中文摘要：

为确定以Na2CO3和Na HCO3为主要成分的苏打盐碱胁迫对甜高粱植株有机酸含量的影响,研究了盐碱胁迫下甜高粱品种314B和M-81E地上部和根部有机酸含量变化及磷酸烯醇式丙酮酸羧化酶（PEPC）活性。结果表明：盐碱胁迫后,甜高粱地上部和根部均检测到草酸、酒石酸、甲酸、丙酮酸、苹果酸、乳酸、乙酸及柠檬酸等8种有机酸,琥珀酸仅在根中被检出;在苏打盐碱胁迫后,除极少数有机酸含量略微增加外,其余各酸含量降低,且随胁迫浓度增加含量下降程度增大;低浓度胁迫时PEPC酶活性升高,而高浓度时则降低;有机酸含量与PEPC酶活性不存在相关性,但PEPC酶活性升高,有机酸含量下降幅度小,反之,有机酸含量大幅下降;从有机酸含量及PEPC酶活性可以看出,耐性强品种M-81E受苏打盐碱胁迫的伤害小于耐性弱品种314B。

英文摘要：

In order to understand the effects of saline-sodic （based on the composition of Na2CO3 and NaHCO3 ） stress on the organic acid contents in sweet sorghum plant （Sorghum dochna （ Forssk. ） ）, the changes of organic acid contents and phosphoenolpyruvate earboxylase （PEPC） activities in above- and under-ground parts of sorghum varieties 314B and M-81E were studied. The results showed that eight different acids （i.e., oxalic acid, tartaric acid, formic acid, pyru- vie acid, malie acid, lactic acid, acetic acid, and citric acid） were detected from both of the above- and under-ground parts, while succinic acid was only found in the roots under saline-sodic stress. Meanwhile, the levels of most organic acids decreased with the increment of stress level, whereas few of them increased slightly. The PEPC activity increased at low saline-sodic concen- tration, but decreased at high saline-sodic concentration. There was no correlation between organic acid level and PEPC activity. Nevertheless, when the PEPC activity increased, the de- creasing rate of organic acids changed slightly and vice versa. In terms of the levels of organic acid and PEPC activity, M-81E （stronger tolerance） suffered a weaker damage than 314B （low- er tolerance） under saline-sodic stress.