Abstract:
Allelopathy is a common occurrence in plants and affects the growth of the reacting
species either positive (stimulating) or negative (inhibiting). Allelopathic activity has
been in many plant interactions such as weed on crops, crops on weeds and crops on
crops. Weed allelopathy is important for the future agronomic applications especially
in crops production. Striga asiatica has been known as the invasive weed species that
inhibit the growth of important crops. The present study examined the allelopathic
activity of Striga asiatica on microalgae Chiarella vulgaris (UMT-Ml) . Crude and
supernatant extract of S. asiatica at two, four and six weeks of culture were tested
using the algal plating assay with disc diffusion and agar well diffusion method.
Results showed that crude extract of S. asiatica with agar well method causes positive
allelopathic activity on the growth of Chlorella vulgaris (UMT-Ml) with formation of
dense green zone around the agar well. The highest extract concentration, 50 mg/ml
exhibited the highest stimulating allelopathic activity on the growth of Chlorella
vulgaris (UMT-Ml) by showing the widest stimulating zone radius. The four weeks
old of S. asitaca culture also contributed highest allelopathic activity with significance
level at P<0.05. Allelopathic activity is dependent on the age of plantlets and
concentration used on the microalgae.
