Development of pre-emergence herbicide based on Arabic gum-gelatin, apple pectin and savory essential oil nano-particles: A potential green alternative to metribuzin

This study was conducted as a plot experiment to investigate the phytotoxicity effects of nano-encapsulated savory essential oil (EO) when it is incorporated separately into carbohydrate and protein natural polymers (Arabic gum-gelatin, apple pectin and gelatin) and two cross-linkers including one poly acid and one enzyme (citric acid and transglutaminase enzyme). Each product was tested as a pre-emergence herbicide against amaranth and tomato. The evaluations also involved determining the stability, morphology, encapsulation efficiency and release properties of the prepared formulations. Coating the savory EO with cross-linked biopolymers enhanced its stability and herbicidal activity, compared to the EO nano-emulsion without any polymer or cross-linker. Among the tested formulations, the strongest inhibitory effect against amaranth germination and growth was caused by Arabic gum-gelatin and apple pectin biopolymers at the concentration of 3 ml/L of EO, when cross-linked with citric acid. These two treatments had slight effects on tomato seedlings, however. The suppressive ability of the formulations was almost similar and comparable to the chemical herbicide metribuzin (1.75 g/L). In conclusion, Arabic gum-gelatin and apple pectin cross-linked by citric acid containing savory EO can be considered as potential, green and safe replacements for metribuzin in organic tomato production.