PHYTOTOXIC POTENTIAL OF BARK EXTRACTS OF ACACIA NILOTICA AND SYZYGIUM CUMINI AGAINST PARTHENIUM HYSTEROPHORUS

Effect of aqueous and n-hexane bark extracts of allelopathic tree species viz., Acacia nilotica and Syzygium cumini (L.) Skeels was studied on germination and seedling growth of Parthenium hysterophorus L. In laboratory trials, all the concentrations of aqueous extract of both the test plants increased seed germination of target weed while by employing n-hexane concentrations of A. nilotica the number of germinated seeds remained the same as in control except 20%. However, among all the concentrations of n-hexane extract of S. cumini, significantly minimum seed germination (about 50%) was recorded at 20% concentration. There was a negative phytotoxic response on weed growth by aqueous extracts of both test plants. Conversely a pronounced effect on plant growth (shoot and root length) was exhibited by n-hexane extract of test plants. Similarly, the biomass was significantly reduced by both aqueous and n-hexane extracts of both test plants. In pot trials, all the n-hexane concentrations of test plants invariably suppressed the root and shoot growth of target weed. There was 30-35%, 20-27%, 50% and 50-55%, 80% and 80-82% reduction in shoot length, root length and fresh/dry biomass of parthenium by n-hexane extracts of A. nilotica and S. cumini, respectively.