Growth Stage of Cyperus esculentus Influences Its Allelopathic Effect on Ectomycorrhizal and Higher Plant Species

Abstract

Summary Live plants and plant material in various forms have important roles in ecological processes. Weeds may be involved in interactions with desirable species at different trophic levels through the production and release of allelochemicals. The allelopathic potential of the weed Cyperus esculentus (yellow nutsedge) was assessed by preparing aqueous extracts from tubers and foliage from immature or mature plants, and testing their effects on an ectomycorrhiza and two higher plant species. The extracts from tubers and both foliage types significantly reduced the colony diameter of the ectomycorrhiza Boletus maxaria, which was isolated from roots of the forestry species Pinus patula, on agar medium. Extracts (2% m/v) from C. esculentus tubers and the foliage of immature plants inhibited the germination of lettuce (Lactuca sativa) seeds significantly. At 5% concentration, the extracts from foliage of immature weed plants completely inhibited the germination of lettuce seeds at the end of the 7-day trial period. The emergence of corn (Zea mays) was retarded in soil where C. esculentus tubers were planted 28 days before planting the crop, irrespective of whether the weeds continued to grow or were physically removed at the time the corn was sown. In contrast, where weed tubers and corn seeds were planted at the same time, emergence of corn was not affected. It is suggested that the growth stage of weeds be considered in the assessment of their direct and indirect allelopathic effects, and in predictions for their impacts on crop development and yield.