低磷胁迫对玉米自交系苗期根系分泌有机酸的影响

Effect of Low-Phosphorus Stress on Root Exudation of Maize Inbred Lines at the Seedling Stage

采用低磷和对照盆栽试验，以磷高效04419和磷低效04065玉米自交系为材料，研究二者在苗期根系分泌有机酸的差异。结果表明，在低磷和对照2种磷水平下，04419和04065根系分泌的有机酸种类随叶期而增加，4～8叶期二者根系分泌的主要有机酸是：草酸、丁二酸、柠檬酸、苹果酸和乙酸；草酸是二者根系分泌的最主要有机酸。低磷胁迫下，04419根系在4叶期草酸和柠檬酸的分泌量、在5～6叶期苹果酸和草酸的分泌量、在7叶期苹果酸的分泌量、在8叶期乙酸和柠檬酸的分泌量较04065明显增多，因而04419根系分泌有机酸总量明显高于04065。可见，低磷条件下，04419和04065根系分泌有机酸总量的能力在一定程度上与其耐低磷能力的大小相关。

The maize inbred lines 04419 and 04065 as test materials were grown in the pots amended with a low-P level and a control level to study the difference of root exudation during their seedling period. Under the two P levels, the major forms of organic acids exuded from the roots at the four-to eight-leaf stages in- cluded oxalic acid, butyric acid, citric acid, malic acid and acetic acid, oxalic acid being predominant among the organic acids in the root exudation of the two P levels. Under P deficiency, at the four-leaf stage, the amount of oxalic and citric acids exuded from line 04419 root was much more than that from line 04065 root; at the five- and six-leaf stages, the amount of malic and oxalic acids exuded from line 04419 root was much more than that from line 04065 root; at the seven-leaf, the amount of malic acid exuded from line 04419 increased greatly compared with that from line 04065; at the eight-leaf-aged stage, the amount of acetic and citric acids exuded from line 04419 root was much greater than that from line 04065 root. Consequently, the content of total organic acids from line 04419 root was much greater than that from line 04065 root. It is thus concluded that the total exudation of organic acids by the roots of the two inbred lines under low-P stress is, to some extent, associated with their tolerance to low-P stress.