Assessment of Culture Media on Alternaria alternata (Fr.) Keissler) on Brinjal for Most Suitable Mycelia Growth under in-vitro Conditions

Abstract

Brinjal (Solanum melongena L.), also referred to as eggplant, aubergine or garden egg, is a globally important vegetable crop, with India ranking among the top producers. Its cultivation is often hindered by foliar diseases, particularly leaf spot caused by Alternaria alternata, which can result in significant yield losses. Effective management of this disease requires understanding the growth and sporulation behavior of the pathogen under different nutritional conditions. The present study evaluated the effect of fourteen solid culture media, including natural, semi-synthetic and synthetic types, on the mycelial growth and sporulation of A. alternata isolated from infected brinjal leaves. Observations on radial growth, colony morphology and sporulation were recorded under controlled laboratory conditions. The results demonstrated significant differences among the media in supporting fungal development. Potato Dextrose Agar (PDA) supported the maximum radial growth (86.67 mm), followed by Richard Agar (79.67 mm), Asthana and Hawkers medium (74.33 mm) and Oat Meal Agar (71.67 mm), whereas the lowest growth (41.00 mm) was observed on Brinjal Leaf Agar. Colony characteristics varied with media with colours ranging from grayish-white to black and textures classified as smooth, compact, or fluffy. Sporulation also differed significantly; PDA, Oat Meal Agar, Richard Agar and Asthana and Hawkers medium exhibited excellent (++++) sporulation, while Brinjal Leaf Agar and Coon’s Agar showed poor (+) sporulation. These variations are likely due to differences in nutrient composition and the type of carbon sources available in each medium. PDA proved to be the most suitable medium for in vitro growth and sporulation of A. alternata, providing a reliable substrate for further studies on its pathogenicity and biology.