Abstract

Rhazya stricta is an evergreen poisonous shrub rapidly invading large areas of rangelands in Saudi Arabia. A laboratory study was conducted to investigate the effect of its leaf aqueous extracts on seed germination and some growth parameters of Zea mays, Sorghum durra and Cucumis sativus seedlings. Results indicate that increasing of R. stricta leaves aqueous concentrations decreased germination in the three studied species. All of the studied treatments decreased the plant height in the three studied species; and increased of dry weight of plant and dry weight of shoot system in both S. durra and C. sativus plants. Roots growth was more restricted than shoots. In general, allelopathic effect depends on treatment concentration, plant species and plant organ.

Key words: Rhazya stricta, Leaves Leachate, Germination, Seedlings.