SINGLE AND COMBINED EFFECTS OF THREE FUSARIUM SPECIES ASSOCIATED WITH RICE SEEDS ON THE SEVERITY OF BAKANAE DISEASE OF RICE
B.M. Bashyal, R. Aggarwal, S. Sharma, S. Gupta, U.B. Singh
Fusarium spp. associated with susceptible rice variety Pusa Basmati 1121 were isolated. Based on translation elongation factor 1α (TEF-1α) Fusarium spp. were identified as F. fujikuroi, F. proliferatum, F. verticillioides (F. moniliforme), F. sacchari, F. pseudonygamai, F. thapsinum and F. andiyazi. Pathogenicity test conducted on susceptible variety Pusa Basmati 1121 confirmed that only F. fujikuroi, F. proliferatum and F. verticillioides produced bakanae disease as elongation, rotting or both types of symptoms. Gibberellic acid was exclusively extracted from the isolates of F. fujikuroi and it ranged from 450 μg/g to 4361 μg/g of mycelium. Gibberellic acid content was positively correlated (r=0.79) with elongation symptom of the disease. Fusaric acid was present in all the species of Fusarium, ranging from 60 μg/g to 2920 μg/g of mycelium. However, significant correlation between fusaric acid content and disease severity could not be established. Co-inoculations of pathogens showed significant reduction in percent seed germination and increased disease severity compared to pathogen inoculated individually. Therefore, present investigation will be helpful to understand the effect of different Fusarium spp. in bakanae disease etiology.