Lauric acid and 2, 6-ditertbutyl phenol, two major allelochemicals from <i>Rehmannia glutinosa</I> inhibiting the germination of succeeding crop, <i>Sesamum indicum</i>

Abstract

Rehmannia glutinosa Libosch, a well known herb for Chinese traditional medicine, and sesame are two main crops in Northwestern Henan, China. It has been known however that, a rotation of these two crops, for example, cultivation of sesame preceeded with R. glutinosa Libosch, leads to decreased yield and poor quality of sesame. In order to identify the compound or allelochemicals which inhibit the growth of sesame, the effect of the crude tissue extractions of R. glutinosa on the germination rate, seedling height, root length and fresh weight of sesame was analysized. We found that most allelochemicals exist in the ethyl acetate extraction of the leaves. Further fractionation of the leaf extraction on silica gel column chromatography was followed by GC-MS (gas chromatography mass spectrometry). We for the first time identified lauric acid and 2,6-ditertbutyl phenol as two main alllelochemicals, which inhibit the seed germination of sesame. The identification of the allelochemicals in this study paves the way for further characterization of the molecular interaction of allelochemicals from the preceeding crop R. glutinosa, the soil and the succeeding crop sesame, which could be
beneficial for improvement of the crop rotation between R. glutinosa and sesame.

Keywords: Rehmannia glutinosa Libosch, sesame, allelopathy, allelochemicals