Phytotoxic Effects Of Bacillus Thuringiensis On Seedlings Of Some Plants

• F.M. Barakat1.; Karima2, H.E. Haggag2; Wafaa, M. El-Deeb2 and G.A. Ghanem1
• ¹ Plant Pathol. Dept., Fac. of Agric, Cairo Univ., Giza, Egypt
• ² Pest Rearing Dept., Central Agricultural Pesticides Laboratory, Dokki, Giza, Egypt

Abstract

Loss in germination of plant seeds treated with Bacillus thuringiensis were recorded on radish, cucumber, bean and tomatoes under laboratory conditions ranging from 25.0 to 97.5 %. Bean and radish seeds were severely affected by the bacteria while tomato was tolerant. Abnormal symptoms due to phytotoxicity as brown or black spots on cotyledonary leaves or primary roots were recorded among treated germinated radish seeds. On cucumber seedlings, they showed brown or black spots on cotyledonary leaves only, while on bean seedlings symptoms appeared as softening of primary roots and yellow spots on cotyledonary leaves. Germinated tomato seedlings were free from any abnormal symptoms. Plant seeds treated with B. thuringiensis and grown under greenhouse conditions showed different rates of loss in germination. Abnormal symptoms associated with juvenile seedlings revealed that; radish seedlings shown yellowing on cotyledonary leaves and brown spots spreading from leaf margins then wilting occurred after 4 days from the appearance of the first true leaf. Cucumber seedlings showed yellowish, brown spots on leaves and wilting of cotyledonary leaves. Tomato seedlings were almost weak having shorter shoots and smaller leaves with slight yellowish spots on cotyledonary leaves. Histopathological studies indicated that B. thuringiensis bacteria could induce some changes in the anatomical structures of radish and tomato roots and epicotyl of bean tissues.