• Welsh onions (Allium fistulosum L.) are often affected by stressful environments, such as high light and drought, during summer cultivation, which hinders their growth.
• We used CO₂ assimilation, OJIP transient and MR curves to analyse the photosynthetic characteristics of Welsh onion.
• The results showed that single high light stress caused a decrease in the net photosynthesis rate through stomatal limitation, while the single drought treatment and the combined stress induced nonstomatal limitation. F_O and F_J increased, F_m decreased, and a distinct K‐phase was induced. High light and drought stress blocked MR transients, leading to a gradual decrease in V_PSI and V_PSII‐PSI.
• In general, photosynthesis of Welsh onion was inhibited by high light and drought, which destroyed the receptor and donor side of PSII and reduced electron transport capacity of PSII and PSI.

中文翻译：

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不同光照强度和土壤水分条件下大葱叶片光合电子传递的变化。

• 夏季栽培期间，大葱（葱属葱）通常会受到压力环境的影响，例如强光和干旱，这会阻碍其生长。
• 我们使用了CO ₂同化，OJIP瞬态和MR曲线来分析大葱的光合特性。
• 结果表明，单一的高光照胁迫通过气孔限制导致净光合速率降低，而单一的干旱处理和联合胁迫导致非气孔限制。F _O和F _J增大，F _m减小，并且诱导出明显的K相。高光照和干旱胁迫阻止了MR瞬变，导致V _PSI和V _PSII-PSI逐渐降低。
• 通常，强光和干旱会抑制大葱的光合作用，从而破坏PSII的受体和供体，并降低PSII和PSI的电子传输能力。