Laboratory Safety Evaluation and Weed Control Potential of Pre- and Post-Emergence Herbicides for Quinoa

Abstract

In this study, we aimed to identify suitable herbicides for quinoa fields in Anhui Province and explore the value of their potential application in order to achieve the sustainable weed management of the crop and tackle the global issue of unregistered herbicides in quinoa fields. Employing a pre-emergence seed soaking method, we evaluated the effects of different herbicides, such as anilofos, prometryn, pendimethalin, and atrazine on the germination inhibition rate of quinoa seeds, as well as their impacts on the growth indicators of quinoa seedlings. Our findings show that, while these herbicides initially suppressed quinoa seed germination, this effect decreased over time, allowing for the successful germination of all seeds, suggesting the existence of a recovery mechanism in quinoa. An increase in herbicide concentration was correlated with significant decreases in the germination vigor and index of quinoa seeds, along with a decrease in plant height, root length, and fresh weight. Notably, anilofos, prometryn, pendimethalin, and atrazine demonstrated significant inhibitory effects on quinoa seedlings, thus providing critical insights into the sensitivity of quinoa to these chemicals. Greenhouse pot experiments showed that pre-emergence herbicides, such as napropamide, pretilachlor, s-metolachlor, and anilofos, and post-emergence herbicides, including fluroxypyr, penoxsulam, clethodim, quizalofop-P-ethyl, oxaziclomefone, metamifop, benzobicyclon, nicosulfuron, and pinoxaden, are safe for quinoa and suitable for further field trials, broadening the options for integrated weed management strategies. The results of the mixture experiments indicated that penoxsulam and metamifop are safe for quinoa at a ratio of 1:4.6, and their combined activities against dominant weeds in quinoa fields in Anhui Province, such as Digitaria sanguinalis, Cyperus iria, and Amaranthus viridis, were higher than those of single-agent doses, with fresh weight inhibition rates ranging from 66.98% to 92.16% and selectivity indexes ranging from 176.88 to 3282.17. Therefore, this mixture offers a promising approach to enhanced weed control in a sustainable manner.