Toll Free Helpline (India): 1800 1234 070

Rest of World: +91-9810852116

Free Publication Certificate

Vol. 12, Issue 2 (2023)

Cultural, morphological variability and pathogenic diversity of Alternaria isolates of cotton from major cotton growing areas of India

Author(s):
A Sampathkumar and AH Prakash
Abstract:
Alternaria leaf spot is most important foliar disease of cotton. Alternaria pathogen was isolated on PDA from collected leaf samples and ninety-six isolates were used for cultural, morphological characterization and pathogenicity study. Colony characters varied from grey to ashy grey, whitish grey, blackish grey with smooth or irregular margin. Colony texture varied from velvety to rough with flat, medium raised or raised mycelial growth. Alternaria species identification was performed based on beak length of the obclavate or muri form conidia. Out of 33 Alternaria isolates from Tamil Nadu, 27 found to be A. macrospora and 6 as A. alternata based on conidial characters. Out of 25 isolates from Karnataka, 20 found to be A. macrospora and 5 as A. alternata. Out of 22 isolates from Telangana, 19 isolates found to be A. macrospora and 3 as A. alternata. Isolates from Andhra Pradesh (9), Maharashtra (4), Gujarat (2) and Madhya Pradesh (1) were found to be A. macrospora based on conidial characters. Microscopic examinations revealed that the mean conidial length varied from 15.43 to 53.66 µm and width varied from 2.54 to 9.87 µm for A. macrospora. Length varied from 7.53 to 12.95 µm and width from 4.58 to 7.84 µm for A. alternata. Beak length recorded from 19.74 to 52.74 µm and 7.59 to 14.74 µm for A. macrospora and A. alternata respectively. Horizontal septa varied from 4 to 9 and 3 to 5 for A. macrospora and A. alternata respectively. Vertical septa varied from 1 to 4 and 1 to 2 for A. macrospora and A. alternata respectively. Pathogenicity and virulence characterization of Alternaria isolates was performed on susceptible genotype LRA 5166 under glasshouse conditions. Symptom expression was started 9 days after inoculation and maximum at 30 days after inoculation with variation in virulence among the isolates. Initially water-soaked lesions were appeared on upper surface of leaves. Later the lesions were expanded in size and produced circular to irregular spots with greyish centre surrounded by dark brown rings or yellow halo. All the isolates were pathogenic to cotton. Results revealed that Telangana isolates were more virulent (7.0 to 51.8 PDI) followed by Karnataka (10.0 to 45.0 PDI), Andhra Pradesh (19.5 to 39.0 PDI), Tamil Nadu (4.8 to 20.3 PDI) and others. Out of 96 isolates, 8 from Telangana and 3 from Karnataka recorded as highly virulent (>40 PDI) isolates and others recorded as moderately virulent or less virulent.
Pages: 3321-3329  |  370 Views  213 Downloads


The Pharma Innovation Journal
How to cite this article:
A Sampathkumar, AH Prakash. Cultural, morphological variability and pathogenic diversity of Alternaria isolates of cotton from major cotton growing areas of India. Pharma Innovation 2023;12(2):3321-3329.

Call for book chapter