磷亏缺下不同植物根系有机酸的分泌

通过液培试验，采用直接收集法和气相色谱技术测定了适应性较强的6种植物根分泌物中低分子量有机酸的种类和数量。结果表明：在磷亏缺下6种植物根系有机酸分泌的总量与正常供磷下相比都呈不同倍数的增长。不同植物种根系分泌的有机酸种类与数量（某有机酸占有机酸总量的百分率）以及增长的倍数有所差异。其中肥田萝卜：酒石酸（73％）和苹果酸（20％），总量增长43倍；印度豇豆：酒名酸（99％）增长4倍；养麦：酒石酸（84％）总量和草酸（16％）总量增长8倍；玉米（农大60）：酒石酸（94％）增长4倍；白羽扇豆；柠檬酸（65％）增长11倍。油菜：苹果酸（80％）和柠檬酸（17％）增长38倍。

Exudation of Organic Acids by the Roots of Different Plant Species under Phosphorus Deficiency

The kinds and amount of low molecular weight (LMW) organic acids collected directly from roots of six pIant species with high ability of P adaptation under water solution culture were analyzed by gas chromatography technique. Results showed that the total amount of LMW organic acids excreted by the roots of six plants with P deficiency treatment.increased in different extents and the release of LMW organic acid also varied in the kind and proportion of total amount of LMW organic acid, compared to the plants with adequate P supply. For example, 73% and 20% of LMW organic acids released by radish were tartaric acid and malic acid respectively and their total released amount increased by 43 times. 99%of LMW organic acids was tartaric acid and only increased by 4 times in India cowpea. In buckwheat 84% and 16% of LMW organic acids were tartaric acid and oxalic acid respectively and their total released amount increased by 8 times. In corn(ND60) 94 % of LMW organic acids with 4-time increment was tartaric acid. However, for white lupin the dominant LMW organic acid, 65% of LMW organic acids was citric acid and increased by 11 times.For rape, 80% and 17% of LMW organic acids were malic acid and oxalic acid respectively and the increment was 38 times.