Study on biology of conidia of Ustilaginoidea virens

The study on biology of conidia of Ustilaginoidea virens (Cke.) Tak. indicated that nutrient in media had an important effect on germination of conidia. Pure water was not good for germination. PSA was the optimum media for germination. Glucose inhibited germination strongly. Potato juice could counteract the inhibition of glucose and stimulate germination. The germination rate was higher in solid agar media than that in liquid media. The suitable temperature for germination was 22-31℃, with the optimum of 28℃. The pH value had a sharp effect on germination, and pH 6-7 was optimum for germination. The germination rate of conidia began to decrease after growing 10 days by shaking culture. Water had a significant effect on viability of the conidia. In the case that conidia were kept in water for 8 days, germination rate of the conidia did not decrease, and in the case that they were kept in 100% RH for 8 days, the germination rate declined slightly, but in the case that they were kept in 25% RH for 5 hours, the germination rate dropped sharply. Based on these cha- racteristics, hypothesis about behavior of the conidia in the field was proposed.