Comparisons of Phytotoxicity of Barley Parts Extracts in Three Growth Stages on Annual Ryegrass

Abstract

Problem statement: The importance of allelopathy in nature and in agroecosystem has attracted researcher's attention with the main goal of using the phenomenon in biological control of weeds. currently, active involvement of scientists from different disciplines made allelopathy a multidisciplinary subject, and transformed the research from basic to applied, enabling use of allelopathy in agriculture and forestry. Screening accessions of allelopathic crops and natural vegetation for their ability to reduce weeds is the basic approach for utilizing the phenomenon. Approach: Phytotoxicity of barley extracts (Hordeum vulgare L.) on Annual ryegrass (Lolium rigidum L.) was investigated. Water extracts of barley, four varieties were bioassayed on germination and seedling growth of Lolium rigidum to: (i) test the heterotoxicity of barley on Lolium rigidum, (ii) study the dynamics of allelopathic potential over three growth stages and (iii) identify the most allelopathic plant part of barley. Roots, stems and leaves were extracted at three growth stage separately. (iv) indicated which variety has the highest allelopathic potential. Results: Seedling growth bioassays demonstrated that the Lolium rigidum responded differently to the allelopathic potential of barley. For Lolium rigidum radicle growth and germination were more depressed than coleoptile growth, though. The allelopathic potential of barley plant parts was not stable over its life cycle for Lolium rigidum. Leaves were the most phytotoxic barley plant parts for Lolium rigidum in the all stages. Leaves extract of barely at stage 11 had the highest inhibition on germination. The most inhibition of coleoptile growth when treated with leaves extract at stage 11.At stage 8 the leaves extract of Jonob variety had the highest inhibition on radicle growth of Lolium rigidum. Conclusions: Results suggested that the response by Lolium rigidum varied depending on the source of allelochemicals (plant part) and the growth stage of the barley plant and kind of variety.