Elucidation of allelopathic potentialities of an invasive plant S. nodiflora towards an aggressive weed mimosa and documentation of the contributing allelochemicals
摘要
Weeds are one of the major contaminants of a crop field and seriously hamper agricultural production. The synthetic weedicides used to control weeds affect both ecosystem functioning and human health. Thus, novel techniques, especially nature-based solutions, are in great need as a replacement for the chemical weedicides. The use of phytochemicals obtained from invasive species can be the best sustainable approach. They are known to be allelopathic plants, and their synthesised metabolites, i.e., allelochemicals, exhibit strong selective phytotoxic activity. Invasive taxa synthesise these unique metabolites as a method of niche specialisation or territorial signature that can be exploited biotechnologically for the development of alternative herbicides. The phytochemicals were extracted from leaves of S. nodiflora using different solvents and tested for their allelopathic potentiality on Mimosa pudica seeds. The different germination behaviour and seed biochemical parameters were noted. The allelochemicals were applied to seedlings, and the changes in standard physical and critical biochemical events were reported. The contributing allelochemicals were identified through bioassay-guided fractionation followed by GC–MS-based identification. In the present investigation, phyto-metabolites from methanolic extracts of leaves of S. nodiflora exhibit potent seed germination inhibition activity against mimosa and affect its normal external morphology and internal biochemical machinery. The T50 (time required for the germination of 50% seeds) value was prolonged, and the reduction in insoluble carbohydrates, nucleic acid, and protein contents, as well as amylase action, was observed. Stress-related antioxidant enzymes- catalase, and peroxidase were drastically reduced. The pigment profiles, i.e., chlorophyll a, b, and carotenoids, were critically lowered, whereas the degree of lipid peroxidation increased. Compared to the control, the common physical parameters related to shoot and root length, dry, and fresh weight were affected in treated seedlings. The major metabolites present in the methanolic extracts responsible for such a promising allelopathic activity were quinic acid, protocatechuic acid, gentisic acid, caffeic acid, and ferulic acid, etc. The allelochemicals of S. nodiflora can be employed for the development of alternative eco-friendly herbicides and also pave the way for the management of alien species.