Submitted to: Journal of Plant Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/21/2001
Publication Date: 12/21/2002
Citation: BEN-HAMMOUDA, M., GHORBAL, H., KREMER, R.J., OUSLATT, O. AUTOTOXICITY OF BARLEY. JOURNAL OF PLANT NUTRITION. 2002. V. 25. P. 1155-1161. Interpretive Summary: Cereal crops are cultivated in many semi-arid regions of the world because they are adapted to low available soil water and increased salt accumulation in soil. Because few other crops are adapted to such conditions, cereal crops are often grown continuously in the same fields. As demonstrated for other crops, residues of crop plants (stalks, straw, leaves) remaining after grain harvest may suppress growth of the next crop planted in the same field, a condition known as allelopathy or autotoxicity if a crop plant is inhibited by its own residues in the soil. The objectives of our research were to determine potential autotoxiciy in barley and the source of allelopathic effects among different plant parts of the barley plant. Intact plants as well as leaves, stems, and roots were extracted with water in which germinating barley was grown. We found that the Rihane barley variety greatly inhibited seedling growth of three other barley varieties. Extracts of leaves from mature plants inhibited root growth to the greatest extent. Results of this research suggest that producers should consider alternative crops in their cereal production systems because barley planted after barley may grow poorly and result in lower grain yield due to potential autotoxicity of previous crop residues.
Technical Abstract: Allelopathic potential of a crop species varies depending on stage of growth. Because allelopathy of barley, an important cereal grain adapted to semi-arid conditions of Tunisia, has not been widely reported, a study was conducted to determine the potential autotoxicity of barley and differential allelopathic potential of barley plant components at four phenological stages. Barley seed germination and seedling growth were assayed for detection of allelopathic activity. Plant parts of field-grown Rihane barley were extracted with water and bioassayed on four varieties of barley. At growth stage 4 (stems not well developed), whole plants were extracted. Thereafter, roots, stems, and leaves were extracted separately. Seedling growth bioassays were autotoxic to barley, which was more pronounced on radicle growth than coleoptile growth especially with extracts of plants near physiological maturity. Autotoxicity was not significant when Rihane barley was simultaneously the donor and recipient of water extracts. Leaves were the most important source of allelopathic substances. Root extracts were least inhibitory toward both radicle and coleoptile growth. Results suggest that allelopathic substances in barley plant parts change qualitatively and quantitatively during plant development.