted with other plant materials have an influence on allelopathic potential of parthenium. Two emergence and growth experiments were conducted using lettuce as a model plant. Fresh parthenium reduced lettuce emergence percentage and rate and radicle and plumule lengths by 93, 95, 97 and 93%, respectively. Composted parthenium however reduced emergence percentage and rate and radicle and plumule lengths by 0, 33, 35 and 43%, respectively. Composting parthenium with other plant materials reduced allelopathic inhibition effects of parthenium on lettuce emergence rate and radicle and plumule lengths more than composting parthenium alone. Our results clearly showed that composting greatly reduced allelopathic effects of parthenium compared to fresh parthenium. Furthermore, composting parthenium with other plants resulted in lower inhibition of emergence rate and radicle and plumule lengths compared to composting parthenium alone. Hence, we suggest parthenium composting with locally available plant materials as a means to reduce its allelopathic inhibitory effect and as a way of parthenium management by utilization.   Key words: Allelopathy, compost, germination, invasive alien weed, Parthenium hysterophorus, seedling growth.