STUDIES ON THE INFECTION OF RICE KERNEL SMUT

C.T.LU AND H.Y.LI

High percentage of chlamydospore germination of Neovossia horrida (Tak.)P.& K.with abundant basidiospore production was obtained by placing moistenedspores in a Petri dish with limited supply of water,the dish-cover being inkedblue to insure a favordable light condition.Moistened spores applied on the sur-face of kernels of a growing rice head enclosed in a paraffin paper bag was alsofound to germinate by producing a very short basidium and a large number ofbasidiospores.It is,therefore,concluded that not only light but also oxygen isrequired for normal germination of the spores of the rice kernel smut. Results of a series of inoculation experiments conclusively show that thefungus infects rice kernels during the milky dough stage.Basidiospore inoculationgives higher percentage of infection than chlamydospore inoculation. Field observation indicates that the incidence of high percentage of infectionis coincident with the excessive application of nitrogenous fertilizer.Fluctuationof the amount of infection from year to year is probably determined chiefly by theduration of high moisture period from heading to dough stage.There are someevidences of varietal difference in the susceptibility of rice to the kernel smut.