ARC Centre of Excellence for Translational Photosynthesis, Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Dookie, Victoria, 3647, Australia.
Plant Mol Biol. 2022 Nov;110(4-5):365-384. doi: 10.1007/s11103-022-01276-7. Epub 2022 Jun 1.
Heat stress (HS) under well-watered conditions was not detrimental to leaf photosynthesis or yield but modified the elevated CO response of photosynthesis and yield in two contrasting wheat cultivars. Climate change is increasing the frequency of extreme events such as heat waves, adversely affecting crop productivity. While positive impacts of elevated carbon dioxide (eCO) on crop productivity are evident, the interactive effects of eCO and environmental stresses are still unclear. To investigate the interactive effects of elevated CO and heat stress (HS), we grew two contrasting wheat cultivars, early-maturing Scout and high-tillering Yitpi, under non-limiting water and nutrients at ambient (aCO, 450 ppm) or elevated (eCO, 650 ppm) CO and 22 °C in the glasshouse. Plants were exposed to two 3-day HS cycles at the vegetative (38.1 °C) and/or flowering (33.5 °C) stage. At aCO, both wheat cultivars showed similar responses of photosynthesis and mesophyll conductance to temperature and produced similar grain yield. Relative to aCO, eCO enhanced photosynthesis rate and reduced stomatal conductance and maximal carboxylation rate (V). During HS, high temperature stimulated photosynthesis at eCO in both cultivars, while eCO stimulated photosynthesis in Scout. Electron transport rate (J) was unaffected by any treatment. eCO equally enhanced biomass and grain yield of both cultivars in control, but not HS, plants. HS reduced biomass and yield of Scout at eCO. Yitpi, the cultivar with higher grain nitrogen, underwent a trade-off between grain yield and nitrogen. In conclusion, eCO improved photosynthesis of control and HS wheat, and improved biomass and grain yield of control plants only. Under well-watered conditions, HS was not detrimental to photosynthesis or growth but precluded a yield response to eCO.
在水分充足的条件下，热应激（HS）不会对叶片光合作用或产量造成不利影响，但会改变两种不同小麦品种光合作用和产量对高浓度 CO 的响应。气候变化增加了热浪等极端事件的频率，对作物生产力产生不利影响。虽然升高二氧化碳（eCO）对作物生产力的积极影响是明显的，但 eCO 和环境胁迫的相互作用仍不清楚。为了研究升高 CO 和热应激（HS）的相互作用，我们在温室中以非限制水和养分条件下，在环境（aCO，450 ppm）或升高（eCO，650 ppm）CO 和 22°C 下生长两个具有鲜明对比的小麦品种，早熟 Scout 和高分枝 Yitpi。在营养生长期（38.1°C）和/或开花期（33.5°C），植物经历了两个为期 3 天的 HS 循环。在 aCO 下，两个小麦品种的光合作用和叶肉导度对温度的响应相似，并产生相似的籽粒产量。与 aCO 相比，eCO 增强了光合作用速率，并降低了气孔导度和最大羧化速率（V）。在 HS 期间，高温在两个品种中都刺激了 eCO 下的光合作用，而 eCO 刺激了 Scout 的光合作用。电子传递速率（J）不受任何处理的影响。eCO 在对照条件下同等提高了两个品种的生物量和籽粒产量，但在 HS 条件下没有提高。HS 降低了 eCO 下 Scout 的生物量和产量。Yitpi，一种含氮量较高的品种，在籽粒产量和氮之间进行了权衡。总之，eCO 提高了对照和 HS 小麦的光合作用，并仅提高了对照植株的生物量和籽粒产量。在水分充足的条件下，HS 对光合作用或生长没有不利影响，但排除了对 eCO 的产量响应。
