Submitted to: Agronomie Agriculture Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2001
Publication Date: 12/1/2001
Citation: BEN-HAMMOUDA, M., GHORBAL, H., KREMER, R.J., OUSLATT, O. ALLELOPATHIC EFFECTS OF BARLEY EXTRACTS ON GERMINATION AND SEEDLING GROWTH OF BREAD AND DURUM WHEAT. AGRONOMIE AGRICULTURE ENVIRONMENT. 2001. V. 21. P. 65-71. Interpretive Summary: Cereal grain crops including bread and durum wheat and barley are staple food sources cultivated in many parts of the world. These crops are often grown in sequence in the same production fields. This type of production system often adversely affects growth of succeeding crops due to substances released from plant remains of a previous crop into the soil. This situation is known as allelopathy. Our objectives were to study the potential for allelopathic effects from barley residues on succeeding durum and bread wheat varieties. Intact barley plants as well as leaves, stems, and roots were extracted with water in which germinating wheat was then grown. We found that the Rihane barley variety greatly inhibited seedling growth of both wheat 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 wheat planted after barley may grow poorly and result in lower grain yield due to potential allelopathy of previous barley crops.
Technical Abstract: Phytotoxicity of barley extracts on durum wheat and bread wheat was investigated. Water extracts of barley cv. Rihane were bioassayed on germination and seedling growth of both wheat species to: i) test the heterotoxicity of barley on wheat; ii) study the dynamics of allelopathic potential over four growth stages; and iii) identify the most allelopathic plant part of barley. Whole barley plants were extracted at growth stage (leaf sheaths lengthening), with plants at subsequent growth stages separated into roots, stems, and leaves and extracted separately. Seedling growth bioassays demonstrated that the two wheat species responded differently to the allelopathic potential of barley with a greater sensitivity shown by the bread wheat. For both wheat species, radicle growth was more depressed than coleoptile growth, although seedling growth in durum wheat was stimulated. The allelopathic potential of barley plant parts increased near physiological maturity. Leaves and roots were the most phytotoxic barley plant parts for durum and bread wheat, respectively. Results suggested that the response by durum wheat and bread wheat varied depending on the source of allelochemicals (plant part) and the growth stage of the barley plant. Consequently, barley should be considered a depressive previous crop for both durum wheat and bread wheat in a field cropping sequence.