Allelopathic effects of Sterculia foetida (L.) against four major weeds

Isolation and identification of allelopathic substances from plants is an important step to study allelopathy. The herbicidal potential of crude, column fractions and an isolated pure compound of Sterculia foetida (L.) seeds were assessed against the 4-Indian major weeds: Calotropis gigantea (R.Br.), Parthenium hysterophorus (L.), Datura metel (L.) and Tridax procumbens (L.). The potent herbicidal constituent of S. foetida seeds was characterized as a cyclopropene fatty acid structurally elucidated as (2n-octylcycloprop-1-enyl)-octanoic acid (I) by spectroscopic analysis. The foliar application of S. foetida seed derived pure compound acted as a contact herbicide, causing initial chlorosis and necrosis followed by defoliation. The herbicidal potential of the isolated compounds were examined against seed germination, shoot and root length of the weed plants. The S. foetida seed derived crude, column fractions and isolated pure compound at 150, 75 and 10 mg/L, significantly inhibited the seed germination, shoot and root length respectively.