Effect of drought stress on herbicide performance and photosynthetic activity of Avena sterilis subsp. ludoviciana (winter wild oat) and Hordeum spontaneum (wild barley)

Abstract

The severity of drought is increasing owing to global climate change. Knowledge about the influence of drought on weeds and herbicide performance is necessary for optimising herbicide applications. Therefore, dose-response trials were conducted to investigate the influence of drought stress on the efficacy of four herbicides.Drought-stressed and non-stressed Hordeum spontaneum seedlings were exposed to nine doses of sulfosulfuron and sulfosulfuron + metsulfuron-methyl. Clodinafoppropargyl and mesosulfuron-methyl + iodosulfuron-methyl sodium were applied to drought-stressed and non-stressed seedlings of Avena sterilis subsp. ludoviciana. Leaf greenness index (SPAD), total chlorophyll content, stomatal conductance and photosynthesis rate of both species were measured. The efficacy of herbicides on H. spontaneum was not influenced by drought stress. In contrast, the performance of herbicides on A. sterilis subsp. ludoviciana was reduced under drought stress, where the ED 50 increased by 1.5-fold. The low doses (<2.2 g a.i. ha −1 ) of mesosulfuronmethyl + iodosulfuron-methyl-sodium caused hormesis on A. sterilis subsp. ludoviciana. Total chlorophyll content and SPAD index of both species increased due to drought stress. The stomatal conductance and photosynthesis rate of A. sterilis subsp. ludoviciana decreased under drought stress, while H. spontaneum was not influenced. The lack of detrimental effect of drought stress on sulfosulfuron and sulfosulfuron + metsulfuron-methyl performance might be attributed to similar stomatal conductance and photosynthesis rate of the drought-stressed and non-stressed H. spontaneum. The performance reduction in herbicides on drought-stressed A. sterilis subsp. ludoviciana might be owing to the reduction in stomatal conductance and photosynthesis rate. Using adjuvants, diverse formulations and early application of herbicides were suggested for future research to hamper the negative effect of drought on herbicides.

Smooth scouringrush (Equisetum laevigatum) control with glyphosate is affected by surfactant choice and application time

“…A severe drought occurred in the Pacific Northwest in the summer of 2021 that reduced winter wheat yields by 44% in Washington (Ansah and Walsh 2021). The literature suggests that plants exposed to dry soil conditions, water stress, or both have reduced herbicide uptake and translocation compared to non-stressed plants (Alizade et al 2021; Skelton et al 2016; Waldecker and Wyse 1985). Treatments applied at Reardan were applied later in the season than those at the other sites; thus, the plants at Reardan may have been experiencing greater drought stress, which may also explain the lower stem density at this site compared to Malden and Rock Lake.…”

Impact of Futuristic Climate Variables on Weed Biology and Herbicidal Efficacy: A Review

“…Increased CO 2 levels can decrease stomatal conductance by up to 50% in some plant species [65]. The activity of foliage-applied herbicides might be altered by decreased stomatal conductance [66]. Furthermore, increased leaf thickness and the reduced count of open stomata due to high levels of CO 2 may reduce the efficacy of the post-emergence herbicides directly absorbed by the plants.…”

Divergent Cross-Adaptation of Herbicide-Treated Wheat and Triticale Affected by Drought or Waterlogging

“…It has been already established that herbicide action could be modified under unfavorable environmental conditions, like varying temperatures [40], drought [41], and high salinity [42]. Weed control in waterlogged fields resulting from heavy precipitation at the beginning of vegetation is particularly unpredictable.…”