Effect of Aqueous Leaf Extracts of Allelopathic Trees on Germination and Seed-borne Mycoflora of Wheat

Effect of aqueous leaf extracts of 8 allelopathic tree species viz., Accacia nilotica (L.) Willd ex Del., Alstonia scholaris (L.) R. Br., Azadirachta indica (L.) A. Juss., Eucalyptus citriodora Hook, Ficus bengalensis L., Mangifera indica L., Melia azedarach L. and Syzygium cumini (L.) Skeels was studied on germination and seed-borne mycoflora of wheat (Triticum aestivum L.). Wheat seeds were soaked in 20% aqueous leaf extract of test allelopathic tree species for 10 and 20 minutes. Surface sterilization of seeds with 1% Sodium hypochlorite for 2 minutes was used as reference. Five fungal species were isolated from untreated seeds. Alternaria alternata (Fr.) Keissler was recorded with highest percentage (43%) followed by Fusarium solani (Mart.) Appel & Wr. (30%), Cladosporium sp. (17%) Rhizopus arrhizus A. Fischer (7%) and Aspergillus niger Van Tieghem (3.3%). Surface sterilization with HgCl2 significantly reduced A. alternata (13%) and completely checked the growth of all other fungi. Aqueous extracts of all the test tree species significantly reduced the frequency of occurrence of the two most frequent seed-borne fungi viz., A. alternata and F. solani. Generally there was not any pronounced difference between effectiveness of 10 and 20 minutes treatments. Aqueous treatment for 10 minutes generally enhanced seed germination as compared to control.