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<p>This study was performed to examine some physiological responses related to net photosynthesis in acai (<i>Euterpe oleracea</i> Mart.) seedlings to high temperature (HT) stress. The seedlings were incubated at 28&#xa0;°C (Control) and at 40&#xa0;°C (HT-stress treatment) for 1, 6 and 11&#xa0;days. Relative to control, the HT-stressed seedlings showed 36%, 81% and 87% decreases in <i>A</i> on days 1, 6 and 11. The stomatal conductance and transpiration decreased by 80% regardless of stress duration, while substomatal CO<sub>2</sub> concentration increased over time until reach the highest average on day 11. The relative water content in HT-stressed seedlings was decreased by 31% on days 1 and 6 and by 85% on day 11. Significant decrease in the maximum quantum efficiency of photosystem (PS) II photochemistry was only observed on day 11, but actual quantum yield of PSII electron transport, photochemical and non-photochemical quenching and Rubisco-initial activity were progressively decreased over the stress period. Relative to control, glycolate oxidase activity in HT-stressed plants was only increased (59%) on day 11. The HT-stress induced 37% and 66% decreases in sucrose and starch contents regardless of stress period and induced 22% (days 1 and 6) and 46% (day 11) decreases in glucose. Lipid peroxidation in HT-stressed plants was evident on days 1 and 11. Therefore, net photosynthesis was strongly constrained by reduced Rubisco carboxylase activity and enhanced photorespiration, highlighting the sensitivity of acai seedlings to HT stress.</p>

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Limitations to photosynthesis during progressive exposure of acai seedlings to high temperature stress

  • 期刊论文

  • 发表日期：

    2026年3月16日

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  • Rodolfo Inacio Nunes Santos,
  • Wagner Romulo Lima Lopes Filho,
  • Flavio Henrique Santos Rodrigues,
  • Patrícia Cardoso Andrade Navegantes,
  • Roberto Lisboa Cunha,
  • Dênmora Gomes Araujo,
  • Hugo Alves Pinheiro

摘要

This study was performed to examine some physiological responses related to net photosynthesis in acai (Euterpe oleracea Mart.) seedlings to high temperature (HT) stress. The seedlings were incubated at 28 °C (Control) and at 40 °C (HT-stress treatment) for 1, 6 and 11 days. Relative to control, the HT-stressed seedlings showed 36%, 81% and 87% decreases in A on days 1, 6 and 11. The stomatal conductance and transpiration decreased by 80% regardless of stress duration, while substomatal CO2 concentration increased over time until reach the highest average on day 11. The relative water content in HT-stressed seedlings was decreased by 31% on days 1 and 6 and by 85% on day 11. Significant decrease in the maximum quantum efficiency of photosystem (PS) II photochemistry was only observed on day 11, but actual quantum yield of PSII electron transport, photochemical and non-photochemical quenching and Rubisco-initial activity were progressively decreased over the stress period. Relative to control, glycolate oxidase activity in HT-stressed plants was only increased (59%) on day 11. The HT-stress induced 37% and 66% decreases in sucrose and starch contents regardless of stress period and induced 22% (days 1 and 6) and 46% (day 11) decreases in glucose. Lipid peroxidation in HT-stressed plants was evident on days 1 and 11. Therefore, net photosynthesis was strongly constrained by reduced Rubisco carboxylase activity and enhanced photorespiration, highlighting the sensitivity of acai seedlings to HT stress.