Foliar application of fulvic acid minimises the damage of glyphosate drift to wheat (Triticum aestivum L.) during early growth

Abstract

Abstract Background and aims Glyphosate drift from applications to glyphosate-resistant crops can negatively affect growth of nearby wheat. Fulvic acid has demonstrated efficacy in alleviating various abiotic stresses in plants, underpinning a hypothesis it may also alleviate glyphosate-induced damage in wheat. Methods This study evaluated the effectiveness of fulvic acid foliar sprays (1, 3, 5, 7, 10, and 15 g/L) in minimising damage from simulated glyphosate drift [3% (w/v) of the recommended weed-kill rate] on wheat at the early growth stage (Zadoks Z13). Fulvic acid was foliarly applied either 3 days before (on day 15 after sowing, DAS), immediately before glyphosate application (18 DAS), or mixed with glyphosate (18 DAS). Based on initial experiments, the optimum fulvic acid dose (5 g/L) was subsequently tested on two wheat cultivars differing in sensitivity to glyphosate. Results Fulvic acid application significantly reduced the glyphosate damage, enhancing plant biomass, root length, chlorophyll concentration, gas exchange parameters, and micronutrient accumulation (Cu, Mn, Fe, and Zn) in shoots compared to the control. Pre-application (15 DAS) of fulvic acid compared to the same-day application (18 DAS) was more effective in minimising glyphosate damage, while the mixture of fulvic acid and glyphosate resulted in no observable damage to either wheat cultivar. Cultivar Scepter was significantly more sensitive to glyphosate compared to cultivar Magenta; moreover, foliarly applied fulvic acid mitigated the glyphosate drift stress to a greater extent in Magenta than Scepter. Conclusions Foliar application of fulvic acid represents a promising strategy for protecting wheat plants from glyphosate drift stress.