PLANT-GROWTH INHIBITORS (PROANTHOCYANIDINS) FROM PRUNUS-ARMENIACA

A field survey in Prunus armeniaca growing areas of Garhwal Himalaya w as conducted with reference to the germination and growth of some comp anion crops at various sites of different soil fertility. Retardation in germination, growth and yield were noted in nearby Triticum aestivu m plants, particularly on those sites where the percentage of soil org anic matter was low. It was also observed that the magnitude of interf erence gradually decreased as the distance from the tree increased. Aq ueous and organic solvent extracts of the aerial parts of Plume armeni aca were made and their residues were tested, after proper dilution, f or their phytotoxic effect on germination and growth of the test crop. Residues of light petroleum and ethyl acetate extracts showed maximum inhibition in growth and germination of the test species. The isolate d compounds were identified with the help of spectroscopic techniques and bioassays. beta-Sitosterol, 2,6-dihydroxy-4-methoxyacetophenone an d kaempferol were isolated from a petroleum extract whereas aromadendr in, quercetin, beta-sitosterol-beta-D-glucoside, pleoside and tannins (four proanthocyanidins - A-type) were characterized from an ethyl ace tate extract. Of these, proanthocyanidins showed maximum inhibition, w hereas quercetin, aromadendrin, kaempferol and genin of pleoside inhib ited to a lesser extent. (C) 1998 Elsevier Science Ltd. All rights res erved.