CO2浓度升高对大豆干旱胁迫的缓解效应

CO₂浓度升高和干旱带来的气候变化势必对大豆的生长造成影响。目前,CO₂浓度升高对干旱胁迫下大豆生理生化的影响研究较少。本试验研究了不同CO₂浓度(400、600 μmol·mol^–1)和水分处理下(正常水分:叶片相对含水量为83%～90%;干旱:叶片相对含水量为64%～70%)大豆开花期的光合能力、光合色素积累、抗氧化水平、渗透调节物质、激素水平、信号转导酶和基因表达量的变化。结果表明: 干旱胁迫下CO₂浓度升高显著提高了大豆叶片蒸腾速率、水分利用效率和净光合速率,但降低了叶绿素b含量。CO₂浓度升高显著增加了干旱胁迫下叶片过氧化物酶活性和脱落酸含量,显著降低了脯氨酸含量,对可溶性糖含量没有显著影响。干旱胁迫下CO₂浓度升高显著增加了钙依赖蛋白激酶含量和谷胱甘肽-S-转移酶活性,并且其基因表达量均显著上调;显著降低了丝裂原活化蛋白激酶和热休克蛋白含量,并下调了其基因表达量。研究结果将有助于了解气候变化对大豆生长和生理生化的影响,为应对未来气候变化下大豆生产采取必要措施。

Elevated CO2 concentration mitigate the effects of drought stress on soybean

The climate change caused by elevated CO₂ concentration and drought are bound to affect the growth of soybean. Few studies have addressed the effects of elevated CO₂ concentration on the physiology and biochemistry of soybean under drought stress. Here, we examined the changes of photosynthetic ability, photosynthetic pigment accumulation, antioxidant level, osmotic adjustment substances, hormone levels, signal transduction enzymes and gene expression level of soybean at flowering stage under different CO₂ concentration (400 and 600 μmol·mol^-1) and drought stress (normal water: leaf relative water content was 83%-90%; drought stress: leaf relative water content was 64%-70%). The results showed that the transpiration rate, water use efficiency and net photosynthetic rate of soybean leaves were significantly increased by elevated CO₂ concentration, but the content of chlorophyll b was decreased under drought stress. Elevated CO₂ concentration significantly increased peroxidase activity and abscisic acid content of leaves under drought stress, decreased the content of proline, and did not affect the content of soluble saccharides. The increased CO₂ concentration under drought stress significantly promoted the content of calcium-dependent protein kinase and glutathione-S-transferase, and up-regulated the expression of related genes, while significantly decreased the content of mitogen-activated protein kinase and the heat shock protein, and down-regulated the expression of their genes. The results would be helpful to understand the impacts of climate change on the growth, physiology and biochemistry of soybean, and to deal with the production problems of soybean under future climate change.