Allelopathy in two species of Chenopodium -inhibition of germination and seedling growth of certain weeds

Abstract

The activity of washed leaf and inflorescence material of <em>Chenopodium ambrosioides</em> and <em>C. murale</em>, decaying leaves and inflorescences, and field soils collected beneath <em>Chenopodium</em> plants were examined in terms of the inhibition of seed germination and seedling growth of five weeds, viz. <em>Abutilon indicum, Cassia sophera</em> var. <em>purpurea, C. tora, Evolvulus numularius</em> and <em>Tephrosia hamiltonii</em>. The allelopathic pattern varied in each of the two test species and this depended on the type of test matter. However, the germination as well as the root and hypocotyl growth of <em>A. indicum</em> and <em>E. nummularius</em> were more hampered by phytotoxins or inhibitors from <em>Chenopodium</em> than were the other weeds. Since the leaf and inflorescence of Chenopodium formed the source of inhibitors, the respective plant-parts from the two species were chemically analysed and the presence of three terpenes (p-cymene, ascaridole and aritazone) from <em>C. ambrosioides</em> and an organic acid (oxalic acid) from <em>C. murale</em> were implicated in the allelopathic effect.