THE EFFECT OF TEMPERATURE ON THE GERMINATION OF TELIOSPORES OF PUCCINIA-PUNCTIFORMIS

Germination of teliospores was analyzed as a time-dependent process. N onlinear regression was used to fit germination progress curves for 5, 10, 15, and 20 C. Germination was characterized by the maximum fracti on of teliospores germinated, the mid germination time (one-half of th e maximum germinated), and the rate of germination at the mid germinat ion time. Temperature had a major effect on the mid germination time a nd, to a smaller extent, on the rate of germination. The mid germinati on time was shortest at 15 C, longer at 10 and 20 C, and longest at 5 C. The rate of germination was highest at 10 and 15 C and lower at 5 a nd 20 C. No effect of temperature was detected on the maximum fraction of teliospores germinated. The consequences of the germination dynami cs for infection of Cirsium arvense root buds by Puccinia punctiformis are discussed.