Chemical synthesis, characterization, and dose optimization of chitosan-based nanoparticles of clodinofop propargyl and fenoxaprop-p-ethyl for management of Phalaris minor (little seed canary grass): First report

Abstract

Phalaris minor is the main and troublesome weed of wheat all over the globe. Chemical weed control is a quick and effective method for weed management. However, herbicides are criticized for environmental pollution and the development of resistance in weeds. Therefore, the present study was planned for chemical synthesis, characterization, and dose optimization of chitosan-based nanoparticles of clodinofop propargyl and fenoxaprop-p-ethyl for the management of Phalaris minor grown in wheat. Chitosan-based nanoparticles of clodinofop propargyl and fenoxaprop-p-ethyl were prepared by the ionic gelification technique. The nanoparticles (NPs) of clodinofop propargyl and fenoxaprop-p-ethyl were sprayed at 3–4 leaf stage of the P. minor weed. Seven different doses (D0 = weedy check, D1 = normal herbicide at recommended dose, D2 = nano herbicide at the recommended dose of normal herbicide, D3 = 5-fold lower dose of nano herbicide, D4 = 10-fold lower dose of nano herbicide, D5 = 15-fold lower dose of nano herbicide, and D6 = 20-fold lower dose of nano herbicide) were used. Chitosan-based NPs of herbicides were characterized using UV absorbance, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) studies. SEM demonstrated particles in the cluster form with porous structure and the average size ranged from 30 to 60 nm. XRD results confirmed the existence of (2θ) peak at 29.79 related to 160 anatase form in the NPs of clodinofop propargyl and 24.65 related to 76 anatase form in the case of fenoxaprop-p-ethyl. The FT-IR analysis of chitosan-based NPs of both the herbicides perfectly matched the standard parameters. UV-visible spectra exhibited absorption peaks at 300 and 330 nm, for the NPs of fenoxaprop-p-ethyl and clodinofop, respectively. The chitosan-based particles of clodinofop propargyl and fenoxaprop-p-ethyl at the recommended dose of normal herbicide caused 100% mortality and visual injury. However, a 5-fold lower dose of chitosan-based NPs of clodinofop propargyl and fenoxaprop-p-ethyl caused the maximum visual injury (94.00%), mortality (93.75%), minimum chlorophyll contents (7.47%), plant height (cm), fresh biomass (0.27 g), and dry biomass (0.08 g) of P. minor. The chitosan-based NPs of clodinofop propargyl and fenoxaprop-p-ethyl at a 10-fold lower dose of normal herbicides and recommended dose produced a similar effect on the previously mentioned traits of P. minor.

Keywords

• phalaris minor (canary grass)
• chitosan-based nanoparticles
• chlorophyll content
• plant height
• plant biomass