苍耳对盐碱胁迫的生理响应

采用不同浓度的NaCl、NaHCO_3溶液对苍耳幼苗进行胁迫处理,分析胁迫处理对苍耳幼苗的生长、光合指标、无机离子、有机溶质及渗透调节剂的渗透调节贡献率的影响,重点研究苍耳对碱胁迫的生理适应机制。结果表明:盐碱胁迫显著抑制了苍耳的生长和光合。随胁迫强度的增加,叶内Na~+质量摩尔浓度、Na~+质量摩尔浓度与K~+质量摩尔浓度的比增加,碱胁迫下增加幅度更大。盐胁迫下,在根部和叶内,Na~+、K~+和游离脯氨酸均是主要的渗透调节物质;3者渗透调节中的平均贡献率的总,在根部为73.89%、在叶内为61.96%。碱胁迫下,根部和叶片显示出不同的渗透调节机制:在根部,Na~+和游离脯氨酸是主要的渗透调节物质,平均贡献率分别为58.44%和16.25%,K~+的渗透调节作用很小;在叶内,Na~+、K~+、游离脯氨酸均起到重要的渗透调节作用。与盐胁迫相比,碱胁迫对植物的伤害作用更大。苍耳通过Na~+、K~+、游离脯氨酸等渗透剂对根部和叶内渗透调节的积极参与,对碱胁迫具有一定的适应能力。

Physiological Responses of Xanthium sibiricum to Salt and Alkali Stresses

An experiment was conducted to study the effects of salt and alkali stresses on the growth, photosynthesis, the concentrations and contributions of inorganic ions and organic solutes of Xanthium sibiricum seedlings treated with different contents of NaCl or NaHCO3 focusing on its physiological adaptive mechanisms against alkali stresses.The salt and alkali stresses clearly inhibited growth and photosynthesis.With increasing salinity, the Na+ content and Na+/K+ ratio in leaves were increased, with greater degrees of increase under alkali than under salt stress.Under salt stress, Na+, K+ and free proline were the main osmolytes in both roots and leaves, with the sums of the average contributions of 73.89% and 61.96% in roots and leaves, respectively.Under alkali stress, roots and leaves revealed different mechanisms of osmotic regulation.Na+ and free proline were the main osmolytes in roots under alkali stress with the average contributions of 58.44% and 16.25% respectively, and the osmotic role of K+ was small;however, in leaves, Na+, K+ and free proline all played important osmotic roles.The injurious effect of alkali stress on plants were more severe, and Xanthium sibiricum had a certain adaptability to alkali stress with the active participations of Na+, K+ and free proline in the osmotic adjustments in roots and leaves.