CITRIC-ACID EXCRETION AND PRECIPITATION OF CALCIUM CITRATE IN THE RHIZOSPHERE OF WHITE LUPIN (LUPINUS-ALBUS L)
CITRIC-ACID EXCRETION AND PRECIPITATION OF CALCIUM CITRATE IN THE RHIZOSPHERE OF WHITE LUPIN (LUPINUS-ALBUS L)
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DOI：
10.1111/j.1365-3040.1989.tb01942.x
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发表时间：
1989-04-01
影响因子：
7.3
通讯作者：
MARSCHNER, H
中科院分区：
文献类型：
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作者：
DINKELAKER, B;ROMHELD, V;MARSCHNER, H
羽扇豆属(Lupinus albus L.)在缺磷石灰性土壤(20%CaCO3，pH(H2O)17.5)上种植13周，种植前消毒，并以硝酸盐为氮源。在缺磷条件下，蛋白质类根大量生长，约占根干重的50%。蛋白根区根际土壤pH降至4.8，可见丰富的白色沉淀物。X射线光谱分析和化学分析表明，这些沉淀物由柠檬酸钙组成。13周龄植株根系分泌物中柠檬酸的释放量约为1g株-1，约占收获时植株总干重的23%。蛋白根区根际土壤有效磷含量降低，有效铁、锰、锌含量增加。根际的强烈酸化和植物对阳离子/阴离子的吸收比率强烈地表明，白羽扇豆的蛋白质类根将柠檬酸而不是柠檬酸分泌到根际，导致有限土壤体积的密集化学提取。在石灰性土壤中，柠檬酸的排泄导致CaCO3的溶解和蛋白质根区柠檬酸钙的沉淀。
While lupin (Lupinus albus L.) was grown for 13 weeks in a phosphorus (P) deficient calcareous soil (20% CaCO3, pH(H2O) l7.5) which had been sterilized prior to planting and fertilized with nitrate as source of nitrogen. In response to P deficiency, proteoid roots developed which accounted for about 50% of the root dry weight. In the rhizosphere soil of the proteoid root zones, the pH dropped to 4.8 and abundant white precipitates became visible. X-ray spectroscopy and chemical analysis showed that these precipitates consisted of calcium citrate. The amount of citrate released as root exudate by 13-week-old plants was about 1 g plant-1, representing about 23% of the total plant dry weight at harvest. In the rhizosphere soil of the proteoid root zones the concentrations of available P decreased and of available Fe, Mn and Zn increased. The strong acidification of the rhizosphere and the cation/anion uptake ratio of the plants strongly suggests that proteoid roots of white lupin excrete citric acid, rather than citrate, into the rhizosphere leading to intensive chemical extraction of a limited soil volume. In a calcareous soil, citric acid excretion leads to dissolution of CaCO3 and precipitation of calcium citrate in the zone of proteoid roots.