摘要
摘要:大气CO₂浓度升高导致全球变暖，同时亦对作物生长发育产生深刻影响。作为光合作用的底物，大气CO₂的浓度升高增加水稻产量，但对稻米品质的影响及其品种间差异的研究相对较少且存在分歧。本研究利用稻田FACE（free air CO₂ enrichment）技术平台，以8个水稻品种为材料，设背景CO₂浓度（Ambient）和高CO₂浓度（增200 μmol·mol^-1，FACE）两个水平，研究大气CO₂浓度升高对稻米加工品质、外观品质、食味品质以及部分营养品质的影响及其种间差异。本研究所有测定的品质性状供试品种间均存在显著或极显著差异。与Ambient相比，FACE处理下水稻糙米率、精米率和整精米率略降，但单位面积糙米、精米和整精米产量平均分别极显著增加23.7%、23.5%和20.9%。FACE处理对整精米长度、宽度和长宽比影响较小，但使整精米垩白率和垩白度平均分别增加18.6%和31.8%，均达极显著水平。FACE处理使所有品种稻米直链淀粉含量和胶稠度平均分别下降6.5%和3.1%，但均未达显著水平。从淀粉RVA谱看，FACE处理使所有品种峰值黏度、崩解值平均增加1.3%、6.9%，使热浆黏度、冷胶黏度、消减值分别下降2.2%、5.1%和65.6%，其中消减值达显著水平。FACE处理使所有品种整精米植酸含量平均增加5.3%，而蛋白质含量平均减少9.9%，均达显著水平。不同品种稻米品质性状对高CO₂浓度的响应方向和程度存在一定差异，其中FACE处理与品种对整精米长度、垩白率、垩白度、峰值黏度、热浆黏度和最终黏度存在显著的互作效应。以上数据表明，大气CO₂浓度升高使水稻产量大幅增加，稻米加工、外观和营养品质呈变劣趋势，但适口性可能变优，稻米品质对大气CO₂浓度增高的响应存在不同程度的品种差异。
关键词:气候变化/
水稻/
CO₂浓度增高/
稻米品质
Abstract:Increasing atmospheric carbon dioxide (CO₂) concentration leads to global warming and has a profound effect on the growth and development of crops. As a substrate for plant photosynthesis, high CO₂ concentration can increase rice yields, but the effect on rice quality is still unclear. The genotypic variation in rice quality in response to high CO₂ concentration is less studied than rice yield. In this study, eight rice varieties were grown under ambient and elevated CO₂ concentrations (200 μmol·mol^-1 higher than ambient) in a free-air CO₂ enrichment (FACE) platform. The effects of elevated CO₂ concentrations on rice processing quality, appearance quality, eating quality, and nutritional quality were studied, and grain quality differences among rice varieties in response to elevated CO₂ concentration were also investigated. All of the quality traits varied significantly among the tested varieties. Compared with rice plants grown under ambient CO₂ concentration, plants grown under FACE treatment tended to have decreased brown rice percentage, white rice percentage, and head rice percentage, but had significantly increased yields of brown rice, white rice, and head rice (by 23.7%, 23.5%, and 20.9%, respectively). FACE treatment had little effect on the head rice length, head rice width, and the ratio of head rice length to width, but significantly increased the chalky rice rate and chalkiness degree. Averaged across all rice varieties, the elevated CO₂ concentration increased the chalky rice rate and chalkiness degree by 18.6% and 31.8%, respectively. FACE treatment reduced the amylose concentration and gel consistency by an average of 6.5% and 3.1%, respectively, but the reduction was not significant. The response in the rapid visco analyzer (RVA) profile of rice starch to elevated CO₂ concentration was also studied. FACE treatment increased the mean value of peak viscosity and breakdown by 1.3% and 6.9%, respectively, for all varieties, but decreased the mean value of hot viscosity, cold viscosity, and setback by 2.2%, 5.1%, and 65.6%, respectively. However, only the reduction in setback was statistically significant. The phytic acid concentration of the rice grains significantly increased by 5.3% on average, whereas the protein content significantly decreased by 9.9% under FACE conditions. The response of the rice quality traits to high CO₂ concentration varied in direction and magnitude among different varieties. An interaction between CO₂ treatment and rice variety was found for head rice length, chalky rice rate, chalkiness degree, peak viscosity, hot viscosity, and cold viscosity. The above data suggest that increased atmospheric CO₂ concentration significantly increased grain yield, but tended to diminish the processing quality, appearance quality, and nutritional quality of the rice grains while improving the palatability of cooked rice. The response of rice grain quality to elevated CO₂ concentration varied across rice varieties.
Key words:Climate change/
Rice/
CO₂ concentration enrichment/
Rice quality



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