Humic substances might mitigate negative effects of pyroxsulam and 2,4-D herbicides on wheat (Triticum aestivum L.) productivity.

Abstract

Ensuring food security requires enhancing agricultural productivity while implementing sustainable practices to minimize environmental impact and conserve resources. Biostimulants have emerged as an effective means to promote plant growth and improve resilience to stress. This study aimed to evaluate whether combining two herbicides with a humic substance (HS) could reduce herbicide-induced phytotoxicity in wheat, compared to herbicide application alone. Field trials were conducted using wheat cv. TBIO Ponteiro® in two separate experiments: trial #1 with pyroxsulam and trial #2 with 2,4-D. Both trials included four treatments: an untreated control (T1), herbicide-only application (T2), herbicide plus HS applied three days later (T3), and herbicide plus HS applied on the same day (T4). Variables measured included the number of tillers (NT), spikelets (NS), fresh aboveground biomass (FAB), hectoliter weight (HW), and crop yield (CY). In trial #1, NT, NS, and HW were similar across treatments, but T2 showed significantly lower FAB and CY values compared to T4 and T1, suggesting that HS facilitated plant recovery. Trial #2 showed a similar pattern, with herbicide-only treatment reducing NT, NS, and CY relative to at least some HS-treated or untreated treatments, whereas FAB and HW remained unaffected. These findings suggest humic substances can mitigate the negative effects of herbicides like pyroxsulam and 2,4-D on wheat.