Allelopathy based bio-synthesized nanoparticles and bio-utilization for the management of water hyacinth (Eichhornia crassipes (Mart.) Solms)

Abstract

The research work entitled “Allelopathy based bio-synthesized nanoparticles and bio-utilization for the management of water hyacinth (Eichhornia crassipes (Mart.) Solms)” was undertaken at College of Agriculture, Vellayani during 2020-2022 to evaluate the efficacy of allelopathic weed extract mediated biosynthesized nanoparticles on water hyacinth; bio-utilization of water hyacinth as nutritive manure and its physico-chemical characterization.The effect of plant extract mediated bio-synthesized nanoparticles on water hyacinth was studied at College of Agriculture, Vellayani during June 2022 in completely randomized design with ten treatments and three replications. The treatments included T1: Lantana camara aqueous leachate at 3%, T2: Lantana camara mediated silver nanoparticles at 0.1%, T3: Lantana camara mediated silver nanoparticles at 1%, T4: Parthenium hysterophorus aqueous leachate at 3%, T5: Parthenium hysterophorus mediated silver nanoparticles at 0.1%, T6: Parthenium hysterophorus mediated silver nanoparticles at 1%, T7: Coleus amboinicus aqueous leachate at 3%, T8: Coleus amboinicus mediated silver nanoparticles at 0.1%, T9: Coleus amboinicus mediated silver nanoparticles at 1%, T10: Distilled water (control). Allelopathy-based biosynthesized silver nanoparticles were synthesized in the lab following a biosynthesis protocol. Characterization studies of the three biosynthesized silver nanoparticles (AgNPs) revealed that the reduction of silver ions (Ag+) to silver nanoparticles (Ag0) occurred. It was initially indicated by colour change and was confirmed by UV-vis spectroscopy. The absorbance ranged between 287 nm and 450 nm. Zeta potential data showed higher stability for P. hysterophorus mediated silver nanoparticles (-32.7 mV) and Dynamic Light Scattering data showed a PDI (Polydispersity Index) of 0.52 and an average size of 213 nm. The SEM image of parthenium mediated silver nanoparticles showed almost spherical shape. X-ray diffraction profile of three plant mediated AgNPs suspension showed face centred cubic structure. The average size of allelopathy-based bio-synthesized nanoparticles was found to be 13.76 nm, 9.96 nm and 17.29 nm respectively for lantana mediated AgNPs, parthenium mediated AgNPs and coleus mediated AgNPs which were calculated using the Debye-Scherrer’s equation.While comparing the effect of allelopathy based aqueous leachates and biosynthesized AgNPs on morphological parameters of water hyacinth, it was found that all the treatment applications showed negative effect on morphological parameters when compared to control. The P. hysterophorus mediated AgNPs affected the plant morphology in a concentration dependent manner. P. hysterophorus mediated AgNPs recorded lowest number of leaves (3.0), bud diameter (3.16 cm), length (5.0 cm) and width (5.26 cm) of leaves and root length (17.46 cm) at 9 days after treatment (DAT). The same treatment showed 100 per cent reduction in biomass within 12 DAT. There was 100 per cent reduction of root and shoot fresh and dry weight and there was no regeneration of ramets till 15 DAT with 100