This study was designed to estimate the allelophatic effect of cogongrass (Imperata
cylindrica L.), in the growth of one year old of olive seedlings, in a nursery (greenhouse)
conditions. Two experiments were conducted in this study. In the first e
xperiment, the
effect of the aqueous extracts of cognograss leaves, rhizomes, and roots, at concentrations
of (2%, 4% and 8%) on the growth of olive seedlings (total length and diameter) were
evaluated. The results of this experiment indicated an inhibitory effect of the 4% and 8%
aqueous extracts on growth parameters. It was found that treatments with 4% and 8%
aqueous extracts caused significant reduction (60.2% and 83%) respectively in the total
length, in compare to the control. As for the 2% aqueous extract, it showed a stimulation
effect in the growth, an increase about 31.5% was recorded for the total length in compare
to the control. A similar result was observed in regard the seedlings diameter growth. The
2% aqueous extract showed an 56.8% increase in the rate of diameter growth, while the
4% and 8% extracts showed a reduction effects 80% and 91.5% respectively. The second
experiment evaluated the effect of dried powder of cogongrass parts at concentrations of
(2%, 4% and 8%) on the growth of olive seedlings.
