Allelopathic Effect Of Glossonema Edule (Asclepiadaceae) On Associated Flowering Plants And Rhizosphere Fungi In Qatar

Abstract

Laboratory experiments were conducted to determine whether there were allelopathic effects of Glossonema edule (Asclepiadaceae) on six associated flowering plant species and three soil fungi. The tested species were the four perennial flowering plants Farsetia hamiltonii(Crucifeiae), Lycium shawii (Solanaceae), Salvia aegyptia (Labiatae) and Savygnia parviflora (cruciferae), and the two annuals Plantago ciliata (Plantaginaceae) and Spergula fallax (Caryophyllaceae), and the two rhizosphere fungi Aspergillus terreus and Aspergillus fumigatus and the rhizosphere fungus Chaetomium globosum. The effect of water, ethyl alcohol and petroleum ether extracts on the flowering plant seed germination and the fungal mycelial growth was tested. Low concentration of G. edule extracts showed a stimulating effect on seed germination of F. hamiltonii and S. parviflora, at least during the early germination days. Germination of the other test species was inhibited by all tested extract concentrations. The annual flowering plant species were found to be more sensitive than perennial species to the alielopathic effect of G. edule. It is suggested that they have not developed resistance to toxins as they grow during the rainy season where allelopatthic effects may not operate in nature during winter due to soil washing by rain. The extracts were inhibiting to the mycelial growth of the three tested fungal species. If the sensitivity of the fungal growth to G. edule extracts is taken as a measure of sensitivity, the following sequence from highest to lowest of the fungal species was observed: Chaetomium globosum, Aspergillus fumigatus and Aspergillus terms.