The effects of nitrogen (N) supply on the response of leaf gas exchange, leaf water relations and plant nutrient uptake of tomato plants exposed to progressive soil drying under elevated CO₂ (e[CO₂], 800 ppm) were investigated. Two tomato genotypes differing in their endogenous abscisic acid (ABA) level, i.e. Ailsa Craig and its ABA-deficient mutant (flacca) were grown in pots in greenhouse cells with either ambient CO₂ (a[CO₂], 400 ppm) or e[CO₂]. Two N levels, i.e., N1, 0.5 g pot⁻¹ and N2, 1.0 g pot⁻¹ were used and the N fertilizer (NH₄NO₃) was applied with the irrigation water before transplanting. The results showed that e[CO₂] and N2 increased photosynthesis and water use efficiency (WUE) of tomato plants. N2 improved plant water relations by sensitizing the decline of transpiration rate during soil drying. The plant N acquisition and major ionic concentrations in xylem sap were lowered under e[CO₂], such negative effect was compensated by increasing N supply. For WT, the ABA concentrations in leaf ([ABA]_leaf) and xylem sap ([ABA]_xylem) were increased with the decrease of the fraction of transpirable soil water, whereas, for flacca this was only observed in [ABA]_leaf. Compared to WT, flacca had lower xylem sap ionic concentrations and WUE. Collectively, the responses of tomato plants to e[CO₂] and N supply under progressive soil drying were genotypic-dependent, and endogenous ABA level could play an important role in modulating the responses.

研究了氮 (N) 供应对暴露于升高的 CO ₂ ( e [CO ₂ ], 800 ppm)下渐进式土壤干燥的番茄植株的叶片气体交换响应、叶片水分关系和植物养分吸收的影响。两种内源脱落酸 (ABA) 水平不同的番茄基因型，即 Ailsa Craig 及其 ABA 缺陷突变体 ( flacca ) 在温室细胞的盆中生长，环境 CO ₂ ( a [CO ₂ ], 400 ppm) 或e [CO ₂ ]。使用两个 N 水平，即 N1，0.5 g pot ^-1和 N2，1.0 g pot ^-1和 N 肥料（NH ₄NO ₃ )在移栽前与灌溉水一起施用。结果表明，e [CO ₂ ] 和 N2 提高了番茄植株的光合作用和水分利用效率 (WUE)。N2 通过提高土壤干燥过程中蒸腾速率下降的敏感性来改善植物水分关系。在e [CO ₂ ] 下，植物 N 获取和木质部汁液中的主要离子浓度降低，这种负面影响通过增加 N 供应得到补偿。对于 WT，叶 ([ABA]_叶) 和木质部汁液 ([ABA]_木质部) 中的 ABA 浓度随着可蒸发土壤水分含量的减少而增加，而对于flacca这仅在 [ABA]_叶中观察到。与 WT 相比，flacca具有较低的木质部汁液离子浓度和 WUE。总的来说，番茄植物对渐进式土壤干燥条件下e [CO ₂ ] 和 N 供应的反应是基因型依赖性的，内源 ABA 水平可以在调节反应中发挥重要作用。