鲜地黄（Rehmannia glutinosa (Gaert. ) Libosch. ex Fisch. et Mey.）根中的梓醇具缓泻利尿作用。因此其含量是评价药材质量的重要指标之一。为了提高鲜地黄质量以及充分开发利用其资源，对鲜地黄根中的梓醇含量与外形的相关性进行了研究，结果表明梓醇含量与根直径／长度比有较强的正相关，说明地黄根的径向膨大是梓醇含量增加的关键。从资源利用分析看地黄根被舍弃部分占总梓醇量的１６～２７％，这部分资源应当充分开发利用。

The catalpol in fresh root of Kehmannia glvlinosa (Gaert. ) Libosch. ex Fisch. et Mey. (Radix Rehmanniae) has the effects of diarrhoea lysis and diuresis, therefore the content level of catalpol is one of the major indicators when evaluating its quality. In order to improve the quality and make better use of the resources, it has been conducted to study the interrelation between the catalpol content and appearance of the fresh root. It has been shown that the content level of catalpol with diameter/length of the root has strong positive interrelation, this means that radix thickening is essential to the increase of the content level of catalpol. After the investigating the utilized circumstance of this plant resources, 16-- 27% of the total content of catalpol is abandoned by removing the slender and material roots, while these left parts are also worth to use.