Comparative assessment of allelopathic herbicidal actions and total phenolics content of seven Indian medicinal plants

Allelopathy is a vital ecological process that influences the dynamics of ecological succession, structure, and composition of plant communities. The present study aimed to evaluate a comparative account of allelopathic inhibitory actions in relation to total phenolic contents of aqueous extracts from seven traditionally used medicinal plants of India. Triticum aestivum and Cicer arietinum seedlings were used to test seed germination inhibition, seedling growth retardation and branch root sprouting inhibition. Allium cepa root tip cells were used for mitotic index inhibition and abnormal cell percentage analysis. The correlation between the total phenolics content and allelopathic activities was analyzed. The different extracts show the varied degree of allelopathic inhibitory activity. Out of these seven used extracts, Crinum asiaticum leaf extract (CaLAE) showed the highest allelopathic inhibitory action and it could reduce 94.3 and 79.59% root and shoot growth respectively at 96 h of treatment (1 mg/mL) and that was increased to 96.18 and 93.78% respectively with 2 mg/mL. The quantitative phytochemical analysis also revealed that CaLAE also possess relatively higher amounts of total phenolics. The growth retardation effects of the extract are in accordance with the mito-depression and increased chromosomal abnormality in A. cepa root tip cells. In conclusion, Crinum asiaticum may be considered as a prospective source of allelochemicals for plant growth regulation and a source of commercial herbicidal products.