Journal of Environmental Biology

Enhanced sporulation by different light

and nutritional sources in Bipolaris oryzae

causing brown spot disease of rice

K. Basavaraj*, G.S. Jasudasu, V. Prakasam, D. Ladhalakshmi, C. Kannan, D. Krishnaveni, G.S. Laha, Ch. Suvarna Rani and M.S. Prasad

Department of Plant Pathology, ICAR-Indian Institute of Rice Research, Hyderabad-500 030, India

*Corresponding Author Email : basavaraj4229@gmail.com                  *ORCiD: https://orcid.org/0000-0002-4361-1966

Received: 25.11.2021                                                                                        Revised: 14.03.2022                                                                      Accepted: 25.07.2022

Abstract

Aim: The present study aimed to investigate the inter-relation of different light and nutritional sources on the sporulation of fungus.

Methodology: Two isolates of Bipolaris oryzae collected from IIRR, Hyderabad and Lonavala were used in the present study. These isolates were cultured on routine culture media-potato dextrose agar for five days and irradiated with different regimes of near ultraviolet (NUV), ultraviolet and visible light to assess their ability to induce sporulation in fungus. With standardized light source (exposure of fungus to NUV 12hr and 12 hr of darkness), different stresses such as nutrient stress, cold and heat stresses were assessed for its ability to support the abundant sporulation.

Results: The enhanced sporulation in B. oryzae (55.9x10⁴ and 36.2x10⁴ spores ml^-1, respectively, in IIRR and Lonavala isolates) was obtained by culturing fungus on rabbit food agar media for five days under darkness and later 12 hr alternate exposure of near ultraviolet light and darkness.

Interpretation: The maximum sporulation obtained in the present study used in pathogenesis test can be employed in screening programme for identification of resistant genotype for brown spot disease.  

Key words: Brown spot, Bipolaris oryzae, Nutrition, Rice, Sporulation

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