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<p>Soil salinization and drought, exacerbated by climate change, pose a significant threat to global crop productivity, yet the response of weeds, which are key competitors in agro-ecosystems, remains underexplored. This study aimed to evaluate the morphological, physiological, and biochemical responses and stress tolerance of five dominant summer weed species (<i>Dactyloctenium aegyptium</i>, <i>Echinochloa crus-galli</i>, <i>Setaria viridis</i>, <i>Trianthema portulacastrum</i>, and <i>Amaranthus viridis</i>) under salinity (8.0 dS m⁻<sup>1</sup>) and drought (50.0% field capacity) stress. A controlled pot experiment was conducted to assess plant growth, gas exchange parameters, membrane stability, antioxidant enzyme activities, and oxidative stress markers<b>.</b> Both salinity and drought significantly (<i>p</i> ≤ 0.05) reduced plant dry weight by 4.0–18.0% and 8.0–31.0%, respectively, depending on species. Under salinity stress, <i>Dactyloctenium aegyptium</i> and <i>Echinochloa crus-galli</i> exhibited minimal biomass reductions (4.0% and 5.0%), whereas <i>Setaria viridis</i> showed the greatest decline (18.0%). Under drought, <i>Trianthema portulacastrum</i> was least affected (8.0% reduction), while <i>Echinochloa crus-galli</i> and <i>Setaria viridis</i> exhibited the largest reductions (31.0% and 28.0%). Photosynthetic rate declined by 8.0–15.0% under salinity and 7.0–22.0% under drought, accompanied by significant reductions in stomatal conductance and transpiration rate. Electrolyte leakage increased markedly under stress, reaching up to 94.0%, while relative water content decreased by up to 40.0% under salinity. Antioxidant enzyme activities were significantly enhanced, with superoxide dismutase increasing by 35.0–87.0%, peroxidase by 21.0–76.0%, and catalase by 14.0–50.0%. Malondialdehyde content increased by up to 58.0%, indicating oxidative stress. Overall, species exhibiting greater physiological stability and stronger antioxidant responses showed higher tolerance to stress conditions. These findings provide comparative physiological insight into species-specific adaptive responses to salinity and drought stress and may support future research on weed ecology and stress adaptation under changing environmental conditions.</p>

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Divergent physiological and biochemical strategies confer differential salinity and drought tolerance in five prevalent summer weeds

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Saira Shafiq,
  • Muhammad Zia Ul Haq,
  • Muhammad Shahbaz,
  • Iftikhar Ali

摘要

Soil salinization and drought, exacerbated by climate change, pose a significant threat to global crop productivity, yet the response of weeds, which are key competitors in agro-ecosystems, remains underexplored. This study aimed to evaluate the morphological, physiological, and biochemical responses and stress tolerance of five dominant summer weed species (Dactyloctenium aegyptium, Echinochloa crus-galli, Setaria viridis, Trianthema portulacastrum, and Amaranthus viridis) under salinity (8.0 dS m⁻1) and drought (50.0% field capacity) stress. A controlled pot experiment was conducted to assess plant growth, gas exchange parameters, membrane stability, antioxidant enzyme activities, and oxidative stress markers. Both salinity and drought significantly (p ≤ 0.05) reduced plant dry weight by 4.0–18.0% and 8.0–31.0%, respectively, depending on species. Under salinity stress, Dactyloctenium aegyptium and Echinochloa crus-galli exhibited minimal biomass reductions (4.0% and 5.0%), whereas Setaria viridis showed the greatest decline (18.0%). Under drought, Trianthema portulacastrum was least affected (8.0% reduction), while Echinochloa crus-galli and Setaria viridis exhibited the largest reductions (31.0% and 28.0%). Photosynthetic rate declined by 8.0–15.0% under salinity and 7.0–22.0% under drought, accompanied by significant reductions in stomatal conductance and transpiration rate. Electrolyte leakage increased markedly under stress, reaching up to 94.0%, while relative water content decreased by up to 40.0% under salinity. Antioxidant enzyme activities were significantly enhanced, with superoxide dismutase increasing by 35.0–87.0%, peroxidase by 21.0–76.0%, and catalase by 14.0–50.0%. Malondialdehyde content increased by up to 58.0%, indicating oxidative stress. Overall, species exhibiting greater physiological stability and stronger antioxidant responses showed higher tolerance to stress conditions. These findings provide comparative physiological insight into species-specific adaptive responses to salinity and drought stress and may support future research on weed ecology and stress adaptation under changing environmental conditions.