中文摘要：

为研发酸化土壤的生物修复技术，本文用水培实验和电位滴定方法研究了酸性条件下氮素形态对西红柿根系释放羟基的影响，结果表明，在初始pH为4．0、NO3-／NH4＋比为15：1、5：1、1：1和1：5的营养液中，由于西红柿对NO3-N的偏好吸收导致根系释放羟基，培养液pH升高。培养1周后4个NO3-／NH4＋比培养液pH分别升高了1．60、1．15、0．57和O29，与西红柿对NO3--N的吸收量和羟基释放量的大小一致。当西红柿生长在初始pH为5．O营养液中时，仅NO3-／NH4＋比为15：1和5：1体系中西红柿根系释放羟基，导致培养液pH升高：在NO3＋／NH4＋比为1：1和1：5体系中西红柿根系释放质子，导致培养液pH降低。初始pH5．0条件下西红柿吸收的NO3--N低于初始pH4．0条件下的，其根系释放的羟基量也低于pH4．0体系中的。这些结果说明低pH条件有利于西红柿对NO3-N的吸收，话红柿根系也会释放更多的羟基。因此可以根据西红柿在强酸性条什下对NO3--N的偏好吸收和根系释放羟基的特点对酸化土壤进行生物修复。

英文摘要：

In order to develop biorcmediation technology for acidified soils, effect of NO3＋/NH4＋ molar ratio on release of hydroxyl from tomato roots under acidic conditions was investigated with solution culture experiments and automatic potentiometric titrations. When the initial pH was 4.0 and NO3＋/NH4＋ molar ratios were 15：1, 5：1, 1：1 and 1：5, tomato took up more nitrate from culture solution and its roots released hydroxyl into culture solutions, and thus led to the increase of solution pH. The pH of cultore solutions with NO3＋/NH4＋ molar ratios of 15：1, 5：1, 1：1 and 1：5 was increased by 1.60, 1.15, 0.57 and 0.29 units after 7 days of tomato cultivation. The change of solution pH was consistent with the amounts of nitrate absorbed by tomato and hydroxyl released by its roots. When tomato grew in the culture solution with initial pH of 5.0, its roots released hydroxyl in the solutions with NO3＋/NH4＋ molar ration of 15：1 and 5：1, while they released proton in the solutions with NO3＋/NH4＋ molar ratios of 1：1 and 1：5. Tomato absorbed more nitrate and its roots released more amount of hydroxyl in the solutions of initial pH 4.0 than in the solutions of initial pH5.0. Therefore, tomato can be used to remediate acidified soils due to its preferential absorption for nitrate and the release of hydroxyl from its roots.