Morph-Cultural Variability among Different Isolates of Alternaria alternata Causing Leaf Spot of Ber (Ziziphus mauritiana Lamk) in Eastern Uttar Pradesh

Abstract

Alternaria alternata is one of the most important foliar fungi causing leaf spot of ber. Leaf spot diseased samples were collected from different districts of Uttar Pradesh. Six different isolates of A. alternata were obtained in pure culture and designated as Aa1, Aa2, Aa3, Aa4, Aa5 and Aa6. The results revealed that there is a greater variation among different isolates of A. alternata. The maximum mycelial growth after 10 DAI (days after incubation) was found in Aa2 (90.10 mm) followed Aa5 (88.36) and Aa6 (86.53). Colony characters like color varied as greenish (Aa1), dark olivaceous green (Aa2), brown blackish (Aa3 and Aa6), brownish green with black center (Aa5), Greenish brown with white center (Aa4) and growth was slow (Aa4 and Aa5), medium (Aa1 and Aa6) and fast (Aa2 and Aa3). Growth appearance varied from fluffy (Aa1, Aa4, Aa5 and Aa6) and compressed (Aa2 and Aa3) with margin regular (Aa2 and Aa4) or irregular margin (Aa1, Aa3, Aa5 and Aa6). Sporulation was recorded in all six isolates but very good sporulation was observed in Aa2, Aa4 and Aa5. Highest average conidial length was recorded in isolates Aa4 (38.88μm) followed by Aa3 (30.20μm). Highest average width was recorded in Aa5 (15.06μm) followed by Aa3 (14.04 μm). Maximum beak length was observed in Aa2 (17.28 µm). The number of septa also varied among isolates. Maximum number of transverse septa was found in Aa5 (4-5). Maximum number of longitudinal septa was found in Aa5 (2-4).