Inas Sabah Mohammed Shareif - Department of Biology, College of Science, University of Basrah, Iraq
Sahar A.A. Malik Al-saadi - Department of Biology, College of Science, University of Basrah, Iraq
Hussein K. Al-Kaaby۲ - Department of Biology, College of Education for Pure Sciences, University of Basrah, Basrah, Iraq

The allelopathic interactions of different concentrations (۰, ۲, ۴, ۶, ۱۰ g in ۱۰۰ mL-۱) of alcoholic extract of Nerium oleander flower on Arabidopsis thaliana (Columbia-۰) were studied. The results showed that leaf area, plant height and inflorescence emerge period decreased by elevation in the treatment concentration. The highest value of leaf area (۱.۱۷۶ cm²) was recorded in control group, while it was ۰.۶۳ cm² in treatment ۲ g in ۱۰۰ mL-۱ (T۲) and ۰.۵ cm² in T۱۰. Chlorophyll concentrations were decreased by the upraised concentrations. The highest value (۴.۱۵ mg g-۱) was recorded in control, while the lowest (۳.۳ mg g-۱) in T۱۰. Anatomical study revealed that the internal structure of stem and root undergone numerous character changes. The thickness of the stem varies between treatments. The control exhibited the highest average (۱۰۹.۳۷ µm), while T۱۰ had the lowest average (۸۱.۲۵ µm). Collenchyma layer increased in all exposure treatments, compared to control. There was a change in the internal structure of the roots between the control and the alcoholic extract treatment. The root shape exhibited a lot of modification: it seemed circular in control, semi-circular in T۴, while elliptic or irregular shape in T۱۰. The root thickness reached ۹۵ µm in T۲ and T۴, whereas the lowest thickness in T۱۰ (۷۰.۳۳ µm). Vascular bundle in the control was cylindrical. However, there was some irregular growth on one side of the root in T۴. In T۱۰, larger vascular bundles and random growth were observed, while the root shape appeared to be irregular, due to the abnormal growth of vascular bundles or irregular growth.

Allelochemicals, allelopathy, Nerium, Arabidopsis thaliana, anatomy, Stem, Root