胡枝子对盐碱胁迫的生理响应

Physiological Responses of Lespedeza bicolor under Salinity Stress

试验采用不同浓度的Na2CO3、NaHCO3及盐碱混合(n(Na2CO3)∶n(NaHCO3)=1∶1)溶液对胡枝子幼苗进行胁迫处理,比较分析盐碱胁迫对胡枝子幼苗的生长及其叶片质膜透性、游离脯氨酸及可溶性糖的影响,初步探讨胡枝子的抗盐碱能力。结果显示:在3种盐碱胁迫下,胡枝子叶片电导率、脯氨酸质量分数、可溶性糖质量分数均随胁迫强度的增加、时间的延长而增加。低、中浓度胁迫对植株造成的伤害相对较弱,高浓度胁迫下胡枝子表现出较严重的盐害症状,生理指标的分析结果与实际生长状态基本一致。到胁迫后期第55天时,Na2CO3浓度为150 mmol.L-1、NaHCO3浓度为150 mmol.L-1、Na2CO3和NaHCO3的混合溶液浓度为150 mmol.L-1处理下电导率分别达到对照的2.24、1.84、1.72倍,脯氨酸质量分数分别为对照的7.32、5.76、5.37倍,可溶性糖质量分数较对照分别增加了67.37%、56.65%、52.50%。脯氨酸、可溶性糖的增加都可以看作是植物适应盐渍环境及增加自身抗盐能力的表现,说明胡枝子对碳酸盐具有一定的适应能力。3种胁迫对胡枝子的伤害程度不同,Na2CO3造成的伤害最大,NaHCO3次之,混合盐碱对胡枝子造成的伤害程度最弱。

An experiment was conducted to study the effects of saline-alkali stress on growth of Lespedeza bicolor seedlings treated with different concentrations of Na2COs, NaHCO3 or their mixed solution （ Na2CO3 and NaHCO3 molar ratio of 1 ： 1 ）, as well as on membrane permeability and contents of free proline and soluble sugar in leaves. The saline-alkali tolerance of L. bicolor was analyzed. Results showed that, with prolonged stress and increasing stress concentration, the electrical conductivi- ty, proline content and soluble sugar content showed upward trends under the three kinds of stress. Low and moderate concentra- tions of stress exhibited relatively weak damage to the seedlings, while the seedlings under high concentrations of stress showed more serious symptoms of salt injury. The analysis results of physiological indicators and the actual growth state were basically the same. On the 55th day after stress, when the concentrations of Na2CO3 , NaHCO3 or their mixed solution were all 150 mmol . L-1 , the electrical conductivity values of the three treatments were 2.24, 1.84, 1.72 times and the proline con- tents were 7.32, 5.76, 5.37 times that of the control, and the soluble sugar content increased by 67.37%, 56.65%, 52.50%. The increase of proline and soluble sugar can be regarded as plant adaptation to saline environment and their enhancement of stress tolerance, indicating that L. bicolor has a certain adaptability to carbonate environments. These three kinds of stress caused different levels of damage to L. bicolor. NaCOs caused the most serious damage, followed by NailCO3 and mixed solution.