Allelopathic potential of an annual weed, Polypogon monspeliensis, in crops in India.
Investigations were carried out to elucidate the involvement and mode of operation of allelopathy in Polypogon monspeliensis. Comparative studies of soils associated with and without the weed under field conditions revealed that there was no significant difference in toxicity of the two soils, and thus the possibility of its allelopathic effect on crops grown in the same season could be ruled out. However, soil amended with weed straw had significantly higher total phenolics, including higher relative concentrations of phenolic fractions that were not detected in unamended soil. Phenolic fractions significantly affected the seedling growth of radish and cluster beans [guar]. It is likely that P. monspeliensis did not interfere chemically with the crops cultivated during the same season, but interfered with the following season crop through incorporated straw. These results indicate how a monocarpic annual such as P. monspeliensis can be allelopathic under field conditions and how allelopathic potential can be managed.