Cultural, Morphological and Pathogenic Characterization of Alternaria porri Causing Purple Blotch of Onion

Abstract

Twenty seven (27) isolates of Alternaria porri were isolated from diseased leaf samples collected from different onion growing regions of Bangladesh and characterized for cultural, morphological and pathogenic variabilities. A. porri colonies colony colour ranged between light to dark olivacious and grayish white with irregular, regular with concentric ring and regular without concentric ring shape. Margin of colonies were entire, irregular and wavy with effuse, fluffy and velvety texture. Isolates impregnated media with colour ranged between grey to brown on the reverse of the plates. Growth rate of isolates ranged between 2.433 and 3.950 mm/day with fast growth in isolate DSTR 02 and least in MMBH. Morphological variation in conidia production was between 7.720×10 3 to 47.02×10 3 per mm 2 with sporulation time 3.33 to 11.00 days. The conidial shape was straight to curve with light to deep brown colour. The number of horizontal and vertical separation in the conidia ranged from 3.00 to 6.00 × 1.00 to 2.00 with size from 11.20 to 39.20 × 4.76 to 11.43 µm. In pathogenicity test isolates also exhibited variations in size of the lesions (2.77 to 7.55 mm) produced on onion leaves. The results demonstrate existence of considerable variation in cultural, morphological, and pathogenic characters of A. porri isolates prevalent in Bangladesh environment.

Cultural, Morphological Characterization and Aggressiveness of Alternaria alternata Causing Leaf Spot of Soybean

“…Cultural, Morphological Characterization and Aggressiveness of Alternaria alternata Causing Leaf Spot of Soybean observed that variation in colony diameter varied from 21.0 mm to 42.0 mm and abundant sporulation (12 × 10 4 spores ml -1 ) in isolates of A. helianthin. Our results are also collaborated with Nikam et al (2015) and Mohsin et al (2016).…”

“…The way in which fungal populations depends primarily on the type of genetic variability available and also variation in population structure of the pathogen becomes the major reason for resistance break down of many high yielding resistant varieties. The similar pathogenic variability results were obtained byMohsin et al (2016) reported that test isolates of A. porri also exhibited variations in size of the lesions (2.77 to 7.55 mm) produced on onion leaves Jankar et al (2018). reported that all isolates of are pathogenic, while Isolate Aa-5 (Nagpur) was the most virulent isolate and Aa-4 (Akola) was the less virulent isolate of A. causing fruit rot of chilli.…”

Cultural, Morphological and Biochemical Variability Studies among the Isolates of Alternaria solani, the Causal Agent of Early Blight Disease of Tomato

“…Mohsin et al (2016) worked on variation studies in twenty-seven isolates of Alternaria porri and revealed that the isolates varied in colony diameter, colony and substrate colour, margin, topography, zonation, pigmentation and sporulation on different culture media. Similarly, Loganathan et al (2016) observed variability in seventeen isolates of Alternaria spp based on culture colour and conidial dimensions.…”