EVALUATION OF ALLELOCHEMICAL EFFECTS OF Hordeum vulgare EXTRACTS

There is increasing interest in the development of allelopathic crop varieties for weed suppression. The study was conducted to investigate the allelopathic potential of Hordeum vulgare varieties namely, BARI Barley-1, BARI Barley-2, BHL-3 and BL-1 that were collected from Bangladesh Agricultural Research Institute (BARI) and grown in control condition at Research Field of Tokyo University of Agriculture and Technology, Japan in 2010. 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. Screening accessions of allelopathic crops and natural vegetation for their ability to reduce weeds is the basic approach for utilizing the phenomenon. Extracts of examined plant on annual ryegrass (Lolium rigidum L.) was investigated. Water extracts of 4 studied varieties were bioassayed on germination and seedling growth of Lolium rigidum such as, a) to test the heterotoxicity of barley on Lolium rigidum; b) to study the dynamics of allelopathic potential over three growth stages; c) to identify the most allelopathic plant part of barley; d) to indicate which variety has the highest allelopathic potentiality. Stems, roots, and leaves were extracted at three growth stage separately. Results of seedling growth bioassays demonstrated that Lolium rigidum responded differently to the allelopathic potential of H. vulgare. For L. rigidum radicle growth and germination were more depressed than coleoptile growth. The allelopathic potential of investigated plant parts was not stable over its life cycle for L. rigidum. Leaves were the most phytotoxic part of H. vulgare for L. rigidum in the all stages. The leaves extract of BHL-3 variety had the highest inhibition on radicle growth of L. rigidum. Results suggested that the response by L. rigidum varied depending on the source of allelochemicals (plant part) and the growth stage of the H. vulgare plant. The findings may be driven by the recognition that agro-ecological applications of allelopathy may provide alternatives to synthetic herbicides for weed control.