Atmospheric CO₂ elevation (e[CO₂]) could alleviate the impact of soil water deficit, yet the underlying mechanisms remains largely elusive. This study aimed to investigate whether different endogenous abscisic acid (ABA) level modulates the response of barley and tomato plants to soil water deficit combined with e[CO₂]. Wild type (WT) genotypes (Steptoe barley and AC tomato) and their corresponding ABA-deficient mutants (Az34 barley and AC-flacca) were grown in pots separately in greenhouse cells with ambient (a[CO₂], 400 ppm) and e[CO₂] (800 ppm) and were either well-watered or exposed to soil water deficit. The results showed that, compared to well-watered regime, soil water deficit decreased aboveground dry matter (ADM), leaf area (LA) and specific leaf area (SLA) while enhanced water use efficiency (WUE) in all genotypes. e[CO₂] increased ADM and LA in tomato genotypes. Moreover, it reduced SLA, leaf N concentration while improved WUE and nitrogen use efficiency (NUE) in WT plants, not in ABA-deficient mutants. These results indicate that endogenous ABA level played an important role in modulating the response of WUE and NUE of barley and tomato to e[CO₂] environment, which advances our knowledge on the physiological mechanisms of crop plants adapt to future climate changed scenarios.

大气中的CO ₂升高（e [CO ₂ ]）可以减轻土壤缺水的影响，但其潜在机制仍然难以捉摸。这项研究旨在调查不同内源脱落酸（ABA）的水平是否调节大麦和番茄对土壤水分亏缺与e [CO ₂ ]的响应。野生型（WT）基因型（斯特普托大麦和AC番茄）和它们相应的ABA缺失突变体（AZ34大麦和AC- flacca）生长在盆中分别在温室细胞与环境（一个[CO ₂ ]，为400ppm）和Ë [CO ₂]（800 ppm），并且浇水充分或暴露于土壤缺水状态。结果表明，与良好灌溉制度相比，土壤水分亏缺减少了所有基因型的地上干物质（ADM），叶面积（LA）和比叶面积（SLA），同时提高了水分利用效率（WUE）。e [CO ₂ ]增加了番茄基因型中的ADM和LA。此外，它降低了WT植物中而不是缺乏ABA的突变体中的SLA，叶片氮浓度，同时提高了WUE和氮利用效率（NUE）。这些结果表明内源性ABA水平在调节大麦和番茄的WUE和NUE对e [CO ₂]环境，这使我们对作物植物适应未来气候变化情景的生理机制的认识进一步提高。