The simultaneous increase of carbon dioxide and temperature causes significant changes in rice physiology and production, but limited studies have been performed in the past to examine the interactive effect of these two key variables on lipid peroxidation, anti-oxidative properties, gas exchange parameters, and grain yield of rice. Thus, an experiment was conducted by growing two rice genotypes (IR83376-B-B-24–2 and IR64) inside field-based open-top chambers (OTCs) with two levels of [CO₂] (ambient and elevated; (500±25 ppm) and temperature (ambient and ambient+2°C) in order to determine their simultaneous effect on lipid peroxidation (thio-barbituric acid substances, TBARS), anti-oxidant properties (catalase, CAT and superoxide dismutase, SOD), gas exchange parameters (P_N rate, g_s, E), WUE and grain yield during the kharif seasons. Our study showed that under simultaneous elevation (CO₂ and temperature), the activity of CAT and SOD were improved. CAT showed significant alterations in activity which was detected for genotype IR83376-B-B-24–2 (twelve-fold increase) under elevated temperature compared to ambient temperature. SOD activity was decreased by 35.1 and 35.7% with elevated [CO₂] while it increased under elevated temperature by 103.6 and 41.1% in IR83376-B-B-24–2 and IR64, respectively. No significant difference in TBARS content was observed under combined elevation of both [CO₂] and temperature, as compared to ambient conditions. However, elevation in temperature by 2°C led to a reduction in photosynthetic rate and WUE but increased the rate of transpiration, CAT and SOD activity. Grain yield was also improved under elevated [CO₂] while elevated temperature has negative impact on grain yield. Thus, the findings suggest that there are differential biochemical (TBARS, CAT, and SOD) and physiological (P_N rate, g_s, E, and WUE) responses of rice towards predicted climatic conditions. This study represents the significant findings on the anti-oxidant defence mechanism in rice under combined elevated [CO₂] and temperature levels. Furthermore, the genotypic differences observed in terms of photosynthesis mechanism and ROS scavenging system imply that it is possible to breed varieties that will be more suited for future rice production scenarios.

中文翻译：

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[CO2] 升高和温度升高对水稻光合过程、抗氧化特性和产量的交互影响

二氧化碳和温度的同时升高会导致水稻生理和产量发生显着变化，但过去进行了有限的研究来检验这两个关键变量对脂质过氧化、抗氧化特性、气体交换参数和水稻的粮食产量。因此，通过在具有两个 [CO ₂ ] 水平（常温和升高；（500±25 ppm）和温度（环境和环境+2°C），以确定它们对脂质过氧化（硫代巴比妥酸物质，TBARS）、抗氧化特性（过氧化氢酶、CAT 和超氧化物歧化酶，SOD）、气体交换的同时影响参数（P _N率, g _s , E ), WUE 和kharif季节的粮食产量。我们的研究表明，在同时升高（CO ₂和温度）的情况下，CAT和SOD的活性得到提高。与环境温度相比，在升高的温度下检测到基因型 IR83376-BB-24-2（增加 12 倍）的活性显着改变。_{在 IR83376-BB-24-2 和 IR64 中，SOD 活性随着 [CO 2} ]升高而降低了 35.1% 和 35.7%，而在升高的温度下它分别增加了 103.6% 和 41.1%。在两种[CO ₂] 和温度，与环境条件相比。然而，温度升高 2°C 会导致光合速率和 WUE 降低，但会增加蒸腾速率、CAT 和 SOD 活性。_{在[CO 2} ]升高的情况下，粮食产量也有所提高，而高温对粮食产量有负面影响。因此，研究结果表明水稻对预测的气候条件有不同的生化（TBARS、CAT 和 SOD）和生理（P _N率、g _s、E和 WUE）响应。_{该研究代表了在联合升高的[CO 2}条件下水稻抗氧化防御机制的重要发现] 和温度水平。此外，在光合作用机制和 ROS 清除系统方面观察到的基因型差异意味着有可能培育出更适合未来水稻生产情景的品种。