INFLUENCE OF ABIOTIC FACTORS ON THE VEGETATIVE GROWTH AND SPORULATION OF MAGNAPORTHE ORYZAE COUCH

Abstract

Abiotic factors including culture media, photo-periods and temperature greatly influenced mycelial growth and sporulation of rice blast fungus Magnapothe oryzae. Under laboratory conditions maximum colony growth of M. oryzae was recorded on potato dextrose agar (PDA) followed potato carrot agar (PCA), whereas oat meal agar (OMA) produced minimum growth. For sporulation, PDA appeared as most favourable medium, the number of conidia formed on it were even more than those produced in all remaining five media. Alternate 12 hours light and 12 hours dark appeared best light regime for mycelial growth of M. oryzae, whereas maximum sporulation occurred when culture was exposed to 8 and 16 hours light and darkness cycles. Temperature studies indicated that M. oryzae grew between 10-350C and 300C was the optimum temperature for mycelial growth. The conidial production of M. oryzae gradually increased with increasing temperature and maximum conidial formation occurred at 350C.