Formulation and assessment of nano-encapsulated bioherbicides based on biopolymers and essential oil

Abstract

Excessive uses of chemical pesticides have resulted in the occurrence of a wide array of problems consequently using plant natural products is gaining more attention. In this study, different concentrations of savory (Satureja hortensis L.) essential oil (control, 5, 10 and 15 ml/L) were nano-encapsulated using Arabic gum (AG), Persian gum/gelatin (PGG), Persian gum (PG) as wall materials. The nanocapsules had their herbicidal activity against tomato (Lycopersicon esculentum Mill.) and amaranth (Amaranthus retroflexus L.) evaluated by measuring 18 physiological and biochemical parameters. The average size of the nanocapsules varied between 81 and 208 nm, while polydispersity index showed variation between 0.210 and 0.536. The encapsulation efficiency of nanoparticles varied between 72.1–92.8 %. Nano-encapsulated herbicides (NCHs) stability was investigated for 42 days and a mathematical model was followed during oil release. Nano-encapsulated herbicides showed considerable herbicidal activity against amaranth while they had a mild effect on tomato. Moreover, herbicidal activity results exhibited the improvement of encapsulated savory essential oil (EO) efficiencies as compared to non-nano EO emulsion (without polymer). The greatest and fastest injury to amaranth caused by encapsulated EO using cross-linked Persian gum at 15 ml/L which asserted 100 % weed control after 48 h. The aforementioned data suggest the encapsulation of essential oils by biopolymers and with the help of cross-linkers can be used as a valuable tool for the production of organic, natural herbicides.