With the intensification and frequency of heat waves and periods of water deficit stress, along with rising atmospheric carbon dioxide [CO₂], understanding the seasonal leaf-gas-exchange responses to combined abiotic factors will be important in predicting crop performance in semi-arid production systems. In peanut (Arachis hypogaea L.), the availability of developmental stage physiological data on the response to repeated water deficit stress periods in an elevated [CO₂] (EC) environment is limited and necessary to improve crop model predictions. Here, we investigated the effects of season-long EC (650 µmol CO₂ m⁻² s⁻¹) on the physiology and productivity of peanut in a semi-arid environment. This study was conducted over two-growing seasons using field-based growth chambers to maintain EC conditions, and impose water-stress at three critical developmental stages. Our results showed that relative to ambient [CO₂] (AC), long-term EC during water-stress episodes, increased leaf-level light-saturated CO₂ assimilation (A_sat), transpiration efficiency (TE), vegetative biomass, and pod yield by 58%, 73%, 58%, and 39%, respectively. Although leaf nitrogen content was reduced by 16%, there was 41% increase in maximum Rubisco carboxylation efficiency in EC, indicating that there was minimal photosynthetic down-regulation. Furthermore, long-term EC modified the short-term physiological response (A_sat) to rapid changes in [CO₂] during the water-stress episodes, generating a much greater change in EC (54%) compared to AC (10%). Additionally, long-term EC generated a 23% greater A_sat compared to the short-term EC during the water-stress episodes. These findings indicate high levels of physiological adjustment in EC, which may increase drought resilience. We concluded that EC may reduce the negative impacts of repeated water-stress events at critical developmental stages on rain-fed peanut in semi-arid regions. These results can inform current models to improve the projections of peanut response to future climates.

随着热浪的加剧和频率以及缺水压力的周期，以及大气二氧化碳 [CO ₂ ] 的上升，了解对组合非生物因素的季节性叶气交换反应对于预测半干旱地区的作物性能将很重要。生产系统。在花生 ( Arachis hypogaea L.) 中，关于在升高的 [CO ₂ ] (EC) 环境中对重复缺水胁迫期的反应的发育阶段生理数据的可用性是有限的，并且对于改进作物模型预测是必要的。在这里，我们研究了季节性 EC (650 µmol CO ₂ m ^-2 s ^-1) 对半干旱环境下花生的生理和生产力的影响。这项研究是在两个生长季节进行的，使用基于田间的生长室来维持 EC 条件，并在三个关键发育阶段施加水分压力。我们的结果表明，相对于环境 [CO ₂ ] (AC)，水分胁迫期间的长期 EC，增加叶片水平光饱和 CO ₂同化 ( A _sat )，蒸腾效率 ( TE)、营养生物量和豆荚产量分别提高了 58%、73%、58% 和 39%。尽管叶氮含量降低了 16%，但 EC 中最大 Rubisco 羧化效率增加了 41%，表明光合下调幅度很小。此外，长期 EC 修改了短期生理反应 ( A _sat ) 以应对水分胁迫期间[CO ₂ ] 的快速变化，与 AC (10%) 相比，EC (54%) 产生了更大的变化. 此外，长期 EC 产生的A _sat增加了 23%与缺水期间的短期 EC 相比。这些发现表明 EC 的生理调节水平很高，这可能会增加抗旱能力。我们得出的结论是，EC 可能会减少关键发育阶段反复出现的缺水事件对半干旱地区雨养花生的负面影响。这些结果可以为当前模型提供信息，以改进花生对未来气候反应的预测。