CO_(2)浓度升高对干旱胁迫下谷子细胞结构和抗逆生理的影响

Effects of elevated CO_(2) concentration on cell structure and stress resistance physiology of Setaria italica under drought stress

在未来气候进一步变暖的背景下干旱发生的频率也将增加,而CO_(2)浓度升高和干旱均会对作物生长造成影响。本研究对不同CO_(2)浓度(环境大气CO_(2)浓度、环境大气CO_(2)浓度+200μmol·mol-1)和水分处理(土壤含水量为45%~55%和70%~80%的田间土壤最大持水量,分别为适宜土壤含水量和轻度干旱)下谷子叶片细胞结构、光合生理、抗氧化酶、渗透调节物质和产量的变化进行分析。结果表明:CO_(2)浓度升高增加了谷子叶肉细胞叶绿体内淀粉粒个数、单个淀粉粒面积和淀粉粒总面积。与仅轻度干旱处理相比,轻度干旱条件下CO_(2)浓度升高处理孕穗期谷子叶片净光合速率增加37.9%,但对该时期水分利用效率无显著影响,灌浆期谷子叶片净光合速率和水分利用效率分别增加15.0%和44.2%;孕穗期谷子叶片过氧化物酶(POD)活性和可溶性糖含量分别增加39.3%和8.0%,脯氨酸含量下降31.5%,灌浆期谷子叶片POD活性增加26.5%,丙二醛(MDA)和脯氨酸含量分别下降37.2%和39.3%。CO_(2)浓度升高处理下,轻度干旱条件使谷子穗粒数较正常水分条件两年平均显著增加44.7%,产量显著升高52.3%,且与环境大气CO_(2)浓度相比,CO_(2)浓度升高对谷子籽粒产量的增幅在轻度干旱条件下高于正常水分条件下。轻度干旱条件下大气CO_(2)浓度升高增加了谷子叶片厚度、维管束鞘截面积、净光合速率和水分利用效率,提高了叶片抗氧化酶活性,改变了叶片渗透调节物质含量,从而降低了干旱对谷子的负面影响,提高了谷子穗粒数和产量。本研究可为未来气候变化背景下谷子生产及干旱地区农业可持续发展提供理论依据。

The frequency of drought will increase under further warming.The increase in atmospheric CO_(2) concen⁃tration,along with more frequent drought,will affect crop growth.We examined the changes of cell structure,pho⁃tosynthetic physiology,antioxidant enzymes,osmotic regulatory substances,and yield of foxtail millet(Setaria ita⁃lica)leaves under different CO_(2) concentrations(ambient air CO_(2) concentration and ambient atmospheric CO_(2) con⁃centration+200μmol·mol-1)and water treatment(soil moisture content maintained at 45%-55%,and 70%-80%of field capacity,representing mild drought and normal water condition,respectively).The results showed that elevated CO_(2) concentration increased the number of starch grains,the area of single starch grains,and the total area of starch grains in the chloroplast of millet mesophyll cells.Under mild drought condition,elevated CO_(2) con⁃centration increased net photosynthetic rate of millet leaves at the booting stage by 37.9%,but did not affect water use efficiency at this stage.Elevated CO_(2) concentration increased net photosynthetic rate and water use efficiency of millet leaves under mild drought condition at the filling stage by 15.0%and 44.2%,respectively.Under mild drought condition,elevated CO_(2) concentration increased the content of peroxidase(POD)and soluble sugar in mil⁃let leaves at the booting stage by 39.3%and 8.0%,respectively,but decreased proline content by 31.5%.It increased the content of POD in millet leaves at the filling stage by 26.5%but decreased the content of MDA and proline by 37.2%and 39.3%,respectively.Under mild drought condition,elevated CO_(2) concentration significantly increased the number of grain spikes by 44.7%and yield by 52.3%in both years compared with normal water con⁃dition.The effect of elevated CO_(2) concentration on grain yield under mild drought conditions was higher than that under normal water condition.Under mild drought conditions,elevated CO_(2) concentration increased leaf thickness,vascular bundle sheath cross⁃sectional area,net photosynthetic rate,and water use efficiency of millet,improved the antioxidant oxidase activity,and changed the concentration of osmotic regulatory substances,alleviated the nega⁃tive effect of drought on foxtail millet,and finally increased the number of grains per ear and yield of foxtail millet.This study would provide a theoretical basis for millet production and sustainable agricultural development in arid areas under future climate change.