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Abstract <p>Global warming exacerbates the risk of soil drought, posing a serious threat to the growth and development of maize seedlings. However, the synergistic effects and interaction mechanisms underlying combined high temperature and drought stress in the root zone are still not well understood. In this study, a hydroponic experiment was conducted using two maize cultivars: a stress-tolerant variety (Zhengdan 958) and a conventional variety (Liaodan 565). Three temperature regimes—low temperature (LT), moderate temperature (MT), and high temperature (HT)—were combined with three drought levels (0, 10, and 15%&#xa0;PEG) to investigate the impact of root-zone warming on photosynthetic performance and senescence characteristics under drought conditions. Results showed that leaf area, chlorophyll content, net photosynthetic rate (<i>P</i><sub>n</sub>), light energy utilization efficiency Y(II), electron transport rate ETR(II), photochemical quenching coefficient (qP), and antioxidant enzyme activity in both varieties exhibited a biphasic response to temperature, initially increasing and then decreasing, with peak values observed under MT treatment. Leaf water potential (Ψ<sub>w</sub>) declined progressively with rising temperature, while leaf osmotic potential (Ψ<sub>s</sub>) first decreased and then increased as temperature increased. Under intensified drought stress, most of these physiological parameters—except for antioxidant enzyme activity and Ψ<sub>w</sub>—declined consistently in both varieties. The combination of HT and PEG-induced drought (10 and 15%) severely suppressed photosynthesis, impaired photosystem II function, induced overproduction of reactive oxygen species (ROS), and accelerated leaf senescence, with the magnitude of damage significantly exceeding that caused by either stress applied individually. Importantly, the stress-tolerant variety (Zhengdan 958) exhibited markedly lower levels of photosynthetic inhibition and senescence compared to the conventional variety (Liaodan 565) across all stress conditions. These findings demonstrate that under the context of global warming, the co-occurrence of high temperature and drought in the root zone exerts synergistic adverse effects on maize seedlings, while the cultivation of stress-resistant cultivars offers a promising strategy to mitigate such detrimental impacts.</p>

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The Effects of Varying Root Zone Temperatures and Drought Intensities on the Photosynthetic and Physiological Mechanisms of Maize Seedlings

  • 期刊论文

  • 发表日期：

    2026年3月19日

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  • J. C. Lin,
  • T. H. Zhang,
  • X. Y. Lv,
  • Z. Q. Xia,
  • Y. X. Gong,
  • H. D. Lu

摘要

Abstract

Global warming exacerbates the risk of soil drought, posing a serious threat to the growth and development of maize seedlings. However, the synergistic effects and interaction mechanisms underlying combined high temperature and drought stress in the root zone are still not well understood. In this study, a hydroponic experiment was conducted using two maize cultivars: a stress-tolerant variety (Zhengdan 958) and a conventional variety (Liaodan 565). Three temperature regimes—low temperature (LT), moderate temperature (MT), and high temperature (HT)—were combined with three drought levels (0, 10, and 15% PEG) to investigate the impact of root-zone warming on photosynthetic performance and senescence characteristics under drought conditions. Results showed that leaf area, chlorophyll content, net photosynthetic rate (Pn), light energy utilization efficiency Y(II), electron transport rate ETR(II), photochemical quenching coefficient (qP), and antioxidant enzyme activity in both varieties exhibited a biphasic response to temperature, initially increasing and then decreasing, with peak values observed under MT treatment. Leaf water potential (Ψw) declined progressively with rising temperature, while leaf osmotic potential (Ψs) first decreased and then increased as temperature increased. Under intensified drought stress, most of these physiological parameters—except for antioxidant enzyme activity and Ψw—declined consistently in both varieties. The combination of HT and PEG-induced drought (10 and 15%) severely suppressed photosynthesis, impaired photosystem II function, induced overproduction of reactive oxygen species (ROS), and accelerated leaf senescence, with the magnitude of damage significantly exceeding that caused by either stress applied individually. Importantly, the stress-tolerant variety (Zhengdan 958) exhibited markedly lower levels of photosynthetic inhibition and senescence compared to the conventional variety (Liaodan 565) across all stress conditions. These findings demonstrate that under the context of global warming, the co-occurrence of high temperature and drought in the root zone exerts synergistic adverse effects on maize seedlings, while the cultivation of stress-resistant cultivars offers a promising strategy to mitigate such detrimental impacts.