Allelochemicals were isolated from the germinating maize (Zea mays L.) seeds in order to know the allelopathic constituents in the plants at the early developmental stage. Three allelochemicals were found in the acetone extract obtained from the mesocotyls and coleoptiles of the 5-day-old seedlings. By spectral analysis, they were identified as 5-chloro-6-methoxy-2-benzoxazolinone (Cl-MBOA) which is a naturally occurring new benzoxazolinone, 6-methoxy-2-benzoxazolinone (MBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA). At concentrations greater than 0.03 mM for Cl-MBOA and DIBOA and 0.1 mM for MBOA, respectively, were inhibited the growth of the roots of cress (Lepidium sativum L.) seedlings. Activity of a new benzoxazolinone, Cl-MBOA, was greater than that of its analogue, MBOA. These results suggest that germinating maize seeds have at least three allelochemicals which may affect the growth or germination of other plant species.
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