Allelopathic effect of Cassia tora on seed germination and growth of mustard

Cassia tora L. (CT) is a widely growing weed in India with medicinal value and has been reported to show allelopathic potential causing biological suppression on crops. The present study was conducted to observe its suppression on Brassica campestris L. (mustard). The rate of seed germination and the root length, shoot length, chlorophyll content, fresh weight (FW), dry weight (DW), and relative water content (RWC) of 10-day-old mustard seedlings were observed after treatment with aqueous extracts of the roots, leaves, and seeds of CT and compared with control sets treated with distilled water. A confirmatory chemical test was conducted to determine the presence of phenols, ketones, acids, and alcohols in the CT plant extracts. Different concentrations of the extracts showed inhibition (up to 100%) or deterioration in all of the parameters. Roots were more affected than shoots and the extract taken from leaves was more suppressive than that taken from other plant parts. The FW, DW, and RWC were considerably reduced upon treatment with the tested extracts. The extracts (>25%) also caused a reduction in the chlorophyll content. The overall results indicate the possible suppressive effect of allelochemicals (phenols, ketones, acids, and alcohols) present in CT on mustard. The overall results with regard to mustard plants followed the same trend of concentration-dependent inhibition in the order of leaf > seed > root.