The responses of leaf gas exchange of wheat (Triticum aestivum L.) to elevated atmospheric CO2 concentration (e[CO2]) were often investigated within a single generation, while the long‐term acclimation of photosynthesis to growth in e[CO2] over multiple generations has not been systematically studied. Here, five wheat cultivars were grown under either ambient (a[CO2], 400 ppm) or elevated (e[CO2], 800 ppm) CO2 concentration for three consecutive generations (G1 to G3) with two N‐fertilisation levels (1N–1 g N pot−1 and 2N–2 g N pot−1) in climate‐controlled greenhouses. Leaf gas exchange was determined in each generation of plants under different treatments. It was found that at both N levels, e[CO2] stimulated photosynthetic rate while reducing stomatal conductance, transpiration rate and leaf N concentration, resulting in an enhanced water use efficiency and photosynthetic N use efficiency. The N level modulated the intergenerational responses of photosynthetic capacity to e[CO2]; under low N supply, the maximum carboxylation rate (Vcmax), the maximum electron transport rate (Jmax) and the rate of triose phosphate utilisation (TPU) were significantly downregulated by e[CO2] from the first to the second generation, but recovered in the third generation; whereas at high N levels, photosynthetic acclimation was diminished with the progress of generations, with Vcmax, Jmax and TPU increased under e[CO2] in the third generation. These results suggest that intergenerational adaptation could alleviate the e[CO2]‐induced reduction of the photosynthetic capacity, but plants with different N status responded differently to adapt to the long‐term exposure to e[CO2]. Among the five cultivars, 325Jimai showed a better photosynthetic performance under e[CO2] over the three generations, while 02‐1Shiluan appeared to be more inhibited by CO2 elevation in the long term conditions. These findings provide new insights for breeding strategies in the future CO2‐enriched environments.

中文翻译：

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增加 CO2 和 N 供应对小麦植株叶片气体交换特性的多代效应


小麦 (Triticum aestivum L.) 叶片气体交换对大气 CO2 浓度 (e[CO2]) 升高的响应通常在一代内进行研究，而光合作用对 e[CO2] 生长的长期适应则需要经过多代的研究。几代人尚未得到系统研究。在这里，五个小麦品种在环境（a[CO2]，400 ppm）或高浓度（e[CO2]，800 ppm）CO2 浓度下连续生长三代（G1 至 G3），并采用两种氮肥水平（1N- 1 g N pot−1 和 2N–2 g N pot−1) 在气候控制温室中。在不同处理下测定每一代植物的叶子气体交换。研究发现，在两个氮水平上，e[CO2]刺激光合速率，同时降低气孔导度、蒸腾速率和叶片氮浓度，从而提高水分利用效率和光合氮利用效率。氮水平调节光合能力对e[CO2]的代际响应；在低氮供应下，从第一代到第二代，最大羧化速率（Vcmax）、最大电子传递速率（Jmax）和磷酸丙糖利用率（TPU）均被e[CO2]显着下调，但在第三代；而在高氮水平下，光合适应随着世代的进步而减弱，在第三代e[CO2]下，Vcmax、Jmax和TPU增加。这些结果表明，代际适应可以缓解e[CO2]引起的光合能力下降，但不同氮状态的植物对长期暴露于e[CO2]的反应不同。 五个品种中，325吉麦在三代的e[CO2]下表现出更好的光合性能，而02-1石鸾在长期条件下似乎更容易受到CO2升高的抑制。这些发现为未来富含二氧化碳的环境中的育种策略提供了新的见解。